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Biology - MCAT > Class Five > Flashcards

Class Five Flashcards

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1
Q

function of the nucleus (3)

A

contact + protect DNA

transcription

partial assembly of ribosomes

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2
Q

function of the mitochondria (2)

A

produce ATP via the Krebs cycle & oxidative phosphorylation

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3
Q

function of ribosomes

A

synthesize proteins

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4
Q

function of rough ER

A

location of synthesis/modification of secretory, membrane-bound & organelle proteins

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5
Q

function of smooth ER (2)

A

detoxification and glycogen breakdown in liver

steroid synthesis in gonads

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6
Q

function of Golgi apparatus

A

modification and sorting of protein, some synthesis

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7
Q

function of lysosomes

A

contain acid hydrolases that digest various substances

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8
Q

function of peroxisomes

A

metabolize lipids and toxins using H2O2

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9
Q

what 2 organelles have 2 membranes surrounding them

A

nucleus and mitochondria

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10
Q

what 2 organelles have no membranes surrounding them

A

ribosomes and rough ER

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11
Q

purpose of nuclear envelope

A

separates the contents of the nucleus from the cytoplasm and other organelles

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12
Q

how many human chromosomes

A

23

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13
Q

which chromosomes do we not have 2 copies of

A

sex chromosomes

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14
Q

inactivity of telomerase

A

implicated in cell aging and death

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15
Q

regions of a chromosomes where genes are inaccessible

A

heterochromatin

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16
Q

loosely packed regions of chromosomes - more accessible

A

euchromatin

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17
Q

nucleolus

A

region within the nucleus that functions as a ribosome factory

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18
Q

function of nuclear pores

A

allow the passage of material into and out of the nucleus

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19
Q

nuclear localization sequence

A

proteins with this are translated on cytoplasmic ribosomes and then imported into the nucleus by specific transport mechanisms

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20
Q

site of oxidative phosphorylation

A

mitochondria

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21
Q

inner membrane of the mitochondria

A

location of the electron transport chain

impermeable to polar substances

folded into cristae

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22
Q

endosymbiotic theory of mitochondrial evolution

A

mitochondria has a second system of inheritance → theory that mitochondria originated as independent unicellular organisms

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23
Q

mitochondrial maternal inheritance

A

mitochondria are inherited only from the mother (cytoplasm of egg becomes cytoplasm of the zygote)

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24
Q

why is rough ER rough

A

lots of ribosomes bound to its surface

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25
Q

two sites of protein synthesis

A

on free ribosomes in cytoplasm

or ribosomes bound to the rough ER

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26
Q

where do proteins translated on free ribosomes go

A

peroxisomes, mitochondria, nucleus or stay in cytoplasm

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27
Q

where do proteins synthesized on the rough ER go

A

secreted into extracellular environment

plasma membrane proteins

or in the membrane of the ER, Golgi apparatus or lysosomes

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28
Q

what happens if a protein has a signal sequence

A

recognized by signal recognition particles (found on the rough ER)

gets translated on the rough ER

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29
Q

how are signal sequences removed

A

removed by a signal peptidase in the ER lumen

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30
Q

where are signal sequences found

A

N terminus

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31
Q

what has transmembrane domains

A

integral membrane proteins

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32
Q

purpose of transmembrane domains

A

they are hydrophobic amino acid residues that allow to pass through lipid bilayer membranes

signal sequences found in the interior of proteins

not removed after translation

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33
Q

glycosylation

A

addition of saccharides - post translational modification

occurs in the lumen of the ER and Golgi apparatus

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34
Q

functions of the Golgi (3)

A

modification of proteins made in RER

sorting + sending proteins to their destinations

synthesize macromolecules (polysaccharides etc)

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35
Q

direction of flow in Golgi

A

vesicles from ER fuse with cis stack

they are then transferred to the medial stack for more modification

proteins leave the Golgi at the trans stack

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36
Q

constitutive secretory pathway

A

proteins are sent in vesicles from the Golgi immediately to the cell surface

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37
Q

regulate secretory pathway

A

some secretory proteins are stored but vesicles and only released at certain times (signal from extracellular environment)

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38
Q

what do lysosomes do

A

degrade macromolecules via hydrolysis

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39
Q

where are lysosome proteins made

A

RER

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40
Q

autophagy

A

lysosomes eating damaged organelles

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41
Q

phagocytosis

A

degradation of large matters by lysosomes

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42
Q

crinophagy

A

lysosomal digestion of excess secretory products

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43
Q

enzymes responsible for lysosomal degradation

A

acid hydrolases

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44
Q

safety mechanism - lysosomes

A

acid hydrolases only hydrolyze substances in acidic environments

if a lysosome is ruptured, the enzymes cannot act in the cytoplasm (higher pH)

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45
Q

what does catalase do

A

converts H2O2 into H2O + O2 to protect the rest of the peroxisomes

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46
Q

three lipids of eukaryotic membranes

A

phospholipids

glycolipids

cholesterol

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47
Q

where are there a higher number of proteins than lipids in membranes

A

mitochondrial inner membrane

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48
Q

peripheral vs integral membrane proteins

A

integrated: embedded in the membrane, held by hydrophobic interactions
peripheral: stuck to an integral protein, held by H bonding

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49
Q

unsaturated fatty acids effect In membrane fluidity

A

more kinks = higher fluidity

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50
Q

what do colligative properties depend on

A

the number of solute particles in solution rather than the type of particle

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51
Q

4 colligative properties

A

vapour pressure depression

boiling point elevation

freezing point depression

osmotic pressure

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52
Q

boiling point elevation

A

delta Tb = kbiim

53
Q

freezing point depression formula

A

delta Tf = -kfim

54
Q

diffusion

A

solutes move towards equilibrium

55
Q

osmosis

A

solvent moves towards equilibrium

56
Q

isotonic environment

A

solute conc is the same inside and outside the cell

57
Q

hypotonic solution

A

less solute

58
Q

hypertonic solution

A

more solute

59
Q

osmotic pressure

A

the pressure it would take to stop osmosis from occurring

60
Q

osmotic pressure formula

A

MiRT

61
Q

passive transport

A

thermodynamically favourable movement of solute across a membrane

aka diffusion

62
Q

types of passive transport

A

simple and facilitated diffusion

63
Q

simple diffusion

A

diffusion of a solute through a membrane without help from a protein

64
Q

facilitated diffusion

A

movement of a solute across a membrane down a gradient with the use of proteins

65
Q

types of proteins for facilitated diffusion

A

channel proteins and carrier proteins

66
Q

symporters vs antiporters

A

symporters: 2 molecules in the same direction
antiporters: 2 molecules in opposite directions

67
Q

active transport

A

movement of molecules through a membrane against a gradient

requires energy input

68
Q

primary active transport

A

transport of a molecule is coupled to ATP hydrolysis

69
Q

secondary active transport

A

transport process is driven by an ATP gradient

70
Q

sodium potassium pump molecules

A

3 sodium out of the cell

2 potassium into the cell

hydrolysis of one ATP

71
Q

3 main functions of sodium potassium pump

A

maintains osmotic balance between inside/outside of cell

establishes RMP

provides conc gradient to drive secondary active transport

72
Q

exocytosis

A

vesicle in cytoplasm fuses with plasma membrane → expelled into extracellular space

73
Q

endocytosis

A

materials taken into the cell by invagination of cell membrane

74
Q

3 types of endocytosis

A

phagocytosis

pinocytosis

receptor mediated endocytosis

75
Q

phagocytosis

A

nonspecific uptake of material into phagocytic vesicle (later merges with lysosome)

e.g. macrophages

76
Q

pinocytosis

A

nonspecific uptake of small molecules and extracellular fluid via invagination

77
Q

receptor mediated endocytosis

A

very specific

sites of endocytosis is marked by pits coated with clathrin & receptors

e.g. cholesterol

78
Q

3 types of signal transducing cell surface receptors

A

ligand gated ion channels

catalytic receptors

G protein linked receptors

79
Q

ligand gated ion channels

A

opening of an ion channel upon binding a ligand

80
Q

catalytic receptors

A

initiates enzyme activity by ligand binding

81
Q

G protein linked receptors

A

don’t directly transduce a signal → transmits it onto the cell with the aid of a second messenger

82
Q

most important second messenger

A

cyclic AMP

universal hunger signal → second messenger for epinephrin and glucagon

allows for greater signal

83
Q

3 proteins that make up the cytoskeleton

A

microtubules

intermediate filaments

microfilaments

84
Q

proteins that finish translation at the rough ER

A

secreted proteins

transmembrane proteins

lysosomal proteins

85
Q

who has signal sequences (3)

A

secreted proteins

lysosomal proteins

membrane bound proteins

86
Q

where is signal sequence found for membrane bound proteins

A

anywhere in amino acid sequence

87
Q

what is a microtubule

A

hollow rod with 2 proteins: alpha and beta tubulins

88
Q

why can’t one end of a microtubule elongate

A

it is anchored to the microtubule organizing center (MTOC)

89
Q

aster

A

microtubules that come out from centrioles during mitosis

90
Q

polar fibers

A

microtubules that connect the chromosomes to aster

91
Q

centromere of each chromosome contains..

A

kinetochore

92
Q

what is essential for mitosis and what is not

A

MTOC = essential

centrioles = not (plant cells don’t have them, but still undergo mitosis)

93
Q

what has a 9 +2 arrangement

A

cilia and flagellum

94
Q

dynein

A

connects microtubules, allows for movement of filaments

95
Q

what is cilium/flagellum anchored to the plasma membrane by

A

basal body

96
Q

microfilaments are formed from..

A

the polymerization of actin

97
Q

amoeboid movement

A

changes in cytoplasmic structure which causes cytoplasm and the rest of the cell to flow in one direction

98
Q

what causes amoeboid movement

A

microfilaments

99
Q

differences with intermediate filaments

A

heterogenous - wide range of polypeptides

more permanent than microfilaments/tubules

100
Q

tight junctions

A

form a seal between membranes of cells - blocks flow of molecules

101
Q

desmosomes

A

just holds cells together

anchored to plasma membrane by keratin plaque

intermediate filaments from cytoplasm attach here

102
Q

gap junctions

A

connections between cells so their cytoplasm can mix

exchange of small soulutes

e.g. cardiac muscle, action potentials

103
Q

what happens in S (synthesis) phase

A

cell actively replicates its genome

104
Q

what happens in mitosis

A

partitioning of cellular components into halves

105
Q

what happens in cytokinesis

A

physical process of cell division

106
Q

the cell spends most of its time in..

A

interphase

107
Q

4 phases of mitosis

A

prophase

metaphase

anaphase

telophase

108
Q

first sign of prophase

A

genome becomes visible → densely packed chromosomes

109
Q

two copies of a chromosome =

A

sister chromatids

110
Q

key points of prophase

A

nucleolus disappears

spindle & kinetochore fibers appear

centriole pairs begin to move to opposite sides

2 MTOCs aka asters

111
Q

key points of metaphase

A

chromosomes lined up at center of cell → metaphase plate

kinetochore of each sister chromatid attached to spindle fibers that attach to MTOC on opposite ends of cell

112
Q

key points of anaphase

A

spindle fibers shorten → centromeres pulled apart

cell elongates

formation of cleavage by microfilaments

113
Q

key points of telophase

A

nuclear membrane forms around the end of each cell

chromosomes decondense

nucleolus becomes visible for each cell

each daughter chromosome has 2n chromosomes

114
Q

karyotype

A

display of organism’s genome

photograph is taken during metaphase

115
Q

mutated genes that induce cancer

A

oncogenes

116
Q

protooncogenes

A

normal versions of the genes that allow for regular growth pattern → can be converted into oncogenes in the right circumstances

117
Q

tumour suppressor genes

A

produce proteins that are the inherent defence system to prevent conversion of cells into cancer cells

118
Q

apoptosis

A

allows a cell to shrink + dose without damaging neighbouring cells

119
Q

internal cause of apoptosis

A

p53 (tumor suppressor proteins)

120
Q

caspases

A

family of proteases that carry out event of apoptosis

cleave target proteins at aspartic acid sites

121
Q

initiator caspases

A

respond to extra/intracellular death signals by clustering together (activating each other)

122
Q

effector caspases

A

cleave a variety of cellular proteins to trigger apoptosis

123
Q

oxidative stress

A

level of reactive oxygen species builds up

124
Q

oxidative stress - cancer

A

can damage DNA, proteins & lipid bilayers

allows oncogenes to be activated

125
Q

senescence

A

biological aging that occurs at the cellular and organismal levels

length of the telomeres is indicative

126
Q

___ and ___ decrease with addition of solutes to solution

A

freezing point and vapour pressure

127
Q

___ and ___ increase with increased number of particles

A

boiling point and osmotic pressure

128
Q

where in the cell cycle is it highly regulated

A

between G1 and S

Biology - MCAT (11 decks)

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