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nucleic acids Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what does a nucleotide consist of?

A

phospate, a pentose sugar and a nitrogenous base

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2
Q

what sugar does DNA have?

A

deoxyribose

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3
Q

what sugar does RNA have?

A

ribose

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4
Q

what reaction happens to create a polynucleotide?

A

condensation

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4
Q

where does a phosphodiester bond form?

A

between the phosphate group and carbon 3 on the sugar

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5
Q

which carbon is the nitogenous base bonded to?

A

1

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6
Q

which carbon is the phospate bonded to ?

A

5

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6
Q

draw a nucleotide and label the carbons, the components and the 5 and 3 prime ends

A

5 prime end is up by phosphate group and 3 prime is by carbon 3 of the sugar

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7
Q

what is a pyrimidine base?

A

one carbon ring

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8
Q

what bases are pyramidine?

A

thymine and cytosine

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8
Q

what is a purine base?

A

2 carbon rings

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9
Q

why does a purine bond to a pyramidine?

A

helps base pairs be complementory to each other, so there are equal sized rungs which can twist to form a double helix therefore giving the molecule stability and dosnt allow the DNA to come apart

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9
Q

what bases are purine?

A

adenene and guanine

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10
Q

what are 4 nucleotide functions?

A

monomers for DNA and RNA

allows phosphorolated nucleotides to be used in repiration (ATP, ADP)

regulate metabolic pathways ATP to ADP
can be a component of coenzymes

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11
Q

why does a DNA or RNA molecule need to be antiparallel?

A

creates a stable molecule because coded infomation is protected by being inside of the molecule

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12
Q

how many hydrogen bonds form between A and T?

A

2

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12
Q

how many hydrogen bonds form between C and G?

A

3

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12
Q

state the meaning of antiparallel

A

when 1 backbone of DNA runs one way and the other backbone runs in the opposite

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13
Q

where is DNA organised in prokaryotic organisms?

A

in a loop in cytoplasm can also be in a plasmid
not wound around histone proteins

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13
Q

state 5 differences between DNA and RNA

A

DNA is double stranded whereas RNA is single stranded
DNA has bases ATGC, RNA has AUGC

DNA fragments are long whereas RNA is shorter fragments

DNA is found mainly in nucleas whereas RNA is found in the nucleas, cytoplasm and ribosomes

DNA has sugar deoxyribose whereas RNA has sugar ribose

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14
Q

where is DNA organised in eukaryotic organisms?

A

in chromazones in the nucleas

wound around histone proteins

mitochondria and chloraplasts have a loop of DNA

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15
Q

describe the function of the enzyme gyrase in DNA replication

A

unwind DNA double helix

15
Q

state the 5 enzymes used in DNA replication

A

gyrase, helicase, polymerase, primase, ligase

16
Q

describe the function of the enzyme DNA helicase in DNA replication

A

separates 2 strands by breaking hydrogen bonds between bases

16
Q

describe the function of the enzyme primase in DNA replication

A

synthisises RNA primers at specific places in the base sequence

16
Q

describe the function of the enzyme
DnA polymerase in DNA replication

A

binds to primer and adds comlplementory free nucleotides along the strand

16
Q

describe the function of the enzyme DNA ligase in DNA replication

A

joins up phosphate sugar backbone by reforming phosphodiester bonds

17
Q

what direction does DNA polymerase work in ?

A

5 prime to 3 prime

18
Q

what are the first 2 steps in DNA replication?

A

double helix is unwound by gyrase enzyme, hydrogen bonds between bases are separated using DNA helicase, this creates the formation of a replication fork

19
Q

what is a replication fork?

A

when DnA backbones are separated there are now 2 separate strands but these travel in different ways

19
Q

what direction does the leading strand travel in?

A

3 prime to 5 prime

20
Q

what direction does the lagging strand travel in?

A

5 prime to 3 prime

21
Q

decribe the process of DNA replication of the leading strand

A

DNA primase synthisises RNA primers at specific points, dNA polymerase binds to these primers and catalyses addition of complementory free nucleotides in 5 prime to 3 prime.

22
Q

how is the leading strand synthisised?why?

A

continously because DNA polymerase work in the same direction as the dna strands are getting pulled apart

23
Q

how is the lagging strand synthisised?why?

A

discontinously because dna polymerase works in the opposite direction to how DNA strands are pulled apart

23
Q

how does the lagging strand replicate?

A

primers are synthisysed by primase, polymerase calalyses addition of bases from the primer to the next this forms an okozaki fragment, primers are removed, polymerase catalyses addition of free nucleotides to gaps where primers were. DNa ligase joins up the DNA backbone and reforms phosphodiester bonds

24
Q

what does semi-conservative mean?

A

2 DNA molecules are produced, each with one new strand and one old strand

25
Q

what is a mutation?

A

change in dna base sequences

25
Q

what is an okazaki fragment?

A

short sections of double stranded dna inbetween primers

26
Q

what is splicing?

A

when non-coding regions of mRNA gets cut out so the whole thing only codes for amino acids

27
Q

what out of transcription or translation comes first?

A

transcription

27
Q
A
27
Q

what is a triplet code?

A

when 3 bases code for one amino acid

28
Q

what does degenerate mean ?

A

when an amino acid has more than one triplet code that codes for them

28
Q

what is a silent mutation?

A

when there is a mutation on one of the bases in a triplet code, but the new triplet code still codes for the same amino acid

29
Q

what direction is the sense strand?

A

5 to 3 prime

30
Q

what direction is the antisense strand?

A

3 to 5 prime

30
Q

which strand gets copied in protein synthesis?why?

A

antisense because the complenentory bases will create the sense strand

31
Q

describe the process of transcription

A

the DNA helix is unwound by DNA helicase at a start codon and hydrogen bonds between bases break. The antisense strand is copied by RNA bases pairing with exposes bases on antisense strand creates a sense strand of RNA. DNA polymerase joins RNA nucleotides together with phosphodiester bonds. this then leaves the nucleas to go to a ribosome

32
Q

when does transcription stop?

A

when a stop codon is reached, this then forms mRNA and leaves nucleas to go to a ribosome

33
Q

why does DNA helix reform after transcription?

A

DNA double helix automatically reforms because it is more energetically favourable

34
Q

what is tRNA ?

A

tRNA is a folded peice of RNA with 3 bases complementory to the 3 bases that it will bind to on mRNA, each tRNA carries an amino acid complementory to the 3 bases on mRNA

35
Q

what is the anticodon on tRNA?

A

the 3 bases complementory to the 3 bases on mRNA

36
Q

describe the process of translation

A

tRNA brings amino acids to the mRNA and allows amino acids to be in close proximity so that peptide bonds form between amino acids and eventually form a polypeptide chain which folds into its tertiary structure

Biology (12 decks)

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