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MCBG > gene expression > Flashcards

gene expression Flashcards

1
Q

where does transcription occur?

A

nucleus

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2
Q

where does translation occur?

A

cytoplasm

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3
Q

3 properties of DNA replication

A

uses DNA pol, uses DNA as template and needs deoxynucelotides

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4
Q

3 properties of RNA transcription

A

uses RNA pol, uses DNA template and uses ribonucleotides

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5
Q

3 properties of RNA translation

A

uses ribosome (has enzymatic abilities and enzymes inside it), mRNA as template and uses amino acids.

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6
Q

what is a promoter?

A

a protein which gives of a signal. A transcription factor will bind to the promoter region and the gene will be transcribed. This can happen in both directions. down stream, with gene and upstream against gene but both times 5’ to 3’. produces product

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7
Q

how can a promoter control a gene when it is not attached to it directly

A

may bind the transcription factor which will lead to production of a mediator that activates or inhibits the promoter elsewhere on the gene.

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8
Q

turning premRNA to mature mRNA x3

A

capping
5’ cap prevents degeneration by nucleosomes in the cytoplasm
tailing
poly A at 3’ end to prevent degradation
splicing
interons removed and exons joined by endonucleases

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9
Q

what is an isonine base?

A

a base which can code for an A, U or C but always produces the same gene. it is a complication of RNA translation.

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10
Q

4 letter code 5’/3’ ( base ) and after translation it is…?

A

20 letter code with an N and C terminus (amino acids)

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11
Q

stop codons

A

UAA, UAG, UGA

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12
Q

start codons

A

AUG

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13
Q

describe the process of translation

A

initiation
mRNA strand binds to ribosome and AUG Condon is recognised by tRNA anticodon. Once bound the ribosome moves onto next codon.
elongation
N terminus to C terminus is translated and peptide bonds form between the amino acids catalysed by peptidyl transferase
termination
when stop codon is reached ribosome detaches. tRNA and water is released

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14
Q

what determines the phenotype

A

the genes which determine the proteins which determines the phenotype

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15
Q

why is gene expression important

A

ability to turn on and off genes because not all genes needed in every cell at all times

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16
Q

what is a gene

A

stretch of DNA which a chromosomal locus and is the code and regulation for a protein

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17
Q

which prime is DNA transcribed from and what does this make the mRNA primes

A

transcribed starting from 3’ to 5’ and therefore the complimentary copied strand of mRNA is from 5’ to 3’

18
Q

describe the process of DNA replication

A

recognition of origin of replication initiation proteins and DNA pol will bind to this adding a nucleotide on the end so replication can begin
5’ to 3’ chain growth
when replication forks meet replication is terminated

19
Q

what is a replication fork

A

the DNA strand is unwound by DNA helicase as far as the gene is needing to be transcribed. after this the DNA is wound together. DNA transcription cannot go any further than this so when the forks meet at this point this is when replication is terminated

20
Q

describe transcription

A

promotoer is recognised and RNA pol binds allowing 5’ to 3’ chain growth of the mRNA strand by complimentary base pairing using ribonucleotides and it is then terminated once the stop sequence has been reached

21
Q

what drives direction of transcription

A

when a ribonucleotide binds to the template strand pyrophosphate is released driving the reaction in the correct direction

22
Q

example of a promoter

A

TATAAA (tatabox) recognised and bound by transcription factor starting a whole sequence of events and transcription factor drives direction of transcription

23
Q

what happens if DNA is upside down

A

then transcription factor will still bind the promoter the other way round and direction of transition changes

24
Q

where does transcription starts from

A

from the first nucleotide after where the DNA pol is bound. not necessarily start from promoter sequence. this is called +1

25
Q

what is upstream and what is downstream

A

upstream has sequences of promotors and no DNA is actually transcribed here. down stream is after the start of transcription site

26
Q

what happens if there is a mutation in upstream promoter sequence

A

have problem with gene expression

27
Q

what is the template strand

A

strand opposite the promoter sequence and is copied exactly using complimentary base pairs. this strand is 3’ to 5’ so that the mRNA can be 5’ to 3’

28
Q

what is the coding strand

A

the strand identical to the mRNA

29
Q

what is capping

A

at 5’ end (start) f mRNA added cap to protect from degradation

30
Q

what is tailing

A

at 3’ end a poly A tail is added to protect against degradation. lots of A’s. called polyadenylation

31
Q

what is splicing

A

in the middle. removes introns and connects exons. if mutation in the site of being cut then may be cut wrong?

32
Q

how does polyedenylation work

A

sequence recognised to terminate transcription and a little downstream it is then cleaved. its cut by a specific endonuclease and then the poly A tail is added to a little bit of excess mRNA after the termination sequence

33
Q

what is mature mRNA

A

only contains exons and is the template of translation

34
Q

what type of ribosomes in prokaryotes and eukaryotes

A

80s = eu and 70s = pro

35
Q

types of RNA

A

rRNA - ribosomal (Most common about 80%) because part of ribosome and are massively important and complex. but only a few kinds
mRNA - messenger (tiny amount 2%) 100,000 of kinds with few copies because different mRNA from same gene
tRNA- transfer

36
Q

wha is the genetic code

A

20 letter code read in triplets. is degenerate and non-overlapping. read from 5’ to3’ making protein from N terminus to C terminus

37
Q

what does degenerate mean

A

multiple sequences code for same amino acid

38
Q

tRNA structure

A

form stem loops by hydrogen bonds (those loops). is single stranded have phosphate on 1 end nd hydroxyl on over. on end contains anticodon.

39
Q

what is an anticodon

A

it recognises the codon on mRNA in opposite direction

40
Q

what are wobble bases

A

A wobble base pair is a pairing between two nucleotides in RNA molecules that does not follow Watson-Crick base pair rules. This includes asinine

41
Q

how are amino acids activated

A

they are catalysed by an enzyme using ATP to join together a tRNA with the correct anticodon and the correct amino acid.

MCBG (16 decks)

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