things i often forget Flashcards

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1
Q

what is the name of the process that results in more than one protein being produced from a single gene

A

alternative rna splicing

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2
Q

what are the factors that affect the set of proteins expressed by a given cell type

A
  • metabolic activity
  • cellular stress
  • response to signalling molecules
  • diseased vs healthy cells
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3
Q

where are lipids synthesised

A

smooth endoplasmic reticulum

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4
Q

what is a signal sequence and what does it do

A

a short stretch of amino acids at one end of the polypeptide
it determines the eventual location of a protein in a cell

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5
Q

what do transmembrane proteins carry

A

a signal sequence

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6
Q

what does a signal sequence do

A

it halts translation and directs the ribosome synthesising the protein to dock with the ER forming the RER

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7
Q

where do proteins undergo post translational modification

A

golgi apparatus

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8
Q

where do secreted proteins get translated

A

in the rough endoplasmic reticulum

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9
Q

what is the classification of an r group with an amine group

A

basic

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10
Q

what is the classification of an r group with a carbonyl group

A

polar

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11
Q

what is the classification of an r group with a hydroxyl group

A

polar

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12
Q

what is the classification of an r group with a carboxyl group

A

acidic

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13
Q

what is the classification of an r group with a hydrocarbon group

A

hydrophobic

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14
Q

what kind of bond results in regions of secondary structure

A

hydrogen bonding along the backbone

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15
Q

what is an alpha helice

A

looks similar to the dna double helix shape

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16
Q

what is a beta pleated sheet

A

really long arrow, no overlap but loops and comes back up and then back down

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17
Q

what is a turn

A

arrow, flip, arrow

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18
Q

what is a prosthetic group

A

a non protein unit tightly bound to a protein and necessary for its function

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19
Q

why does a change in pH disrupt the protein structure

A

as pH changes from the optimum, the normal ionic interactions between charged group ions are lost, which changes the conformation of the protein until it becomes denatured

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20
Q

where do allosteric interactions occur

A

between spatially distinct sites

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21
Q

why are allosteric interactions of biological importance

A

the activity of allosteric enzymes can vary greatly with small changes in substrate concentration

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22
Q

what do modulators do

A

they regulate the activity of the enzyme when they bind to the allosteric site

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23
Q

what do positive modulators do

A

they increase the enzymes affinity for the substrate

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24
Q

what do negative modulators do

A

they decrease the enzymes affinity for the substrate

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25
Q

what is meant by cooperativity in binding

A

changes in binding at one subunit alter the affinity of the remaining subunits

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26
Q

what do protein kinases do

A

they catalyse the transfer of a phosphate group to other proteins

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27
Q

what do protein phosphotases do

A

they catalyse the reverse reaction

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28
Q

does adding a phosphate add negative or positive charges

A

negative

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29
Q

where is a peripheral membrane protein on the membrane

A

on the edge, no overlap

30
Q

where is the integral membrane protein on the membrane

A

inside, but open to the edge of the membrane

31
Q

what is facilitated diffusion

A

the passive transport of substances across the membrane through specific transmembrane proteins

32
Q

what is aquaporin

A

water channels which allow water to diffuse through the membrane

33
Q

what are ligand gated channels controlled by

A

binding of signal molecules

34
Q

what are voltage gated channels controlled by

A

ion concentration

35
Q

what are the three steps in a signal transduction pathway

A
  • reception
  • transduction
  • response
36
Q

what are hormone response elements

A

specific dna sequences that the hormone receptor complex binds to

37
Q

what happens when the hormone receptor complex binds to hormone response elements

A

the rate of transcription is influenced, with each steroid hormone affecting the gene expression of many different genes.

38
Q

do hydrophylic signalling molecules enter the cytosol

A

no

39
Q

what do g proteins do

A

they relay signals from activated receptors to target proteins such as enzymes and ion channels

40
Q

what is an activated receptor

A

receptors that have bound to a signalling molecule

41
Q

what does binding of insulin to its receptors result in

A

an intracellular signalling cascade that triggers the recruitment of glut4 glucose transporter proteins to the cell membrane of fat and muscle cells

42
Q

what is resting membrane potential

A

a state where there is no net flow of ions across the membrane

43
Q

what is an action potential

A

a wave of electrical excitation across a neurons plasma membrane

44
Q

how do neurotransmitters initiate a response

A

by binding to their receptors at a synapse

45
Q

what is depolarisation

A

a change in the membrane potential to a less negative value inside the cell

46
Q

what is the refractory period

A

period in which neuron is unresponsive to stimulation as the ion distribution s being restored

47
Q

what is repolarisation

A

an electrical change within a neuron from a relatively positive charge to a negative charge

48
Q

what are microtubules

A

hollow cylinders made from the protein tubulin

49
Q

what are transcription factors

A

proteins that when bound to dna can either stimulate or inhibit initiation of transcription

50
Q

what are neurotransmitter receptors

A

ligand gated ion channels

51
Q

how do neurotransmitters initiate a response

A

by binding to their receptors at a synapse

52
Q

how can resting membrane potential be restored

A

by inactivating the sodium channels and opening the potassium channels

53
Q

what happens when the action potential reaches the end of a neuron

A

vesicles containing neurotransmitter fuse with the membrane. this releases neurotransmitter, which stimulates a response in a connecting cell

54
Q

how are signals amplified in the eye

A

cascade of proteins

55
Q

what does cell division require

A

the remodelling of the cytoskeleton

56
Q

what are checkpoints

A

mechanisms within the cell that assess the condition of the cell during cell division and halt progression to the next phase until certain requirements are met

57
Q

what is involved in regulating the cell cycle

A

cyclin proteins that accumulate during cell growth

58
Q

what happens at the g1 checkpoint

A

retinoblastoma protein acts as a tumour suppressor by inhibiting the transcription of genes that code for proteins needed for dna replication

59
Q

what happens at the g2 checkpoint

A

the success of dna replication and any damage to dna is assessed

60
Q

what does dna damage trigger

A

the activation of several proteins including p53 that can stimulate dna repair, arrest the cell cycle, or cause cell death.

61
Q

what happens at the metaphase checkpoint

A

progression is halted until chromosome is aligned correctly on the metaphase plate and attached to the spindle microtubules.

62
Q

what may result in degenerative diseases

A

an uncontrolled reduction in the rate of the cell cycle

63
Q

what may result in tumour formation

A

an uncontrolled increase in the rate of the cell cycle

64
Q

what is a proto-oncogene

A

a normal gene usually involved in the control of cell growth or division, which can mutate to form a tumour promoting oncogene

65
Q

what is an example of an external death signal

A

the production of death signal molecules from lymphocytes

66
Q

what is an example of an internal death signal

A

dna damage

67
Q

what causes the activation of p53 tumour suppressor proteins

A

internal death signal

68
Q

what is p53

A

a tumour suppressor protein

69
Q

what is a caspase

A

a type of protease enzyme

70
Q

why is apoptosis essential during the cell development of an organism

A

to remove cells no longer required as development progresses or during metamorphosis

71
Q

explain the importance of a system being able to return target proteins to their inactive state

A

so that the target protein can respond again

72
Q

explain how the action of protein kinase can switch a target protein from inactive to active

A

the kinase adds a phosphate to the target protein, causing it to change conformation