Chapter 3 Flashcards
(146 cards)
1
Q
prokaryotic cells
A
simple cells with no nucleus
2
Q
eukaryotic cells
A
complex cells with a nucleus & sub cellular structures (organelles)
3
Q
all eukaryotic cells are composed of (3) main parts
A
1) plasma membrane
2) cytoplasm
3) nucleus
4
Q
1) plasma membrane
2) cytoplasm
3) nucleus
A
1) outer boundary & separates cells internal environment from outside
2) gelatin-like substance + structural fibers b/w pm & nucleus - includes organelles (not nucleus)
3) contains genetic library of cell
5
Q
cytoplasm
(2) components
A
1) cytosol - fluid portion
2) organelles - subcellular structure embedded in cytosol
6
Q
Plasma Membrane - functions
A
covers, protects, controls in/outflow, links to other cells, tells other cells who it is (flying flags)
7
Q
Fluid Mosaic Model
A
arrangement of molecules within the membrane
- resembles sea of phospholipids with protein “icebergs” floating in it
- Lipids act as barrier to certain polar substances
- proteins act as gatekeepers, allowing passage of specific molecules/ions
8
Q
phospholipids
A
form lipid bilayer - cholesterol & glycolipids
9
Q
Integral proteins
A
extend into/through bilayer
10
Q
(2) Integral proteins
A
transmembrane
peripheral
11
Q
Transmembrane proteins
A
(most integral proteins) span the entire lipid bilayer.
12
Q
Peripheral proteins
A
attach to inner or outer surface but don’t extend through membrane
13
Q
Structure of the membrane
A
phosphlipids
integral proteins
2 back-2-back layers of phospholipid molecules (& cholesterol & glycoproteins)
polar head faces water on inside & outside
14
Q
the plasma membrane’s arrangement is due to…
A
amphipathic nature of lipid molecules
15
Q
Glycoproteins
A
membrane proteins with carb group attached that protrude into ECF
16
Q
Glycocalyx
A
entire sugar-coating surrounding membrane
- carb portion of glycolipids & glycoproteins
-
17
Q
Glycocalyx enables…
A
WBCs to detect foreign organisms, allows cells to adhere to one another & protects cells from enzymes in ECF
18
Q
Functions of the membrane (5)
A
ion channels carrier receptor enzymes cell-identity markers
19
Q
Examples of different membrane proteins include (6)…
A
1) ion channels (integral)
2) carriers (integral)
3) receptors (integral)
4) enzymes (integral & peripheral)
5) linkers (int. & perip)
6) cell-identity markers (glycoprotein)
20
Q
1) ion channels (integral)
A
allow ions to move through water-filled pore
21
Q
2) carriers (integral)
aka transporters
A
carries specific substances across membrane by changing shape
(ex. amino acids)
22
Q
3) receptors (integral)
A
recognizes specific ligand & alters cells functions in some way.
23
Q
4) enzymes (integral & peripheral)
A
catalyzes rxn inside or outside cell (depending on which direction active site faces)
24
Q
5) linkers (int. & perip)
A
anchors filaments inside & outside PM providing structural stability & shape for cell
- may also help movement or link 2 cells together
25
6) cell-identity markers (glycoprotein)
distinguishes your cells from anyone else's
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selective permeability
membrane allows some substances across (small, non polar) but not others (large, polar)
27
Rule of Thumb about Selective Permeability
small neutrally-charged lipid-soluble substances can freely pass
28
Exception to the Rule of Thumb about Selective Permeability
Water is a special case
| - highly polar but still can pass b/c of its small size
29
How do impermeable substances cross the PM?
transmembrane proteins that act as channels & transporters
30
[O2] & [Na+]
a) inside cell (cytosol)
b) outside cell (ECF)
a) [lower]
| b) [higher]
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[CO2] & [K+]
a) inside cell (cytosol)
b) outside cell (ECF)
a) [higher]
| b) [lower]
32
Charge of:
a) inner cell surface
b) outer cell surface
a) negatively charged
| b) positively charged
33
the negative charged inner surface and the positively charged outer surface creates a...
electrochemical gradient (membrane potential)
34
Transport Processes
passive processes
| active processes
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Passive processes (3)
a) diffusion of solutes
b) diffusion of water (osmosis)
c) facilitated diffusion
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Diffusion
passive spread of particles through random motion from areas of [high] to [low]
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Diffusion is affected by the amount of ___ & ___ of ___ ___
substance & steepness of concentration gradient
38
Diffusion is also affected by (3)
1) temperature (fever)
2) surface area (emphysema)
3) diffusion distance (pneumonia)
39
Passive Transport Processes - types of diffusion (3) (not including osmosis)
a) simple diffusion
b) channel-mediated facilitated diffusion
c) carrier-mediated facilitated diffusion
40
a) simple diffusion
when substances move through lipid bilayer without transport proteins
- non-polar hydrophobic molecules move this way
41
b) channel-mediated facilitated diffusion
process where solutes move down [gradient] through membrane channel
- small hydrophillic molecules
- gates operate randomly or mediated by electrical/chemical changes
42
c) carrier-mediated facilitated diffusion
process where carrier protein moves solute down [gradient]
- solute binds to carrier on one side & is released on other side when carrier changes shape
(# of carriers limit speed)
43
Is Simple Diffusion or Channel-Mediated Facilitated Diffusion slower? Why?
Channel-mediated facilitated diffusion is slower b/c of small SA of transmembrane protein
44
Example of channel-mediated facilitated diffusion
passage of K+ ions through gated K+ channel
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Example of carrier-mediated facilitated diffusion
glute 4 transportes
| - passage of glucose across cell membrane
46
Osmosis
net movement of water through selectively permeable membrane from area of high [water] concentration to one of lower [water]
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Osmosis only occurs when..
membrane is permeable to water & not solute
48
water can pass through PM in (2) ways
1) through lipid bilayer (by simple diffusion)
| 2) through aquaporins (integral membrane proteins)
49
osmotic pressure
force generated by movement of water from [high] to [low] of water
**minimum pressure which needs to be applied to solution to prevent inward flow of water across a semipermeable membrane**
50
Active transport processes
transportation of solutes against concentration gradient by using energy
51
Primary active transport
ATP changes shape of carrier protein which pumps substance across membrane against gradient
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Primary active transporters are also known as...
pump
53
Cells expend __%of the ATP they produce on primary active transport
~40%
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Primary active transport
| - pushes __ out & __ into cell in order to maintain...
Na+ out
K+ in
to maintain low [Na+] inside cell & [K+] outside
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secondary active transport (co-transport)
energy stored in Na+ or H+ gradient is used to drive other substances across their own gradients
- indirectly uses energy from ATP
56
Secondary Active Transport Mechanisms (2)
1) Antiporters
| 2) Symporters
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1) Antiporters
carry 2 substances across membrane in opposite directions
58
2) Symporters
carry 2 substances across membrane in same direction
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Example of Antiporter
Na+ in
Ca2+ out
Na+ in
H+ out
60
Example of Symporter
Na+ & glucose/amino acid in
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Vesicle
small spherical sac formed by budding off from membrane
62
Endocytosis
materials move into a cell in a vesicle formed from the plasma membrane
63
(3) types of Endocytosis
1) receptor-mediated endocytosis
2) phagocytosis
3) bulk-phase endocytosis (pinocytosis)
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Exocytosis
materials move out of cell by fusion of vesicle formed inside cell with PM - releases contents into ECF
65
Transcytosis
combination of endocytosis & exocytosis
66
Receptor-Mediated Endocytosis - steps
1) binding
2) vesicle formation
3) uncoating
4) fusion with endosome
5) recycling of receptors to PM
6) degradation in lyosome
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Receptor-Mediated Endocytosis
1) binding
2) vesicle formation
3) uncoating
4) fusion with endosome
5) recycling of receptors to PM
6) degradation in lyosome
1) LDL particle binds to receptor
2) invagination of clathrin-coated PM to form vesicle
3) uncoating of clathrin
4) fusion of vesicle with endosome
5) receptors are recycled back to PM
6) lysosomes degrade remaining molecules
68
Phagocytosis
pseudopods engulf microbe attached to
- forms phagosome, fuses with lysosome
lysosomal enzymes digest leaving residual body
- secreted via exocytosis or remain stored in cell as lipofuscin granules
69
Pinocytosis (bulk-phase endocytosis)
non-specific - inward folding of PM forms vesicle containing droplet of ECF
- vesicle detaches from PM & enters cytosol
-fluid & dissolved solutes in vesicle
fusion of lysosome & vesicle -
digestion of solutes by lysosmal enzymes
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(2) Components of the cytoplasm
1) cytosol
| 2) organelles
71
1) cytosol
intracellular fluid surrounding organelles
75-90% water
- site of many chemical rxns which provide building blocks for cell maintenance, structure, function & gowth
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2) organelles
Specialized structures within the cell, each with specific enzymes
73
Cytoskeleton
network of protein filaments throughout cytosol
| that provides structural support for cell
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(3) types of protein filaments of the Cytoskeleton
1) microfilaments
2) intermediate filaments
3) microtubules
75
1) microfilaments
thinnest
- composed of proteins actin & myosin
functions in structure (provides support) & movement (muscle contractions)
76
2) intermediate filaments
second largest/widest
| - help stabilize organelles & attach cells to one another
77
3) microtubules
Largest
- composed of protein tubulin
- attached to centromeres
- help determine cell shape
- function in movement of organelles/xsomes/cilia/flagella
78
Centrosome
located near nucleus, consists of 2 centrioles (right angles) & periocentriolar material
- organizing centre important in cell division
79
Cilia
short, hair-like projections from the cell surface, move fluids along a cell surface
80
Flagella
longer than cilia, move an entire cell
| only example is the sperm cell’s tail
81
endoplasmic reticulum
network of membrane in shape of flattened sacs/tubules
82
ribosomes
site of protein synthesis
83
Rough ER
series of membrane sacs connected to nuclear envelope
| - surface studded with ribosomes to produce proteins
84
Smooth ER
network of membrane tubules, no ribosomes but contains enzymes that play key role in synthesis of FAs & steroids, detox of certain drugs (alcohol)
85
Golgi complex
consists of 3-20 flattened, membranous sacs called cisternae
86
Cisternae
the flattened, membranous sacs of the Golgi Complex
87
Golgi Complex - proteins & packaging
1) transport vesicle from rough ER transported to cis face
2) fuse with cis face membrane & empty contents into lumen
3) proteins are modified (enzymes add carbs (glycoprotein) or lipids (lipoprotein) in the medial cistern
4) sort & package proteins for transport to different destinations on trans face
88
proteins are sorted & packaged into (3) vesicles
1) secretory - proteins exported from cell by exocytosis
2) membrane - proteins in vesicle membrane merge with PM
3) transport - to bind with lysosome
89
Lysosomes
vesicles formed from Golgi complex that contain powerful digestive enzymes that break down molecules within vesicles formed during endocytosis
90
(2) mechanisms of lysosomes
1) autophagy
| 2) autolysis
91
1) autophagy
the process of engulfing other organelles, digesting them & returning their components to the cytosol
92
2) autolysis
process of destroying cells that contain them
93
Peroxisomes
| found where?
organelles smaller than lysosomes that detoxify (contain oxidases) several toxic substances
- abundant in the liver
94
Proteasomes
- function
- location
- contain
continuously destroy unneeded, damaged or faulty proteins
- found in cytosol & nucleus
- contain proteases that breakdown proteins in aa for recycling
95
Mitochondria
generate. .
have. .
powerhouse of cell
- generate ATP through aerobic respiration
- self-replicate
- contain own DNA (from mother)
- have inner & outer mito. membrane with folds in inner membrane (cristae) & a central fluid-filled cavity (matrix)
96
Mitochondria are more prevalent in which cells?
physiologically active cells such as muscle, liver & kidney cells
97
– How would you increase the # of mitochondria in muscle cells?
aerobic activity/exercise at a lower intensity
98
Cristae
series of folds of the inner membrane
99
Matrix
large central fluid-filled cavity
100
Mitochondria self-replicate when? (2)
during times of increased cellular demand or before cell division
101
Mitochondria are located ?
within cell where O2 enters or ATP is used
102
Where are the enzymes that catalyze cellular respiration located in the mitochondria?
located on the cristae & in matrix
103
Nucleus
spherical/oval structure with a nuclear envelope, nuclear pores, nucleoli, genes & chromosomes
104
Nuclear Envelope
double membrane that separates nucleus from cytoplasm (outer membrane continuous with rough ER)
105
Nuclear pores
numerous opening in nuclear envelope that control movement of substances b/w nucleus & cytoplasm
106
Nucleoli
spherical body in nucleus that produces ribosomes
107
Genes
cells hereditary units arranged along xsomes
| - that control activities & structure of cell
108
Chromosomes
long molecules of DNA combined with protein molecules
109
Transcription
DNA → RNA → mRNA
promotor region initiates transcription of gene
RNA polymerase unwinds double helix and adds matching RNA nucleotides until terminator sequence is reached
110
Translation
| (1) initiation
mRNA → protein
initiation begins when small subunit of ribosome attaches to 5' end cap & moves to initiation site
- tRNA with complementary anticodon binds to start codon (AUG).
- large subunit now binds to create P & A site.
111
Translation
| (2) elongation
- a 2nd tRNA occupies P site.
- aa from first tRNA (met) is transferred to A site aa & then exits.
- ribosome moves along mRNA (shifting 2nd tRNA to P site) & next tRNA enters
- growing peptide continuously transferred to A-site tRNA
112
Translation
| (3) termination
- continues until stop codon is encountered & release factor enters A site
- translation terminated →ribosome dissociates & newly formed polypeptide (protein) is released
113
Somatic Cell Division - Mitosis
each daughter cell is genetically identical to the parent cell
114
Somatic cells
any cell other than a germ cell (reproductive cell)
115
Cell Cycle
sequence of events in which a body cell duplicates its contents & divides into 2
116
Human somatic cells contain ___ pairs of xsomes
23
| total of 46
117
homologous xsomes (homologs)
the 2 xsomes that make up each pair
118
diploid cells
somatic cells that contain 2 sets of xsomes
119
Cell Division - Cell Cycle
| (2) phases
1) Interphase
| 2) Mitotic phase
120
1) Interphase
cell is NOT dividing
- replicates its DNA
consists of (3) phases
121
(3) phases of Interphase
1) G1
2) S
3) G2
122
1) G1
1) metabolically active, duplicates organelles & cytosolic components, centrosome replication begins
123
2) S
DNA replicated
124
3) G2
reaches max size
- centrosome replication completed
- enzymes & proteins synthesized
125
length of time for
1) G1
2) S
3) G2
a) 8-10 hours
b) 8 hours
c) 4-6 hours
126
2) Mitotic Phase
consists of nuclear division (mitosis) & cytoplasmic division (cytokinesis) to form 2 identical cells
127
Nuclear Division: MITOSIS
| (4) phases
1) prophase
2) metaphase
3) anaphase
4) telophase
128
1) prophase
chromatin fibers condense into xsomes
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2) metaphase
microtubules align centromeres of chromatid pairs at metaphase plate
130
3) anaphase
chromatid pairs split at centromere & move to opposite poles of cell
131
4) telophase
2 identical nuclei are formed around identical sets of xsomes now in their chromatin form
132
Cytokinesis
division of cells cytoplasms to form 2 identical cells
133
When do Cytokinesis begin?
usually in late anaphase (before telophase)
134
Cytokinesis: process
plasma membrane constricts at its middle forming a CLEAVAGE FURROW
- cells eventually splits into 2 daughter cells
135
Once Cytokinesis is complete, what happens?
Interphase begins
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average adult has __ __ cells
nearly 100 trillion
137
__ different types of cells
200
138
cellular diversity permits __ of cells into more __ __ & __
organization
| complex tissues & organs
139
largest human cell
female egg cell - about the diameter of a human hair
140
telomeres
DNA sequences found at tips of each xsome
141
Telomeres - function/purpose
protect xsomes from sticking to one another & from erosion
142
Aging & Telomeres - shortening
normal cell divison shortens telomeres & after many years telomeres become significantly shorter
- also stress shortens telomeres
143
Aging & Glucose
glucose is added to proteins creating crosslinks with neighbouring proteins - decreases elasticity
144
Immune System & Aging
may attack bodies cell
| - caused by changes in cell-indentity markers thus marking cell for destruction
145
Hydrostatic pressure
pressure which is exerted on portion of a column of water as a result of the weight of the fluid above it
pressure exerted by a fluid at equilibrium at given point within the fluid, due to force of gravity
146
Sodium-Potassium Pump
works to maintain a [low Na+ ] and a [high K+] in cytosol
- binding of 3 Na+ triggers hydrolysis of ATP & phosphorylates pump protein
- reaction changes shape of pump protein, expelling 3 Na+ into ECF & binds 2 K+
- triggers release of P which causes shape change & releases the 2 K+ into cytosol
