ch 3 cells Flashcards
(138 cards)
1
Q
three main parts of a cell
A
plasma membrane
cytoplasm
nucleus
2
Q
plasma membrane
A
forms the cell’s flexible outer surface, separating the cell’s internal environment from the external environment
3
Q
plasma membrane functions
A
- selective barrier that regulates the flow of material into and out of a cell
- helps establish and maintain the appropriate environment for normal cellular activities
- communication among cells and between cells and their external environment
4
Q
cytoplasm
A
consists of all the cellular contents between the plasma membrane and the nucleus
5
Q
two components of the cytoplasm
A
cytosol and organelles
6
Q
cytosol
A
the fluid portion of cytoplasm, contains water, dissolved solutes, and suspended particles
7
Q
organelles
A
“little organs” that are surround by cytosol
8
Q
nucleus
A
a large organelle that houses most of the cell’s DNA
9
Q
gene
A
hereditary units
10
Q
fluid mosaic model
A
molecule arrangement of the plasma membrane that resembles an ever moving sea of fluid lipids that contains a mosaic of many different proteins
11
Q
lipid bilayer
A
the basic structural framework of the plasma membrane
two back to back layers made up of three types of lipid molecules (phospholipids, cholesterol, and glycolipids)
12
Q
phospholipids
A
lipids that contain phosphorus
about 75% of membrane proteins
13
Q
cholesterol
A
a steroid with an attached -OH group
about 20% of membrane proteins
14
Q
glycolipids
A
lipids with attached carb groups
about 5% of membrane proteins
15
Q
amphipathic
A
have both polar and nonpolar parts
16
Q
integral proteins
A
extend into or through the lipid bilayer among the fatty acid tails and are firmly embedded in it
17
Q
transmembrane proteins
A
span the entire lipid bilayer and protrude into both the cytosol and ecf
18
Q
peripheral proteins
A
not as firmly embedded in the membrane
associate more loosely with the polar heads of membrane lipids or with integral proteins at the inner or outer surface of the membrane
19
Q
glycoproteins
A
proteins with carb groups attached to the ends that protrude into the ecf
20
Q
glycocalyx
A
extensive sugary coat on carbohydrate portions of glycolipids and glycoproteins
21
Q
ion channels
A
- integral
forms a pore through which a specific ion can flow to get across membrane
22
Q
carrier/transporter
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- integral
transport a specific substance across membrane by undergoing a change in shape
23
Q
receptors
A
- integral
recognizes specific ligand and alters cell’s function in some way
24
Q
ligand
A
a specific molecule that binds to a receptor
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enzyme
- integral and peripheral
catalyzes reaction inside or outside cell
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linker
- integral and peripheral
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
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glycoprotein
- cell identity marker
enable a cell to recognize other cells of the same kind during tissue formation or to recognize and respond to potentially dangerous foreign cells
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functions of the membrane proteins (5)
- ion channels (integral)
- carrier (integral)
- receptors (integral)
- enzyme (integral and peripheral)
- linker (integral and peripheral)
- cell identity marker
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cytosol
the fluid portion of the cytoplasm that surrounds organelles and constitutes about 55% of the total cell volume
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organelles
tiny specialized structures within the cell that have characteristic shapes
- perform specific functions in cellular growth, maintenance, and reproduction
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ribosomes
the sites of protein synthesis
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ribosomal RNA
type of RNA that makes up ribosomes
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free ribosomes
unattached to any structure in the cytoplasm
synthesize proteins used in the cytosol
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bound ribosomes
attached to the outer surface or the ER and nucleus
synthesize proteins destined for export from the cell for insertion in the plasma membrane or for specific organelles within the cell
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ER
a network of membranes in the form of flattened sacs of tubules
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rough ER
extends from the nuclear envelope (membrane around the nucleus) and is folded into a series of flattened sacs
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rough ER produces...
secretory proteins, membrane proteins, and many organellar proteins
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smooth ER
extends from the rough ER to form a network of membrane tubules
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smooth ER synthesizes...
fatty acids and steroids like estrogens and testosterone
40
golgi complex
consist of 3 to 20 cisternae, small flattened membranous sacs with bulging edges that resemble a stack of pita bread
- further modifies proteins received from the rough ER
- once the proteins are modified, the golgi sorts and packages them into membrane-enclosed vesicles for transport to another destination
41
8 steps of the Golgi complex
1. proteins synthesized by ribosomes on the rough ER are surrounded by a piece of the ER membrane, which eventually buds from the membrane surface to form transport vesicles
2. transport vesicles move toward the entry face of the golgi complex
3. fusion of several transport vesicles creates the entry face of the golgi complex and releases proteins into its lumen
4. the porteins then move from the entry face into the lumen of the medial cisternae and then into the lumen of the exit face. as the proteins move through the cisternae, they are chemically modified
5. after the proteins are modified, they are sorted and packaged
6. some of the process proteins leave the exit face and are stored in secretory vesicles. these vesicles deliver the proteins to the plasma membrane, where they are discharged by exocytosis into the EFC
7. other processed proteins leave the exit face in membrane vesicles that deliver their contents to the plasma membrane for incorporation into the membrane
8. finally, some processed proteins leave the exit face in transport vesicles that will carry the proteins to other organelles such as lysosomes
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mitochondria
generate most of the ATP through aerobic respiration
- consist of an outer mitochondrial membrane and an inner mitochondrial membrane with a small space, intermembrane space, between them
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cristae
series of folds that make up the inner mitochondrial membrane
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matrix
the central fluid-filled cavity of a mitochondrion, enclosed by the inner mitochondrial membrane
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lysosomes
membrane-enclosed vesicles that contain digestive enzymes that break down a wide variety of molecules once lysosomes fuse with vesicles formed during endocytosis
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endocytosis
the process by which materials move into a cell in a vesicle formed from the plasma membrane
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autophagy
the process by which entire worn-out organelles are digested
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autophagosome
vesicle that is membrane derived from the ER that organelle to be digested is enclosed by
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autolysis
process by which lysosomal enzymes destroy the entire cell that contains them
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peroxisomes
contain oxidases and catalase to oxidize for metabolism and detoxify damaging substances
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proteasomes
tiny barrel-shaped structures consisting of four stacked rings of proteins around a central core
- function is the continuous destruction of unneeded, damaged, or faulty proteins
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cytoskeleton
network of protein filaments that extends throughout the cytosol
- provides structural framework, aids in movement of the whole cell and components of the cell
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three components of the cytoskeleton
- microfilaments
- intermediate filament
- microtubules
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microvilli
nonmotile, microscopic fingerlike projections of the plasma membrane that increase surface area of the cell in increase absorption
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intermediate filaments
found in parts of cells subject to mechanical stress and help stabilize the position of organelles
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microtubules
- largest of the components
- long, unbranched hollow tubes composed mainly of the protein tubulin
- assembly begins in centrosome, grow outward toward the periphery of the cell
function to help determine cell shape and in movement of organelles, secretory vesicles, chromosomes, and specialized cell projections such as cilia and flagella
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centrosome
located near the nucleus, consist of two components: a pair of centrioles and pericentriolar material
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centrioles
cylindrical structures, each composed of nine clusters of three microtubules arranged in a circular pattern
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pericentriolar material
surround the centrioles, composed of the protein tubulin - organizing centers for the mitotic spindle
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cilia
numerous, short, hairlike projections that extend from the surface of certain types of cells that propel fluids across the surfaces of cells that are firmly anchored in place
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basal body
similar in structure to a centriole and functions in initiating the assembly of cilia and flagella
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flagella
similar in structure to cilia but are typically longer and usually move an entire cell
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nucleus
houses most of the cell's DNA, which contains hereditary units called genes that control cellular structure and direct cellular activities
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nuclear envelope
double membrane that separates the nucleus from the cytoplasm
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nuclear pores
openings that extend through the nuclear envelope
- allow certain substances to move between the nucleus and the cytoplasm
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nucleoli
sites of synthesis of rRNA and assembly of rRNA and proteins into ribosomal subunits
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chromatin
complex of DNA and proteins, packages long DNA molecules into more compact, denser structures
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structure/components of chromatin
bead-on-a-string structure
- bead is a nucleosome - consists of DNA wrapped twice around a histone which help organize the coiling and folding of DNA
- string is linker DNA - holds adjacent nucleosomes together
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chromosomes
short, thick structures that carry genetic info in the form of genes
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sister chromatids
identical strands that make up a single chromosome
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centromere
connection point between sister chromatids
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genome
the total genetic info carried in a cell of an organism
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proteome
all of an organism's proteins
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gene expression
gene's DNA is used as a template for synthesis of a specific protien
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transcription
info encoded in a specific region of DNA is copied into a specific molecules of RNA
- occurs in the nucleus
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translation
RNA attaches to a ribosome, where the info contained in RNA is used to direct the assembly of amino acids into a protein
- occurs in the nucleus
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base triplet
a sequence of three such nucleotides in DNA
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codon
each DNA base triplet is transcribed into RNA as a complementary sequence of three nucleotides
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genetic code
set of rules that relate the base triplet sequence of DNA to the corresponding codons of RNA and the amino acids they specify
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three types of RNA made from the DNA template
1. mRNA - directs the synthesis of a protein
2. rRNA - joins with ribosomal proteins to make ribosomes
3. tRNA - translates the genetic code from mRNA into amino acids
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RNA polymerase
catalyzes transcription of DNA
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promoter
special nucleotide sequence located near the beginning of a gene where transcription begins
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terminator
special nucleotide sequence which specifies the end of the gene
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intron
regions within a gene that do not code for parts of proteins
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exons
regions that do code for segments of a protein
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pre-mRNA
transcript that includes both introns and exons
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small nuclear ribonucleoproteins (snRNPs)
remove the introns in pre-mRNA and splice together the exons
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alternative splicing
process in which the pre-mRNA transcribed from a gene is spliced in different ways to produce several different mRNAs
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P (peptidyl) site
binds the tRNA carrying the growing polypeptide chain
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A (aminoacyl) site
binds the tRNA carrying the next amino acid to be added to the growing polypeptide
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e (exit) site
binds tRNA just before it is released from the ribosome
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polyribosome
several ribosomes attached to the same mRNA
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somatic cell division produces
two identical cells
- replaces dead or injured cells and adds new ones during tissue growth
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reproductive cell division produces
gametes
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somatic cell
any cell of the body other than a gamete
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gamete
a sperm cell or an egg
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two major phases of the cell cycle
interphase - when a cell is not dividing
mitotic phase - when a cell is dividing
100
homologous chromosomes/homologues
the two chromosomes of each pair
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main functions of interphase
- cell replicates its DNA
- produces additional organelles and cytosolic components in anticipation of cell division
- state of high metabolic activity
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three phases of interphase
G1 - replicates most of its organelles and cytosolic components but not DNA, replication of centrosomes begins
S - DNA replication occurs
G2 - cell growth continues, enzymes and other proteins are synthesized in preparation for cell division, replication of centrosomes is completed
103
two major parts of M phase
nuclear division (mitosis)
cytoplasmic division (cytokinesis)
104
mitosis
- prophase - chromatin condenses and centrosomes get pushed to the poles, nucleolus disappears and the nuclear envelope breaks down
- metaphase - microtubules of the mitotic spindle align
- anaphase - centromeres split
- telophase - chromosomes uncoil and revert to the threadlike chromatin form, nuclear envelope forms and nucleoli reappear
105
cytokinesis
formation of cleavage furrow begins in late anaphase and is completed after telophase. actin microfilaments form a contractile ring that pulls the plasma membrane progressively inward and ultimately pinches the cell in two
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cyclin-dependent protein kinases
enzymes that transfer a phosphate group from ATP to a protein to activate the protein
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cyclins
cellular proteins that are responsible for switching Cdks on and off
108
apoptosis
orderly, genetically programmed death
109
necrosis
a pathological type of cell death that results from tissue injury
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four basic types of tissue
epithelial
connective
muscle
nervous
111
epithelial tissue
covers body surfaces, lines hollow organs and ducts, and forms glands
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basement membrane
an extracellular structure that connects epithelial tissue to underlying connective tissue and provides support to epithelial cells
113
three major functions of epithelial tissue
1. serves as a physical barrier that protect against harmful agents in the environment
2. secretes substances onto the body surface or into hollow organs or the blood
3. absorbs material into the bloodstream or lymph
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two major types of epithelial tissue
covering and lining epithelium - forms the outer covering
glandular epithelium - makes up secreting portion of glands
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endocrine glands enter
the interstitial fluid and then diffuse directly into the bloodstream
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exocrine glands enter
ducts that empty onto the body or into the lumen of a hollow organ
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connective tissue
- binds together, supports, and strengthens other body tissues
- protects and insulates internal organs
- serves as the major transport system within the body
- the primary location of stored energy reserves
- main source of immune response
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two basic elements of connective tissues
extracellular matrix
cells
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three types of protein fibers embedded in the extracellular matrix
collagen fibers - strong and resist pulling forces
elastic fibers - strong but stretchy
reticular fibers - provide support and strength
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ground substance
material between the cells and fibers of connective tissues, can be fluid, gel, or solid
- supports cells, bind them together, stores water, and provides a medium through which substances are exchanged between the blood and cells
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fibroblasts
secrete fibers and ground substance of the extracellular matrix
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macrophages
engulf bacteria and cellular debris by phagocytosis
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plasma cells
secrete antibodies
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mast cells
produce histamine
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adipocyts
store triglycerides
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muscle tissue
consist of muscle fibers that are highly specialized to contract
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three types of muscle tissue
skeletal muscle - usually attached to bones; produce movement, maintain posture, generate heat
cardiac muscle - forms bulk of heart wall
smooth muscle - regulate movement of blood, food, air, urine
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nervous tissue
detect changes in the body's external or internal environment and then elicits an appropriate response
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two main types of nervous tissue
neurons/nerve cells
neuroglia
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neurons
sensitive to a variety of stimuli
convert action potentials and conduct these action potentials to other neurons, muscle fibers, or glands
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neuroglia
do not generate or conduct action potentials, but do have other important supportive functions
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cell junctions
contact points between the plasma membranes of tissue cells
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five types of cell junction
tight
adherens
desmosomes
hemidesmosomes
gap
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tight junctions
fuse together the outer surface or adjacent plasma membranes to seal off passageways between adjacent cells
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adherens junction
contain plaque, a dense layer of protein, that attaches both to membrane proteins and to microfilaments of the cytoskeleton to resist separation during contractile activities
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desmosomes
contain plaque and have cadherins that extend into the intercellular space between adjacent cell membranes and attach cells to one another to contribute stability
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hemidesomosomes
anchor cells not to each other but to the basement membrane
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gap junctions
connexins from connexons that connect neighboring cells. the plasma membranes are not fused together, through the connexons, ions and small molecules can diffuse from the cytosol of one cell to another
