Physiology Flashcards
1
Q
name the components of the nuclear pore
A
nuclear basket
nuclear ring
cytoplasmic filaments
cytoplasmic ring
2
Q
name what enters the nuclear pore and what exits it
A
enter: ribosomes, materials for DNA/RNA synthesis, molecules used to provide energy
exit: ribosomal sub-units,
3
Q
what is the NLS and the NES, and what purpose do the serve
A
nuclear localisation signal is an amino acid sequence that tags proteins for entry
nuclear export signal tags proteins for exit
allows distinct protein populations between nucleus and cytoplasm
4
Q
the signal amino acid sequence usually contains what sequence of amino acids
A
Poly A
5
Q
What is the role of GTP in co-translational translocation?
A
phosphorilyses the SER when it it binds to its receptor to release the signal amino acid sequence into the trasnlocon
6
Q
how is the translocon opened and what is the role of signal peptidase?
A
forms hydrophobic interactions with the translocon, and the peptide kinda just pushes through aswell.
7
Q
where do O-links occur and what molecule reacts with specific amino acids to form them?
A
O-links occur exclusively in the golgi
oxygen with serine/threonine
8
Q
where do N-links occur and what molecule reacts with a specific amino acid to form it?
A
N-links begin in the ER and finish in the golgi
nitrogen with asparagine
9
Q
name the phospholipid heads
A
glycerol choline serine ethanolanine sphingolipids
10
Q
How does a cis double bond in the fatty acid tail affect overall membrane fluidity?
A
increases fluidity
11
Q
What are lipid rafts composed of?
A
cholesterol and sphingolipids
12
Q
What can barely diffuse into the nucleus via diffusion in Daltons
A
50kda
13
Q
What does the ER store and what is it used for?
A
Ca2+, cell signalling
14
Q
What is the structure called when multiple ribosomes are bound to a single mRNA?
A
polysomes
15
Q
Name the enzyme that catalyses the transfer of precursor oligosaccharide from dolichol lipid anchor
A
oligosacharyl transferase enzyme
16
Q
What is the function of cardiolipin and where is it located?
A
makes membranes impermeable to ions
located in the inner membrane of the mitochondria
17
Q
What are granules?
A
newly synthesised RNA
18
Q
What oxidative enzymes do peroxisomes contain?
A
Catalase, urate oxidase
19
Q
Why does the lysosome not self digest?
A
highly glycosylated proteins in its membrane
20
Q
What is the most stable component of the cytoskeleton?
A
intermediate filaments
21
Q
Where does alpha actin operate
A
skeletal muscle, smooth muscle, cardiac muscle
22
Q
what is the difference between beta and gamma actin
A
beta actin - only operates in non-muscle tissue
gamma actin - operates in non-muscle tissue and smooth muscle tissue
23
Q
Function of Arp2/Arp3?
A
Are forms of actin that cannot polymerise so they act as a primer for actin to bind to
24
Q
Functions of thymosin/prolifin?
A
thymosin: binds to actin - inhibiting its polymerisation
prolifin: binds to actin but aids in its polymerisation
25
function of filamin homodimers
takes microfilaments and cross links them to form a network
26
Where do microtubules grow from?
gamma rings found on centrosomes
27
Name the 2 microtubule motors and which direction they travel in
kinesins - plus end
| dyenisins - minus end
28
What does the cell check at the G2/M transition?
DNA
29
What is checked at the metaphase to anaphase transition?
spindle fibres are correctly attached to kinetichores
30
Function of CDc25?
dephosphorylises CDK-cyclin complex to activate it
31
Function of Myt1/wee1?
phosphorylises CDK-cyclin complex to deactivate it
32
How does CDK-cyclin progress the cell cycle?
CDK-cyclin removes proteins that sit on the promoter region to allow transcription and progression of the cell cycle.
33
What occurs if damaged DNA is detected in terms of MDm2-P53?
MDm2-P53 is phosphorylised, freeing P53, allowing it to bind to the regulatory region to synthesise CDK-inhibitory regions that destroy the CDK active site, halting the cell cycle
34
What 2 protiens act to form a chromatin loop?
Cohesin and CTFC
35
what happens during prometaphase
nuclear envelope breaks down
| spindle fibres attach to kinetichores
36
how do spindle fibres connect to kinetichores
the microtubule's plus end is facing the kinetichore
| the kinetichore contains connecting proteins which form a collar around the microtubule
37
what happens to securin once all kinetichores are correctly attached to a spindle fibre and what does this mean for seperase
securin degrades which frees seperase, activating it
38
what is the function of seperase
cleaves cohesin which allows the cell to enter anaphase
39
what is the function of APC/C
ubiquinates cyclin B1, which degrades it, leaving only CDK1 - triggering mitotic exit
Ubiquitinates Securin
40
function of mitogens?
triggers a wave of G/S-Cdk activity that removes cell cycle inhibitors
41
purpose of a synaptonemal complex
binds 2 homologous chromosomes to form a bi-valent structure
42
where is the synaptonemal complex formed
the zygotene
43
where is the synaptonemal complex fully completed
pachytene
44
where does the disassembly of the synaptonemal complex occur
diplotene
45
what is chiasmata and when is it visible
crossing over of sections of chromatids along their locus
| visible after synaptonemal complex disassembly
46
what is a proplastid
a pre-cursor of all plastids
47
what are chromoplasts
non-photosynthetic plastids
48
what is amyloplast
starch storage plastid
49
Difference between leucoplast and elaioplast?
leucoplast is involved in lipid synthesis whereas elaioplast stores mostly sterol esters
50
what percentage of chloroplast protein is encoded by the chloroplast itself?
10%
51
function of N-terminal transit peptides
target proteins encoded by the nucleus into the chloroplast.
52
What is functional syncitia and whats the purpose of it?
when cells are are fused together with gap junctions
| allows cascading signal to affect the neighbouring cell
53
What is functional syncitia and whats the purpose of it?
when cells are are fused together with gap junctions
| allows cascading signal to affect the neighbouring cell
54
What creates the impermeable seal of tight junctions?
occludin/claudin create seals with the neighbouring cell's occludin/claudin
55
What are cadherins dependent on?
Ca2+
56
How do cadherins form anchoring junctions?
the bind to cadherins of the same type on the cell surface of a neighbouring cell which forms a dimer
57
How do proteoglycans provide a compressive strenght?
water absorption, the protein contains highly negatively charged sugars - draws in water
58
What does the high charge of proteoglycans give them as an extra function
acts as a binding site for many signalling molecules
59
where is laminin located and what does it form?
forms the basement layer in Bowman's Capsule
60
Catecholamines are derived from what 2 amino acid residues?
tyrosin and tryptophan
61
Most hormones can be expressed as a 1:1 ratio, outline the equation demonstrating this
Kd = [H][R]/[HR]
62
What does Kd stand for?
concentration of hormone when half of the receptors are bound
63
What is the slope on a Scatchard’s plot?
1/Kd
| inverse of Kd
64
How is maximum biokogical response achieved for insulin when only 2-3% of receptors are bound (nowhere near the Bmax)?
very potent amplification system
65
what is the difference between a tropic and a trophic hormone?
tropic hormones target endocrine glands - anterior pituitary
| trophic hormones target non-endocrine glands - insulin
66
Where do nerves carry tropic hormones from and to?
hypothalamus to the anterior pituitary
67
What 2 receptors are involved in ADH regulation?
baroreceptors and osmoreceptors
68
Where are barorecptors located and how do they detect changes in blood pressure?
located in the aorta and detect change in plasma volume
69
Function of angiotensin II
regulates aldosterone synthase
70
What does zona glomerulosa release?
aldosterone
71
What does zona fasciculata/reticulata release?
cortisol
corticosterone
androstenedione
72
What does the Medulla release?
catecholamines
73
Function of ACTH
regulates 17alpha-hydroxylase
| converts cholesterol into pregnenolone
74
What does 17 alpha-hydroxylase do to pregnenolone/progesterone
adds an OH group
| hydroxypregnenolone/hydroxyprogesterone
75
Where is 17 alpha-hydroxylase located?
zona reticulata/fasciculata
76
Which product does not require 17 alpha-hydroxylase?
corticosterone
77
Since 17 alpha-hydroxylase is not present in the glomerulosa, it can only produce corticosterone, but what is this converted into?
aldosterone
78
How does a low filtration pressure in the Bowaman’s capsule lead to the release of renin?
low Na+/K+ detected due to low filtration pressure, leads to activation of juxta-glomelular cells to release renin.
79
Function of renin?
renin cleaves angiotensinogen into angiotensin I
80
what is the function of ACE
converts angiotensin I into angiotensin II
81
What detects the high blood pressure and what does it release
atrial muscle
| ANF
82
function of ANF
inhibits renin formation
83
Function of aldosterone?
increases Na+ - increases water absorbtion - increases blood pressure
decreases K+/H+
ionic balance
84
When starving (low blood-glucose levels), what does the liver convert triglycerides into?
acetyl CoA then into:
| acetoacetate or beta-hydroxybutyrate
85
Why does the liver then convert acetyl CoA into ketone bodies?
to be transported into other cells
acetyl CoA can't
is converted back into acetyl CoA in the target tissue
86
How is glucose released from the body when when blood-glucose levels are too high?
in the urine
| causes dehydration because water is then absorbed into the urine
87
What do both insulin and glucagon do?
they both induce uptake of amino acids by the liver
insulin for protein synthesis
glucagon for energy
88
If glucose does not enter cells in type 2 diabetes, what else is used as fuel?
lipids and amino acids
89
What is metabolic acidosis?
lipid conversion into ketone bodies - they are acidic
| causes acetone breath
90
What hormone does the hypothalamus send to the anterior pituitary for hormonal action in males?
GnRH
91
What does the anterior pituitary send to steroli cells and leydig cells?
Function of leydig cells?
steroli cells - FSH
leydig cells - LH
leydig cells - convert androstenedione into testosterone
92
What produces dihydrotestosterone?
steroli cells
93
Where is FSH and LH sent to in female hormonal action from the anterior pituitary?
FSH - granulosa cells
| LH - thecal cells
94
Function of FSH in females?
converts androgen into 17beta-estradiol
95
What phases of the cycle does ovulation occur
follicular and proliferative phase
96
What cycle stages does menses occur
luteal and secretory phase
97
Function of 17beta-estradiol?
promotes cell division of granulosa cells - uterus growth
| promotes a positive feedback loop
98
What is the localised positive feedback loop in the granulosa cells?
17beta-estradiol increases the amount of FSH receptors on the granulosa cell, increasing the amount of androgen converted into 17beta-estradiol
99
What happens when FSH receptors are converted into LH receptors in the corpus luteum?
corpus luteum mass produces progesterone which is released in the blood and causes a negative feedback loop back at the hypothalamus - decreasing the amount of FSH/LH being released - leads to corpus luteum death
100
What is the placenta formed from
syncytiotrophoblast/cytotrophoblast
101
What forms the yolk sac
hypobast
102
What forms the embryo?
epiblast
103
What does syncytistrophoblast secrete.
hCG - human Chrionic Ganadotropin
104
What does hCG do?
performs many of the same functions as LH, also binds to LH receptors
105
The corpus luteum decreases the levels of LH so it will eventually die, but since human chrionic ganadotropin is released by the embryo, what does it mean if the corpus luteum is still alive?
pregnancy
| congratulations
106
how long are fatty acids in terms of carbon
14-24 carbons
107
what is sphingomyelin derived from
sphingosine
108
which is the only phospholipid to carry a negative charge
phosphoatidylserine
109
do bacteria contain cholesterol and what do plants contain instead of cholesterol
no
| related sterol compounds
110
what happens to membrane at low temperatures
less kinetic energy, so decreased fluidity
| cholesterol increases spacing between phospholipids to increase fluidity
111
what happens to membranes at high temperature
increase fluidity due to increased kinetic energy
| cholesterol pulls hydrocarbon tails (fatty acid tails) together to decrease fluidity
112
what does the endomembrane system include
```
vesicles
golgi apparatus
nuclear envelope
plasma membrane
endoplasmic reticulum
```
113
what are the 2 pathways through the Golgi apparatus
cisternal maturation
| vesicle transport
114
how is the vesicular tubular cluster formed
COP II sheds to form a COP II coat which fuses to form the vesicular tubular cluster
115
function of KDEL receptors?
retrieve proteins back to the ER
116
what occurs at the cis golgi network
phosphorylisation of olligosaccharides on lysosomal proteins
117
what happens at the golgi stack?
removal of Man - manose
addition of Gal - galacatose
addition of NANA - N-acetylineuraminic acid/
addition of GlcNAc - N-acetylgloseamine
118
what happens at the trans-golgi network
sulfation of tyrosines and carbohydrates
119
what are the products when pyruvate is oxidised
CO2
H20
15ATP
120
where does NADH carry electrons to
inner membrane
121
in most organisms is mtDNA paternally or maternally inherited
maternally inherited
122
what is the difference between a type I and type II ribosome inactivating protein
type I cannot cross the cell membrane - non-cytotoxic
| type II can cross the cell membrane due to a binding domain
123
what C-terminal amino acids form the peroxisome form its signal sequence
lysine, serine, leucine
124
what type of enzymes are the ones within a lysosome
acid hydrolases
125
function of endosomes
sort and deliver material to the lysosome/vacuole
126
what are the different protein sub-units of vault complexes
TEP1
VPARP
MVP
127
what are the potential functions of vault complexes
```
associated with nuclear pore complexes
nuclear-cytoplasmic transport
cell signalling
mRNA localisation
drug resistance
```
128
what is the structure of proteosomes
central hollow cylinder
4 stacked heptameric rings
core particle in between 2 regulatory particles
129
what happens when glomelular actin (G-actin) is phophsorylised
filamentous actin (F-actin) is formed
130
what is an actin filament comprised of
2 twisted F-actins
131
what frees gelsolin and what does this lead to?
PIP2
| produces negative free positive ends for rapid actin polymerisation
132
what is the difference between alpha and beta tubulin
alpha-tubulin - has a bound molecule of GTP that does not hydrolyse
beta-tubulin - may have bound GTP or GDP
133
function of stathmin and why
binds 2 alpha/beta tubulin dimers together
thus reduces the pool of tubulin able to polymerise
allows GTP-hydrolysis to catch up
causes the microtubule to shrink
134
function of Microtubule Associated Proteins (MAP's)
allow crosslinking of microtubules
135
what is the diameter of an intermediate filament
8-10nm
136
how is the length of intermediate filaments regulated
proteases are able to degrade specific classes of intermediate filaments
137
what is saltatory movement
movement of mitochondria/lysosomes along a track in the cytoskeleton
138
how are motor proteins able to walk along the microtubule?
2 conformational changes
1 conformation stabilised by bound ATP
another conformation from ADP after hydrolyses
139
in terms of motor proteins what is the function of the globular head regions and the tail region
globular head - engages with the filament and moves along it
| tail - point of attachment for the motor protein and its cargo
140
what is the function of myosin difference between myosin XI and myosin V
myosin XI - cytoplasmic streaming
| myosin V - vesicle and organelle transport
141
what does movement/migration of cells require
anchorage and an active cytoskeleton
142
how does cilium (cilia) move
Dynein movements cause microtubules to slide of each other
| causes the cilium to bend
143
whats the difference between ABP type I/II/III
type I - binds to membrane via lipid interactions
type II - is an integral membrane protein
type III - binds to an integral membrane protein
143
whats the difference between ABP type I/II/III
type I - binds to membrane via lipid interactions
type II - is an integral membrane protein
type III - binds to an integral membrane protein
144
what are the structural units of a chromatin are and what are the structural sub-units of that
nucleosomes
| histone octamer
145
what is spectral karyotyping
technique to paint chromosomes using multi-coloured FISH
| helps visualise entire chromosomes
146
What are the functions of E1, E2 and E3 in terms of ubiquitin
E1 - ubiquitin activating enzyme - activates ubiquitin
E2 - is a ubiquitin conjugating enzyme
E3 - is a ubiquitin ligase - attaches ubiquitin to the target protein
147
when is APC/C and its substrates active in the cell cycle
| when is SCF and its substrates active in the cell cycle
APC/C+substrates - mid M to late G1
| SCF+substrates - late G1 to early M
148
what frequently contacts the cell cortex in terms of microtubules
astral microtubules
149
function of colchicine
binds to alpha-beta microtubules preventing polymerisation
prevents spindle fibre attachment to kinetichores
triggers SAC response
150
what can P53 cause
cell cycle arrest
senescence
apoptosis
151
what do thylakoids form and what do they form and what holds it together
granum disc
granum stack
stroma lamella
152
what is the function of FNR in PS I
reduces NADP to NADPH
153
what is the function of Rubisco
converts ribulose-1,5-bisphosphate into 3-phosphoglycerate
| up to 50% of the proteins in the stroma
154
what is a paracrine signal and give some examples
when a signal affects cells in its immediate vicinity
| neuronal synapses/immune cells
155
name paracrine siganl mediators released into the interstitial fluid
histamine
TGF-beta
cytokines
growth factors
156
what type of signals have the lowest concentration of its mediators in interstitial fluid and why
hormone signals
| hormone receptors usually have a high affinity, and the induce potent amplification responses
157
what are the types of fatty acid derivatives external meesengers
eicosanoid
thromboxanes
leukotrienes
PAF
158
what type of signalling produces slower responses related to changes in gene activity
lipophilic (hydrophobic)
159
function of cyclic AMP
activates protein kinases
mainly PKA
binds to ion channels
160
function of cyclic GMP
activates protein kinases
| mainly PKG
161
function of IP3
releases Ca2+ from intracellular stores
162
function of DAG
activates protein kinase C
163
function of acetyl cholinesterase
breaks down acetylcholine at the synapse
164
what is receptor-ligand internalisation and give examples
as a way to stop signalling, the receptor and its ligands are taken into the cell
LH
somatostatin
165
what is the function of neostigmine and what does it treat
blacks acetylcholine esterase
increases effectivity of acetylcholine
myasthenia gravis
166
function of fluoxetine (prozac) and what does it treat
blocks serotonin uptake
| used to treat depression
167
what are the 3 forms of NO synthase and where do they occur
eNOS - blood vessel endothelial cells
nNOS - neuronal cells
iNOS - inducible isoform occurring in immune cells
168
what does NO target and what does the product of this cause
gaunylate cyclase
forms cGMP
causes relaxations
169
how does phosphodiesterase stop the NO signal
converts cGMP back into GMP
170
what is the function of phospholipase C and how is it activated
cleaves PIP2 into IP3 and DAG
| activated by G-alpha subunit
171
give an example of an enzyme-linked receptor
receptor serine/threonine-kinases
172
how is a tyrosine kinase domain activated
binding of a receptor in the form of a dimer which dimerises 2 inactive tyrosine kinase domains into an active piece
173
what are the failures of tight junctions
related to auto-immune diseases
chronic inflammation
IBD
174
what enters the Wnt pathway and what is it used for
beta-catenin
| regulates cell division
175
how does the whole notch thing work
notch binds to delta-ligand receptor on the cell membrane of a different cell
notch is then cleaved at site 2, allowing it to fuck off
notch is then cleaved at site 3 allowing it to enter the nucleus
acts as a transcription factor
176
what gives regulated breakdown of collagenous breakdown
MMP's
177
function and properties of elastin
gives elastic properties in tissues
| highly hydrophobic - gives it a random structure and function
178
what does integrin act as
acts as a nucleation site for actin polymerisation
179
function of hemidesmosomes
binds epithelial cells to the basement layer
180
what do parathyroid hormones activate in the kidney and bone tissue
kidney - increases Ca2+ uptake by the distal convoluted tubule
bone - activates osteocytes and octeoclasts
181
function of nuclear translocation signals
target the receptor-hormone complex to the nucleus
182
what does is cortisol bound to in blood plasma
transcortin
183
what is Cushing's disease caused by
hyper secretion of glucocorticoids by the adrenal glands
184
what causes Addison's disease
reduced aldosterone
loss of Na+ in urine
K+ build up
185
what enzymes are needed to convert beta-hydroxybutyrate into acetone
hydroxybutyrate dehydrogenase into acetoacetate
| acetoacetate decarboxylase into acetone
186
whats the difference between a type 1 and type 2 receptor tyrosine kinase and give an example of a class 2 receptor tyrosine kinase
```
class 1 - the receptors come together upon ligand binding
class 2 - are permanently linked disulphide-linked tetramers
insulin receptor
```
187
what is the function of GLUT4 and AA, and what cells don't need them and why
make the cell membrane permeable to glucose and amino acids
| beta-pancreatic cells as they always need glucose
188
what are adipocytes
lipid storage - stops lipid breakdown
189
what is fibrosis and glycation cuased by
long-term hbyperglycemia
190
what is Maillard's reaction and what does it cause
when reducing sugars bind to a protein
| causes glycated proteins to cross-link
191
where is retinoic acid formed from
steroli cells
192
what do steroli cells convert testosterone into
dihydrotestosterone
193
how does testosterone in the blood affect GnRH levels
decreases it - negative feedback
194
what enzyme converts androstenedione and testosterone into 17-beta estradiol
aromatase
195
what does the luteinisation of granulosa cell cause
converts it to a corpus luteum
