Class Five Flashcards
1
Q
function of the nucleus (3)
A
contact + protect DNA
transcription
partial assembly of ribosomes
2
Q
function of the mitochondria (2)
A
produce ATP via the Krebs cycle & oxidative phosphorylation
3
Q
function of ribosomes
A
synthesize proteins
4
Q
function of rough ER
A
location of synthesis/modification of secretory, membrane-bound & organelle proteins
5
Q
function of smooth ER (2)
A
detoxification and glycogen breakdown in liver
steroid synthesis in gonads
6
Q
function of Golgi apparatus
A
modification and sorting of protein, some synthesis
7
Q
function of lysosomes
A
contain acid hydrolases that digest various substances
8
Q
function of peroxisomes
A
metabolize lipids and toxins using H2O2
9
Q
what 2 organelles have 2 membranes surrounding them
A
nucleus and mitochondria
10
Q
what 2 organelles have no membranes surrounding them
A
ribosomes and rough ER
11
Q
purpose of nuclear envelope
A
separates the contents of the nucleus from the cytoplasm and other organelles
12
Q
how many human chromosomes
A
23
13
Q
which chromosomes do we not have 2 copies of
A
sex chromosomes
14
Q
inactivity of telomerase
A
implicated in cell aging and death
15
Q
regions of a chromosomes where genes are inaccessible
A
heterochromatin
16
Q
loosely packed regions of chromosomes - more accessible
A
euchromatin
17
Q
nucleolus
A
region within the nucleus that functions as a ribosome factory
18
Q
function of nuclear pores
A
allow the passage of material into and out of the nucleus
19
Q
nuclear localization sequence
A
proteins with this are translated on cytoplasmic ribosomes and then imported into the nucleus by specific transport mechanisms
20
Q
site of oxidative phosphorylation
A
mitochondria
21
Q
inner membrane of the mitochondria
A
location of the electron transport chain
impermeable to polar substances
folded into cristae
22
Q
endosymbiotic theory of mitochondrial evolution
A
mitochondria has a second system of inheritance → theory that mitochondria originated as independent unicellular organisms
23
Q
mitochondrial maternal inheritance
A
mitochondria are inherited only from the mother (cytoplasm of egg becomes cytoplasm of the zygote)
24
Q
why is rough ER rough
A
lots of ribosomes bound to its surface
25
two sites of protein synthesis
on free ribosomes in cytoplasm
or ribosomes bound to the rough ER
26
where do proteins translated on free ribosomes go
peroxisomes, mitochondria, nucleus or stay in cytoplasm
27
where do proteins synthesized on the rough ER go
secreted into extracellular environment
plasma membrane proteins
or in the membrane of the ER, Golgi apparatus or lysosomes
28
what happens if a protein has a signal sequence
recognized by signal recognition particles (found on the rough ER)
gets translated on the rough ER
29
how are signal sequences removed
removed by a signal peptidase in the ER lumen
30
where are signal sequences found
N terminus
31
what has transmembrane domains
integral membrane proteins
32
purpose of transmembrane domains
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
33
glycosylation
addition of saccharides - post translational modification
occurs in the lumen of the ER and Golgi apparatus
34
functions of the Golgi (3)
modification of proteins made in RER
sorting + sending proteins to their destinations
synthesize macromolecules (polysaccharides etc)
35
direction of flow in Golgi
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
36
constitutive secretory pathway
proteins are sent in vesicles from the Golgi immediately to the cell surface
37
regulate secretory pathway
some secretory proteins are stored but vesicles and only released at certain times (signal from extracellular environment)
38
what do lysosomes do
degrade macromolecules via hydrolysis
39
where are lysosome proteins made
RER
40
autophagy
lysosomes eating damaged organelles
41
phagocytosis
degradation of large matters by lysosomes
42
crinophagy
lysosomal digestion of excess secretory products
43
enzymes responsible for lysosomal degradation
acid hydrolases
44
safety mechanism - lysosomes
acid hydrolases only hydrolyze substances in acidic environments
if a lysosome is ruptured, the enzymes cannot act in the cytoplasm (higher pH)
45
what does catalase do
converts H2O2 into H2O + O2 to protect the rest of the peroxisomes
46
three lipids of eukaryotic membranes
phospholipids
glycolipids
cholesterol
47
where are there a higher number of proteins than lipids in membranes
mitochondrial inner membrane
48
peripheral vs integral membrane proteins
integrated: embedded in the membrane, held by hydrophobic interactions
peripheral: stuck to an integral protein, held by H bonding
49
unsaturated fatty acids effect In membrane fluidity
more kinks = higher fluidity
50
what do colligative properties depend on
the number of solute particles in solution rather than the type of particle
51
4 colligative properties
vapour pressure depression
boiling point elevation
freezing point depression
osmotic pressure
52
boiling point elevation
delta Tb = kbiim
53
freezing point depression formula
delta Tf = -kfim
54
diffusion
solutes move towards equilibrium
55
osmosis
solvent moves towards equilibrium
56
isotonic environment
solute conc is the same inside and outside the cell
57
hypotonic solution
less solute
58
hypertonic solution
more solute
59
osmotic pressure
the pressure it would take to stop osmosis from occurring
60
osmotic pressure formula
MiRT
61
passive transport
thermodynamically favourable movement of solute across a membrane
aka diffusion
62
types of passive transport
simple and facilitated diffusion
63
simple diffusion
diffusion of a solute through a membrane without help from a protein
64
facilitated diffusion
movement of a solute across a membrane down a gradient with the use of proteins
65
types of proteins for facilitated diffusion
channel proteins and carrier proteins
66
symporters vs antiporters
symporters: 2 molecules in the same direction
antiporters: 2 molecules in opposite directions
67
active transport
movement of molecules through a membrane against a gradient
requires energy input
68
primary active transport
transport of a molecule is coupled to ATP hydrolysis
69
secondary active transport
transport process is driven by an ATP gradient
70
sodium potassium pump molecules
3 sodium out of the cell
2 potassium into the cell
hydrolysis of one ATP
71
3 main functions of sodium potassium pump
maintains osmotic balance between inside/outside of cell
establishes RMP
provides conc gradient to drive secondary active transport
72
exocytosis
vesicle in cytoplasm fuses with plasma membrane → expelled into extracellular space
73
endocytosis
materials taken into the cell by invagination of cell membrane
74
3 types of endocytosis
phagocytosis
pinocytosis
receptor mediated endocytosis
75
phagocytosis
nonspecific uptake of material into phagocytic vesicle (later merges with lysosome)
e.g. macrophages
76
pinocytosis
nonspecific uptake of small molecules and extracellular fluid via invagination
77
receptor mediated endocytosis
very specific
sites of endocytosis is marked by pits coated with clathrin & receptors
e.g. cholesterol
78
3 types of signal transducing cell surface receptors
ligand gated ion channels
catalytic receptors
G protein linked receptors
79
ligand gated ion channels
opening of an ion channel upon binding a ligand
80
catalytic receptors
initiates enzyme activity by ligand binding
81
G protein linked receptors
don't directly transduce a signal → transmits it onto the cell with the aid of a second messenger
82
most important second messenger
cyclic AMP
universal hunger signal → second messenger for epinephrin and glucagon
allows for greater signal
83
3 proteins that make up the cytoskeleton
microtubules
intermediate filaments
microfilaments
84
proteins that finish translation at the rough ER
secreted proteins
transmembrane proteins
lysosomal proteins
85
who has signal sequences (3)
secreted proteins
lysosomal proteins
membrane bound proteins
86
where is signal sequence found for membrane bound proteins
anywhere in amino acid sequence
87
what is a microtubule
hollow rod with 2 proteins: alpha and beta tubulins
88
why can't one end of a microtubule elongate
it is anchored to the microtubule organizing center (MTOC)
89
aster
microtubules that come out from centrioles during mitosis
90
polar fibers
microtubules that connect the chromosomes to aster
91
centromere of each chromosome contains..
kinetochore
92
what is essential for mitosis and what is not
MTOC = essential
centrioles = not (plant cells don't have them, but still undergo mitosis)
93
what has a 9 +2 arrangement
cilia and flagellum
94
dynein
connects microtubules, allows for movement of filaments
95
what is cilium/flagellum anchored to the plasma membrane by
basal body
96
microfilaments are formed from..
the polymerization of actin
97
amoeboid movement
changes in cytoplasmic structure which causes cytoplasm and the rest of the cell to flow in one direction
98
what causes amoeboid movement
microfilaments
99
differences with intermediate filaments
heterogenous - wide range of polypeptides
more permanent than microfilaments/tubules
100
tight junctions
form a seal between membranes of cells - blocks flow of molecules
101
desmosomes
just holds cells together
anchored to plasma membrane by keratin plaque
intermediate filaments from cytoplasm attach here
102
gap junctions
connections between cells so their cytoplasm can mix
exchange of small soulutes
e.g. cardiac muscle, action potentials
103
what happens in S (synthesis) phase
cell actively replicates its genome
104
what happens in mitosis
partitioning of cellular components into halves
105
what happens in cytokinesis
physical process of cell division
106
the cell spends most of its time in..
interphase
107
4 phases of mitosis
prophase
metaphase
anaphase
telophase
108
first sign of prophase
genome becomes visible → densely packed chromosomes
109
two copies of a chromosome =
sister chromatids
110
key points of prophase
nucleolus disappears
spindle & kinetochore fibers appear
centriole pairs begin to move to opposite sides
2 MTOCs aka asters
111
key points of metaphase
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
key points of anaphase
spindle fibers shorten → centromeres pulled apart
cell elongates
formation of cleavage by microfilaments
113
key points of telophase
nuclear membrane forms around the end of each cell
chromosomes decondense
nucleolus becomes visible for each cell
each daughter chromosome has 2n chromosomes
114
karyotype
display of organism's genome
photograph is taken during metaphase
115
mutated genes that induce cancer
oncogenes
116
protooncogenes
normal versions of the genes that allow for regular growth pattern → can be converted into oncogenes in the right circumstances
117
tumour suppressor genes
produce proteins that are the inherent defence system to prevent conversion of cells into cancer cells
118
apoptosis
allows a cell to shrink + dose without damaging neighbouring cells
119
internal cause of apoptosis
p53 (tumor suppressor proteins)
120
caspases
family of proteases that carry out event of apoptosis
cleave target proteins at aspartic acid sites
121
initiator caspases
respond to extra/intracellular death signals by clustering together (activating each other)
122
effector caspases
cleave a variety of cellular proteins to trigger apoptosis
123
oxidative stress
level of reactive oxygen species builds up
124
oxidative stress - cancer
can damage DNA, proteins & lipid bilayers
allows oncogenes to be activated
125
senescence
biological aging that occurs at the cellular and organismal levels
length of the telomeres is indicative
126
\_\_\_ and ___ decrease with addition of solutes to solution
freezing point and vapour pressure
127
\_\_\_ and ___ increase with increased number of particles
boiling point and osmotic pressure
128
where in the cell cycle is it highly regulated
between G1 and S
