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Biology topic 1 (biological molecules) > how DNA works, genetic code, protein synthesis > Flashcards

how DNA works, genetic code, protein synthesis Flashcards

1
Q

who found the double helix model

A

watson and crick

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2
Q

conservative replication

A

in conservative replication, the original double helix remained intact and in some way instructed the formation of a new identical double helix made up of entirely new material

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3
Q

semiconservative replication model

A

assumed that the dna unzipped and new nucleotides aligned along each strand, each new double helix contained one strand of the original dna and one strand made up of new material.

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4
Q

who proved semi conservative replication

A

mselson and stahl

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5
Q

steps of the semi conservative replication experiment

A

-grew generations of ecoli bacteria in nitrogenous medium
bacteria took up isotope to make cell chemicals including dna and proteins
-moved to N14 medium
-measured density of dna and they produced

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6
Q

what isotopes were used for the ecoli bacteria

A

N 15 and N14

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7
Q

which isotope is usually denser

A

N 15 rather than the commonly found N14

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8
Q

what isotope base were the bacteria first placed in

A

N15 and then moved to N14

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9
Q

what would the results look like if DNA replicated conservativly

A

some of the dna would have the density expected if it had nothing but N 15 and some would have nothing but density of N 14

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10
Q

what were the results proving semi conservative replication

A

all of dna would have same density half of N14 and half of N 15

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11
Q

role of DNA helicase

A

the two strands of the dna molecule unzip along the line of hydrogen bonds and unravel. the strand acts as a template for the new dna strands

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12
Q

role of DNA polymerase

A

exposed bases attract free DNA nucleotides and new hydrogen bonds are formed between matching base pairs. polymerase lines up and catalyses the linking up of the nucleotides along the template strand

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13
Q

role of DNA ligase

A

catalyses the formation of phosphodiester bonds between the two strands of DNA

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14
Q

whats the result of DNA replication

A

two new strands of DNA identical with original strand, new molecules coil up into double helix as weak hydrogen bonds form within the structure

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15
Q

whats the genetic code

A

means that three bases are a triplet code that code for one amino acid

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16
Q

define genes

A

gene is a sequence of bases on a DNA molecule coding for a sequence of amino acids in a polypeptide chain that affect the charesteristic in the phenotype of an organism

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17
Q

whats a codon

A

a sequence of three bases on the DNA or RNA

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18
Q

what happens because of codons on DNA being to big

A

because codons on DNA are difficult to work with because they are so big the work done on codons is on codons of smaller molecule mRNA

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19
Q

what is this mRNA formed as

A

a complementary strand to the DNA like a reverse image of original base sequence

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20
Q

how can we know DNA pairs with RNA pairs

A

because we work out the complementary bases

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21
Q

what do studies about genetic code suggest

A

that almost all genetic code in humans is identical

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22
Q

whats non coding DNA

A

large parts of the DNA that dont code for protein and make up most of codings

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23
Q

translation

A

process by which proteins are produced via RNA using genetic code found in DNA and takes place in ribosomes

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24
Q

a non overlapping code

A

only one codon codes for one amino acid meaning if they were to overlap it would only effect one amino acid

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25
Q

a degenerate code

A

the base of the amino acids producing only matters with the first two bases meaning if there was a mutation occured in the last base it wouldnt effect the amino acid produced

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26
Q

what differs RNA and DNA

A

RNA has ribose
no double helix
uracil instead of thymine

27
Q

3 main roles of RNA in protein synthesis

A

1- it carries instructions for a polypeptide from the DNA in the nucleus to the ribosomes where the proteins are made
2-picks up specific amino acids from the protoplasm and carried them to surface of ribosomes
3-makes up bulk of ribosomes themselves

28
Q

where is mRNA formed

A

in the nucleus

29
Q

what does mRNA carry insturcions for

A

one polypeptide chain

30
Q

antisense strand

A

the mRNA template strand

31
Q

sense strand

A

the coding strand of DNA

32
Q

DNA directed RNA polymerase

A

parts of DNA molecule unravel and are transcribed onto strands of mRNA by that enzyme

33
Q

how is another strand of mRNA formed

A

the complementary bases of DNA and RNA line up alongside each other. RNA nucleotides from the nucleoplasm line up alongside the exposed DNA. initial hydrogen bonds replaced by phosphodiester bonds catalysed by RNA polymerase to form strand of mRNA

34
Q

what does the mRNA molecule do after being made

A

passes through the nuclear pores carrying the instructions for the genes in the nucleus to the cytoplasm. they then move to the surface of the ribosomes where the protein synthesis takes place

35
Q

transcription definiton

A

copying a part of DNA into RNA

36
Q

where is tRNA found

A

in the cytoplasm

37
Q

what shape is the tRNA often described as

A

clover shape

38
Q

why does the tRNA have clover shape

A

result of hydrogen bonds between different bases

39
Q

anticodon

A

on part of tRNA molecule has sequence of three bases that match genetic code of DNA and correspond for one amino acid. sequence of three bases is an anticodon

40
Q

binding site in tRNA

A

which it picks up one particular amino acid from lots always free in the cytoplasm

41
Q

what do tRNA molecules line up with

A

mRNA molecules

42
Q

anticodons of the tRNA role

A

line up with mRNA codons held in place with hydrogen bonds with each complementary base

43
Q

what happens once the amino acids are lined up with each other

A

peptide bonds form between then building longer chain of amino acids

44
Q

where is rRNA made

A

made in the nucleus under the control of the nucleoli

45
Q

role of rRNA after being made

A

moves out into the cytoplasm from the nucleus where it binds with proteins to form ribosomes.

46
Q

structure of ribosomes in rRNA

A

made of small and large subunit
-surround and bind to parts of the mRNA that are being translated and move along to the next codon

47
Q

job of ribosomes in rRNA

A

hold together the mRNA AND tRNA and act as enzymes controlling process of protein synthesis

48
Q

protein synthesis summary

A

DNA of nucleus transcribed into mRNA
-mRNA moves into cytoplasm and attached to ribosomes
-molecules of tRNA carry out separate amino acids to surface of ribosome
-tRNA anticodon with codon mRNA and link amino acids together with peptide bonds
-tRNA breaks off and gets another amino acid
-ribosomesw move along molecule of mRNA and leaves a completed polypeptide chain

49
Q

describe structure of mononucleotides found in RNA

A

has sugar like ribose pentose and phosphate group and nitrogenous base like A C G T U

50
Q

how cystic fibrosis effects person as a result of point mutation

A

-different amino acid/primary structure
-change in shape/function of protein
-role of protein in taking chlorine ions
-ions not moving out of cell and water moves in via osmosis
-musus not dilluted with water
thick musuc cant be removed via coughing and cillia

51
Q

ways gene therapy could be used to treat cystic fibrosis

A

introducing genes to lungs that can make musus
via injection
repeated because of cell reproduction
using a vector

52
Q

how scientists find other works

A

scientific peer reviewed journals
media reports

53
Q

2 parts that form mononucleotides

A

deoxyribose and phosphate

54
Q

translation of mRNA results in polypeptide chain

A

each tRNA molecule attached to one AA
tRNA anticodon with each AA
codons on mRNA
hyrdogen bonds between strands
peptide bonds between chains formed

55
Q

non overlapping defiintion

A

each base only used once in a triplet code

56
Q

importance of codes stop

A

stop codons
occur at end of gene code
transcrobed by mRNA into opposite strand
recognised by ribosome
signal end of peptide chain

57
Q

how are amino acids joined together in a polypeptide chain

A

peptide bond
between cooh and na
condensation reaction
role of tRNA in joining amino acids together

58
Q

how molecule of mRNA is made during transcription

A

-DNA molecule unwinds
-RNA mononucleotides line up against antisense strand
-base pairing
-phospodiester bonds
-condensation reaction
-mRNA detached form DNA

59
Q

how structure of tRNA differs from mRNA structure

A

-tRNA folded and mRNA straight
-tRNA has hydrogen bonds mRNA doesnt
-tRNA has anticodons but mRNA had codons

60
Q

why can DNA be described as a double bonded polynucleotide chain

A

two strands
strands joined by hydrogen bonds
many nucleotides
nucleotides joined by phosphodiester bonds

61
Q

describe structure of amino acid

A

amine group
r group
carboxyl group

62
Q

explain how RNA templates used to specify the chemical structure of a protein

A

-triplet code is code for amino acid
mRNA binds to ribosome and codon
tRNA decoded M and gives right sequence for AA
-two tRNA sites in ribosome
-two AA brought together with peptide bond
-sections of DNA templates for RNA

63
Q
A

Biology topic 1 (biological molecules) (11 decks)

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