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CIE Biology A1 > Nucleic acids and protein synthesis > Flashcards

Nucleic acids and protein synthesis Flashcards

structure and replication of DNA protein synthesis (86 cards)

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1
Q

nucleotide derivatives and their cellular role

A

ATP and GTP work with energy transfers in the cell

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2
Q

phosphate

A

represented via circles

form backbone of DNA or RNA molecule, linking neighbouring sugars

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3
Q

base

A

carries coded genetic message in nucleic acid

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4
Q

pyrimidines examples

A

cytosine
thymine
uracil

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5
Q

pyrimidines

A

single ringed bases

smaller than purines

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6
Q

purines

A

double ringed bases

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7
Q

examples of purines

A

guanine and adenine

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8
Q

sugar in dna

A

deoxyribose

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9
Q

sugar in rna

A

ribose

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10
Q

ATP

A

adenine triphosphate

provides chemical energy for metabolism, consisting of adenine linked to a ribose sugar and 3 phosphate groups

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11
Q

how is energy transferred from ATP

A

when a phosphate group is transferred to a target molecule

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12
Q

how are nucleotides formed?

A

phosphoric acid and a base are chemically bonded via a condensation reaction
reverse is hydrolysis

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13
Q

nucleic acids

A

macromolecules made up of long chains of nucleotides to transfer and store genetic info.
eg dna and rna

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14
Q

ribonucleic acid roles

A

read genetic info

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15
Q

how do dinucleotides form?

A

2 nucleotides are linked together via a condensation reaction between the phosphateof one nucleotide and the sugar of another.

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16
Q

which direction does dna replication work in?

A

the 5’-3’ direction

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17
Q

rna molecule

A

single strand of nucleotides linked together, often folded back in on itself.
uracil replaces thymine
ribose sugar replaces deoxyribose sugar

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18
Q

deoxyribose nucleic acid

A

double strand of nucleotides linked in atwisted double helix shape
asymmetrical and antiparallel structure

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19
Q

5 prime end of dna

A

terminal phosphate group off of carbon 5

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20
Q

3 prime end of dna

A

terminal hydroxyl group off carbon 3

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21
Q

what determines base pairs

A

the number of bonds available to form and the configuration of bases.

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22
Q

mRNA

A

transcribed from dna, carrying a copy of genetic info from the dna to the ribosomes to be translated into a polypeptide

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23
Q

tRNA

A

carries amino acids to thegrowing polypeptide chain, one end carrying the anticodon and the other an amino acid.

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24
Q

where does the amino acid link to in the tRNA

A

the 3 prime end

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25
rRNA
ribosomal rna | forms ribosomes from 2 (large and small) subunits
26
evidence for structure of dna
x ray crystallography in which x rays are shone through crystallised molecules to produce a pattern on film. eg photo 51 produced by Rosalind franklin and Maurice wilkins
27
what did photo 51 indicate of dna structure?
x pattern indicates helix structure gaps indicate pattern of double helix and allows for calculation of the length of one full turn of helix diamond spaces indicate a continuous and constant dimension with a sugar phosphate backbone outside the helix.
28
what does dna extraction buffer consist of?
water, detergent, salt
29
detergent purpose in buffer
breaks down cellular membrane and deactivates DNAases which would ordinarily chop up dna
30
salt purpose in buffer
removes proteins bound to dna and keeps them in solution while neutralising negative charge of dna.
31
ethanol purpose in buffer solution
enables dna to precipitate out aided by low temps which limit DNAase activity
32
semi conservative dna replication
produces 2 identical copies of dna, half original and half new material
33
hows the dna unwound in replication?
helicase unzips it at high speed at a replication fork while another enzyme prevents supercoiling
34
purpose of dna polymerase
catalyses the condensation reaction joining adjacent nucleotides.
35
what direction does dna polymerase work in
5'-3' direction so that they are assembled continuously in one strand and fragmented as okazaki fragments (later joined by ligase)
36
purpose of dna replication
to double DNA, allowing each cell to have a complete set of genes before cell division.
37
3 main steps in replication
unwinding dna synthesising dna polymerase rewinding of the dna molecule
38
2 ways of correction within dna replication
proof-reading | mismatch repair
39
helicase purpose
unwinds and separates double stranded dna at replication fork at high speed.
40
RNA polymerase purpose in replication
synthesises a short RNA primer
41
DNA polymerase 3 purpose in replication | what direction does it go in?
extends the RNA primer with complimentary dna found from free nucleotides floating around via catalysing the condensation reaction between nucleotides. moves in the 5'-3' direction, synthesising the leading strand continuously.
42
DNA polymerase 1 purpose in replication
digests RNA primer to replace w dna
43
DNA ligase purpose in replication
joins neighbouring fragments together
44
how often are mistakes made in replication?
every 100000 nucleotides replicated
45
conservative model
DNA comprised 2 new strands
46
dispersive model
new and old dna mixed throughout them
47
generation 0
the sample removed of e coli bacteria after being grown in a nutrient broth containing N15 after 14 generations.
48
where is generation 0 put?
a solution containing excess N14 so that new dna incorporates the N14 with the N15 isotope.
49
Where is each generation placed?
in a CsCl solution which provides a density gradient for DNA separation
50
How high and long are samples spun in a centrifuge
at 14,000 g for 20 hours
51
genetic code
the set of rules by which the genetic info in DNA or mRNA is translated into proteins
52
codons
3 letter codes on mRNA, representing 1 of 20 amino acids used to make proteins.
53
degeneracy and where is it mostly located
the flexibility in which there may be more than one codon for each amino acid, mostly found in the 3rd nucleotide of a codon.
54
genes
sections of dna that code for proteins
55
gene expression
the process of rewriting a gene into a protein, involving transcriptionof DNA into mRNA before translating the mRNA into a protein.
56
where is a gene bounded?
at a promoter region upstream of the gene
57
where is a gene finished?
at a terminator region downstream of the gene
58
promoter region
where rna polymerase binds
59
terminator region
where rna polymerase dissasociates
60
where does translation stop and start?
at the start and stop codon
61
first amino acid
methionine
62
Gene mutations
Localised changes to the DNA sequence, able to produce new, heritable alleles.
63
Causes of mutations
Mutagens Errors during replication Deletion/substitution/ insertion of bases into DNA sequence leads to a single gene mutation
64
Mutation responsible for NSRD
Deletion of 35th base (G)
65
Cause of sickle cell disease
Substitution of one nucleotide from T to A Gene mutation Hbs produces a faulty beta chain haemoglobin protein. New amino acid is hydrophobic not hydrophilic so collapses in on itself when deprived of oxygen.
66
Sickle cell disease
Inherited blood disorder caused by gene mutation Hbs, producing deformed red blood cells with a reduced capacity to carry oxygen
67
Red blood cells
Contain 270 million haemoglobin molecules, have a flattened disc shape. Made up of 2 alpha and 2 beta chains linked together.
68
Sickle cells | What do they cause?
Reduced solubility and precipitates when deprived of oxygen, preventing movement through capillaries. Sickle cell anaemia is caused as rigid shape blocks small vessels and damages tissue and organs.
69
Relationship between sickle cell disease and malaria
Heterozygotes are less susceptible to malaria than unaffected as the parasite can’t affect deformed cells. Therefore high frequency of it in malaria regions.
70
Where does transcription take place
Nucleus
71
DNA replication overview
Helicase RNA polymerase primer DNA polymerase 3 catalyses condensation reaction between amino acids DNA polymerase digests RNA and replaces with DNA Ligase joins neighbouring fragments DNA rewinds
72
Enzyme controlling transcription
RNA polymerase forms a strand of mRNA from template strand, transcribing a gene length at a time, recognising start and stop signals.
73
What allows a high rate of mRNA synthesis to occur
Multiple RNA polymerase enzymes on one length of dna at any one time.
74
Introns
Non coding sections of mRNA that must be removed before translation can occur
75
Exons
Remaining dna that must be spliced together to form mature mRNA.
76
Where does transcription occur in prokaryotic cells
In the cytoplasm | Therefore is quicker
77
Antisense strand
The temp,ate strand that stores info transcribed into mRNA.
78
Transcription overview
RNA polymerase binds to a promoter region and joins rna nucleotides together, ending when it reaches a terminator sequence and final triplet is transcribed coding for stop.
79
Where does translation occur?
In the cytoplasm associated w free ribosomes/ the rough endoplasmic reticulum.
80
Where does the mRNA strand go after it leaves the nuclear pore?
Into the cytoplasm to attach to a ribosome.
81
tRNA structure
They have a triplet of bases at one end and a region for amino acids to attach at the other end. Roughly 80 nucleotides in length.
82
tRNA role in translation
They pick up free amino acids and brings to ribosome, matching anticodon on tRNA w codon on mRNA (complimentary).
83
How many tRNA molecules fit onto the ribosome at any one time
2
84
What bonds are formed between amino acids in translation
Peptide bonds
85
Ribosomes structure
Made up of a complex of ribosomal RNA and proteins, existing as 2 separate subunits (large and small) until they are attracted to a binding site on mRNA. Have binding sites that attract tRNA
86
Anticodon
The site of the 3 base sequence that matches up w the codon on mRNA.

CIE Biology A1 (15 decks)

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