D1.2 Protein Synthesis Flashcards

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1
Q

transcription definition

A

synthesis of messenger RNA using a DNA template

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2
Q

what is rna polymerase

A

enzyme that catalyses the synthesis of RNA molecules from a DNA template

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3
Q

where does transcription occur

A

cytoplasm for prokaryotes
nucleus in eukaryotes

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4
Q

process of transcription simple

A

part of dna unwinds because hydrogen bonds between complementary base pairs break

complementary copy of code from gene is made by building mRNA

RNA nucleotides pair up with complementary bases on unzipped DNA molecule

double stranded dna re-formed when hydrogen bonds between mRNA and DNA strands break

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5
Q

coding strand `

A

strand of dna that carries the genetic code

not used as template during replication

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6
Q

template strand

A

opposite dna strand which doesnt carry genetic code

used during transcription to produce mRNA

complementary to coding strand of DNA

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7
Q

role of hydrogen bonds in transcription

A

broken in dna to unzip it
formed between mRNA strand and DNA strand for complementary base pairing

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8
Q

which strand is transcribed to form MRNA molecule

A

template strand

to get an rna transcript of coding strand

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9
Q

why is dna is a very stable molecule

A

due to hydrogen bonding between the DNA bases of the 2 strands and the strong phosphodiester bonds between adjacent nucleotides in each strand

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10
Q

what does sugar phosphate backbone ensure

A

ensures stability of base sequence

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11
Q

why is stability important

A

so that genetic code is not prone to spontaneously breaking or changing

allows dna to act as reliable templates for transcription

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12
Q

gene expression

A

the process by which the information encoded in a gene is used to direct the synthesis of a protein molecule

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13
Q

what to specialised cells do to match requirements of cell

A

switch them on or off

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14
Q

which genes get switched on

A

genes that are expressed and undergo transcription and translation

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15
Q

which genes get switched off or silenced

A

genes that are not expressed and do not go through transcription or translation

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16
Q

translation definition

A

the information. of mRNA is decoded into proteins

involves taking the genetic code from the mRNA and synthesising a polypeptide

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17
Q

where does translation occur

A

in the cytoplasm

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18
Q

when does translation occur

A

after transcription as the mRNA template comes from transcription

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19
Q

what are the parts of a ribosome

A

2 - big and small

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20
Q

what are ribosomes made of

A

protein and rRNA
ribosomal rna

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21
Q

where in a ribosome does mRNA bind to

A

small subunit

22
Q

where in a ribosome does tRNA bind to

A

2 of them bind simultaneously to the large subunit

23
Q

what does complementary base pairing in translation happen between

A

codons and anticodons

24
Q

triplet

A

a sequence of 3 DNA bases that codes for a specific amino acid

25
Q

codon

A

a sequence of 3 mRNA bases that codes for a specific amino acid

26
Q

what is codon complementary to

A

triplet

26
Q

Anticodon

A

a sequence of 3 tRNA bases that are complementary to a codon

27
Q

what does tRNA carry

A

the appropriate amino acid to the ribosome

28
Q

what commands to codons carry

A

start and stop
to start and stop translation when the polypeptide chain is complete

29
Q

what are the stop codons

A

UAA
UAG
UGA

30
Q

sites of an amino acid

A

A - aminoacyl
P - pepticyle
E - exit site

31
Q

how many amines are there to be coded for

A

20

32
Q

how many bases for one amino

A

3

33
Q

what translations 3 base sequence to an amino acid sequence

A

tRNA

34
Q

to what are the amino acids bonded

A

bonded covalently to the site at the bottom of tRNA

only 1 particular amino can be bonded for one particular tRNA

35
Q

why are enzymes important in attaching amino to tRNA

A

enzymes are specific to amino acids which is a way of making sure that the correct amino acids are used in the right sequence

36
Q

how are amino acid completes held in position

A

temporarily held in position by hydrogen bonds

37
Q

the genetic code ideas

A
  • common original of life on earth
  • process of reading the code and process of protein synthesis through use of ribosomes and RNA are very similar in prokaryotes and eukaryotes
38
Q

universality of genetic code

A

means that almost every organisms uses the same code

genetic info is transferable between species

reason why genetic engineering is possible

39
Q

result of start and stop codons

A

reads dna correctly and produces the correct sequences of amino acids that it requires to function properly

40
Q

how many codons possible

A

64 because 4 bases (ATCG)
4^3=64

41
Q

degenerate

A

multiple codons can be coded for the same amino acid

42
Q

why can codes be degenerate

A

because 20 amino acids but 64 codons possible

can limit effect of mutation s

43
Q

how can the amino be read - table

A

first convert DNA to mRNA or any RNA
check table from that and name it

44
Q

how is the polypeptide chain elongated

A
  • during translation the ribosome moves in steps along mRNA
  • in each step the ribosomes moves 3 bases along the mRNA
  • repetition leads to a polypeptide being formed and elongated
45
Q

what are gene mutations

A

copying errors that take place when DNA is replicated during synthesis and interphase

46
Q

what mutations are not inherited

A

mutations preset in normal body cells are not inherited and eliminated when affected cells die

47
Q

what mutations are inherited

A

mutations within gametes are inherited by offspring

48
Q

point mutations

A

when one base in the DNA sequence is altered
can result in changed amino acid at location

49
Q

examples of point mutation

A

sickle cell disease

50
Q

why is sickle cell disease caused

A

caused by a single point mutation within the gene that codes for alpha global peptide in haemoglobin

most humans have the allele HbA
mutation results in HbB

51
Q

effects of sickle cell disease

A

have limited oxygen carrying capacity
blocks the capillaries and limit flow for normal RBCs