L3: Cells Flashcards
(500 cards)
1
Q
The basic, living, structural, and functional units of the body.
A
Cells
2
Q
The scientific study of cells
A
cell biology or cytology
3
Q
Forms the cell’s flexible outer surface, separating the cell’s internal environment (everything inside the cell) from the external environment (everything outside the cell)
A
plasma membrane (plasmalemma)
4
Q
It is a selective barrier that regulates the flow of materials into and out of a cell.
A
plasma membrane (plasmalemma)
5
Q
It consists of all the cellular contents between the plasma membrane and the nucleus.
A
cytoplasm
6
Q
The fluid portion of cytoplasm, also called intracellular fluid, contains water, dissolved solutes, and suspended particles.
A
Cytosol
7
Q
Within the cytosol are several different types of? (little organs)
A
organelles
8
Q
A large organelle that houses most of a cell’s DNA
A
nucleus
9
Q
Within the nucleus, each ______, a single molecule of DNA associated with several proteins contains thousands of hereditary units called ____ that control most aspects of cellular structure and function.
A
chromosome, genes
10
Q
The plasma membrane, a flexible yet sturdy barrier that surrounds and contains the cytoplasm of a cell, is best described by using a structural model called the ______.
A
fluid mosaic model
11
Q
According to this model, the molecular arrangement of the plasma membrane resembles a continually moving sea of fluid lipids that contains a mosaic of many different proteins
A
fluid mosaic model
12
Q
The basic structural framework of the plasma membrane is the _______, two back-to-back layers made up of three types of lipid molecules—________, ________, and ______.
A
Lipid bilayer; phospholipids, cholesterol, and glycolipids
13
Q
About 75% of the membrane lipids are ______, lipids that contain phosphorus.
A
phospholipids
14
Q
Present in smaller amounts are ______ (about 20%), a steroid with an attached ⏤OH (hydroxyl) group,
A
cholesterol
15
Q
(about 5%), lipids with attached carbohydrate groups
A
glycolipids
16
Q
The bilayer arrangement occurs because the lipids are _______ molecules, which means that they have both polar and nonpolar parts.
A
amphiphatic
17
Q
the polar part is the phosphate-containing “head,” which is _____; water-loving
A
hydrophilic
18
Q
The nonpolar parts are the two long fatty acid “tails,” which are _____ hydrocarbon chains; water fearing
A
hydrophobic
19
Q
T or F: Membranes are fluid structures because the lipids and many of the proteins are free to rotate and move sideways in their own half of the bilayer.
A
t
20
Q
What are the functions of the plasma membrane?
A
- Acts as a barrier separating inside and outside of the cell.
- Controls the flow of substances into and out of the cell.
- Helps identify the cell to other cells (e.g.,
immune cells). - Participates in intercellular signaling.
21
Q
T or F: Membrane proteins are classified as integral or peripheral according to whether they are firmly embedded in the membrane.
A
t
22
Q
Proteins that extend into or through the lipid bilayer and are firmly embedded in it.
A
Integral proteins
23
Q
Most integral proteins are ______, which means that they span the entire lipid bilayer and protrude into both the cytosol and extracellular fluid.
A
transmembrane proteins
24
Q
Proteins that are not as firmly embedded in the membrane. They are attached to the polar heads of membrane lipids or to integral proteins at the inner or outer surface of the membrane.
A
Peripheral proteins
25
Many integral proteins are_____, proteins with carbohydrate groups attached to the ends that protrude into the extracellular fluid.
glycoproteins
26
The carbohydrates are ____, chains of 2 to 60 monosaccharides that may be straight or branched.
oligosaccharides (oligo- = few; -saccharides = sugars)
27
The carbohydrate portions of glycolipids and glycoproteins form an extensive sugary coat called the
glycocalyx
28
The ____ acts like a molecular “signature” that enables cells to recognize one another.
glycocalyx
29
Some integral proteins form _____, pores or holes that specific ions, such as potassium ions (K+), can flow through to get into or out of the cell.
ion channels
30
Other integral proteins act as ____, selectively moving a polar substance or ion from one side of the membrane to the other. Carriers are also known as _____.
carriers; transporters
31
Integral proteins called ______ serve as cellular recognition sites. Each type of this recognizes and binds a specific type of molecule.
receptors
32
A specific molecule that binds to a receptor is called a ____ of that receptor.
ligand
33
Integral proteins may also serve as _____ that anchor proteins in the plasma membranes of neighboring cells to one another or to protein filaments inside and outside the cell. Peripheral proteins also serve as enzymes and linkers.
linkers
34
Membrane glycoproteins and glycolipids often serve as ______. They may enable a cell to (1) recognize other cells of the same kind during tissue formation or (2) recognize and respond to potentially dangerous foreign cells.
cell-identity markers
35
Forms a pore through which a specific ion can flow to get across membrane. Most plasma membranes include specific channels for several common ions.
Ion channel (integral)
36
Transports a specific substance across membrane by undergoing a change in shape. For example, amino acids, needed to synthesize new proteins, enter body cells via carriers.
Carrier
37
Carrier proteins are also known as _____.
Transporters
38
Recognizes specific ligand and alters cell’s function insome way. For example, antidiuretic hormone binds to receptors in the kidneys and changes the water permeability of certain plasma membranes.
Receptor (integral)
39
Catalyzes reaction inside or outside cell (depending on which direction the active site faces). For example, lactase protruding from epithelial cells lining your small intestine splits the disaccharide lactose in the milk you drink
Enzyme (integral & peripheral)
40
Anchors filaments inside and outside the plasma membrane, providing structural stability and shape for the cell. May also participate in movement of the cell or link two cells together.
Linker (integral and peripheral)
41
Distinguishes your cells from anyone else’s (unless you are an identical twin). An important class of such markers is the major histocompatibility (MHC) proteins.
Cell identity marker
42
The term ______ means that a structure permits the passage of substances through it, while _____ means that a structure does not permit the passage of substances through it.
permeable; impermeable
43
The permeability of the plasma membrane to different substances varies. Plasma membranes permit some substances to pass more readily than others. This property of membranes is termed _________.
selective permeability
44
A difference in the concentration of a chemical from one place to another, such as from the inside to the outside of the plasma membrane.
Concentration gradient
45
A difference in electrical charges between two regions constitutes an ______. Because it occurs across the plasma membrane, this charge difference is termed the ______.
electrical gradient; membrane potential
46
The combined influence of the concentration gradient and the electrical gradient on movement of a particular ion is referred to as its _____.
electrochemical gradient
47
Substances generally move across cellular membranes via transport processes that can be classified as ____ or ____, depending on whether they require cellular energy.
passive or active
48
A substance moves down its concentration or electrical gradient to cross the membrane using only its own kinetic energy (energy of motion).
Passive processes
49
Cellular energy is used to drive the substance “uphill” against its concentration or electrical gradient.
Active processes
50
The cellular energy used is usually in the form of
ATP
51
A passive process in which the random mixing of particles in a solution occurs because of the particles’ kinetic energy.
52
T or F: If a particular solute is present in high concentration in one area of a solution and in low concentration in another area, solute molecules will diffuse toward the area of lower concentration—they move down their concentration gradient.
t
53
The greater the difference in concentration between the two sides of the membrane, the higher the rate of diffusion. When charged particles are diffusing, the steepness of the electrochemical gradient determines the diffusion rate across the membrane.
Steepness of the concentration gradient.
54
The higher the _____, the faster the rate of diffusion. All of the body’s diffusion processes occur more rapidly in a person with a fever
temperature
55
The larger the mass of the diffusing particle, the slower its diffusion rate. Smaller molecules diffuse more rapidly than larger ones.
Mass of the diffusing substance
56
The larger the membrane surface area available for diffusion, the faster the diffusion rate.
Surface area
57
The greater the distance over which diffusion must occur, the longer it takes.
Diffusion distance
58
A passive process in which substances move freely through the lipid bilayer of the plasma membranes of cells without the help of membrane transport proteins
Simple diffusion
59
Nonpolar, hydrophobic molecules move across the lipid bilayer through the process of
Simple diffusion
60
Solutes that are too polar or highly charged to move through the lipid bilayer by simple diffusion can cross the plasma membrane by a passive process called
Facilitated diffusion
61
In this process, an integral membrane protein assists a specific substance across the membrane. The integral membrane proteins can either form a channel or function as a carrier.
Facilitated diffusion
62
Small, uncharged polar molecules such as water, urea, and small alcohols also pass through the lipid bilayer by
Simple diffusion
63
A solute moves down its concentration gradient across the lipid bilayer through a membrane channel
Channel-Mediated Facilitated Diffusion
64
A substance moves across the lipid bilayer of the plasma membrane without the help of membrane transport proteins.
Simple diffusion
65
A substance moves across the lipid bilayer of the plasma membrane without the help of membrane transport proteins.
Facilitated diffusion
66
Are integral membrane proteins that allow specific, small, inorganic ions to pass across the membrane by facilitated diffusion.
Channels
67
A carrier (also called a transporter) moves a solute down its concentration gradient across the plasma membrane
carriermediated facilitated diffusion
68
The number of carriers available in a plasma membrane places an upper limit, called the _______, on the rate at which facilitated diffusion can occur.
transport maximum
69
The body’s preferred energy source for making ATP, enters many body cells by carrier-mediated facilitated diffusion
Glucose
70
An inability to produce or utilize insulin
diabetes mellitus
71
A type of diffusion in which there is net movement of a solvent through a selectively permeable membrane.
Osmosis
72
In living systems, the solvent is _____, which moves by ____ across plasma membranes from an area of higher water concentration to an area of lower water concentration.
water; osmosis
73
Integral membrane proteins that function as water channels.
Aquaporins
74
Pressure exerted in this way by a liquid, known as _________, forces water molecules to move back into the left arm.
hydrostatic pressure
75
The solution with the impermeable solute also exerts a force, called the ________. The _______ of a solution is proportional to the concentration of the solute particles that cannot cross the membrane—the higher the solute concentration, the higher the solution’s osmotic pressure.
Osmotic pressure
76
A measure of the solution’s ability to change the volume of cells by altering their water content.
Tonicity
77
The rupture of RBCs is called _______; the rupture of other types of cells due to placement in a hypotonic solution is referred to simply as ___.
hemolysis (hē-MOL-i-sis; hemo- = blood; -lysis = to loosen or split apart);
lysis
78
shrinkage of cells is called ____.
crenation
79
T or F: Red blood cells placed in an isotonic solution maintain their shape because there is no net water movement into or out of the cells.
t
80
Any solution in which a cell—for example, a red blood cell (RBC)—maintains its normal shape and volume is an
Isotonic solution
81
(Ex. RBC) A different situation results if RBCs are placed in a ________, a solution that has a lower concentration of solutes than the cytosol inside the RBCs
hypotonic solution (hī′-pō-TON-ik; hypo- = less than)
82
A ______ has a higher concentration of solutes than does the cytosol inside RBCs
hypertonic solution (hī′-per-TON-ik; hyper- = greater than)
83
an active process because energy is required for carrier proteins to move solutes across the membrane against a concentration gradient.
Active transport
84
the source in primary active transport
Energy obtained from hydrolysis of adenosine triphosphate (ATP)
85
the source in secondary active transport.
energy stored in an ionic concentration gradient
86
energy derived from hydrolysis of ATP changes the shape of a carrier protein, which “pumps” a substance across a plasma membrane against its concentration gradient.
Primary active transport
87
carrier proteins that mediate primary active transport are often called ___.
pumps
88
the energy stored in a Na+ or H+ concentration gradient is used to drive other substances across the membrane against their own concentration gradients.
Secondary active transport
89
If the transporters move two substances in the same direction they are called ____
symporters
90
If transporters move two substances in opposite directions across the membrane, it is called ____.
antiporters
91
a small, spherical sac
Vesicle
92
materials move into a cell in a vesicle formed from the plasma membrane.
Endocytosis
93
materials move out of a cell by the fusion with the plasma membrane of vesicles formed inside the cell.
Exocytosis
94
Three types of endocytosis:
receptor-mediated endocytosis, phagocytosis, and bulkphase endocytosis.
95
a highly selective type of endocytosis by which cells take up specific ligands.
Receptor-mediated endocytosis
96
A vesicle forms after a receptor protein in the plasma membrane recognizes and binds to a particular particle in the extracellular fluid.
Receptor-mediated endocytosis
97
Process of receptor-mediated endocytosis of LDL particle:
1. Binding
2. Vesicle formation
3. Uncoating
4. Fusion with endosome
5. Recycling of receptors to plasma membrane
6. Degradation in lysosomes
98
“cell eating” is a form of endocytosis in which the cell engulfs large solid particles, such as worn-out cells, whole bacteria, or viruses.
Phagocytosis
99
Body cells that carry out phagocytosis
Phagocytes
100
Two main types of phagocytes:
Macrophages and neutrophils
101
Phagocytosis begins when the particle binds to a plasma membrane receptor on the phagocyte, causing it to extend _____, , projections of its plasma membrane and cytoplasm.
pseudopods
102
any undigested materials in the phagosome remain indefinitely in a vesicle called a _____
residual body
103
“cell drinking,” a form of endocytosis in which tiny droplets of extracellular fluid are taken up
bulk-phase endocytosis or pinocytosis
104
No receptor proteins are involved; all solutes dissolved in the extracellular fluid are brought into the cell.
bulk-phase endocytosis or pinocytosis
105
It releases materials from a cell. It is especially important in two types of cells: (1) secretory cells that liberate digestive enzymes, hormones, mucus, or other secretions and (2) nerve cells that release substances called neurotransmitters
Exocytosis
106
During exocytosis, membrane-enclosed vesicles called _______ form inside the cell, fuse with the plasma membrane, and release their contents into the extracellular fluid
secretory vesicles
107
In this active process, vesicles undergo endocytosis on one side of a cell, move across the cell, and then undergo exocytosis on the opposite side.
Transcytosis
108
consists of all the cellular contents between the plasma membrane and the nucleus, and has two components: (1) the cytosol and (2) organelles, tiny structures that perform various functions in the cell
Cytoplasm
109
tiny structures that perform various functions in the cell
Organelles
110
The fluid portion of the cytoplasm that surrounds organelles and constitutes about 55% of total cell volume.
Cytosol / intracellular fluid
111
The site of many chemical reactions required for a cell’s existence.
Cytosol / intracellular fluid
112
A network of protein filaments that extends throughout the cytosol
Cytoskeleton
113
Three types of filaments contribute to the cytoskeleton’s structure. What are they?
Microfilaments, intermediate filaments, and microtubules
114
are the thinnest elements of the cytoskeleton.
Microfilaments
115
Microfilaments are composed of the proteins ____ and ____ and are most prevalent at the edge of a cell
actin and myosin
116
____ have two general functions: They help generate movement and provide mechanical support.
Microfilaments
117
Microfilaments also provide mechanical support for cell extensions called ______, nonmotile, microscopic fingerlike projections of the plasma membrane.
microvilli (micro- =
small; -villi = tufts of hair; singular is microvillus)
118
_____ are thicker than microfilaments but thinner than microtubules.
intermediate filaments
119
The largest of the cytoskeletal components, are long, unbranched hollow tubes composed mainly of the protein tubulin.
Microtubules
120
____ help determine cell shape. They also function in the movement of organelles such as secretory vesicles, of chromosomes during cell division, and of specialized cell projections, such as cilia and flagella.
Microtubules
121
The _____ is a network of three types of protein filaments—microfilaments, intermediate filaments, and microtubules—that extend throughout the cytoplasm.
cytoskeleton
122
____ are specialized structures within the cell that have characteristic shapes, and they perform specific functions in cellular growth, maintenance, and reproduction.
Organelles
123
The _____ , or microtubule organizing center, located near the nucleus, consists of two components: a pair of centrioles and the pericentriolar matrix
centrosome
124
The two _____ of a centrosome are cylindrical structures, each composed of nine clusters of microtubular triplets arranged in a circular pattern
centrioles
125
Surrounding the centrioles is the _______, which contains hundreds of ring-shaped complexes composed of the protein tubulin.
pericentriolar matrix
126
____ are numerous, short, hairlike projections that extend from the surface of the cell
Cilia
127
Each cilium contains a core of __ microtubules surrounded by plasma membrane
20
128
Located near the nucleus, the centrosome consists of a pair of centrioles and the pericentriolar matrix.
Centrosome
129
T or F: The centrioles of the centrosome forms the mitotic spindle during cell division.
False - Pericentriolar matrix
130
A ___ contains a core of microtubules with one pair in the center surrounded by nine clusters of doublet microtubules.
cilium / cilia
131
_____ are similar in structure to cilia but are typically much longer. ____ usually move an entire cell. A ____ generates forward motion along its axis by rapidly wiggling in a wavelike pattern
Flagella / Flagellum
132
The only example of a flagellum in the human body is a ____, which propels the sperm toward the oocyte in the uterine tube
sperm’s tail
133
The sites of protein synthesis
Ribosomes
134
A network of membranes in the form of flattened sacs or tubules
Endoplasmic reticulum
135
The _____ extends from the nuclear envelope (membrane around the nucleus), to which it is connected and projects throughout the cytoplasm.
Endoplasmic reticulum
136
The ER that is continuous with the nuclear membrane and usually is folded into a series of flattened sacs. The outer surface of this is studded with ribosomes.
ROUGH endoplasmic reticulum
137
ER that does not have ribosomes on the outer surfaces of its membrane. However, smooth ER contains unique enzymes. It doesn't synthesize proteins, it synthesize fatty acids and steroids
SMOOTH endoplasmic reticulum
138
The ____ is a network of membrane-enclosed sacs or tubules that extend throughout the cytoplasm and connect to the nuclear envelope.
endoplasmic reticulum
139
It consists of 3 to 20 saccules, small, flattened membranous sacs with bulging edges.
Golgi complex
140
The convex ______ is a saccule that faces the rough ER.
entry (cis) face
141
The concave ____ is a saccule that faces the plasma membrane.
exit (trans) face
142
Sacs between the entry and exit faces are called ______.
intermediate saccules
143
It is an organelle that modifies, sorts, packages, and transports proteins received from the rough ER.
Golgi complex
144
Some of the processed proteins leave the exit face and are stored in _____. These vesicles deliver the proteins to the plasma membrane, where they are discharged by exocytosis into the extracellular fluid.
secretory vesicles
145
The word lyso- means
dissolving
146
The word -somes means
bodies
147
are membrane-enclosed vesicles that form from the Golgi complex
Lysosomes
148
They can contain as many as 60 kinds of powerful digestive and hydrolytic enzymes that can break down a wide variety of molecules once it fuse with vesicles formed during endocytosis.
Lysosomes
149
Because lysosomal enzymes work best at an ___, the lysosomal membrane includes active transport pumps that import hydrogen ions (H+)
acidic pH
150
Thus, the lysosomal interior has a pH of ___, which is 100 times more acidic than the pH of the cytosol (pH 7)
5
151
also includes transporters that move the final products of digestion, such as glucose, fatty acids, and amino acids, into the cytosol.
lysosomal membrane
152
also help recycle worn-out cell structures.
lysosomal enzymes
153
can engulf another organelle, digest it, and return the digested components to the cytosol for reuse. In this way, old organelles are continually replaced.
lysosome
154
The process by which entire worn-out organelles are digested is called
autophagy
155
The word -auto means
self
156
The word -phagy means
eating
157
In autophagy, the organelle to be digested is enclosed by a membrane derived from the ER to create a vesicle called an ___, the vesicle then fuses with a lysosome.
autophagosome
158
is also involved in cellular differentiation, control of growth, tissue remodeling, adaptation to adverse environments, and cell defense.
autophagy
159
Lysosomal enzymes may also destroy the entire cell that contains them, a process known as
autolysis
160
occurs in some pathological conditions and also is responsible for the tissue deterioration that occurs immediately after death.
Autolysis
161
TRUE or FALSE. Most lysosomal enzymes act within a cell. However, some operate in extracellular digestion.
t
162
One example that operates in extracellular digestion occurs during fertilization. The head of a sperm releases lysosomal enzymes that aid its penetration of the oocyte by dissolving its protective coating in a process called the ___
acrosomal reaction
163
contain several types of powerful digestive enzymes.
Lysosomes
164
What are the functions of lysosomes?
1. Digest substances that enter a cell via endocytosis and transport final products of digestion into cytosol.
2. Carry out autophagy, the digestion of worn-out organelles.
3. Implement autolysis, the digestion of an entire cell.
4. Accomplish extracellular digestion.
165
most often affects children of Ashkenazi (Eastern European Jewish) descent, is an inherited condition characterized by the absence of a single lysosomal enzyme called Hex A.
Tay-Sachs disease or gangliosidosis
166
typically experience seizures and muscle rigidity. They gradually become blind, demented, and uncoordinated and usually die before the age of 5.
Tay-Sachs disease or gangliosidosis
167
Another group of organelles similar in structure to lysosomes, but smaller, are the
Peroxisomes
168
The word peroxi- means
peroxide
169
The word -somes means
bodies
170
contain several oxidases, enzymes that can oxidize (remove hydrogen atoms from) various organic substances.
Peroxisomes or microbodies
171
___ and ___ are oxidized in peroxisomes as part of normal metabolism.
amino acids; fatty acids
172
enzymes in peroxisomes oxidize toxic substances, such as ___
alcohol
173
abundant in the liver, where detoxification of alcohol and other damaging substances occurs.
peroxisomes
174
A byproduct of the oxidation reactions is ___, a potentially toxic compound, and associated free radicals such as superoxide.
hydrogen peroxide (H2O2)
175
peroxisomes also contain the enzyme ___, which decomposes H2O2
catalase
176
also contain enzymes that destroy superoxide. Without it, byproducts of metabolism could accumulate inside a cell and result in cellular death.
peroxisomes
177
TRUE or FALSE. Peroxisomes can not self-replicate.
FALSE (it can)
178
Continuous destruction of unneeded, damaged, or faulty proteins is the function of tiny barrel-shaped structures consisting of four stacked rings of proteins around a central core called
Proteosomes
179
Proteosomes means
protein bodies
180
A typical body cell contains many thousands of proteasomes, in both the ___ and the ___.
cytosol; nucleus
181
Proteasomes were so named because they contain myriad ___, enzymes that cut proteins into small peptides.
proteases
182
clumps of misfolded proteins accumulate in brain cells of people with
Parkinson’s disease and Alzheimer’s disease
183
Because they generate most of the ATP through aerobic (oxygen-requiring) respiration, they are also referred to as the “powerhouses” of the cell.
Mitochondria
184
Active cells that use ATP at a high rate—such as those found in the ___, ___, and ___ have a large number of mitochondria
muscles, liver and kidneys
185
are usually located within the fiber where oxygen enters the cell or where the ATP is used, for example, among the contractile proteins in muscle cells.
Mitochondria
186
A mitochondrion consists of an ___ and ___ with a small fluid-filled space between them
external mitochondrial membrane; internal mitochondrial membrane
187
The word mito- means
thread
188
The word -chondria means
granules
189
The internal mito chondrial membrane contains a series of folds called
mitochondrial cristae
190
The word Kris-te means
ridges
191
The central fluid-filled cavity of a mitochondrion, enclosed by the internal mitochondrial membrane, is the
mitochondrial matrix
192
The elaborate folds of the cristae provide an enormous surface area for the chemical reactions that are part of the aerobic phase of ___, the reactions that produce most of a cell’s ATP
cellular respiration
193
Mitochondria also play an important and early role in ___, the orderly, genetically programmed death of a cell.
Apoptosis
194
Apoptosis means
falling off
195
One of the chemicals released into the cytosol of the cell is ___, which while inside the mitochondria is involved in aerobic cellular respiration.
cytochrome c
196
mitochondria ___, a process that occurs during times of increased cellular energy demand or before cell division.
self-replicate
197
Synthesis of some of the proteins needed for mitochondrial functions occurs on the ___ that are present in the mitochondrial matrix
ribosomes
198
Mitochondria even have their own DNA, in the form of multiple copies of a circular DNA molecule that contains ___ genes. These mitochondrial genes control the synthesis of 2 ribosomal RNAs, 22 transfer RNAs, and 13 proteins that build mitochondrial components.
37
199
mitochondrial genes are inherited only from your
mother
200
Within mitochondria, chemical reactions of aerobic cellular respiration generate
ATP
201
Functions of mitochondria
1. Generate ATP through reactions of aerobic cellular respiration.
2. Play an important early role in apoptosis.
202
is a spherical or oval-shaped structure that usually is the most prominent feature of a cell
Nucleus
203
A double membrane called the ___ separates the nucleus from the cytoplasm.
nuclear envelope
204
Both layers of the nuclear envelope are ____ similar to the plasma membrane.
lipid bilayers
205
The outer layer of the nuclear envelope is continuous with ___ and resembles it in structure.
Rough ER
206
Many openings called ___ extend through the nuclear envelope.
nuclear pores
207
control the movement of substances between the nucleus and the cytoplasm.
Nuclear pores
208
Small molecules and ions move through the pores passively by
diffusion
209
Most large molecules, such as RNAs and proteins, cannot pass through the nuclear pores by diffusion. Instead, their passage involves an ___ process in which the molecules are recognized and selectively transported through the nuclear pore into or out of the nucleus.
active transport
210
Inside the nucleus are one or more spherical bodies called ___ that function in producing ribosomes. Each nucleolus is simply a cluster of protein, DNA, and RNA; it is not enclosed by a membrane.
Nucleoli
211
are the sites of synthesis of rRNA and assembly of rRNA and proteins into ribosomal subunits.They are quite prominent in cells that synthesize large amounts of protein, such as muscle and liver cells.
Nucleoli
212
Within the nucleus are most of the cell’s hereditary units, called ___, which control cellular structure and direct cellular activities.
Genes
213
Genes are arranged along
chromosomes
214
Human somatic (body) cells have ___ chromosomes, 23 inherited from each parent.
46
215
Each chromosome is a long molecule of ___ that is coiled together with several proteins
DNA
216
This complex of DNA, proteins, and some RNA is called
chromatin
217
The total genetic information carried in a cell or an organism is its
genome
218
Electron micrographs reveal that chromatin has a beads-on-a-string structure. Each bead is a ___ that consists of double-stranded DNA wrapped twice around a core of eight proteins called ___, which help organize the coiling and foiling of DNA
nucleosome; histones
219
The string between the beads is called ___, which holds adjacent nucleosomes together.
linker DNA
220
In cells that are not dividing, another histone promotes coiling of nucleosomes into a larger-diameter ___, which then folds into large loops.
chromatin fiber
221
Just before cell division takes place, however, the DNA replicates (duplicates) and the loops condense even more, forming a pair of
chromatids
222
contains most of the cell’s genes, which are located on chromosomes.
Nucleus
223
Functions of the nucleus
1. Controls cellular structure.
2. Directs cellular activities.
3. Produces ribosomes in nucleoli.
224
the study of the relationships between the genome and the biological functions of an organism
genomics
225
When packing is complete, two identical DNA molecules and their histones form a pair of chromatids, which are held together by a
centromere
226
is a highly coiled and folded DNA molecule that is combined with protein molecules.
chromosome
227
Fluid mosaic lipid bilayer (phospholipids, cholesterol, and glycolipids) studded with proteins; surrounds cytoplasm.
Plasma Membrane
228
Protects cellular contents; makes contact with other cells; contains channels, transporters, receptors, enzymes, cell identity markers, and linker proteins; mediates entry and exit of substances.
Plasma Membrane
229
Cellular contents between plasma membrane and nucleus—cytosol and organelles.
Cytoplasm
230
Site of all intracellular activities except those occurring in the nucleus.
Cytoplasm
231
Composed of water, solutes, suspended particles, lipid droplets, and glycogen granules.
Cytosol
232
Fluid in which many of cell’s metabolic reactions occur.
Cytosol
233
is a network in the cytoplasm composed of three protein filaments: microfilaments, intermediate filaments, and microtubules.
Cytoskeleton
234
maintains shape and general organization of cellular contents; responsible for cell movements
Cytoskeleton
235
Specialized structures with characteristic shapes.
Organelles
236
Pair of centrioles plus pericentriolar matrix.
Centrosome
237
The pericentriolar matrix contains tubulins, which are used for growth of the mitotic spindle and microtubule formation.
Centrosome
238
Motile cell surface projections that contain 20 microtubules and a basal body.
Cilia and Flagella
239
move fluids over cell’s surface
Cilia
240
move entire cell
Flagella
241
Composed of two subunits containing ribosomal RNA and proteins; may be free in cytosol or attached to rough ER.
Ribosome
242
Protein synthesis.
Ribosome
243
Membranous network of flattened sacs or tubules
Endoplasmic Reticulum
244
is covered by ribosomes and is attached to the nuclear envelope
Rough ER
245
lacks ribosomes
Smooth ER
246
synthesizes glycoproteins and phospholipids that are transferred to cellular organelles, inserted into plasma membrane, or secreted during exocytosis
Rough ER
247
synthesizes fatty acids and steroids, inactivates or detoxifies drugs, removes phosphate group from glucose-6-phosphate, and stores and releases calcium ions in muscle cells.
Smooth ER
248
Consists of 3–20 flattened membranous sacs called saccules; structurally and functionally divided into entry (cis) face, medial saccules, and exit (trans) face.
Golgi complex
249
Entry (cis) face accepts proteins from rough ER; medial saccules form glycoproteins, glycolipids, and lipoproteins; exit (trans) face modifies molecules further, then sorts and packages them for transport to their destinations.
Golgi complex
250
Vesicle formed from Golgi complex; contains digestive enzymes.
Lysosomes
251
Fuses with and digests contents of endosomes, phagosomes, and vesicles formed during bulk-phase endocytosis and transports final products of digestion into cytosol; digests worn-out organelles (autophagy), entire cells (autolysis), and extracellular materials.
Lysosomes
252
Vesicle containing oxidases (oxidative enzymes) and catalase (decomposes hydrogen peroxide); new peroxisomes bud from preexisting ones.
Peroxisome
253
Oxidizes amino acids and fatty acids; detoxifies harmful substances, such as hydrogen peroxide and associated free radicals.
Peroxisome
254
Tiny barrel-shaped structure that contains proteases (proteolytic enzymes).
Proteosome
255
Degrades unneeded, damaged, or faulty proteins by cutting them into small peptides
Proteosome
256
Consists of an external and an internal mitochondrial membrane, mitochondrial cristae, and mitochondrial matrix; new mitochondria form from preexisting ones.
Mitochondrion
257
Site of aerobic cellular respiration reactions that produce most of a cell’s ATP. Plays an important early role in apoptosis.
Mitochondrion
258
Consists of a nuclear envelope with pores, nucleoli, and chromosomes, which exist as a tangled mass of chromatin in interphase cells.
Nucleus
259
Nuclear pores control the movement of substances between the nucleus and cytoplasm, nucleoli produce ribosomes, and chromosomes consist of genes that control cellular structure and direct cellular functions.
Nucleus
260
Just as genome means all of the genes in an organism, ___ refers to all of an organism's proteins
Proteome
261
In the process called ___, a gene’s DNA is used as a template for synthesis of a specific protein. First, in a process aptly named ___, the information encoded in a specific region of DNA is transcribed (copied) to produce a specific molecule of RNA (ribonucleic acid). In a second process, referred to as ___, the RNA attaches to a ribosome,where the information contained in RNA is translated into a corresponding sequence of amino acids to form a new protein molecule
gene expression; transcription; translation
262
Transcription occurs in the ___; translation occurs in the ___.
nucleus; cytoplasm
263
DNA and RNA store genetic information as sets of three nucleotides. A sequence of three such nucleotides in DNA is called a
base triplet
264
Each DNA base triplet is transcribed as a complementary sequence of three nucleotides, called a
codon
265
A given codon specifies a particular
amino acid
266
is the set of rules that relate the base triplet sequence of DNA to the corresponding codons of RNA and the amino acids they specify
genetic code
267
occurs in the nucleus, the genetic information represented by the sequence of base triplets in DNA serves as a template for copying the information into a complementary sequence of codons.
transcription
268
Three types of RNA are made from the DNA template:
Messenger RNA (mRNA), Ribosomal RNA (rRNA), and Transfer RNA (tRNA)
269
directs the synthesis of a protein.
Messenger RNA (mRNA)
270
joins with ribosomal proteins to make ribosomes
Ribosomal RNA (rRNA)
271
binds to an amino acid and holds it in place on a ribosome until it is incorporated into a protein during translation.
Transfer RNA (tRNA)
272
One end of the tRNA carries a specific amino acid, and the opposite end consists of a triplet of nucleotides called an
anticodon
273
By pairing between complementary bases, the tRNA anticodon attaches to the
mRNA codon
274
catalyzes transcription of DNA.
RNA polymerase
275
The segment of DNA where transcription begins, a special nucleotide sequence called a ___, is located near the beginning of a gene. This is where RNA polymerase attaches to the DNA.
promoter
276
The bases cytosine (C), guanine (G), and thymine (T) in the DNA template pair with guanine, cytosine, and adenine (A), respectively, in the RNA strand. However, adenine in the DNA template pairs with ___, not thymine, in RNA
uracil (U)
277
Transcription of the DNA strand ends at another special nucleotide sequence called a ___, which specifies the end of the gene. When RNA polymerase reaches it, the enzyme detaches from the transcribed RNA molecule and the DNA strand.
terminator
278
Regions within a gene called ___ do not code for parts of proteins. They are located between regions called ___ that do code for segments of a protein
introns; extrons
279
Immediately after transcription, the transcript includes information from both introns and exons and is called
pre-mRNA
280
The introns are removed from pre-mRNA by
small nuclear ribonucleoproteins (snRNPs)
281
are enzymes that cut out the introns and splice together the exons. The resulting product is a functional mRNA molecule that passes through a pore in the nuclear envelope to reach the cytoplasm, where translation takes place.
snRNPs
282
a process in which the pre-mRNA transcribed from a gene is spliced in different ways to produce several different mRNAs. The different mRNAs are then translated into different proteins.
alternative splicing of mRNA
283
During transcription, the genetic information in DNA is copied to ___.
RNA
284
the nucleotide sequence in an mRNA molecule specifies the amino acid sequence of a protein.
translation
285
carry out translation in the cytoplasm
Ribosomes
286
The small subunit of a ribosome has a binding site for mRNA; the larger subunit has three binding sites for tRNA molecules:
P site, A site, and E site
287
binds the tRNA carrying the growing polypeptide chain
P (peptidyl) site
288
binds the tRNA carrying the next amino acid to be added to the growing polypeptide.
A (aminoacyl) site
289
binds tRNA just before it is released from the ribosome
E (exit) site
290
During protein synthesis, the small and large ribosomal subunits join to form a ___. When the process is complete, they separate
functional ribosome
291
Translation occurs in the following way, arrange the following: 1. Next, the large ribosomal subunit attaches to the small ribosomal subunit–mRNA complex, creating a functional ribosome. The initiator tRNA, with its amino acid (methionine), fits into the P site of the ribosome.
2. A component of the large ribosomal subunit catalyzes the formation of a peptide bond between methionine and the amino acid carried by the tRNA at the A site.
3. After peptide bond formation, the ribosome shifts the mRNA strand by one codon. The tRNA in the P site enters the E site and is subsequently released from the ribosome. The tRNA in the A site bearing the two-peptide protein shifts into the P site, allowing another tRNA with its amino acid to bind to a newly exposed codon at the A site. Steps 3 through 6 occur repeatedly, and the protein lengthens progressively.
4. Protein synthesis ends when the ribosome reaches a stop codon at the A site, which causes the completed protein to detach from the final tRNA. In addition, tRNA vacates the P site and the ribosome splits into its large and small subunits.
5. Following the formation of the peptide bond, the resulting two-peptide protein becomes attached to the tRNA at the A site.
6. An mRNA molecule binds to the small ribosomal subunit at the mRNA binding site. A special tRNA, called initiator tRNA, binds to the start codon (AUG) on mRNA, where translation begins. The tRNA anticodon (UAC) attaches to the mRNA codon (AUG) by pairing between the complementary bases. Besides being the start codon, AUG is also the codon for the amino acid methionine. Thus, methionine is always the first amino acid in a growing polypeptide.
7. The anticodon of another tRNA with its attached amino acid pairs with the second mRNA codon at the A site of the ribosome.
2, 4, 6, 7, 5, 1, 3
292
Protein synthesis progresses at a rate of about __ peptide bonds per second.
15
293
Several ribosomes attached to the same mRNA constitute a
polyribosome
294
Organisms so altered are called ____, and their DNA-- a combination of DNA from different sources—is called
recombinant DNA
295
The technology that has arisen from the manipulation of genetic material is referred to as
genetic engineering
296
required for normal growth and metabolism
Growth Hormone (GH)
297
a hormone that helps regulate blood glucose level and is used by diabetics
insulin
298
an antiviral (and possibly anticancer) substance
interferon (IFN)
299
a hormone that stimulates production of red blood cells.
Erythropoietin (EPO)
300
the process by which cells reproduce themselves
cell division
301
The two types of cell division
somatic cell division and reproductive cell division
302
The word soma means
body
303
is any cell of the body other than a germ cell
somatic cell
304
is a gamete (sperm or oocyte) or any precursor cell destined to become a gamete.
germ cell
305
In somatic cell division, a cell undergoes a nuclear division called ___ and a cytoplasmic division called ___ to produce two identical cells, each with the same number and kind of chromosomes as the original cell
mitosis; cytokinesis
306
The word mitos means
thread
307
The word cyto- means
cell
308
The word -kinesis means
movement
309
replaces dead or injured cells and adds new ones during tissue growth
Somatic cell division
310
is the mechanism that produces gametes, the cells needed to form the next generation of sexually reproducing organisms.
Reproductive cell division
311
The process of reproductive cell division consists of a special two-step division called ___, in which the number of chromosomes in the nucleus is reduced by half
meiosis
312
is an orderly sequence of events in which a somatic cell duplicates its contents and divides in two. Some cells divide more than others.
Cell cycle
313
The two chromosomes that make up each pair are called ___. They contain similar genes arranged in the same (or almost the same) order
Homologous chromosomes or homologs
314
one pair of chromosomes called the ___, designated X and Y.
sex chromosomes
315
Because somatic cells contain two sets of chromosomes, they are called
diploid (2n) cells
316
The word homo- means
same
317
The word dipl- means
double
318
The word -oid means
form
319
The cell cycle consists of two major periods:
interphase and mitotic phase
320
Period of cell cycle where a cell is not dividing
Interphase
321
Period of cell cycle where a cell is dividing
Mitotic (M) phase
322
the cell replicates its DNA through this process. It also produces additional organelles and cytosolic components in anticipation of cell division.
Interphase
323
is a state of high metabolic activity; it is during this time that the cell does most of its growing.
Interphase
324
Interphase consists of three phases:
G1, S (synthesis) and G2 Phase
325
This is the division of the cytoplasm which usually occurs during late anaphase of the mitotic phase
Cytokinesis
326
Because the G phases are periods when there is no activity related to DNA duplication, they are thought of as ___ or interruptions in DNA duplication
Gaps
327
is the interval between the mitotic phase and the S phase.
G1 Phase
328
the cell is metabolically active; it replicates most of its organelles and cytosolic components but not its DNA. Replication of centrosomes also begins in this phase
G1 Phase
329
For a cell with a total cell cycle time of 24 hours, G1 lasts
8-10 hours
330
Cells that remain in G1 for a very long time, perhaps destined never to divide again, are said to be in the
G0 Phase
331
Most nerve cells are in the
G0 Phase
332
the interval between G1 and G2, lasts about 8 hours.
S Phase
333
During this phase, DNA replication occurs. As a result of DNA replication, the two identical cells formed during cell division later in the cell cycle will have the same genetic material.
S Phase
334
is the interval between the S phase and the mitotic phase. It lasts 4 to 6 hours.
G2 Phase
335
cell growth continues, enzymes and other proteins are synthesized in preparation for cell division, and replication of centrosomes is completed.
G2 Phase
336
results in the formation of two identical cells, consists of a nuclear division (mitosis) and a cytoplasmic division (cytokinesis) to form two identical cells.
Mitotic (M) phase
337
is the distribution of two sets of chromosomes into two separate nuclei. The process results in the exact partitioning of genetic information.
Mitosis
338
Wha are the 4 stages of mitosis?
Prophase, Metaphase, Anaphase, and Telophase
339
the chromatin fibers condense and shorten into chromosomes. The condensation process may prevent entangling of the long DNA strands as they move during mitosis.
Prophase
340
Because longitudinal DNA replication took place during the S phase of interphase, each prophase chromosome consists of a pair of identical strands called
Chromatids
341
A constricted region called a ___ holds the chromatid pair together.
Centromere
342
At the outside of each centromere is a protein complex known as the
Kinetochore
343
Later in prophase, tubulins in the pericentriolar material of the centrosomes start to form the ___, a football-shaped assembly of microtubules that attach to the kinetochore
Mitotic spindle
344
is responsible for the separation of chromatids to opposite poles of the cell.
Mitotic spindle
345
the microtubules of the mitotic spindle align the centromeres of the chromatid pairs at the exact center of the mitotic spindle
Metaphase
346
The plane alignment of the centromeres at the exact center is called the
Metaphase plate (equatorial plane)
347
the centromeres split, separating the two members of each chromatid pair, which move toward opposite poles of the cell
Anaphase
348
Once separated, the chromatids are termed
chromosomes
349
As the chromosomes are pulled by the microtubules of the mitotic spindle during this phase, they appear V-shaped because the centromeres lead the way, dragging the trailing arms of the chromosomes toward the pole
Anaphase
350
The final stage of mitosis begins after chromosomal movement stops
Telophase
351
The identical sets of chromosomes, now at opposite poles of the cell, uncoil and revert to the threadlike chromatin form. A nuclear envelope forms around each chromatin mass, nucleoli reappear in the identical nuclei, and the mitotic spindle breaks up.
Telophase
352
The two strands of the double helix separate by breaking the ___ between nucleotides
hydrogen bonds
353
doubles the amount of DNA.
Replication
354
division of a cell’s cytoplasm and organelles into two identical cells is called
Cytokinesis
355
The process of cytokinesis usually begins in late anaphase with the formation of a ___, a slight indentation of the plasma membrane, and is completed after telophase.
Cleavage furrow
356
usually appears midway between the centrosomes and extends around the periphery of the cell
Cleavage furrow
357
Actin microfilaments that lie just inside the plasma membrane form a ___ that pulls the plasma membrane progressively inward. The ring constricts the center of the cell, like tightening a belt around the waist, and ultimately pinches it in two.
contractile ring
358
When cytokinesis is complete,___ begins
Interphase
359
What is the sequence of event of the cell cycle in somatic cells?
G1 --> S phase --> G2 --> Mitosis --> Cytokinesis
360
What are the 3 possible destinies of a cell?
(1) to remain alive and functioning without dividing,(2) to grow and divide, or (3) to die.
361
Homeostasis is maintained when there is a balance between ___ and ___
cell proliferation; cell death
362
In somatic cell division, a single starting cell divides to produce two identical ___ cells.
diploid
363
One of the distinguishing features of cancer cells is uncontrolled division, which results in the formation of a mass of cells called a
neoplasm or tumor
364
One of the ways to treat cancer is by ____, the use of anticancer drugs.
Chemotheraphy
365
Some of these drugs stop cell division by inhibiting the formation of the
Mitotic spindle
366
Period between cell divisions; chromosomes not visible under light microscope.
Interphase
367
Metabolically active cell duplicates most of its organelles and cytosolic components; replication of chromosomes begins (Cells that remain in the G1 phase for a very long time, and possibly never divide again, are said to be in the G0 phase.)
G1 Phase
368
Replication of DNA and centrosomes.
S Phase
369
Cell growth, enzyme and protein synthesis continue; replication of centrosomes complete.
G2 Phase
370
Parent cell produces identical cells with identical chromosomes; chromosomes visible under light microscope.
Mitotic Phase
371
Nuclear division; distribution of two sets of chromosomes into separate nuclei.
Mitosis
372
Chromatin fibers condense into paired chromatids; nucleolus and nuclear envelope disappear; each centrosome moves to an opposite pole of the cell.
Prophase
373
Centromeres of chromatid pairs line up at metaphase plate.
Metaphase
374
Centromeres split; identical sets of chromosomes move to opposite poles of cell.
Anaphase
375
Nuclear envelopes and nucleoli reappear; chromosomes resume chromatin form; mitotic spindle disappears.
Telophase
376
Cytoplasmic division; contractile ring forms cleavage furrow around center of cell, dividing cytoplasm into separate and equal portions.
Cytokinesis
377
can transfer a phosphate group from ATP to a protein to activate the protein; other enzymes can remove the phosphate group from the protein to deactivate it.
Cyclin-dependent protein kinases (Cdk's)
378
Switching the Cdk’s on and off is the responsibility of cellular proteins called ___, so named because their levels rise and fall during the cell cycle.
cyclins
379
Destruction of this cyclin is by
proteosomes
380
an orderly, genetically programmed death
apoptosis
381
In apoptosis, a triggering agent from either outside or inside the cell causes ___ genes to produce enzymes that damage the cell in several ways, including disruption of its cytoskeleton and nucleus.
cell-suicide
382
removes unneeded cells during fetal development, such as the webbing between digits. It continues to occur after birth to regulate the number of cells in a tissue and eliminate potentially dangerous cells such as cancer cells.
apoptosis
383
is a normal type of cell death
apoptosis
384
is a pathological type of cell death that results from tissue injury
necrosis
385
The word necrosis means
death
386
In ___, many adjacent cells swell, burst, and spill their cytoplasm into the interstitial fluid. The cellular debris usually stimulates an inflammatory response by the immune system, a process that does not occur in apoptosis.
necrosis
387
each new organism is the result of the union of two different gametes, one produced by each parent
Sexual reproduction
388
The word mei- means
lessening
389
The word -osis means
condition of
390
the reproductive cell division that occurs in the gonads (ovaries and testes), produces gametes in which the number of chromosomes is reduced by half.
meiosis
391
gametes contain a single set of 23 chromosomes and thus are
haploid (n) cells
392
The word hapl- means
single
393
restores the diploid number of chromosomes.
Fertilization
394
occurs in two successive stages
Meiosis
395
The 2 stages of meiosis are
Meiosis I and Meiosis II
396
begins once chromosomal replication is complete, consists of four phases: prophase I, metaphase I, anaphase I, and telophase I
Meiosis I
397
is an extended phase in which the chromosomes shorten and thicken, the nuclear envelope and nucleoli disappear, and the mitotic spindle forms.
Prophase I
398
Two events that are not seen in mitotic prophase occur during prophase I of meiosis are
Synapsis and crossing over
399
the two sister chromatids of each pair of homologous chromosomes pair off, an event called
Synapsis
400
The resulting four chromatids form a structure called a
Tetrad
401
The word tetra means
four
402
parts of the chromatids of two homologous chromosomes may be exchanged with one another. Such an exchange between parts of nonsister (genetically different) chromatids is called ___. This process, among others, permits an exchange of genes between chromatids of homologous chromosomes
crossing over
403
Crossing-over results in ___, —that is, the formation of new combinations of genes—and accounts for part of the great genetic variation among humans and other organisms that form gametes via meiosis.
genetic recombination
404
the tetrads formed by the homologous pairs of chromosomes line up along the metaphase plate of the cell, with homologous chromosomes side by side
Metaphase I
405
the members of each homologous pair of chromosomes separate as they are pulled to opposite poles of the cell by the microtubules attached to the centromeres. The paired chromatids, held by a centromere, remain together.
Anaphase I
406
The net effect of ___ is that each resulting cell contains the haploid number of chromosomes because it contains only one member of each pair of the homologous chromosomes present in the starting cell.
Meiosis I
407
The second stage of meiosis, also consists of four phases: prophase II, metaphase II, anaphase II, and telophase II
Meiosis II
408
begins with a diploid starting cell and ends with two cells, each with the haploid number of chromosomes.
Meiosis I
409
each of the two haploid cells formed during meiosis I divides; the net result is four haploid gametes that are genetically different from the original diploid starting cell.
Meiosis II
410
In ___, a single diploid starting cell undergoes meiosis I and meiosis II to produce four haploid gametes that are genetically different from the starting cell that produced them.
Reproductive cell division
411
The sizes of cells are measured in units called
micrometers
412
TRUE or FALSE. One micrometer (μm) is equal to 1 one-millionth of a meter, or 10−6 m (1/25,000 of an inch).
t
413
The largest cell, ___, has a diameter of about 140 μm and is barely visible to the unaided eye.
single oocyte
414
has a diameter of 8 μm
red blood cells
415
an average hair from the top of your head is approximately ___ in diameter
100 μm
416
TRUE or FALSE. The shapes of cells also vary considerably, they may be round, oval, flat, cube-shaped, column-shaped, elongated, star-shaped, cylindrical, or disc-shaped. A cell’s shape is related to its function in the body.
t
417
has a long whiplike tail (flagellum) that it uses for locomotion.
Sperm
418
The disc shape of a ___ gives it a large surface area that enhances its ability to pass oxygen to other cells.
red blood cells
419
The long, spindle shape of a relaxed ____ shortens as it contracts
Smooth muscle fiber (cell)
420
are common in the epithelial cells that line the small intestine, where the large surface area speeds the absorption of digested food.
Microvilli
421
have long extensions that permit them to conduct nerve impulses over great distances.
Nerve cells
422
The nearly 100 trillion cells in an average adult human can be classified into about ___ different cell types.
200
423
is a normal process accompanied by a progressive alteration of the body’s homeostatic adaptive responses. It produces observable changes in structure and function and increases vulnerability to environmental stress and disease.
Aging
424
The specialized branch of medicine that deals with the medical problems and care of elderly persons is
Geriatics
425
The word ger- means
old age
426
The word -iatrics means
medicine
427
is the scientific study of the process and problems associated with aging.
Gerontology
428
specific DNA sequences found only at the tips of each chromosome. These pieces of DNA protect the tips of chromosomes from erosion and from sticking to one another.
Telomeres
429
the most abundant sugar in the body, plays a role in the aging process. It is haphazardly added to proteins inside and outside cells, forming irreversible cross-links between adjacent protein molecules. With advancing age, more cross-links form, which contributes to the stiffening and loss of elasticity that occur in aging tissues.
Glucose
430
the immune system may start to attack the body’s own cells. This ___ might be caused by changes in cell-identity markers at the surface of cells that cause antibodies to attach to and mark the cell for destruction.
autoimmune response
431
produce oxidative damage in lipids, proteins, or nucleic acids by “stealing” an electron to accompany their unpaired electrons. Some effects are wrinkled skin, stiff joints, and hardened arteries.
Free radicals
432
Certain dietary substances, such as vitamin E, vitamin C, beta-carotene, zinc, and selenium, are referred to as because they inhibit the formation of free radicals.
antioxidants
433
is a group of diseases characterized by uncontrolled or abnormal cell division.
Cancer
434
When cells in a part of the body divide without control, the excess tissue that develops is called
tumor or neoplasm
435
The word neo- means
new
436
The study of tumors is called
Oncology
437
The word onco- means
swelling or mass
438
A cancerous neoplasm is called a
Malignant tumor or malignancy
439
One property of most malignant tumors is their ability to undergo ___, the spread of cancerous cells to other parts of the body
Metastasis
440
is a neoplasm that does not metastasize. An example is a wart.
benign tumor
441
Most ___ may be removed surgically if they interfere with normal body function or become disfiguring. Some can be inoperable and perhaps fatal.
benign tumor
442
Most human cancers are ___, malignant tumors that arise from epithelial cells.
carcinomas
443
The word carcin means
cancer
444
The word -omas means
tumors
445
are cancerous growths of melanocytes, skin epithelial cells that produce the pigment melanin.
Melanomas
446
The word melan- means
black
447
is a general term for any cancer arising from muscle fibers or connective tissues.
Sarcoma
448
The word sarc- means
flesh
449
the most frequent type of childhood cancer, destroys normal bone tissue
Osteogenic sarcoma
450
The word osteo- means
bone
451
The word -genic means
origin
452
is a cancer of blood-forming organs characterized by rapid growth of abnormal leukocytes
Leukemia
453
The word leuk- means
white
454
The word -emia means
blood
455
is a malignant disease of lymphatic tissue—for example, of lymph nodes.
Lymphoma
456
As malignant cells invade surrounding tissues, they often trigger ___, the growth of new networks of blood vessels.
angiogenesis
457
Proteins that stimulate angiogenesis in tumors are called
Tumor angiogenesis factors (TAFs)
458
What are the factors that may trigger cancer?
Carcinogens, Oncogenes, and Oncogenic Viruses
459
A chemical agent or radiation that produces cancer is called a
Carcinogen
460
are associated with 60–90% of all human cancers
Carcinogen
461
Examples of carcinogens are
hydrocarbons found in cigarette tar, radon gas from the earth, and ultraviolet (UV) radiation in sunlight.
462
cancer-causing genes
Oncogenes
463
derive from normal genes called proto-oncogenes that regulate growth and development. The proto-oncogene undergoes some change that causes it (1) to be expressed inappropriately, (2) to make its products in excessive amounts, or (3) to make its products at the wrong time.
Oncogenes
464
are tiny packages of nucleic acids, either RNA or DNA, that can reproduce only while inside the cells they infect.
Viruses
465
Viruses that cause cancer by stimulating abnormal proliferation of cells. For instance, the human papillomavirus (HPV) causes virtually all cervical cancers in women.
Oncogenic Viruses
466
is a defensive response to tissue damage
Inflammation
467
stimulates the proliferation of mutated cells and enhances their survival, promotes angiogenesis, and contributes to invasion and metastasis of cancer cells.
Chronic Inflammation
468
inflammation of the stomach lining
Chronic Gastritis
469
inflammation of the liver
Chronic Hepatitis
470
is also an underlying contributor to rheumatoid arthritis, Alzheimer’s disease, depression, schizophrenia, cardiovascular disease, and diabetes.
Chronic Inflammation
471
may be a causative factor in 60–90% of stomach cancers
Chronic gastritis and peptic ulcers
472
are believed to be respon sible for about 80% of liver cancers.
Chronic hepatitis and cirrhosis of the liver
473
is 10 times more likely to occur in patients with chronic inflamma tory diseases of the colon, such as ulcerative colitis and Crohn’s disease
Colorectal cancer
474
two chronic lung inflammatory conditions
asbestosis and silicosis
475
is a multistep process of cancer development in which as many as 10 distinct mutations may have to accumulate in a cell before it becomes cancerous.
Carcinogenesis
476
the tumor begins as an area of increased cell proliferation that results from one mutation. This growth then progresses to abnormal, but noncancerous, growths called adenomas. After two or three additional mutations, a mutation of the tumor suppressor gene p53 occurs and a carcinoma develops.
Colon cancer
477
Traditional cancer treatment involve
surgery, chemotherapy, and radiation
478
involves administering drugs that cause the death of cancerous cells by altering or destroying their DNA
Chemotherapy
479
breaks chromosomes, thus blocking cell division
Radiation therapy
480
the use of various procedures that modify and stimulate immune responses to fight cancer
Immunotherapy
481
the use of drugs that target specific genes and proteins found in cancer cells to stop cancer cells from growing and dividing or cutting off their blood supply
Targeted therapy
482
the transplantation of stem cells to restore blood-forming cells in people whose red bone marrow has been destroyed by high doses of radiation and chemotherapy used to treat their cancer
Stem cells transplants
483
using various levels of hormones to slow or stop the growth of cancer cells in tissues that are sensitive to hormonal growth control, such as the breasts and prostate
Hormone therapy
484
the use of remedies that lie outside of traditional medical procedures such as herbal, vitamin, and nutritional supplements; exercise, relaxation techniques, massage, prayer, hypnotherapy, and acupuncture
Complementary and alternative medicine (CAM) therapy
485
is one that affects one part or a limited area of the body
local disease
486
affects the entire body or several parts.
systemic disease
487
The loss of tissue differentiation and function that is characteristic of most malignancies
Anaplasia
488
The word ana means
backwards
489
The word -plasia means
to shape
490
A decrease in the size of cells, with a subsequent decrease in the size of the affected tissue or organ; wasting away.
Atrophy
491
The prefix a- means
without
492
The word -trophy means
nourishment
493
Alteration in the size, shape, and organization of cells due to chronic irritation or inflam mation; may progress to neoplasia (tumor formation, usually malignant) or revert to normal if the irritation is removed.
Dysplasia
494
The word dys- means
abnormal
495
Increase in the number of cells of a tissue due to an increase in the frequency of cell division.
Hyperplasia
496
The word hyper- means
over
497
Increase in the size of cells without cell division.
Hypertrophy
498
The transformation of one type of cell into another.
Metaplasia
499
The word meta- means
change
500
Offspring or descendants.
Progeny
