nucleotides and nucleic acids Flashcards

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1
Q

describe DNA

A

double stranded
genetic code makes proteins
deoxyribose sugar

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2
Q

describe RNA

A

single stranded
3 types of RNA all make proteins
ribose sugar

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3
Q

what are the 3 types of RNA

A

mRNA
tRNA
ribosomal

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4
Q

what is the monomer of RNA and DNA called

A

nucleotides

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5
Q

describe the structure of a nucleotide

A

pentose sugar
organic nitrogenous base
phosphate group

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6
Q

what are the bases of DNA

A

A, T, C, G

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7
Q

what is the base ‘A’ called

A

adenine

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8
Q

what is the base ‘t’ called

A

thymine

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9
Q

what is the base ‘C’ called

A

cytosine

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10
Q

what is the base ‘G’ called

A

guanine

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11
Q

what are the bases of RNA

A

A, U, G, C

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12
Q

what are the 2 purines

A

A and G

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13
Q

what is a purine

A

larger, double ring bases

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14
Q

what are the 3 pyrimidines

A

C, T, U

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15
Q

what is a pyrimidine

A

smaller, single ring bases

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16
Q

how do nucleotides join

A

condensation reaction

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17
Q

what is the polymer of nucleotides called

A

polynucleotide

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18
Q

what are the bonds between the phosphate group and the sugar of a nucleotide called

A

phosphodiester bond

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19
Q

why is the bond between nucleotides referred to as a 3’ 5’ bond

A

the carbon 3 bonds with carbon 5

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20
Q

what bond bonds the helix structure of DNA

A

hydrogen bonds

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21
Q

how many bonds are between A and T

A

2 hydrogen bonds

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22
Q

how many bonds are between C and G

A

3 hydrogen bonds

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23
Q

what does anti-parallel mean

A

one strand is flipped upside down so the bases can pair in the middle

24
Q

give 4 reasons why the structure of DNA is good

A

coiled makes it compact
specific sequence gives a genetic code
double stranded makes it more stable
double stranded structure makes it easy for replication

25
Q

DNA extraction practical: why do you grind the sample with a mortar and pestle

A

to break down the cellulose cell wall

26
Q

DNA extraction practical: why do we mic the sample with detergent

A

to break down the cell membrane and the nuclear membrane

27
Q

DNA extraction practical: why do you add salt

A

takes water away from DNA

28
Q

DNA extraction practical: why do you add protease enzyme

A

break down histone proteins that DNA is wrapped around

29
Q

DNA extraction practical: why do you add a layer of alcohol on top of the sample

A

causes the DNA to precipitate out of solution

30
Q

give 3 reasons why need ATP

A

synthesis
transport
movement

31
Q

draw the structure of ATP

A

adenine
ribose sugar
3 phosphate

32
Q

what is the product after ATP is hydrolysed

A

ADP, phosphate and energy

33
Q

how and where is ATP made in cells

A

mitochondria
aerobic respiration

34
Q

give 4 ways that make ATP a good energy source

A

fairly small
water soluble (can move across membrane)
releases a small amount of energy (just enough for cellular reactions)
easily re-made

35
Q

when does DNA need to replicate itself

A

mitosis or meiosis

36
Q

why does DNA need to replicate itself

A

this is to make enough DNA to be shared amount the new daughter cells

37
Q

describe the method of DNA replication

A

1) double helix had to unwind and separate exposing the bases by hydrogen bonds breaking using the enzyme DNA helicase
2) free nucleotides line up next to the exposed bases by complimentary base pairing
3)new hydrogen bonds form
4) new sugar phosphate back bones are formed (phosphodiester bonds form), using the enzyme DNA polymerase

38
Q

why is DNA replication called semi-conservative

A

each new daughter molecule has an original strand and a new strand

39
Q

what makes DNA replication so accurate

A

complementary base pairing

40
Q

why does one of the strands had to be copied continuously and the other has to be copied in sections

A

DNA polymerase enzyme can only move along the DNA in one direction (3’ 5’)

41
Q

what is it called when the strand is copied in sections

A

okazaki fragments

42
Q

what is the name for an error in a genetic code?

A

mutations

43
Q

what is a gene

A

a specific sequence of DNA nucleotides that code for a particular sequence of amino acids

44
Q

why is mRNA called messenger RNA

A

it carries a version of the genetic code as a message to the ribosome

45
Q

why is tRNA called transfer RNA

A

transfers amino acids to the ribosome to make proteins

46
Q

why is rRNA called ribosomal RNA

A

it makes up the ribosome

47
Q

where are proteins made

A

ribosome/ RER

48
Q

what are the 2 stages of protein synthesis

A

transcription and translation

49
Q

describe the first stage of protein synthesis (transcription)

A

1) enzyme DNA helicase attaches to gene causing it to unwind, breaking hydrogen bonds and making it unwind
2) one strand is the coding and the other is the template strand
3) free nucleotides line up for complementary base pairing (U replaces T)
4) temporary hydrogen bonds form
5) RNA polymerase makes the phosphate sugar backbone
6) once the enzyme leaves the DNA molecule reform, hydrogen bonds reform

50
Q

what are introns

A

non coding gene

51
Q

what are three bases on mRNA called

A

codon

52
Q

describe what happens in translation

A

1) mRNA attaches to a ribosome
2) tRNA molecules contain 3 bases called anticodons which line up next to the codons on the mRNA by complementary base pairing
3) amino acids join by peptide bonds
4) a new tRNA molecule now leaves the ribosome leaving it’s amino acid behind
5) this happens until a ‘stop’ codon on the mRNA is reached
6) polypeptide is then released into the polypeptide

53
Q

where will the polypeptides pass to in order to be modified

A

Golgi apparatus

54
Q

what does it mean when the code is degenerate

A

there are more possible triplet codes than there are amino acids

55
Q

what is the ‘start’ codon called

A

AUG

56
Q

what does AUG code for

A

methionine