Chapter 3 - Cellular Organization Flashcards
(304 cards)
1
Q
What is the approximate diameter of a typical cell?
A
0.1nm
2
Q
Did Robert Hooke actually see cells?
A
No - just the outline of them
3
Q
In what century were microscopes invented?
A
17th century (1665)
4
Q
Name the 4 components of the cell theory
A
- Cells are the building blocks of all plants and animals
- All cells come from the division of preexisting cells
- Cells are the smallest units that perform all vital physiological functions
- Each cell maintains homeostasis at the cellular level. (Homeostasis at the tissue, organ, organ system, and organism reflects the combined action of many cells)
5
Q
The human body contains _____ of cells
A
trillions
6
Q
cytology is part of the broader discipline of …?
A
cell biology
7
Q
cell biology integrates aspects of which 3 sciences?
A
chemistry
biology
physics
8
Q
The human body contains how many general classes of cells and what are they
A
2 - somatic cells
sex cells (germ cells)
9
Q
Name the 4 functions of the plasma membrane
A
- Physical isolation
- Regulation of exchange with the environment
- Sensitivity to the environment
- Structural support
10
Q
What is the 1st part of the cell affected by changes in composition, pH, etc of the extracellular fluid?
A
cell membrane
11
Q
The plasma membrane contains a variety of _______ that allow the cell to recognize and respond to specific molecules in its environment
A
receptors
12
Q
Is the plasma membrane thin or thick? How many nm is it?
A
EXTREMELY THIN. ranges from 6-10nm in thickness
13
Q
The cell membrane contains which 3 biomolecules?
A
carbohydrates, lipids, proteins
14
Q
Which biomolecule makes up most of the SURFACE AREA of the plasma membrane?
A
lipids
15
Q
What % weight is lipids in a cell membrane
A
42%
16
Q
Why is isolation between the cytoplasm and extracellular fluid so important?
A
Because the compositions of the 2 are very different and the cell cannot survive if the differences are eliminated
17
Q
Proteins account for about ____% of the weight of the plasma membrane
A
55%
18
Q
Which are denser - proteins or lipids?
A
proteins
19
Q
What are the 2 structural classes of membrane proteins?
A
Integral proteins and peripheral proteins
20
Q
Can integral proteins be removed?
A
Not without damaging the cell membrane. It’s part of the membrane structure
21
Q
Integral proteins are also known as …..? Why?
A
Transmembrane proteins because they span the width of the membrane one or more times
22
Q
Can peripheral proteins be removed from the membrane?
A
Yes - they are bound to either the inner or outer surface of the membrane and are easily separated from it
23
Q
Which are more abundant - peripheral or integral?
A
integral
24
Q
Membrane proteins can have which 6 functions?
A
- Channel
- Carrier
- Anchoring
- Recognition
- Enzyme
- Receptor
25
What do anchoring proteins do? Where do they attach:
-Inside the cell
-Outside the cell
attach the plasma membrane to other structures and stabilize its position
inside the cell: cytoskeleton
outside the cell: another cell or extracellular protein fibers
26
Recognition proteins are also known as...?
Identifiers
27
Recognition proteins are crucial in the...?
immune system
28
Many important recognition proteins are...?
glycoproteins
29
Are enzymes in the plasma membrane peripheral or integral proteins?
could be either
30
Receptor proteins are sensitive to the presence of...?
ligands
31
What is a ligand?
extracellular molecule. Could be a small ion or a complex hormone
32
The binding of insulin to a receptor protein leads to....?
increase in the rate of glucose absorption by the cell
33
What do carrier proteins do?
bind solutes and transport them across the plasma membrane
34
Carrier proteins may require ___ as _______
ATP as an energy source
35
Do carrier proteins that transport glucose need ATP?
no
36
What does a channel do?
Permits the movement of water and small solutes across the plasma membrane
37
Why can ions not cross the plasma membrane??
They do not dissolve in lipids
38
Many channels are highly _______
specific
39
Membranes are neither ___ nor ____
rigid nor uniform
40
Carbohydrates account for about ___% of the weight of the plasma membrane
3
41
Carbohydrates in the plasma membrane can be components in _____, ______, or _____
protoglycans, glycoproteins, glycolipids
42
What is the glycocalyx?
portions of proteoglycans, glycoproteins, or glycolipids that extend beyond the outer surface of the membrane
43
What are 4 functions of the glycocalyx?
1. Protection and Lubrication
2. Anchoring and Locomotion
3. Specificity in binding (receptors)
4. Recognition
44
Cytoplasm is a general term for the material located between the _____ and the ____ surrounding the ______
plasma membrane and the membrane surrounding the nucleus
45
Which contains more proteins - cytoplasm or extracellular fluid??
cytoplasm
46
Cytoplasm is a _____ with a ___like consistency
colloid with a gel like consistency
47
Cytoplasm =
cytosol + organelles
48
Another name for cytosol is _____ fluid
intracellular fluid
49
Cytosol contains ...?
dissolved nutrients, ions, soluble/insoluble proteins, and waste products
50
What are organelles?
structures suspended within the cytosol that perform specific functions for the cell
51
What are 3 differences between the cytosol and extracellular fluid??
1. Concentration of potassium ions is much higher in the cytosol than extracellular fluid. Sodium conc is much higher in extracellular fluid
2. Cytosol has many more suspended proteins
3. Cytosol has small reserves of amino acids and lipids while extracellular fluid is a transport medium ONLY - no reserves
52
What is fluid within tissues called?
interstitial fluid
53
What are inclusions?
masses of insoluble material within the cytosol
54
cellular organelles can be divided into 2 broad categories:
1. nonmembranous organelles
2. membranous organelles
55
What are the cell's membranous organelles?
ER, golgi, lysosomes, peroxisomes, mitochondria, nucleus
56
What are the 3 components of the cytoskeleton?
microtubules, intermediate filaments, microfilaments
57
Which component of the cytoskeleton is the smallest?
microfilaments
58
Microfilaments are made up of _____
actin
59
microfilaments are generally less than ___nm in diameter
6
60
What are the 3 main functions of microfilaments?
1. Anchor cytoskeleton to integral proteins
2. Determine the consistency of the cytoplasm by interacting with other proteins
3. Actin can interact with myosin to produce movement of the cell or change shape
61
Intermediate filaments range from __to__ nm in diameter
7 to 11nm
62
Intermediate filaments mainly serve as ...?
structural support
63
List 3 functions of intermediate filaments.
1. Strengthen the cell and help maintain its shape
2. Stabilize the positions of organelles
3. Stabilize the position of the cell with respect to surrounding cells through attachment to cell membrane
64
Intermediate filaments are.. (soluble/insoluble)
INSOLUBLE
65
Keratin fibers are which kind of filament?
intermediate filament
66
Most cells contain ______ built from the globular protein _____?
most cells contain MICROTUBULES built from the globular protein tubulin
67
microtubules have a diameter of about ___nm
25
68
Microtubules extend outward from a region near the nucleus known as...?
the centrosome
69
Name 4 functions of the microtubules.
1. Forms the spindle apparatus during mitosis
2. serve as a monorail system to move vesicles
3. Form centrioles, cilia, flagella
70
What are thick filaments?
massive bundles composed of myosin
71
Thick filaments appear only in ...?
muscle cells
72
myosin interacts with ____ to produce powerful contractions
actin
73
What are the small, finger-shape projections of the plasma membrane?
microvilli
74
centrioles are composed of....
short microtubules
75
centrioles are found in which cells?
all animal cells that can undergo mitosis
76
Which types of cells do NOT contain centrioles?
mature red blood cells, skeletal muscle cells, cardiac muscle cells, and neurons - CELLS THAT CANNOT DIVIDE
77
What is the heart of the cytoskeletal system?
the centrosome
78
What is the centrosome?
the cytoplasm surrounding the centriole
79
the organization of centrioles is what kind of array? why?
9+0 array because there are no central microtubules as they form 3 "triplets"
80
Cilia are found on the cells lining which 2 tracts?
respiratory and reproductive
81
What is the array of cilia? why?
9 + 2 array. Nine PAIRS of microtubules surround a central pair
82
The microtubules in cilia are anchored to a ________ which has the same array as a centriole (9+0)
basal body
83
Cilium has 2 strokes:
power stroke and return stroke
84
During what stroke is the cilia relatively stiff?
power stroke
85
Which are the organelles responsible for protein synthesis?
ribosomes
86
Before protein synthesis can begin, what 3 things must join together?
small ribosomal subunit, large ribosomal subunit, mRNA
87
There are 2 types of ribosomes:
fixed ribosomes and free ribosomes
88
Where do free ribosomes produce proteins?
within the cytoplasm
89
What are proteasomes?
organelles that contain an assortment of protein-digesting enzymes (proteases)
90
What is the molecular "tag" attached to proteins for recycling?
ubitiquin
91
What kind of proteins are degraded by proteasomes?
-damaged/denatured proteins
-abnormal proteins (ex: those infected with viruses)
92
The ER is connected to the....
nuclear envelope
93
What are the 4 major functions of the ER?
1. Synthesis
2. Storage
3. Transport
4. Detoxification
94
The ER forms hollow tubes, flattened sheets, and chambers called..?
cisternae
95
The SMOOTH endoplasmic reticulum synthesizes....
lipids and carbohydrates
96
The smooth ER in ____ and ____ cells is responsible for the detoxification or inactivation of drugs
liver and kidney cells
97
What delivers proteins from the rough er to the golgi apparatus?
transport vesicles
98
is the proportion of rough ER to smooth ER the same in all cells?
NO - vary with the activities of the cell
99
Pancreatic cells that manufacture digestive enzymes contain more smooth or rough er?
RER
100
What are 3 major functions of the golgi apparatus?
1. Modify and package secretions such as hormones and enzymes for release through exocytosis
2. modify the plasma membrane
3. package special enzymes within vesicles for use in the cytoplasm
101
Where are lysosomes produced??
The golgi apparatus
102
Lysosomes contain...?
digestive enzymes
103
What are primary lysosomes?
contain inactive enzymes. fuses with the membranes of damaged organelles
104
Lysosomes function in the deconstruction of...?
bacteria
105
Which are larger - lysosomes or peroxisomes?
peroxisomes
106
How are new peroxisomes produced?
From pre existing peroxisomes
107
What is the most abundant enzyme within the peroxisome?
Catalase
108
What do peroxisomes absorb and break down?
fatty acids and other organic molecules
109
In which cells are peroxisomes most abundant?
metabolically active cells such as liver cells
110
All membranous organelles aside from which one are in communication through the movement of vesicles?
mitochondria
111
What is the continuous movement and exchange in the cell called?
membrane flow
112
Which kind of cells lack mitochondria?
red blood cells
113
Which kind of cells have a LOT of mitochondria
heart muscle cells
114
Most of the chemical reactions that RELEASE energy occur in the ____ of the cell
mitochondria
115
Most of the chemical reactions that REQUIRE energy occur in the ____
cytoplasm
116
The first step of cellular respiration is called _____ and occurs in the _____
glycolysis, cytoplasm
117
During glycolysis, each ____ molecule is broken down into 2 molecules of ______
glucose is broken down into 2 molecules of pyruvate
118
Differentiate between the cytoplasm and the cytosol
Cytoplasm is the material between the plasma membrane and the nuclear membrane. Cytosol is the fluid portion of the cytoplasm
119
What is the function of the centriole??
1. movement of chromosomes during cell division
2. Organization of microtubules in cytoskeleton
120
What is the function of the cilia?
1. Movement of materials over cell surface
121
What is the function of microvilli?
Increased surface area to facilitate absorption of extracellular materials
122
What % of ATP required by the cell is produced by the mitochondria?
95%
123
What is the function of peroxisomes?
neutralization of toxic compounds
124
A large amount of mitochondria in the cell indicates....
A high demand for energy
125
Explain why certain cells in the ovaries and testes contain large amounts of smooth endoplasmic reticulum
SER synthesizes lipids, such as steroids. Ovaries and testes produce large amounts of steroid hormones and thus need large amounts of SER
126
What organelle is usually the largest and most conspicuous structure in a cell?
The nucleus
127
The nucleus serves as the _____ for cellular ______
control center for cellular operations
128
Can a cell without a nucleus repair itself?
NO - it will disintegrate in 3-4 months
129
Which kind of cells do not contain nuclei?
mature red blood cells
130
Which kind of cells have MANY nuclei?
skeletal muscle cells
131
What surrounds the nucleus, separating it from the cytosol?
a nuclear envelope
132
What is the nuclear envelope?
a double layer separated by a narrow perinuclear space
133
Where does chemical communication between the nucleus and cytoplasm occur?
nuclear pores
134
Nuclear pores cover around what % of the surface of the nucleus?
10%
135
The fluid contents of the nucleus are called the .....
nucleoplasm
136
Most nuclei contain several dark staining areas called ___?
mucleoli
137
What is the function of nucleoli?
synthesize ribosomal RNA, assemble ribosomal subunits
138
The chemical "language" the cell uses is known as...
genetic code
139
What is the functional unit of heredity?
a gene
140
The nucleus contains what 4 things?
DNA, RNA, enzymes, proteins
141
Each gene codes for a ____________
specific protein
142
Each gene is located....
at a particular site on a specific chromosome
143
What is the first step in the process of transcription?
RNA polymerase binds to the promoter
144
the term "transcription" literally means....
"to copy" or "rewrite"
145
Can DNA leave the nucleus?
NO
146
Where in the cell does protein synthesis occur?
the cytoplasm
147
What are the 2 strands called in DNA?
coding strand, template strand
148
Before transcription can begin, what must happen to the DNA strand?
the 2 strands must be separated
149
Does RNA polymerase attach uracil or thymine?
URACIL
150
a 3 base mRNA sequence is called a.....
codon
151
Which are spliced together in RNA PROCESSING - introns or exons?
exons. introns are snipped out.
152
The amino acids are provided by ____ during the process of translation
tRNA
153
tRNA carries a...
anticodon
154
What is the first step in translation?
mRNA strand binds to a small ribosomal subunit
155
Where does transcription occur?
the nucleus
156
What is protein synthesis?
The assembling of functional polypeptides in the cytoplasm
157
A series of ribosomes attached to the same mRNA strand is called a ....
polyribosome or polysome
158
The nucleus has both ____ and _____ control over the cell
direct and indirect
159
What is gene activation?
gene activation is the process of uncoiling the segment of DNA containing the gene and temporarily removing histones so that the gene can be expressed and affect cell function
160
Transcription is the ____ of genetic _____ on a strand of ______
encoding of genetic instructions on a strand of mRNA
161
What process would be affected by lack of the enzyme RNA polymerase?
This cell would not be able to transcribe RNA from DNA (transcription)
162
What is permeability?
The property of the plasma membrane that determines precisely which substances can enter or leave the cytoplasm
163
A membrane through which NOTHING can pass is said to be....
impermeable
164
A membrane through which ANY substance can pass without difficulty is said to be....
freely permeable
165
The plasma membrane of a cell is said to be....
selectively permeable
166
Passage across the cell membrane is either _____ or ______
passive or active
167
What are the 3 major categories of transport across the cell membrane?
diffusion, carrier-mediated transport, vesicular transport
168
Is diffusion a passive or active process?
passive
169
The difference between high and low concentration is called a..
concentration gradient
170
What are 5 factors that influence diffusion rates?
1. Size
2. Distance
3. Temperature
4. Concentration gradient
5. Electrical forces
171
The larger the molecules size, the _____ the diffusion
slower
172
The higher the temperature, the _____ the diffusion rate
faster
173
The smaller the concentration gradient, the ______ the diffusion rate
slower
174
Which substances can pass through the plasma membrane by SIMPLE DIFFUSION
nonpolar, uncharged molecules such as alcohol, fatty acids, and steroids
175
What are membrane channels?
Very small passageways created by transmembrane proteins
176
Can water molecules and other small ions enter/exit freely through membrane channels?
YES
177
leak channels are also called..?
passive channels
178
Can glucose fit through the membrane channels?
No - it's too big
179
What is the function of a leak/passive channel?
They remain open and allow the passage of ions across the plasma membrane
180
The higher the solute concentration, the ____ the water concentration
lower
181
Water molecules tend to flow across a membrane towards the solution with higher or lower solute concentration?
HIGHER- because the more solute there is, the less water. Water is simply moving down its concentration gradient
182
What is osmosis?
The diffusion of water across a semi permeable membrane
183
What is osmotic pressure?
Indication of the force with which water moves into a solution as a result of solute concentration
184
How can osmosis be prevented?
Resisting the change in volume by applying HYDROSTATIC PRESSURE
185
Why is there a higher water permeability than solute permeability across a membrane?
water molecules can cross a membrane through AQUAPORINS
186
Water molecules can cross a membrane through which two things?
Solute channels and aquaporins
187
Are there more solute channels or aquaporins?
Aquaporins
188
What is another name for osmolarity?
osmotic concentration
189
What is osmolarity?
The total solute concentration in an aqueous solution
190
What does the term isotonic mean?
A solution that does not cause an osmotic flow of water into or out of a cell
191
What is tonicity?
Description of how the solution affects a cell
192
What will happen if a red blood cell is in a HYPOTONIC solution?
Water will flow into the cell, causing it to swell and burst
193
What is the term for when a red blood cell swells and bursts?
hemolysis
194
What will happen when a cell is placed in a HYPERTONIC solution?
The cell will lose water by osmosis, shrivel, and dehydrate
195
What is the term for the shrinking of red blood cells?
crenation
196
Why is saline (NaCl) used when giving patients large volumes of fluid to combat blood loss or dehydration?
sodium and chloride are the most abundant ions in extracellular fluid to little net movement across the membrane occurs. saline is ISOTONIC to body cells
197
Does the crossing of water through the membrane require energy??
NO
198
When is a solution said to be hypertonic?
When a cell is placed in solution with a HIGH solute concentration.
199
When is a solution said to be HYPOTONIC?
When a cell is placed in a solution with a LOW solute concentration
200
What would happen if we drank ocean water??
Sea water is very hypertonic. Water would rush out of our own body cells and our cells would lyse
201
Diffusion proceeds until....
equilibrium is reached
202
How would a decrease in the concentration of oxygen in the lungs affect the diffusion of oxygen into the blood?
Oxygen would diffuse much more slowly into the blood because the concentration gradient is lower
203
Why is using a 10% salt solution as a nasal spray useful in relieving congestion?
the salt solution is hypertonic with respect to the cells lining the nasal cavity. water from the cells of the nasal cavity would rush out, causing the cell to shrink, relieving the congestion
204
Is vesicular transport a passive or active process?
ALWAYS ACTIVE
205
Is carrier mediated transport a passive or active process?
passive or active, depending on the substance transported and the nature of the transport mechanism
206
Another word for cotransport
symport
207
Another word for countertransport
antiport
208
What are 2 examples of carrier-mediated transport?
-Facilitated diffusion
-Active transport
209
Does facilitated diffusion require ATP?
no
210
In facilitated diffusion, the molecule to be transported must first bind to....
the receptor site on the carrier protein
211
All cells move glucose across there membrane through....
facilitated diffusion
212
Does active transport require ATP?
YES
213
Is active transport dependent on concentration gradient?
NO
214
All cells contain carrier proteins called..?
ion pumps
215
What is an EXCHANGE PUMP?
When more than one kind of ion is transported by a carrier protein in OPPOSITE DIRECTIONS
216
What are the 2 principle cations in body fluids?
Sodium and potassium
217
Sodium ion concentrations are high in ____ but low in ____
high in the extracellular fluids, but low in the cytoplasm
218
Homeostasis within the cell depends on the ejection of sodium ions and the recapture of potassium ions. This exchange occurs by a...?
sodium-potassium exchange pump
219
What phrase do you use to remember # sodium/potassium ions?
2 k in, 3 na out
220
What is secondary active transport?
energy doesn't come from ATP, but from a sodium ion gradient (or any substrate)that was produced by ATP
221
Is the sodium potassium exchange pump an example of primary or secondary active transport? why?
primary active transport because the pump directly uses ATP to function
222
Vesicular transport is known as ____transport. Why?
bulk. Tiny droplets of fluid and solutes are transported rather than single molecules
223
What are the 2 major categories of vesicular transport?
endocytosis and exocytosis
224
What are the 3 major types of endocytosis?
1. Receptor-mediated endocytosis
2. Pinocytosis
3. Phagocytosis
225
Endocytic vesicles are generally known as....
endosomes
226
In receptor mediated endocytosis, what are the molecules called that bind to the receptors?
Ligands
227
What are coated vesicles?
endosomes that are formed when receptors are covered with ligands and pinch off the plasma membrane
228
coated vesicles fuse with _____ to form ____
primary lysosomes to form secondary lysosomes
229
Which 2 important molecules enter the cell through receptor mediated endocytosis?
iron and cholesterol
230
What is pinocytosis?
Formation of endosomes filled with extracellular fluid
231
Are receptors and ligands involved in the process of pinocytosis?
NO
232
In phagocytosis, material is brought into the cell enclosed in a _____
phagosome
233
Phagocytosis is performed by what kind of cells?
macrophages
234
Describe the process of carrier -mediated transport
Integral proteins bind specific ions or organic substrates and carry them across the plasma membrane. They are specific, have saturation limits, and are regulated (by hormones)
235
During digestion in the stomach, hydrogen ions rise to higher levels than in the cells lining the stomach. Which transport process must be operating?
Active transport process because energy must be used to transport something against its concentration gradient
236
Describe endocytosis
The movement of relatively large volumes of extracellular material into the cytoplasm via the formation of a membranous vesicle
237
Phagocytosis mainly moves which 2 things?
bacteria and debris
238
Describe exocytosis
The ejection of cytoplasmic materials by the fusion of a membranous vesicle with the plasma membrane
239
What is the process by which certain types of white blood cells engulf bacteria?
phagocytosis
240
Does the inside of the plasma membrane have a slight positive or negative charge with respect to the outside?
slight negative charge
241
What is transmembrane potential?
the potential difference across a plasma membrane
242
What is potential difference?
When positive and negative charges are held apart
243
What is the unit of measurement for potential difference?
millivolts
244
If the plasma membrane were freely permeable to sodium ions, how would the transmembrane potential be affected?
the transmembrane potential would move closer to zero
245
What is the genetically controlled death of cells?
apoptosis
246
What is DNA replication?
the duplication of the cell's genetic material
247
When does DNA replication begin?
When enzymes (helicases) unwind the strands
248
In what stage of the cell cycle does DNA replication occur?
interphase
249
What is the function of the enzyme ligase in DNA replication?
splices segments of the lagging strand together
250
DNA polymerase can oly build in which direction?
5' - 3'
251
How many stages of interphase are there and what are they?
3 - G1, S, G2
252
In which phase of interphase does DNA replication occur?
S phase
253
The completion of which process marks the end of cell division?
cytokinesis
254
When does the cytokinesis process usually begin?
late anaphase
255
What is the correct sequence of events during mitosis?
prophase, anaphase, metaphase, telophase
256
How can the frequency of cell division be estimated?
by the number of cells in mitosis at any time
257
What term is used to discuss the rates of cell division?
mitotic rate
258
The longer the life expectancy, the _____ the mitotic rate
slower
259
What is the only function of stem cells?
the production of daughter cells
260
Do dividing cells use energy?
YES - unusually large amounts
261
Describe interphase and identify its stages
interphase is the portion of a cell's life cycle in which the chromosomes are uncoiled and all normal cell functions except MITOSIS are underway. G1,S,G2,G0
G0=not preparing for cell division
262
A cell is actively manufacturing enough organelles to serve 2 functional cycles. This cell is probably in what phase of its life cycle?
G1
263
What would happen if spindle fibers failed to form in a cell during mitosis?
the cell would not be able to separate the chromosomes into 2 sets. if cytokinesis occurred, the result would be 1 cell with 2 sets of chromosomes and 1 cell with none
264
In which phase of mitosis is the nucleus disassembled?
metaphase
265
In which phase of mitosis do nuclei start to form on either side of the cell?
telophase
266
Where do the 3 checkpoints occur during the cell cycle?
G1, G2, M (during metaphase to ensure the chromosomes are lined up in the middle correctly)
267
If a cell fails at any checkpoint and cannot repair itself, what happens to it?
apoptosis
268
M-phase promoting factor is assembled from which 2 parts?
CDC2, cyclin
269
What does MPF do?
promotes the process of cell division (mitosis)
270
When will MPF appear in the cytoplasm and promote mitosis?
When cyclin levels are high
271
When do cyclin lvels increase?
As the cell life cycle proceeds
272
What can stimulate the division of specific types of cells?
various extracellular compounds, generally peptides
273
What is the term for a group of proteins stimulating the the division of specific types of cells?
growth factors
274
What are repressor genes?
Genes that inhibit cell division
275
What is an important tumor suppressor protein?
p53
276
What are the DNA-protein complexes that form caps at the end of chromosomes?
telomeres
277
Define growth factor, and identify several growth factors that affect cell division
A growth factor is an extracellular compound such as a peptide or hormone that can stimulate the division of specific cell types.
ex: chalones, EGF, FGF, NGF
278
What is another name for a tumor?
a neoplasm
279
If a tumor is benign, the cells usually remain within.....
the epithelium or connective tissue capsule
280
the tumor of origin is called the _______ and the spreading process is called _____
primary tumor, invasion
281
What is metastasis?
The dispersion of malignant cells to other tissues and organs, establishing a secondary tumor
282
When do normal cells become malignant?
When a mutation occurs in a gene involved in cell growth, differentiation, or division
283
The modified, malignant genes are called...?
oncogens
284
Do cancer cells use energy efficiently?
no - they grow and multiply at the expense of healthy tissues
285
Define differentiation
Differentiation is the gradual appearance of characteristic cellular specializations during development. It results from gene activation or repression
286
The process that transports solid objects such as bacteria into the cell is called...?
phagocytosis
287
Plasma membranes are said to be...
SELECTIVELY permeable
288
In a resting transmembrane potential, the inside of the cell is _____ and the cell exterior is ______
inside is slightly negative, exterior is slightly positive
289
Our somatic nuclei contains ____PAIRS of chromosomes
23
290
What is osmosis?
The movement of water across a membrane from an area of low solute concentration to an area of higher solute concentration
291
The interphase of the cell life cycle is divided into:
G0, G1, S, G2
292
List the 4 basic concepts that make up the modern day cell theory.
1. cells are produced from the division of pre existing cells
2. Cells are the building blocks of all plants and animals
3. Cells are the smallest units that perform all vital physiological functions
4. Each cell maintains homeostasis at the cellular level
293
What are the 4 general functions of the plasma membrane?
1. Physical isolation
2. Regulation of exchange with the environment
3. Sensitivity
4. Structural support
294
By what THREE major transport mechanisms do substances get into and out of cells?
1. Diffusion
2. Carrier-mediated transport
3. Vesicular transport
295
Diffusion is important in body fluids because it.....
eliminates local concentration gradients
296
Microvilli are found...
in cells that are actively engaged in absorption
297
The sodium-potassium exchange pump is composed of.....
a carrier protein located in the plasma membrane
298
If a cell lacked ribosomes, it would not be able to---
synthesize proteins
299
List the phases of the interphase stage and briefly describe what happens in each
G0: normal cell functions
G1: cell growth, duplication of organelles, protein synthesis
S: DNA replication and synthesis of histones
G2: protein synthesis
300
What is cytokinesis?
Cytoplasmic movement that separates 2 daughter cells
301
What is the role of cytokinesis in the cell cycle?
completes cell division
302
In facilitated diffusion....
-energy is not required
-substances move in the direction of their concentration gradient
-at concentrations above a given level, rate of diffusion does not increase
303
Solutions A and B are separated by a selectively permeable barrier. Over time, the level of fluid on side A increases. Which solution initially had the higher concentration of SOLUTE
A
304
What is the benefit of having some of the organelles enclosed by a membrane similar to that of the plasma membrane
-the isolation allows them to make and store secretions, enzymes, or toxins that would otherwise adversely affect the cytoplasm
-increased efficiency of having specialized enzyme systems concentrated in one place
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