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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

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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
a degenerate code
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
26
what differs RNA and DNA
RNA has ribose no double helix uracil instead of thymine
27
3 main roles of RNA in protein synthesis
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
where is mRNA formed
in the nucleus
29
what does mRNA carry insturcions for
one polypeptide chain
30
antisense strand
the mRNA template strand
31
sense strand
the coding strand of DNA
32
DNA directed RNA polymerase
parts of DNA molecule unravel and are transcribed onto strands of mRNA by that enzyme
33
how is another strand of mRNA formed
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
what does the mRNA molecule do after being made
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
transcription definiton
copying a part of DNA into RNA
36
where is tRNA found
in the cytoplasm
37
what shape is the tRNA often described as
clover shape
38
why does the tRNA have clover shape
result of hydrogen bonds between different bases
39
anticodon
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
binding site in tRNA
which it picks up one particular amino acid from lots always free in the cytoplasm
41
what do tRNA molecules line up with
mRNA molecules
42
anticodons of the tRNA role
line up with mRNA codons held in place with hydrogen bonds with each complementary base
43
what happens once the amino acids are lined up with each other
peptide bonds form between then building longer chain of amino acids
44
where is rRNA made
made in the nucleus under the control of the nucleoli
45
role of rRNA after being made
moves out into the cytoplasm from the nucleus where it binds with proteins to form ribosomes.
46
structure of ribosomes in rRNA
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
job of ribosomes in rRNA
hold together the mRNA AND tRNA and act as enzymes controlling process of protein synthesis
48
protein synthesis summary
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
describe structure of mononucleotides found in RNA
has sugar like ribose pentose and phosphate group and nitrogenous base like A C G T U
50
how cystic fibrosis effects person as a result of point mutation
-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
ways gene therapy could be used to treat cystic fibrosis
introducing genes to lungs that can make musus via injection repeated because of cell reproduction using a vector
52
how scientists find other works
scientific peer reviewed journals media reports
53
2 parts that form mononucleotides
deoxyribose and phosphate
54
translation of mRNA results in polypeptide chain
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
non overlapping defiintion
each base only used once in a triplet code
56
importance of codes stop
stop codons occur at end of gene code transcrobed by mRNA into opposite strand recognised by ribosome signal end of peptide chain
57
how are amino acids joined together in a polypeptide chain
peptide bond between cooh and na condensation reaction role of tRNA in joining amino acids together
58
how molecule of mRNA is made during transcription
-DNA molecule unwinds -RNA mononucleotides line up against antisense strand -base pairing -phospodiester bonds -condensation reaction -mRNA detached form DNA
59
how structure of tRNA differs from mRNA structure
-tRNA folded and mRNA straight -tRNA has hydrogen bonds mRNA doesnt -tRNA has anticodons but mRNA had codons
60
why can DNA be described as a double bonded polynucleotide chain
two strands strands joined by hydrogen bonds many nucleotides nucleotides joined by phosphodiester bonds
61
describe structure of amino acid
amine group r group carboxyl group
62
explain how RNA templates used to specify the chemical structure of a protein
-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

Biology topic 1 (biological molecules) (11 decks)

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