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Physiology Flashcards

1
Q

name the components of the nuclear pore

A

nuclear basket
nuclear ring
cytoplasmic filaments
cytoplasmic ring

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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,

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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

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4
Q

the signal amino acid sequence usually contains what sequence of amino acids

A

Poly A

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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

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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.

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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

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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

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9
Q

name the phospholipid heads

A 
glycerol
choline
serine
ethanolanine
sphingolipids
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10
Q

How does a cis double bond in the fatty acid tail affect overall membrane fluidity?

A

increases fluidity

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11
Q

What are lipid rafts composed of?

A

cholesterol and sphingolipids

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12
Q

What can barely diffuse into the nucleus via diffusion in Daltons

A

50kda

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13
Q

What does the ER store and what is it used for?

A

Ca2+, cell signalling

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14
Q

What is the structure called when multiple ribosomes are bound to a single mRNA?

A

polysomes

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15
Q

Name the enzyme that catalyses the transfer of precursor oligosaccharide from dolichol lipid anchor

A

oligosacharyl transferase enzyme

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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

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17
Q

What are granules?

A

newly synthesised RNA

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18
Q

What oxidative enzymes do peroxisomes contain?

A

Catalase, urate oxidase

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19
Q

Why does the lysosome not self digest?

A

highly glycosylated proteins in its membrane

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20
Q

What is the most stable component of the cytoskeleton?

A

intermediate filaments

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21
Q

Where does alpha actin operate

A

skeletal muscle, smooth muscle, cardiac muscle

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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

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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

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24
Q

Functions of thymosin/prolifin?

A

thymosin: binds to actin - inhibiting its polymerisation
prolifin: binds to actin but aids in its polymerisation

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25
Q

function of filamin homodimers

A

takes microfilaments and cross links them to form a network

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26
Q

Where do microtubules grow from?

A

gamma rings found on centrosomes

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27
Q

Name the 2 microtubule motors and which direction they travel in

A

kinesins - plus end

dyenisins - minus end

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28
Q

What does the cell check at the G2/M transition?

A

DNA

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29
Q

What is checked at the metaphase to anaphase transition?

A

spindle fibres are correctly attached to kinetichores

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30
Q

Function of CDc25?

A

dephosphorylises CDK-cyclin complex to activate it

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31
Q

Function of Myt1/wee1?

A

phosphorylises CDK-cyclin complex to deactivate it

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32
Q

How does CDK-cyclin progress the cell cycle?

A

CDK-cyclin removes proteins that sit on the promoter region to allow transcription and progression of the cell cycle.

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33
Q

What occurs if damaged DNA is detected in terms of MDm2-P53?

A

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

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34
Q

What 2 protiens act to form a chromatin loop?

A

Cohesin and CTFC

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35
Q

what happens during prometaphase

A

nuclear envelope breaks down

spindle fibres attach to kinetichores

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36
Q

how do spindle fibres connect to kinetichores

A

the microtubule’s plus end is facing the kinetichore

the kinetichore contains connecting proteins which form a collar around the microtubule

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37
Q

what happens to securin once all kinetichores are correctly attached to a spindle fibre and what does this mean for seperase

A

securin degrades which frees seperase, activating it

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38
Q

what is the function of seperase

A

cleaves cohesin which allows the cell to enter anaphase

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39
Q

what is the function of APC/C

A

ubiquinates cyclin B1, which degrades it, leaving only CDK1 - triggering mitotic exit
Ubiquitinates Securin

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40
Q

function of mitogens?

A

triggers a wave of G/S-Cdk activity that removes cell cycle inhibitors

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41
Q

purpose of a synaptonemal complex

A

binds 2 homologous chromosomes to form a bi-valent structure

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42
Q

where is the synaptonemal complex formed

A

the zygotene

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43
Q

where is the synaptonemal complex fully completed

A

pachytene

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44
Q

where does the disassembly of the synaptonemal complex occur

A

diplotene

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45
Q

what is chiasmata and when is it visible

A

crossing over of sections of chromatids along their locus

visible after synaptonemal complex disassembly

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46
Q

what is a proplastid

A

a pre-cursor of all plastids

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47
Q

what are chromoplasts

A

non-photosynthetic plastids

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48
Q

what is amyloplast

A

starch storage plastid

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49
Q

Difference between leucoplast and elaioplast?

A

leucoplast is involved in lipid synthesis whereas elaioplast stores mostly sterol esters

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50
Q

what percentage of chloroplast protein is encoded by the chloroplast itself?

A

10%

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51
Q

function of N-terminal transit peptides

A

target proteins encoded by the nucleus into the chloroplast.

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52
Q

What is functional syncitia and whats the purpose of it?

A

when cells are are fused together with gap junctions

allows cascading signal to affect the neighbouring cell

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53
Q

What is functional syncitia and whats the purpose of it?

A

when cells are are fused together with gap junctions

allows cascading signal to affect the neighbouring cell

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54
Q

What creates the impermeable seal of tight junctions?

A

occludin/claudin create seals with the neighbouring cell’s occludin/claudin

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55
Q

What are cadherins dependent on?

A

Ca2+

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56
Q

How do cadherins form anchoring junctions?

A

the bind to cadherins of the same type on the cell surface of a neighbouring cell which forms a dimer

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57
Q

How do proteoglycans provide a compressive strenght?

A

water absorption, the protein contains highly negatively charged sugars - draws in water

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58
Q

What does the high charge of proteoglycans give them as an extra function

A

acts as a binding site for many signalling molecules

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59
Q

where is laminin located and what does it form?

A

forms the basement layer in Bowman’s Capsule

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60
Q

Catecholamines are derived from what 2 amino acid residues?

A

tyrosin and tryptophan

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61
Q

Most hormones can be expressed as a 1:1 ratio, outline the equation demonstrating this

A

Kd = [H][R]/[HR]

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62
Q

What does Kd stand for?

A

concentration of hormone when half of the receptors are bound

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63
Q

What is the slope on a Scatchard’s plot?

A

1/Kd

inverse of Kd

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64
Q

How is maximum biokogical response achieved for insulin when only 2-3% of receptors are bound (nowhere near the Bmax)?

A

very potent amplification system

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65
Q

what is the difference between a tropic and a trophic hormone?

A

tropic hormones target endocrine glands - anterior pituitary

trophic hormones target non-endocrine glands - insulin

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66
Q

Where do nerves carry tropic hormones from and to?

A

hypothalamus to the anterior pituitary

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67
Q

What 2 receptors are involved in ADH regulation?

A

baroreceptors and osmoreceptors

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68
Q

Where are barorecptors located and how do they detect changes in blood pressure?

A

located in the aorta and detect change in plasma volume

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69
Q

Function of angiotensin II

A

regulates aldosterone synthase

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70
Q

What does zona glomerulosa release?

A

aldosterone

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71
Q

What does zona fasciculata/reticulata release?

A

cortisol
corticosterone
androstenedione

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72
Q

What does the Medulla release?

A

catecholamines

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73
Q

Function of ACTH

A

regulates 17alpha-hydroxylase

converts cholesterol into pregnenolone

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74
Q

What does 17 alpha-hydroxylase do to pregnenolone/progesterone

A

adds an OH group

hydroxypregnenolone/hydroxyprogesterone

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75
Q

Where is 17 alpha-hydroxylase located?

A

zona reticulata/fasciculata

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76
Q

Which product does not require 17 alpha-hydroxylase?

A

corticosterone

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77
Q

Since 17 alpha-hydroxylase is not present in the glomerulosa, it can only produce corticosterone, but what is this converted into?

A

aldosterone

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78
Q

How does a low filtration pressure in the Bowaman’s capsule lead to the release of renin?

A

low Na+/K+ detected due to low filtration pressure, leads to activation of juxta-glomelular cells to release renin.

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79
Q

Function of renin?

A

renin cleaves angiotensinogen into angiotensin I

80
Q

what is the function of ACE

A

converts angiotensin I into angiotensin II

81
Q

What detects the high blood pressure and what does it release

A

atrial muscle

ANF

82
Q

function of ANF

A

inhibits renin formation

83
Q

Function of aldosterone?

A

increases Na+ - increases water absorbtion - increases blood pressure
decreases K+/H+
ionic balance

84
Q

When starving (low blood-glucose levels), what does the liver convert triglycerides into?

A

acetyl CoA then into:

acetoacetate or beta-hydroxybutyrate

85
Q

Why does the liver then convert acetyl CoA into ketone bodies?

A

to be transported into other cells
acetyl CoA can’t
is converted back into acetyl CoA in the target tissue

86
Q

How is glucose released from the body when when blood-glucose levels are too high?

A

in the urine

causes dehydration because water is then absorbed into the urine

87
Q

What do both insulin and glucagon do?

A

they both induce uptake of amino acids by the liver
insulin for protein synthesis
glucagon for energy

88
Q

If glucose does not enter cells in type 2 diabetes, what else is used as fuel?

A

lipids and amino acids

89
Q

What is metabolic acidosis?

A

lipid conversion into ketone bodies - they are acidic

causes acetone breath

90
Q

What hormone does the hypothalamus send to the anterior pituitary for hormonal action in males?

A

GnRH

91
Q

What does the anterior pituitary send to steroli cells and leydig cells?
Function of leydig cells?

A

steroli cells - FSH
leydig cells - LH
leydig cells - convert androstenedione into testosterone

92
Q

What produces dihydrotestosterone?

A

steroli cells

93
Q

Where is FSH and LH sent to in female hormonal action from the anterior pituitary?

A

FSH - granulosa cells

LH - thecal cells

94
Q

Function of FSH in females?

A

converts androgen into 17beta-estradiol

95
Q

What phases of the cycle does ovulation occur

A

follicular and proliferative phase

96
Q

What cycle stages does menses occur

A

luteal and secretory phase

97
Q

Function of 17beta-estradiol?

A

promotes cell division of granulosa cells - uterus growth

promotes a positive feedback loop

98
Q

What is the localised positive feedback loop in the granulosa cells?

A

17beta-estradiol increases the amount of FSH receptors on the granulosa cell, increasing the amount of androgen converted into 17beta-estradiol

99
Q

What happens when FSH receptors are converted into LH receptors in the corpus luteum?

A

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
Q

What is the placenta formed from

A

syncytiotrophoblast/cytotrophoblast

101
Q

What forms the yolk sac

A

hypobast

102
Q

What forms the embryo?

A

epiblast

103
Q

What does syncytistrophoblast secrete.

A

hCG - human Chrionic Ganadotropin

104
Q

What does hCG do?

A

performs many of the same functions as LH, also binds to LH receptors

105
Q

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?

A

pregnancy

congratulations

106
Q

how long are fatty acids in terms of carbon

A

14-24 carbons

107
Q

what is sphingomyelin derived from

A

sphingosine

108
Q

which is the only phospholipid to carry a negative charge

A

phosphoatidylserine

109
Q

do bacteria contain cholesterol and what do plants contain instead of cholesterol

A

no

related sterol compounds

110
Q

what happens to membrane at low temperatures

A

less kinetic energy, so decreased fluidity

cholesterol increases spacing between phospholipids to increase fluidity

111
Q

what happens to membranes at high temperature

A

increase fluidity due to increased kinetic energy

cholesterol pulls hydrocarbon tails (fatty acid tails) together to decrease fluidity

112
Q

what does the endomembrane system include

A 
vesicles
golgi apparatus
nuclear envelope
plasma membrane 
endoplasmic reticulum
113
Q

what are the 2 pathways through the Golgi apparatus

A

cisternal maturation

vesicle transport

114
Q

how is the vesicular tubular cluster formed

A

COP II sheds to form a COP II coat which fuses to form the vesicular tubular cluster

115
Q

function of KDEL receptors?

A

retrieve proteins back to the ER

116
Q

what occurs at the cis golgi network

A

phosphorylisation of olligosaccharides on lysosomal proteins

117
Q

what happens at the golgi stack?

A

removal of Man - manose
addition of Gal - galacatose
addition of NANA - N-acetylineuraminic acid/
addition of GlcNAc - N-acetylgloseamine

118
Q

what happens at the trans-golgi network

A

sulfation of tyrosines and carbohydrates

119
Q

what are the products when pyruvate is oxidised

A

CO2
H20
15ATP

120
Q

where does NADH carry electrons to

A

inner membrane

121
Q

in most organisms is mtDNA paternally or maternally inherited

A

maternally inherited

122
Q

what is the difference between a type I and type II ribosome inactivating protein

A

type I cannot cross the cell membrane - non-cytotoxic

type II can cross the cell membrane due to a binding domain

123
Q

what C-terminal amino acids form the peroxisome form its signal sequence

A

lysine, serine, leucine

124
Q

what type of enzymes are the ones within a lysosome

A

acid hydrolases

125
Q

function of endosomes

A

sort and deliver material to the lysosome/vacuole

126
Q

what are the different protein sub-units of vault complexes

A

TEP1
VPARP
MVP

127
Q

what are the potential functions of vault complexes

A 
associated with nuclear pore complexes
nuclear-cytoplasmic transport
cell signalling
mRNA localisation
drug resistance
128
Q

what is the structure of proteosomes

A

central hollow cylinder
4 stacked heptameric rings
core particle in between 2 regulatory particles

129
Q

what happens when glomelular actin (G-actin) is phophsorylised

A

filamentous actin (F-actin) is formed

130
Q

what is an actin filament comprised of

A

2 twisted F-actins

131
Q

what frees gelsolin and what does this lead to?

A

PIP2

produces negative free positive ends for rapid actin polymerisation

132
Q

what is the difference between alpha and beta tubulin

A

alpha-tubulin - has a bound molecule of GTP that does not hydrolyse
beta-tubulin - may have bound GTP or GDP

133
Q

function of stathmin and why

A

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
Q

function of Microtubule Associated Proteins (MAP’s)

A

allow crosslinking of microtubules

135
Q

what is the diameter of an intermediate filament

A

8-10nm

136
Q

how is the length of intermediate filaments regulated

A

proteases are able to degrade specific classes of intermediate filaments

137
Q

what is saltatory movement

A

movement of mitochondria/lysosomes along a track in the cytoskeleton

138
Q

how are motor proteins able to walk along the microtubule?

A

2 conformational changes
1 conformation stabilised by bound ATP
another conformation from ADP after hydrolyses

139
Q

in terms of motor proteins what is the function of the globular head regions and the tail region

A

globular head - engages with the filament and moves along it

tail - point of attachment for the motor protein and its cargo

140
Q

what is the function of myosin difference between myosin XI and myosin V

A

myosin XI - cytoplasmic streaming

myosin V - vesicle and organelle transport

141
Q

what does movement/migration of cells require

A

anchorage and an active cytoskeleton

142
Q

how does cilium (cilia) move

A

Dynein movements cause microtubules to slide of each other

causes the cilium to bend

143
Q

whats the difference between ABP type I/II/III

A

type I - binds to membrane via lipid interactions
type II - is an integral membrane protein
type III - binds to an integral membrane protein

143
Q

whats the difference between ABP type I/II/III

A

type I - binds to membrane via lipid interactions
type II - is an integral membrane protein
type III - binds to an integral membrane protein

144
Q

what are the structural units of a chromatin are and what are the structural sub-units of that

A

nucleosomes

histone octamer

145
Q

what is spectral karyotyping

A

technique to paint chromosomes using multi-coloured FISH

helps visualise entire chromosomes

146
Q

What are the functions of E1, E2 and E3 in terms of ubiquitin

A

E1 - ubiquitin activating enzyme - activates ubiquitin
E2 - is a ubiquitin conjugating enzyme
E3 - is a ubiquitin ligase - attaches ubiquitin to the target protein

147
Q

when is APC/C and its substrates active in the cell cycle

when is SCF and its substrates active in the cell cycle

A

APC/C+substrates - mid M to late G1

SCF+substrates - late G1 to early M

148
Q

what frequently contacts the cell cortex in terms of microtubules

A

astral microtubules

149
Q

function of colchicine

A

binds to alpha-beta microtubules preventing polymerisation
prevents spindle fibre attachment to kinetichores
triggers SAC response

150
Q

what can P53 cause

A

cell cycle arrest
senescence
apoptosis

151
Q

what do thylakoids form and what do they form and what holds it together

A

granum disc
granum stack
stroma lamella

152
Q

what is the function of FNR in PS I

A

reduces NADP to NADPH

153
Q

what is the function of Rubisco

A

converts ribulose-1,5-bisphosphate into 3-phosphoglycerate

up to 50% of the proteins in the stroma

154
Q

what is a paracrine signal and give some examples

A

when a signal affects cells in its immediate vicinity

neuronal synapses/immune cells

155
Q

name paracrine siganl mediators released into the interstitial fluid

A

histamine
TGF-beta
cytokines
growth factors

156
Q

what type of signals have the lowest concentration of its mediators in interstitial fluid and why

A

hormone signals

hormone receptors usually have a high affinity, and the induce potent amplification responses

157
Q

what are the types of fatty acid derivatives external meesengers

A

eicosanoid
thromboxanes
leukotrienes
PAF

158
Q

what type of signalling produces slower responses related to changes in gene activity

A

lipophilic (hydrophobic)

159
Q

function of cyclic AMP

A

activates protein kinases
mainly PKA
binds to ion channels

160
Q

function of cyclic GMP

A

activates protein kinases

mainly PKG

161
Q

function of IP3

A

releases Ca2+ from intracellular stores

162
Q

function of DAG

A

activates protein kinase C

163
Q

function of acetyl cholinesterase

A

breaks down acetylcholine at the synapse

164
Q

what is receptor-ligand internalisation and give examples

A

as a way to stop signalling, the receptor and its ligands are taken into the cell
LH
somatostatin

165
Q

what is the function of neostigmine and what does it treat

A

blacks acetylcholine esterase
increases effectivity of acetylcholine
myasthenia gravis

166
Q

function of fluoxetine (prozac) and what does it treat

A

blocks serotonin uptake

used to treat depression

167
Q

what are the 3 forms of NO synthase and where do they occur

A

eNOS - blood vessel endothelial cells
nNOS - neuronal cells
iNOS - inducible isoform occurring in immune cells

168
Q

what does NO target and what does the product of this cause

A

gaunylate cyclase
forms cGMP
causes relaxations

169
Q

how does phosphodiesterase stop the NO signal

A

converts cGMP back into GMP

170
Q

what is the function of phospholipase C and how is it activated

A

cleaves PIP2 into IP3 and DAG

activated by G-alpha subunit

171
Q

give an example of an enzyme-linked receptor

A

receptor serine/threonine-kinases

172
Q

how is a tyrosine kinase domain activated

A

binding of a receptor in the form of a dimer which dimerises 2 inactive tyrosine kinase domains into an active piece

173
Q

what are the failures of tight junctions

A

related to auto-immune diseases
chronic inflammation
IBD

174
Q

what enters the Wnt pathway and what is it used for

A

beta-catenin

regulates cell division

175
Q

how does the whole notch thing work

A

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
Q

what gives regulated breakdown of collagenous breakdown

A

MMP’s

177
Q

function and properties of elastin

A

gives elastic properties in tissues

highly hydrophobic - gives it a random structure and function

178
Q

what does integrin act as

A

acts as a nucleation site for actin polymerisation

179
Q

function of hemidesmosomes

A

binds epithelial cells to the basement layer

180
Q

what do parathyroid hormones activate in the kidney and bone tissue

A

kidney - increases Ca2+ uptake by the distal convoluted tubule
bone - activates osteocytes and octeoclasts

181
Q

function of nuclear translocation signals

A

target the receptor-hormone complex to the nucleus

182
Q

what does is cortisol bound to in blood plasma

A

transcortin

183
Q

what is Cushing’s disease caused by

A

hyper secretion of glucocorticoids by the adrenal glands

184
Q

what causes Addison’s disease

A

reduced aldosterone
loss of Na+ in urine
K+ build up

185
Q

what enzymes are needed to convert beta-hydroxybutyrate into acetone

A

hydroxybutyrate dehydrogenase into acetoacetate

acetoacetate decarboxylase into acetone

186
Q

whats the difference between a type 1 and type 2 receptor tyrosine kinase and give an example of a class 2 receptor tyrosine kinase

A 
class 1 - the receptors come together upon ligand binding
class 2 - are permanently linked disulphide-linked tetramers
insulin receptor
187
Q

what is the function of GLUT4 and AA, and what cells don’t need them and why

A

make the cell membrane permeable to glucose and amino acids

beta-pancreatic cells as they always need glucose

188
Q

what are adipocytes

A

lipid storage - stops lipid breakdown

189
Q

what is fibrosis and glycation cuased by

A

long-term hbyperglycemia

190
Q

what is Maillard’s reaction and what does it cause

A

when reducing sugars bind to a protein

causes glycated proteins to cross-link

191
Q

where is retinoic acid formed from

A

steroli cells

192
Q

what do steroli cells convert testosterone into

A

dihydrotestosterone

193
Q

how does testosterone in the blood affect GnRH levels

A

decreases it - negative feedback

194
Q

what enzyme converts androstenedione and testosterone into 17-beta estradiol

A

aromatase

195
Q

what does the luteinisation of granulosa cell cause

A

converts it to a corpus luteum

Biomed (9 decks)

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