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汉语一级 > cell bio exam > Flashcards

cell bio exam Flashcards

1
Q

Membrane lipids are important components of the “fluid” part of the __________________

A

fluid mosaic model

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2
Q

The fluid mosaic model of membrane structure…

A

retains the lipid bilayer of earlier models

However, there is a greater diversity and fluidity of lipids than originally thought

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3
Q

The main classes of membrane lipids are

A

phospholipids, glycolipids, and sterols

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4
Q

most abundant lipids in membranes ?

A

phospholipids

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5
Q

glycerol-based phosphoglycerides

sphingolipids

are examples of what?

A

Phospholipids

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6
Q

alcohols have –

A

1 hydroxyl (OH) group

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7
Q

chemical compounds with one hydroxyl group

A

alcohols

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8
Q

chemical compounds with two hydroxyl groups

A

diols

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9
Q

chemical compounds with three hydroxyl group

A

triols

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10
Q

chemical compounds with four hydroxyl groups

A

tetrols

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11
Q

chemical compounds with multiple hydroxyl groups

A

polyols

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12
Q

smooth ER stores ____ because [blank] is ______

A

smooth ER stores calcium bc Ca is highly reactive

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13
Q

function of Ca?

A

another on/off mechanism like phosphorylation

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14
Q

give example of Ca on/off mechanism

A

muscle contractions

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15
Q

ATP driven pumps take Ca to _______ where it’s stored and then released

A

smooth ER

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16
Q

________ take Ca to the smooth ER where it’s stored and then released

A

ATP driven pumps

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17
Q

smooth ER also produces

A

lipids, i.e. sterols

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18
Q

what does cortisol do

A

suppresses inflam & immune response

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19
Q

chronic stress preserves ________-

A

sugar for brain

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20
Q

chronic stress preserves sugar for brain. how?

A

breaks down muscle into AAs which are deaminated (broken down for energy) in Kreb’s cycle

this increases blood glucose

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21
Q

what do statins do

A

lower cholesterol

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22
Q

vitamin d is actually

A

a steroid hormone

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23
Q

to be a ‘secretion’ it probably requires

A

exocytosis

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24
Q

how do statins work

A

HMG-CoA reductase targeted

decreases smooth ER in liver’s ability to generate cholesterol

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25
Q

lipid rafts components?

A

cholesterol and sphingomyelin

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26
Q

define plasma membrane

A

membrane surrounding cell separating it from extracellular environment

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27
Q

lipid rafts are mainly found in which membranes

A

plasma membranes

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28
Q

Golgi analogy

A

post office (shipping and receiving side

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29
Q

CGN and TGN give acronyms

A

cis-golgi network and trans-golgi network

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30
Q

2 golgi models:

A

cisternae are stationary. mvmt around outside with vesicles

cisternal maturation model

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31
Q

Golgi – glycoproteins (many proteins you know)

A

A & B antigens in blood, insulin…

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32
Q

2 modifications where you can stick a carb to a protein – happens where

A

Golgi

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33
Q

2 modifications where you can stick a carb to a protein – give both

A

N-linked

O-linked

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34
Q

N-linked vs O-linked

define

A

N-linked – nitrogen

O-linked – oxygen

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35
Q

N-linked vs O-linked give all examples

A

N-linked – nitrogen – asparagine

O-linked – oxygen – serine or threonine

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36
Q

what’s a glycan

A

the carb portion of a glucoconjugate

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37
Q

glycosidic bond joins ___________

A

carb to another group

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38
Q

N-Linked glycans:

A

are attached in the endoplasmic reticulum to the nitrogen (N) in the side chain of asparagine (Asn) in the sequon

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39
Q

In _______, O-linked glycans are:

A

eukaryotes

assembled one sugar at a time on a serine or threonine residue of a peptide chain in the Golgi apparatus.

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40
Q

only AAs that can attach sugars

sugars ________

A

asparagine
serine and threonine

can accept a phosphate group

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41
Q

if something dissolves in H2O it can be subjected to ________

____ dissolve in water

therefore ______ are water-soluble

A

if something dissolves in H2O it can be subjected to osmosis

sugars dissolve in water

therefore glycoproteins are water-soluble

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42
Q

removal of misfolded proteins e.g. CFTR happens where

A

rough ER

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43
Q

phosphorylation of lysosomes happens where

A

Golgi

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44
Q

sulphonation =

A

add sulphate to tyronsine

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45
Q

give 3 things that happen in golgi

A

stick carb to protein (n-linked vs o-linked)
phosphorylation of lysosomes
LAST: sulphonation of tyrosine

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46
Q

mechanism for prevention of loss of rough ER proteins

A

retention vs retrieval tags

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47
Q

define constitutive

A

relating to an enzyme or enzyme system that is continuously produced in an organism, regardless of the needs of cells.

After budding from the TGN, some vesicles move directly to the cell surface and immediately fuse with the plasma membrane
This unregulated process is continuous and independent of external signals

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48
Q

2 examples each of constitutive vs NON constitutive production

A

constitutive:
albumin
intestinal mucosa

NON constitutive:
pancreatic enzymes
neurotransmitters

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49
Q

opposite of constitutive system

A

regulative

e.g. neurotransmitters

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50
Q

proteins and nuclear envelope?

A

proteins must be escorted in and out of nucleus

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51
Q

membranes are organised in ________ called _________

A

microdomains

lipid rafts

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52
Q

signal transduction =

A

binding to receptors

Simplified representation of major signal transduction pathways in mammals.
Signal transduction is the process by which a CHEMICAL OR PHYSICAL SIGNAL IS TRANSMITTED THRU A CELL as a series of molecular events,

–>most commonly protein phosphorylation catalysed by protein kinases,

–>which ultimately results in a cellular response.

Proteins responsible for detecting stimuli are generally termed receptors, although in some cases the term sensor is used.[1]

The changes elicited by ligand binding (or signal sensing) in a receptor give rise to a biochemical cascade, which is a chain of biochemical events known as a signalling pathway.

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53
Q

______ is missing from lipid and carb

A

N

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54
Q

limiting factor for protein synthesis

A

nitrogen

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55
Q

what small cellular molecules contain nitrogen

A

DNA, AAs

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56
Q

lipid
carb
protein

which cannot be converted in liver

A

you cannot convert lipid and carb into protein

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57
Q

3 time release fuel types

A

glucose – immediate
glycogen – intermediate (later)
fat – long (much later)

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58
Q

Golgi address labels are

A

proteins

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59
Q

can water go thru membrane? explain.

A

water can go through membrane, but there’s so much

you can leave class through the door or you can leave through the wall

AQUAPORIN

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60
Q

____ controls expression of proteins

A

RNA

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61
Q

AT – active transport

give 3 purposes

A
    • expend energy to collect vital nutrients
    • remove waste products (metabolic by-products can build up to toxic levels)
  • -generate a concentration gradient
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62
Q

biggest ATP drain in cell

A

Na-K pump

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63
Q

I would pit a lysosome against anything small except (3)**

A

TB, prions, viruses

**not really crucial

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64
Q

TB turns off _________-

A

H+ pump of lysosomes

theyre not at optimal pH

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65
Q

active transport: a pump ______ running

A

always

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66
Q

direct AT ____ATP

indirect AT ____ATP

A

direct active transport USES atp

indirect active transport doesn’t use atp

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67
Q

indirect AT=

A

active transport on one side

facilitated diffusion on the other

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68
Q

indirect and direct AT vs concentration gradient

A

indirect AT uses facilitated diffusion syn concentration gradient
direct AT moves against concentration gradient

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69
Q

simple diffusion, facilitated diffusion, & AT

give solutes transported

A

simple diff:

  • small polar (H2O, glycerol)
  • small nonpolar (CO2, O2)
  • large nonpolar (oils, steroids)

facilitated diff:

  • small polar (H2O, glycerol)
  • large polar (glucose)
  • ions (Na+, K+, Ca 2+)

active transport:

  • large polar (glucose)
  • ions (Na+, K+, Ca 2+)
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70
Q

simple diffusion, facilitated diffusion, & AT

direction related to electrochemical gradient?

A

simple diff: down
facilitated diff: down
AT: up

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71
Q

simple diffusion, facilitated diffusion, & AT

metabolic energy required?

A

no, no, yes

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72
Q

simple diffusion, facilitated diffusion, & AT

intrinsic directionality?

A

no, NO, yes

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73
Q

simple diffusion, facilitated diffusion, & AT

saturation kinetics?

A

no, yes, yes

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74
Q

simple diffusion, facilitated diffusion, & AT

competitive inhibition?

A

no, yes, yes

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75
Q

simple diffusion, facilitated diffusion, & AT

membrane protein required?

A

no, yes, yes

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76
Q

cancer cells can mutate to _____________ of chemo drugs

A

pump out or evacuate entire categories

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77
Q

saturation point – simple diffusion

A

No saturation point

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78
Q

describe simple diffusion

A

going thru semipermeable membrane
no transport proteins
no saturation point

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79
Q

give examples of diffusion **

A

milk in instant coffee

air freshener

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80
Q

saturation kinetics implies **

A

whether or not x substance is waiting to cross membrane (if x saturation has been met)

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81
Q

thermodynamic properties **

A

do you need to add energy to get them to react or will concentration gradient – direction relative to electrochemical gradient – render the change spontaneous

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82
Q

compare concentration gradient and intrinsic directionality

A

if following the concentration gradient there’s no intrinsic directionality

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83
Q

give properties of intrinsic directionality

A

desire to build a concentration gradient

will X always diffuse into the cell
will X always diffuse out of the cell

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84
Q

hypertonic solution has

A

more solute

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85
Q

ADH

A

antidiuretic hormone

more aquapores on membranes of kidneys

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86
Q

aquapore is made of

A

aquaporin protein

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87
Q

inside of cell is normally _______ charged

______ keeps charge more neutral

A

negatively

K+

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88
Q

action potential

____ floods in
____ floods out

previously ________ charge becomes ________

A

Na floods in
K floods out

previously – charge becomes ++

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89
Q

sodium is attracted to

A

negative charge inside cell

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90
Q

simple diffusion, facilitated diffusion, & AT

Na-K pumps are which

A

AT

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91
Q

AT is needed to move __________ _____ the concentration gradient

A

AT is needed to move large particles & ions against the concentration gradient

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92
Q

AT protein acts like ______

explain a little

A

an enzyme
saturation kinetics: same
competitive inhibition

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93
Q

indirect AT _______ require ATP

A

doesn’t necessarily

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94
Q

indirect AT eg

using diffusion of Na (from what?) to drive _______

A

using diffusion of Na following concentration gradient built by Na-K pump to drive glucose into cell

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95
Q

simple diffusion, facilitated diffusion, direct & indirect AT

mitochondrial membrane building a gradient is which

A

indirect active transport

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96
Q

v inward = PΔ[S] represents

A

permeability

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97
Q

PΔ[S] – define Δ[S]

A

concentration of substance outside cell minus concentration of same substance inside cell

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98
Q

v inward = PΔ[S]

facilitated diffusion?
at small concentration gradient (= ____ difference)
increased chance to ________

A

(per sec)

at small concentration gradient (small difference) there’s an increased chance (v fast) to bind

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99
Q

define uniport

A

port carries one type of substance

100
Q

give two other types of ports besides uniport

A

2 types of coupled transport

symport
antiport

101
Q

simple diffusion, facilitated diffusion, direct & indirect AT

symport and antiport are which types?

A

can be facilitated diff
can also be AT
(simultaneously)

102
Q

v inward = PΔ[S]

full description

A

.
v inward = rate of diffusion in moles/sec-cm^2
Δ[S] = [S] outside – [S] inside
P = permeability coefficient, which depends on thickness and viscosity of the membrane
Simple diffusion has a linear relationship between inward flux of solute and the concentration gradient of the solute

103
Q

ATPases are

A

Transport proteins driven by ATP hydrolysis!

a class of enzymes that catalyse the decomposition of ATP into ADP and a free phosphate ion or the inverse reaction. This de-phosphorylation reaction releases energy, which the enzyme (in most cases) harnesses to drive other chemical reactions that would not otherwise occur. This process is widely used in all known forms of life.

Some such enzymes are integral membrane proteins (anchored within biological membranes), and move solutes across the membrane, typically against their concentration gradient. These are called transmembrane ATPases.

104
Q

dephosphorylation reaction ______ energy

A

releases energy

105
Q

ATPases are a class of enzymes that catalyse the:

A

decomposition of ATP into ADP and a free phosphate ion or the inverse reaction.

106
Q

ATPases use energy derived from:

to power:

which in terms of a membrane looks like:

A

de-phosphorylation of ATP into ADP and PO4

other chem reactions that wouldn’t otherwise occur

ATPase is an integral membrane protein moving solutes across against concentration gradients

107
Q

name four classes of ATPase*

identify which pertain to the plasma membrane

A

P-type
plasma membrane!

V-type

F-type

ABC-type
plasma membrane!

*to assist with another question not important by itself

108
Q

name four classes of ATPase and give examples of solutes transported by each

A

P-type
cations including bigger metals and H+, phospholipids

V-type
H+

F-type
H+

ABC-type
in eukaryotes: exporters only
exports antitumour drugs, toxins, abx, and lipids

109
Q

give details about P-type ATPases

A

p for phosphorylation

enzymes and also transporters (AT)

110
Q

phosphorylation?

A

on/off switch

111
Q

ptype atpases – P2 cotransporters

A

Ca makes muscle cells contract. don’t want it floating freely in cytosol

112
Q

give details about V-type ATPases

what’s the v for
what do they do & how

A

v for vacuole
acidify compartment
pump in H+

113
Q

give details about F-type ATPases

what’s the f for
classic example
how does it work
where

A

f for factor
classic: ATP synthase
uses H+ gradient to drive atp synthesis
across inner mitochondrial membrane

114
Q

give details about ABC-type ATPases

ABC stands for ?
name subtypes
powered by ?
example discussed?

A

ABC for ATP binding cassette (cassette – something you plug in)

importers and exporters

powered by ATP hydrolysis

e.g., multidrug resistance (MDR)
MDR transport protein

115
Q

ATP hydrolysis is

A

the catabolic reaction process by which chemical energy that has been stored in the high-energy phosphoanhydride bonds in adenosine triphosphate (ATP) is released after splitting these bonds, for example in muscles, by producing work in the form of mechanical energy. The product is adenosine diphosphate (ADP) and an inorganic phosphate (Pi).

116
Q

MDR transport protein in human cells

e.g.?

A

MDR1 – pump out hydrophobic rx

e.g., makes cancer resistant to chemo

117
Q

in bacterial cells, transcription and translation is

A

simultaneous

118
Q

cystic fibrosis affects ______

give some examples

A

secretions

respiratory, digestive, integumentary (salty skin?)

119
Q

cystic fibrosis life expectancy

A

CF usually kills very young

120
Q

CF mutation?

A

1 single gene

CFTR protein

121
Q

CF is

A

a lethal genetic disorder caused by a mutation in a single gene

there are a few other examples of these including sickle-cell anaemia

122
Q

CF mutation details

CFTR

genetic mutation & upshot

pathophysiology

A

CFTR – transport protein
Cl- transporter
uses ATP to transport Cl- (it’s actually facilitated diffusion that uses ATP; just let it be. a zebra in a herd of horses)

2/3 CF sufferers have same mutation: ΔF508 (f for phenylalanine)
Δ meaning deleted
phenylalanine should be there but it’s been deleted in the genetic code
protein won’t fold
Cl- ions can still go thru but because cell thinks it’s misfolded –> retained in rough ER and sent for destruction

Cl- secreted & water goes with it
water follows charge
mucus secretions not diluted
can’t breathe d/t phlegm

123
Q

Δ in a genetic mutation indicates

A

deletion

124
Q

masked gene – don’t say dormant (it sounds like latent)

A

won’t express

masked by dominant and recessive allele

125
Q

masked gene – don’t say dormant (it sounds like latent)

A

won’t express

masked by dominant and recessive allele

126
Q

Na concentration increases, what happens to AAs and sugars’ relative transport rate

what does this imply

what type of transport is this

A

Na conc. increase, AA conc. increase, sugars conc. increase

this implies symport of AAs and sugars into cell

indirect AT – uses diffusion of sodium, takes in both
facilitated diffusion of Na AND active transport of glucose

127
Q

Na-K-ATPase

cell type
enzyme type
exchange rate
do they happen simultaneously ?

A

sodium potassium pump

eukaryotic (might be animal cells only)
P-type ATPase
3 sodium out 2 potassium in
not simultaneous – phosphorylation

128
Q

Na-K pump details

A

(mark as studied if you know it undergoes conformational change)

trimeric protein
α β γ subunits

The pump has a higher affinity for Na⁺ ions than K⁺ ions, thus after binding ATP, binds 3 intracellular Na⁺ ions.[2]
ATP is hydrolyzed, leading to phosphorylation of the pump at a highly conserved aspartate residue and subsequent release of ADP. This process leads to a conformational change in the pump.
The conformational change exposes the Na⁺ ions to the extracellular region. The phosphorylated form of the pump has a low affinity for Na⁺ ions, so they are released; by contrast it has high affinity for the K⁺ ions.
The pump binds 2 extracellular K⁺ ions, which induces dephosphorylation of the pump, reverting it to its previous conformational state, thus releasing the K⁺ ions into the cell.
The unphosphorylated form of the pump has a higher affinity for Na⁺ ions. ATP binds, and the process starts again.

129
Q

Na-K pump conformational change

A

remove phosphate from ATP, release sodium, and add it back, take in K

130
Q

Na and glucose symport – how does it happen

A

they don’t bind to each other but Na changes shape of transport protein

indirect AT of glucose
facil. diff of Na

131
Q

what’s signal transduction (long answer)

A

the process by which a chemical or physical signal is transmitted through a cell as a series of molecular events, most commonly protein phosphorylation catalyzed by protein kinases, which ultimately results in a cellular response.

The changes elicited by ligand binding (or signal sensing) in a receptor give rise to a biochemical cascade,

When signaling pathways interact with one another they form networks, which allow cellular responses to be coordinated, often by combinatorial signaling events.[2] At the molecular level, such responses include changes in the transcription or translation of genes, and post-translational and conformational changes in proteins, as well as changes in their location.

132
Q

signal transduction

A

binding to receptors

133
Q

bile salts do what

A

emulsify lipid so it can be digested

134
Q

albumin does what

A

water loves it; pulls water into vessels

135
Q

rough and smooth ER together do what (give 2 answers)

A

build membrane

lipid synthesis

136
Q

ascites is caused by

A

HTN in hepatic portal vein

137
Q

vacuole & lysosome: pump in _______ constantly

why?

A

H+

maintain acidity so they can break down accumulated wastes

138
Q

vacuole can fuse w/ an _________ to form a __________ (endocytosis)

A

early endosome

larger compartment

139
Q

describe v basic animal cell endocytosis

A

endosome fuse w/ lysosome

lysosome contains digestive enzymes

140
Q

lysosomal pH?

A

v low

4-5

141
Q

____ are too small for endocytosis

instead, what happens?

A

viruses

destroy host cell

142
Q

describe self-antigen ?

and the reverse?

A

the correct version is a ‘do not destroy’ sign to immune system

DNA/RNA not being transcribed as usual – self antigen may not be present and cell might be targeted

143
Q

give some components of receptor-mediated endocytosis

example of a coat that forms on vesicles

A

receptors bind to adaptor proteins then to CLATHRIN
dynamin squeezes off the new vesicle

clathrin

144
Q

which small protein forms football-like structures (hexagon pentagon hexagon) in coated vesicles?

A

clathrin

145
Q

what cuts off a new vesicle?

‘boa constrictor’ ????

A

dynamin

146
Q

self-assembling therefore own energy source

regardless of contents it makes a —

A

clathrin

football shape

147
Q

triskelion & relation to endocytosis

A

a Celtic symbol consisting of three legs or lines radiating from a centre.
–>isle of man flag
clathrin spontaneously forms the lowest-energy shape

148
Q

alcoholism impairs ________

which causes ?

A

endocytosis

decrease in nutrition

149
Q

besides ATP we have GTP

what uses GTP for energy source?

A

dynamin eg

150
Q

chronic inflammation leads to mutations why?

A

required to reproduce cells often

151
Q

pro-inflammatory (esp chronic inflam) assoc with deficiency in _______-

A

vit B12

152
Q

address labelling on ______ is a ______which indicates ________

A

vesicle
protein
destination

153
Q

SNARES

A

hooks

SNAP receptors

154
Q

_________ bind where it’s supposed to go

every compartment coated with ______

A

RABs and tethers

RABs

155
Q

Tay–Sachs disease

A

an inherited metabolic disorder in which certain lipids accumulate in the brain, causing spasticity and death in childhood.

156
Q

Tay–Sachs disease is a class of

A

lipid storage disorder / lysosome storage disease

insufficiency of enzyme – found in lysosomes – to break down sphingolipids

157
Q

give another lysosome storage disease

A

hunter syndrome

large sugar molecules called glycosaminoglycans (or GAGs or mucopolysaccharides) build up in body tissues.

158
Q

transport of O2 necessary for __________

A

cell respiration

159
Q

natural product of cell respiration found in peroxisomes

A

h2o2 hydrogen peroxide

160
Q

peroxisomes are not simply like lysosomes

A

they’re a different organelle

161
Q

peroxisomes’ function

A

catabolism of unusual substances

162
Q

N-containing compounds

A

toxic if formed

N wants to react

163
Q

these cellular components normally have nitrogen

A

DNA and proteins

164
Q

these cellular components normally have nitrogen

A

DNA and proteins

165
Q

resolution limit of light microscope

A

~200 nm

1/2 wavelength 400 nm (blue/violet light)

166
Q

microtubules

A

thickest

water inside

167
Q

microfilaments

A

smallest

just under surface of cell to periphery

168
Q

mitotic spindle made of _________

A

microtubules

169
Q

what’s a mitotic spindle

A

cells divide and pull chromosomes apart using this

170
Q

mitotic spindle attaches to ______-

A

centrosomes

171
Q

centrosomes go where _______is

A

golgi

golgi- near nucleus

172
Q

part of cytoskeleton which independently grows and shrinks

A

microtubules

173
Q

MTOCs?

A

microtubule organising centres

174
Q

plus and minus end of ________

A

protofilament (microtubules)

fast and slow growing end

175
Q

during mitosis what happens to microtubules

A

break
use tubulin to make mitotic spindle
then after division use same tubulin in microtubules

176
Q

colchicine effects

A

stop from building mitotic spindle

177
Q

two ways to stop cell division ?

A

px mitotic spindle from forming

or break it apart

178
Q

two ways to stop cell division ?

A

px mitotic spindle from forming

or break it apart

179
Q

drugs that attack cells which divide rapidly have what problem ?

A

no discrimination

also attack other fast-dividing cells eg bone marrow

180
Q

define exergonic

A

accompanied by the release of energy.

181
Q

facilitated diffusion – 4 characteristics

A

transport proteins
down conc grad (towards equilibrium)
large or polar substances
(exergonic – release energy)

182
Q

Carrier proteins

A

(transporters or permeases) bind solute molecules on one side of a membrane, undergo a CONFORMATIONAL CHANGE, and release the solute on the other side of the membrane

183
Q

Channel proteins

A

form hydrophilic channels through the membrane to provide a passage route for solutes

(facil diff)

184
Q

Pores are formed by transmembrane proteins called

A

porins that allow passage of solutes up to a certain molecular weight to pass (600)
Most channels are smaller and highly selective
ION CHANNELS
quicker than transport – no conformational change

185
Q

Some channels are large and nonspecific, such as

A

the pores on the outer membranes of bacteria, mitochondria, and chloroplasts

186
Q

allosteric

A

allo – different
steric – solid (arrangement of atoms in molecule)

–> relating to or denoting the alteration of the activity of an enzyme by means of a conformational change induced by a different molecule.

187
Q

which type of transmembrane proteins act like enzymes?

A

carrier proteins

in specificity, saturation kinetics…

188
Q

coupled transport list two types (4 names)

A

symport (cotransport)

antiport (countertransport)

189
Q

Channel proteins

list 3 types

A

ion channels
porins
aquaporins

190
Q

ion channels

A

gated – open and close in response to stimulus

muscle contractions
action potential in nerves

191
Q

list 3 types of gated ion channels

A

voltage
mechanical
ligand

192
Q

The transmembrane segments of porins cross the membrane as

A

β barrels

water-filled pore at centre

193
Q

Active transport couples endergonic transport to an exergonic process

A

, usually ATP hydrolysis

194
Q

Indirect active transport depends on

A

the simultaneous transport of two solutes

Favorable movement of one solute down its gradient drives the unfavorable movement of the other up its gradient

simultaneous inward movement of Na+ (animals) or protons (plants, fungi, bacteria) down their gradients

195
Q

Direct Active Transport Depends on WHICH FOUR Types of Transport ATPases

A

P
V
F
ABC

196
Q

AT important example

A

Na - glucose
sodium symporter
sodium dependent glucose transporters

2 Na – 1 glucose
release of glucose allows to return to outward facing conformation

197
Q

components of the endomembrane system

A

The endoplasmic reticulum and the Golgi complex are sites for protein synthesis, processing, and sorting

Endosomes carry and sort material brought into
the cell

Lysosomes digest ingested material and unneeded cellular components

198
Q

ER

The membrane-bound sacs are called ER ______, and the space inside them is the ER _____

A

cisternae

lumen

199
Q

ER functions

A

PROTEIN SYNTHESIS

  • membrane proteins
  • organelles (including in endomembrane system)
  • exports

LIPID SYNTHESIS

200
Q

cytosol

A

the aqueous component of the cytoplasm of a cell, within which various organelles and particles are suspended.

201
Q

Rough endoplasmic reticulum (rough ER) is characterized by

A

ribosomes on the cytosolic side of the membrane

202
Q

A subdomain of rough ER, the transitional elements (TEs)

A

plays a role in the formation of transition vesicles that shuttle lipids and proteins from the ER to the Golgi complex

203
Q

Variation in Amounts of Rough and Smooth ER

A

Cells involved in synthesis of secretory proteins have prominent rough ER networks

Cells producing steroid hormones tend to have extensive networks of smooth ER

204
Q

Rough ER functions

A

add carb to glycoprotein

fold protein

remove misfolded protein (QUALITY CONTROL)

assemble multimeric protein

205
Q

In ER-associated degradation (ERAD), proteins that are incorrectly folded, modified, or assembled are exported for degradation

A

Degradation occurs in cytosolic proteasomes

206
Q

Smooth ER Is Involved in

A

Drug Detoxification

Carbohydrate Metabolism

Calcium Storage

Steroid Biosynthesis

207
Q

drug detoxification often involves

A

hydroxylation

Adding hydroxyl groups to hydrophobic drugs increases their solubility, making them easier to excrete from the body
cytochrome p-450 (monooxygenases)

208
Q

The liver stores glucose as

A

glycogen in granules associated with smooth ER

209
Q

When glucose is needed by the body, glycogen is broken down by

A

phosphorolysis, producing glucose-6-phosphate

210
Q

smooth ER that specializes in calcium storage

A

sarcoplasmic reticulum of muscle cells

211
Q

site of cholesterol and steroid hormone synthesis

A

Smooth ER in some cells

212
Q

Cholesterol, cortisol, and steroid hormones share a _________ but differ in the:

A

four-ring structure

number and arrangement of carbon side chains and hydroxyl groups

213
Q

committed step in cholesterol biosynthesis

A

Hydroxymethylglutaryl-CoA reductase (HMG-CoA reductase)

214
Q

In eukaryotic cells, ______ is the primary source of membrane lipids, with a few exceptions:
Mitochondria synthesize phosphatidylethanolamine
Peroxisomes synthesize cholesterol
Chloroplasts contain enzymes for chloroplast-specific lipids

A

the ER

215
Q

The Golgi complex is functionally and physically linked to the ______

A

ER

Here, glycoproteins and membrane lipids from the ER undergo further processing and are sorted and packaged for transport

MEMBRANE AND PROTEIN TRAFFICKING

216
Q

anterograde transport

A

Movement of material toward the plasma membrane

217
Q

Retrograde transport

A

is the flow of vesicles from Golgi cisternae back to the ER

This allows the cell to balance the flow of lipids toward the plasma membrane

218
Q

glycosylation

A

the addition of carbohydrate side chains to proteins

219
Q

retention tag

A

Arg X Arg

RXR

220
Q

N-methyl-D-aspartate

A

(NMDA) receptor, important in mammalian neurotransmission, has the RXR tag
It is thought that the tripeptide causes subunits of NMDA to be retained in the ER until the complex is completely assembled
The RXR tag must be masked to allow the assembled complex to leave the ER

221
Q

Golgi Complex Proteins May Be Sorted

A

according to the Lengths of Their Membrane-Spanning Domains

hydrophobic domain length vs membrane length

222
Q

The thickness of cellular membranes increases progressively

A

from the ER (5 nm) to the plasma membrane (8 nm)

223
Q

All Golgi-specific proteins are

A

integral membrane proteins with one or more membrane-spanning domains

224
Q

Two methods (unique to eukaryotes) for transporting materials across the plasma membrane are

A

Exocytosis, the process by which secretory vesicles release their contents outside the cell
Endocytosis, the process by which cells internalize external materials

225
Q

secretory granules

A

Secretory pathways move proteins from the ER through the Golgi complex to secretory vesicles and secretory granules

The secretory granules then discharge their contents to the exterior of the cell

226
Q

pinocytosis

A

liquids are taken up

227
Q

phagocytosis

A

solid particles are ingested

228
Q

endocytic vesicles develop into

A

early endosomes, which fuse with vesicles from the TGN

They acquire digestive enzymes and form new lysosomes

229
Q

receptor-mediated endocytosis

A

or clathrin-dependent endocytosis

230
Q

ligand

A

what is bound (receptor-mediated endocytosis)

receptor-ligand complexes

231
Q

Fluid-phase endocytosis

A

is a type of pinocytosis for nonspecific internalization of extracellular fluid
This process does not concentrate the ingested material, and contents are routed to early endosomes
It proceeds at a fairly constant rate and compensates for membrane segments added by exocytosis

232
Q

coated vesicles

A

proteins on outside give specificity to the vesicle

clathrin cop i cop ii

233
Q

caveolae

A

another coat protein
lipid raft
cholesterol uptake

234
Q

promote assembly of clathrin coat

A

adaptor protein complexes

235
Q

dynamin

A

GTPase

GTP hydrolysed; dynamin rings tighten

236
Q

clathrin uncoat

A

uncoating requires ATP

uncoating ATPase

237
Q

SNARE Proteins

A

Mediate Fusion Between Vesicles and Target Membranes

238
Q

Rab GTPases

A

When a vesicle reaches its destination, Rab GTPases (specific for different destinations) lock the complementary SNARE proteins together
This facilitates membrane fusion

239
Q

There are numerous enzymes inside lysosomes;

all are

A

acid hydrolases

240
Q

what are each composed of:
microtubules

intermediate filaments

microfilaments

A

tubulin (dimers)

various

actin

241
Q

critical concntration

A

The tubulin concentration at which MT assembly is exactly balanced by disassembly

242
Q

Centrosomes have large ring-shaped protein complexes in them; these contain γ-tubulin
γ-tubulin is found only in centrosomes
γ-tubulin ring complexes (γ-TuRCs) nucleate the assembly of new MTs away from the centrosome

A

Loss of γ-TuRCs prevents a cell from nucleating MTs

243
Q

centrosome is an

A

mtoc

basal bodies too

244
Q

MAPs

A

microtubule associated proteins

Tau – MT form tight bundles in axons

245
Q

keratins

give one more

A

intermediate filaments

lamins

246
Q

The Cytoskeleton Is a Mechanically Integrated Structure

A

Microtubules resist bending when a cell is compressed
Microfilaments serve as contractile elements that generate tension
Intermediate filaments are elastic and can withstand tensile forces

247
Q

Animal cells have three common types of junctions

A

Adhesive junctions – attach
Tight junctions – seal spaces between cells
Gap junctions – gaps directly from cell to cell

汉语一级 (12 decks)

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