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topic 8 bio > nerves vs hormones > Flashcards

nerves vs hormones Flashcards

1
Q

describe the way a hormone brings about a change in the activity of a target cell (think to topic 3)

A

-hormone binds to target cell receptor
-transcription (initiation) complex froms

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2
Q

whatre restriction enzymes?

A

cuts DNA
fragments cut with sticky ends/single stranded overhangs
fragments with matching overhangs base pair
ligase or smth

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3
Q

what does DNA ligase do?

A

stick DNA together

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4
Q

whats a promoter REGION

A

site on a transcription factor that binds to a specific base sequence
the binding of a transcription factor to a promoter region can either allow or prevent a gene from being expressed

where DNA initially binds

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5
Q

what is a transcription factor

A

a protein tha controls transcription of genes by binding to a specific region of DNA

ensure that genes are being expressed in the correct cells, at the correct time and correct level

transcription factors allow organisms to respond to their environment

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6
Q

what’re transcription factors that increase the rate of transcription?

A

activators

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7
Q

what’re transcription factors that reduce the rate of transcription called?

A

repressors

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8
Q

how do activators work?

A

by helping RNA polymerase to bind to DNA at the start of a gene
beginning transcription of the gene

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9
Q

how do repressors work?

A

stop RNA polymerase from binding to DNA at the start of a gene inhibiting the transcription of that gene

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10
Q
A

some transcription factors bind to promoter region of a gene

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11
Q

what’re operons

A

in prokaryotes control of gene expression often requires binding of transcription factors to operons

they’re sections of DNA that includes a cluster of structural genes transcribed together

a group or cluster of genes controlled by the same promoter

operoms switch genes off or on depending on if theyre needed

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12
Q

what does the lac operon do?

A

operon so group of genes controlled by same promoter

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13
Q

what is an operator region?

A

genetic sequence which allows proteins responsible for transcription to bind to gene sequence

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14
Q

what happens when lac repressor protein binds to operator in lac operon and to lactose

A

-when bound to operator-transcription of structural genes is prevented as RNA polymerase cant attach to the promoter
-when bound to lactose-
shape of repressor protein distorts and repressor protein can no longer bind to operator

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15
Q

what happens when lactose is absent

A

lac repressor protein produced as the regulatory gene is transcribed and translated to produce it

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16
Q

What is a regulatory gene

A

codes for proteins

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17
Q

what is happening when a gene is being expressed?

A

a gene is expressed if the code is being read and converted into a polypeptide

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18
Q

what is enzyme induction

A

the process of switching a gene on

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19
Q

b galactisidase hydrolyses lactose into glucose and galactose

A

when repressor gene attached to operator

gene that codes for b-galacsidase only

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20
Q
A

in the presence of lactose the gene that codes for b galactosidase is switched on
b galactosidase hydrolyses lactose so only necessary when lactose is around

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21
Q

whatre operons

A

unit of DNA containing a cluster of genes under the control of a single section of DNA

operoms switch genes off or on depending on if theyre needed

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22
Q

whatre the (lac)operon components

A

-reglatory gene
-promoter
-operator
-structural genes

23
Q

what do the structural genes in the lac operon do?

A

code for enzymes to break down lactose
and are transcribed as a group

24
Q

operator

A

like the on/off switch of transcription, short sequence of DNA where the REPRESSOR binds preventing RNA polymerase from attaching to the promoter

25
promoter
short sequence of DNA where RNA polymerase attaches
26
regulator gene
regulates the activity of the structural genes codes for a repressor protein normally when glucose is present the repressor protein actively binds to the operator + prevents RNA polymerase from binding to the promoter and transcribing the genes for lactose metabolism
27
what happens to lac operon in presence of glucose
lac operon will be inactive regualtor gene codes for repressor so repressor always present, not always bound to operator though when glucose is present repressor protein binds to operator RNA polymerase prevented from binding to the promoter and transcribing the genes for lactose metabolism so b galactosidase wont be produced and lactose wont be metabolised
28
why is transcription of genes for lactose metabolism not desirable when glucose is present
waste of energy, lactose is metabolised to produce glucose and galactose so more efficient for body to just use glucose genes that encode for lactose metabolism are repressed
29
repressor protein further detail
when repressor protein is bound to the operator RNA polymerase still binds to the promoter but is unable to move past the operator, because it's being blocked by the repressor. so the genes (that encode for the enzymes that metabolise lactose) cant be transcribed into the actual enzymes that metabolise lactose
30
what happens when glucose is absent and lactose is present
lac operon is turns on when glucose is absent it becomes desirable to have enzymes that metabolize glucose- lactose metabolised to produce glucose so RNA polymerase should be able to move past the operator and transcribe the structural genes so the REPRESSOR needs to be inhibited so it cant block RNA polymerase from moving to structural genes
31
how is the repressor inhibited?
lactose binds to it changing its shape so it can no longer fit into operator-still present just inhibited RNA polymerase no longer blocked so can move past the operator and transcribe the genes for lactose metabolism enzymes for metabolism of lactose produced and lactose is digested INCLUDING THE LACTOSE BOUND TO THE REPRESSOR
32
what happens when all available lactose has been digested?
the lactose bound to the repressor (changing its shape) is digested meaning the repressor reverts to its original shape and will no longer bind to the operator + block RNA polymerase so genes for the digestion of lactose once again no longer transcribed
33
lac operon overall
overall lac operon controls the transcription/production of enzymes for lactose metabolism
34
whatre mesenchymal stem cells?
a type of multipotent stem cell (bone)
35
whatre multipotent stem cells?
they have the ability to differentiate in a limited amount of cell types within a specific tissue or organ system
36
explain how sometimes transcription factors can help hormones to achieve their effect
some hormones achieve their effect via transcription factors
37
how do activators work?
helping RNA polymerase to bind to DNA at the start of a gene
38
what is a target cell for hormones?
one that bears receptors for that hormone
39
describe the way in which a hormone brings about a change in ACTIVITY in the target cell
-hormone binds to receptor on target cell->stimulus -transcription complex forms on promoter region of a specific gene -RNA polymerase binds to gene and transcribes it forming mRNA mRNA translated at ribosome to produce a specific protein the protein produced determines the structure/function of the cell
40
RNA polymerase function
responsible for transcription-synthesising RNA from a DNA template
41
what is temporal summation
single presynaptic neuron repeatedly stimulating a post synaptic neuron (several impulses from the same pathway)
42
what is spatial summation
multiple presynaptic neurons converge on a single postsynaptic neuron or effector cell. adding together the effects of neurotransmitters released from many neurons (impulses from many dif neurons)
43
explain how an increase in heart rate is brought about during exercise
lactic acid ends up in blood, lowers blood PH chemoreceptors detect decrease in pH in aorta/carotid artery action potential sent to CV centre in the medulla CV centre in medulla sends an action potential to the SAN via the sympathetic nerve the SAN increases the frequency of depolarisation across the atria, this increases heart rate
44
explain how one gene can give rise to many different proteins
introns spliced out of mRNA to leave exons exons can recombine in a number of different ways dif combination leads to dif codon on mature mRNA dif sequence of codons will code for dif sequence of amino acids in primary structure
45
intron definition
non-coding section of DNA
46
Exon definition
region of a gene that requires info to code for a protein
47
Whatre the methods if post-transcriptional modification?
splicing and alternative splicing
48
what does pre-mRNA include?
introns and exons
48
what is splicing and when does it occur?
splicing occurs after transcription and before mRNA leaves the nucleus splicing is the removal of introns and fusing of exons left behind together mature mRNA produced
48
what does mRNA include
only exons
49
what is a length of DNA that only codes for one polypeptide or protein?
a gene
50
do chromosomes code for multiple or one polypeptide?
several
51
explain alternative splicing
exons together in different combinations so different sequence, codes for dif amino acids and polypeptide sequence

topic 8 bio (12 decks)

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