DNA and protein synthesis Flashcards

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1
Q

gene

A

base sequence of DNA that codes for the amino acid sequence of a polypeptide or a functioning RNA

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2
Q

genome

A

complete set of genes present in a cell

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3
Q

where is a full genome present

A

every cell of an organism

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4
Q

where is a genome expressed

A

not every gene is expressed in every cell, which genes are expressed depends on the type of cell

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5
Q

what controls what genes are expressed

A

the type of cell

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6
Q

proteome

A

full range of proteins a cell is able to produce

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7
Q

is genome or proteome typically larger

A

proteome

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8
Q

why is proteome typically larger than the genome

A

-large amount of post-transnational modification of proteins
-each gene is also capable of producing multiple different proteins by alternative splicing

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9
Q

similarities of DNA and RNA

A

-both polynucleotide as made of many nucleotide together in a long chain
-both contain nitrogenous bases adenine, guanine and cytosine

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10
Q

what is similar about chain of DNA and RNA

A

both polynucleotide as made of many nucleotide linked together in a long chain

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11
Q

similarities of bases in DNA and RNA

A

both have adenine, guanine and thymine

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12
Q

differences in DNA and RNA

A

-DNA contains nitrogenous thymine by RNA contains nitrogenous uracil
-RNA has pentose sugar ribose and DNA has pentose sugar deoxyribse

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13
Q

difference in nitrogenous based of DNA and RNA

A

DNA has thymine and RNA has uracil

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14
Q

difference of pentose sugars of DNA and RNA

A

DNA has deocyribose and RNA has ribose

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15
Q

strand of DNA

A

double-stranded

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16
Q

strand of RNA

A

single-stranded

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17
Q

structure of RNA

A

-ribose (pentose sugar)
-phosphate group
-nitrogenous base of A,U,C,G

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18
Q

structure of DNA

A

-deoxyribose (pentose suagr)
-phosphate group
-nitrogenous base A,T,C,G

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19
Q

what is each RNA polynucleotide strand made of

A

alternating ribose sugars and phosphate groups linked together, with the nitrogenous bases of each nucleotide projecting out sideways from the single-stranded RNA molecule

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20
Q

phosphodiester bonds

A

the sugar-phosphate bonds between different nucleotides in the same strand are covalent bonds

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21
Q

what do phosphodiester bonds between nucleotides form

A

the sugar-phosphate backbone of the RNA polynucleotide strand

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22
Q

what do the phosphodiester bonds link

A

link the 5-carbon of one ribose sugar molecule to the phosphate group from the same nucleotide, which itself is kinked by another phosphodiester bond to the 3-carbon of the ribose sugar of the next molecule in the strand

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23
Q

strand of mRNA

A

single stranded

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24
Q

what is mRNA made of

A

sugar-phosphate backbone and exposed unpaired bases (A,U,C,G)

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25
Q

tRNA strands

A

single-stranded

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26
Q

what is tRNA made of

A

sugar-phosphate backbone

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27
Q

tRNA shape

A

folded or clover leaf shape as hydrogen bonds between some complementary base pairs

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28
Q

where do amino acids bind to tRNA

A

specific region of the molecule

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29
Q

what is the anticodon in tRNA complementary to

A

specific codon on mRNA molecule

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30
Q

what is a gene

A

base sequence of DNA that codes for the amino acids sequence of a polypeptide or functional RNA molecule

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31
Q

what 2 stages do protein synthesis occurs in

A

transcription and translation

32
Q

what is transcription

A

DNA is transcribed and an mRNA molecule if produced

33
Q

where does transcription occur

A

in nucleus of the cell

34
Q

outline transcription

A

-occurs in nucleus of the cell
-part of the DNA molecule unwinds (breaks hydrogen bonds between complementary base pairs break) this is catalysed by DNA helicase
-this exposes the gene to be transcribed
-a complementary copy of the code from the gene is made by building a single-stranded nucleic acid molecule know as mRNA
-free activated RNA nucleotides pair up via hydrogen bonds with their complementary bases on one strand of the unzipped DNA molecule
-the sugar-phosphate bonds of these RNA nucleotides are then bonded together by enzyme RNA polymerase to form sugar-phosphate backbone of mRNA molecule
-when the gene has been transcribed (when the mRNA molecule is complete) the hydrogen bonds between the mRNA and DNA strand break and double-stranded DNA molecule re-forms
-the mRNA molecule leaves the nucleus via pores in the nuclear envelope

35
Q

unwinding of DNA

A

Part of DNA molecule unwinds breaking hydrogen bonds between complementary base pairs which is catalysed by DNA helicase

36
Q

what does unwinding of DNA expose

A

exposes the gene to be transcribed

37
Q

what happens once gene is exposed in transcription

A

complementary copy of code from gene is made by building a single-stranded nucleic acid molecule known as mRNA

38
Q

what do the free floating RNA nucleotides do

A

free activated RNA nucleotides pair up via hydrogen bonds with complementary bases on one strand of the unzipped DNA molecule

39
Q

how is sugar-phosphate backbone form

A

-the sugar-phosphate groups of these RNA nucleotides are then bonded together by enzyme RNA polymerase to form the sugar-phosphate backbone of the mRNA molecule

40
Q

what happens in translation when the gene has been transcribed

A

when the gene has been transcribed the hydrogen bods between the mRNA and DNA strands break and the double-stranded DNA molecule re-forms

41
Q

what happens once the mRNA molecule is done

A

the mRNA molecule leaves the nucleus via pores in the nuclear envelope

42
Q

what is the DNA molecule not transcribed called

A

non-template strand

43
Q

what is the unzipped strand called

A

template strand

44
Q

where can non-coding DNA be found

A

-between genes as non-coding repeats
-within genes as introns

45
Q

what type of DNA has non-coding regions

A

eukaryotic

46
Q

what of the gene is transcribed and what does it make

A

pre-mRNA which contain all introns and exons

47
Q

what happens when pre-mRNA has splicing

A

-non-coding sections are removed
-coding sections are joined together
-the resulting mRNA molecules carriers only the coding sequences of the gene
-mRNA contains only exons and exists the nucleus before joining a ribosome for translation

48
Q

what is another way exons can be spliced

A

through alternative splicing

49
Q

what does alternative splicing mean

A

single eukaryotic gene can code for more than one polypeptide chain, this is part of the reason why proteome is much bigger than the genome

50
Q

what is translation

A

mRNA is translated and an amino acid sequence is produced

51
Q

where does translation occur

A

cytoplasm of the cell

52
Q

outline translation

A

-occurs in cytoplasm of the cell
-after leaving nucleus, the mRNA molecule attaches to a ribosme
-in cytoplasm there are free molecules of tRNA
-these tRNA molecules have a triplet of unpaired bases at one end (anticodon) and a region where a specific amino acid can attach to the other
-there are at least 20 different tRNA molecules, each with a specific anticodon and specific amino acid binding site
-the tRNA molecules bind with their specific amino acids (in cytoplasm) and bring them to the molecule in the ribosome
-the triplet of bases (anticodon) on each tRNA molecule pairs with a complementary triplet (codon) on mRNA molecule
-two tRNA molecules fit onto the ribosome at any one time, bringing the amino acid they are carrying side by side
-a peptide bond is formed between the 2 amino acids, the formation of a peptide bond between amino acids requires energy in the form of ATP, the ATP needed for translation is provided by the mitochondria within the cell
-this process continues until a stop codon on the mRNA molecule is reached, this cats as a signal for translation to stop and at this point the amino acid chain coded for by the mRNA molecule is complete
-this amino acid chain then form the final polypeptide

53
Q

what happens to mRNA molecule after leaving nucleus

A

mRNA attaches to a ribosome

54
Q

what RNA is free floating in cytoplasm

A

free molecules of tRNA

55
Q

tRNA molecules binding sites

A

have a triplet of unpaired bases at one end (anticodon) and a region where a specific amino acids can attach at the other

56
Q

how many different tRNA molecules are there

A

at least 20

57
Q

tRNA binding

A

tRNA molecules bind with their specific amino acids (in cytoplasm) and bring them to the mRNA molecule on the ribosome

58
Q

tRNA anticodon binding

A

the triplet of bases (anticodon) on each tRNA molecule pairs with complementary triplet (codon) on the mRNA molecule

59
Q

how many tRNA molecules can fit onto the ribsome at any one time

A

2, bringing the amino acid they are carrying side by side

60
Q

peptide bond formed between amino acids requires

A

-formation of a peptide bond between amino acids requires energy in the form of ATP
-the ATP needed for translation is provided by the mitochondria within the cell

61
Q

when does translation stop

A

when as stop codon is reached

62
Q

what is a stop codon a signal for

A

signal for translation to stop and at this point the amino acids chain coded for by the mRNA molecule is complete

63
Q

what does the amino acid chain formed from translation form

A

the final polypeptide

64
Q

what is a triplet

A

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

65
Q

what is a codon

A

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

66
Q

where is codon transcribed from

A

triplet

67
Q

what is codon complementary to

A

the triplet

68
Q

what is an anticodon

A

sequence of 3 tRNA bases that are complementary to a codon

69
Q

how many codons can the 4 bases in RNA form

A

64

70
Q

what does genetic code is degenerate mean

A

-multiple mRNA codons can encode the same amino acid

70
Q

what 3 features does DNA have

A

-degenerate
-non overlapping
-universal

70
Q

what does degenerate code mean for mutations

A

change in genetic code doesn’t necessarily result in a change the amino acid sequence

70
Q

what do START codons do

A

mark the start if the protein and therefore initiate the process of translation from the right location (AUG which is methionine in eukaryotic cells)

70
Q

what do STOP codons do

A

casue translation to terminate at the ends of the protein and do not code for any amino acids

71
Q

what does non-overlapping genetic code mean

A

each base is only read once in the codon its part of

72
Q

how can number of amino acids be determined from number of coding mRNA nucleotides

A

divide by 3 and -1 (for stop codon)

73
Q

how to work out number of mRNA nucleotides from number of amino acids

A

multiply by 3 and add 3 (for stop codon)