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AL. AQA Biology > THE GENETIC CODE AND THE CELL CYCLE > Flashcards

THE GENETIC CODE AND THE CELL CYCLE Flashcards

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1
Q

3 aspects of nucleotide structure

A
  • pentose sugar
  • phosphate group
  • organic base
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2
Q

bond between sugar and phosphate in polynucleotide

A

phosphodiester

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3
Q

pentose sugar type on RNA

A

ribose

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4
Q

pentose sugar type on DNA

A

deoxyribose

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5
Q

3 RNA types

A
  • transfer genetic material from DNA to ribosomes
  • ribosomes made up of another RNA type and proteins
  • involved in protein synthesis
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6
Q

bonds between complimentary bases in DNA

A

hydrogen

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7
Q

number of bonds between C and G

A

3

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8
Q

DNA functional adaptations (6)

A
  • double stranded - replication can occur semiconservativly
  • H bonds between strands allow separation during protein synthesis and DNA replication
  • large = lots of genetic material stored
  • base pairs protected within helix by backbone
  • base sequence allows information to be stored
  • long and coiled tightly into chromosomes = space efficient
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9
Q

number of bonds between A and T

A

2

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10
Q

chromosomes in eukaryotes vs prokaryotes

A 
eu = wound tightly around histone proteins to make chromosomes
pro = coiled tightly NOT associated with histones
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11
Q

shape of DNA in eukaryotes vs prokaryotes

A 
eu = long and linear
pro = short and circular
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12
Q

semiconservative replication

A

one strand from old in each of the new strands

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13
Q

DNA helicase function

A

at replication fork - splits double helix by breaking H bonds between bases

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14
Q

DNA polymerase function

A

forms phosphodiester bonds in the backbone on the LEADING STRAND via condensation reaction

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15
Q

DNA ligase function

A

joins Okazaki fragments on LAGGING STRAND via condensation reaction to make phosphodiester bonds and form backbone

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16
Q

replication on leading strand

A

continual, 5 to 3 direction

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17
Q

replication on lagging strand

A

in Okazaki fragments, joined by DNA ligase

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18
Q

prophase

A
  • chromosomes shorten and thicken (visible under microscope)

- nuclear membrane disappears

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19
Q

metaphase

A
  • centrioles migrate to the poles of the cell

- spindle fibres pull chromosomes to align at the equator of the call

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20
Q

anaphase

A
  • spindle fibres pull chromatids to poles of the cell

centromeres split in 2

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21
Q

telophase

A
  • cytokinesis - cytoplasm and membrane split into 2, forming 2 discreet daughter cells
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22
Q

interphase

A
  • chromosomes replicate - now made up of 2 chromatids joined by a centromere
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23
Q

purine bases

A

A T U

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24
Q

pyramidine bases

A

C G

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25
Q

tRNA features 4

A
  • 80 nucleotides roughly
  • single strand that folds up into a clover shape
  • different types each binding to different amino acid
  • has anticodon at end (3 bases)
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26
Q

reaction type forming a dinucleotide

A

condensation reaction

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27
Q

organic bases in RNA

A

C, G, A, U

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28
Q

DNA function

A

passing genetic information between cells

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29
Q

stages of DNA replication (4)

A

1) DNA helices breaks h-bonds between complimentary base pairs, unwinding the molecule into 2 separate strands, exposing template strands
2) exposed polynucleotide strand then acts as a template for complimentary free nucleotide bases to bind to by base pairing
3) nucleotides are joined by DNA polymerase in a series of condensation reactions, forming phosphodiester bonds
4) creating 2 daughter strands, each containing one original strand = semiconservative

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30
Q

requirements of semiconservative replication (4)

A

1) 4 types of free nucleotides, each with their bases must be present
2) both strands of dna act as a template for the attachment of nucleotides
3) enzyme dna polymerase
4) source of chemical energy to drive process

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31
Q

differences between eukaryotic and prokaryotic DNA (2)

A
  • eukaryotic wound around histone proteins to make chromosomes vs. prokaryotic is wound into chromosomes but not associated with histones
  • eukaryotic is long and linear vs prokaryotic is short and circular
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32
Q

codon

A

3 nucleotides which code for an amino acid

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33
Q

degenerate

A

some amino acids are coded for by more then 1 codon

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34
Q

regions of non coding DNA

A

introns

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35
Q

charge carried by nucleic acid molecules

A

negative

36
Q

purines

A

types of organic bases made up of 2 rings of carbon and nitrogen atoms

37
Q

pyrimidines

A

types of organic bases made up of a single ring of carbon and nitrogen atoms

38
Q

product of transcription

A

a mRNA copy of part of DNA

39
Q

translation

A

process by which amino acids are assembled using code carried by mRNA

40
Q

types of mutation (6)

A
  • substitution
  • deletion
  • addition
  • translocation
  • inversion of bases
  • duplication
41
Q

interspecific variation

A

one species differs from another

42
Q

intraspecific variation

A

members of the same species differ from eachother

43
Q

first name in binomial system

A

genus

44
Q

second name in binomial system

A

species

45
Q

how do courtship behaviours increase chance of successful mating? (4)

A
  • recognise members of their own species, insuring mating is only within the species
  • identify mate which is capable of breeding
  • form a pair bond - leading to successful breeding and raising offspring
  • synchronised mating - so takes place at max probability of conception
46
Q

2 main forms of classification

A
  • artificial

- phylogenetic

47
Q

artificial classification

A

divides organisms according to differences that are useful at the time (eg. no of legs, colour, size) - same function but not the same evolutionary oragin

48
Q

phylogenetic classification

A
  • based on evolutionary relationships between organisms and their ancestors
  • classifies into groups using shared characteristics/ features derived from ancestors
  • arranges groups into a hierarchy In which groups are contained within larger, composite groups with no overlap

[- looks at features, behaviours and observations]

49
Q

characteristics which artificial classification is based on

A

analogous - same function but not same evolutionary origins

50
Q

characteristics which phylogenetic classification is based on

A

homologous - similar evolutionary origins regardless of function

51
Q

taxon

A

group within phylogenetic classification

52
Q

3 domains

A

Archea, bacteria and eukarya

53
Q

bacteria

A

group of single celled prokaryotes

54
Q

features of bacteria (5)

A
  • absence of membrane bound organelles
  • unicellular
  • ribosomes are smaller (70s)
  • cell walls are present and made of murein
  • single loop of naked DNA made up of nucleic acid - no histones
55
Q

Archea

A

group of single celled prokaryotes

56
Q

how do archea differ from bacteria (4)

A
  • have genes and undergo protein synthesis
  • membranes contain fatty acid chains attached to glycerol by ester linkages
  • no murein in cell walls
  • more complex form of RNA polymerase
57
Q

eukarya

A

group of organisms made up of 1+ eukaryotic cells

58
Q

features of eukarya (4)

A
  • cells contain membrane bound organelles
  • have membranes containing fatty acid attached to glycerol by ester linkages
  • not all posses a cell wall, but those which do contain no murein
  • ribosomes are larger (80s)
59
Q

4 kingdoms of eukarya

A
  • protoctista
  • fungi
  • plantae
  • Animalia
60
Q

classification rank

A

domain>kingdom>phylum>class>order>family>genus>species

61
Q

why may it be difficult to separate individuals into different species (5)

A
  • species aren’t fixed and constantly evolve - some may develop into new species
  • considerable variation within species
  • many are extinct and have left no fossil record
  • some species rarely, if ever reproduce sexually
  • some individuals in a species may be physically separated and never meet and interbreed
62
Q

species

A

individuals which can breed to produce live, fertile offspring

63
Q

4 methods of investigating biodiversity

A
  • observable characteristics
  • comparing dna base sequences
  • comparing mRNA base sequences
  • comparing amino acid sequences in proteins
64
Q

genome

A

the complete set of genes in a cell

65
Q

proteome

A

the full range of proteins a cell can produce

66
Q

RNA structure

A

single polynucleotide strand containing uracil instead of thymine

  • pentose sugar - ribose
  • phosphate group
67
Q

what stage of protein synthesis is mRNA made in?

A

transcription

68
Q

what stage of protein synthesis is tRNA made in?

A

translation

69
Q

codon

A

3 adjacent bases on mRNA strand

70
Q

function of tRNA

A

carries amino acids used to make proteins to the ribosomes

71
Q

tRNA structure

A

single polynucleotide strand folded into a clover shape by hydrogen bonds between specific base pairs - has anticodon (sequence of 3 specific bases) at one end and amino acid binding site at the other

72
Q

transcription

A

producing an mRNA copy of a gene from DNA (in nucleus in eukaryotes)

73
Q

translation

A

polypeptides made at ribosomes by the joining of amino acids, following codon sequence carried by mRNA

74
Q

why is the code ‘non-overlapping’?

A

each base only read once

75
Q

why is the code ‘universal’?

A

with few exceptions, each triplet codes for same amino acid in all organisms

76
Q

homologous pair

A

a pair of chromosomes, one maternal and one paternal which have the same gene loci and therefore determine the same features

77
Q

structure of mRNA

A

long strand in single helix

- base sequence determined by base sequence of DNA

78
Q

anticodon

A

sequence of 3 organic bases on tRNA molecule, complimentary to a particular codon on mRNA molecule

79
Q

2 factors increasing frequency of mutation

A
  • x rays

- benzene

80
Q

3 differences between tRNA and mRNA

A
  • mRNA has no base pairing, tRNA does
  • mRNA linear, tRNA is clover shaped
  • mRNA has no binding site for amino acids
81
Q

3 possible results of substitution mutation

A

1 - formation of stop codon marking end of polypeptide chain, resulting in stopping of production prematurely = final protein v different
2 - formation of codon for different amino acid - finally polypeptide will differ by 1 amino acid = non functional protein?
3 - formation of codon for same amino acid - code is degenerate therefore no effect on polypeptide chain produced

82
Q

deletion mutation

A

causes FRAME SHIFT to LEFT - reading frame for each 3 letters of code has shifted one to the left
= production of non-functional protein as all amino acids from that point may be different/affected
= alter phenotype significantly
(mutation at start bigger impact then mutation at end)

83
Q

addition mutation

A

causes FRAME SHIFT to RIGHT
- if 3 bases or multiple of 3 added, no frame shift therefore smaller change to polypeptide chain produced, but still different to one from NON-MUTANT gene

84
Q

duplication mutation

A

causes frame shift to right

85
Q

inversion of bases mutation

A

group of bases becomes separate from DNA sequence and rejoins in same position but in inverse order - therefore base sequence REVERSED, amino acid sequence affected

86
Q

translocation of bases

A
  • group of bases separated from DNA on one chromosome and is inserted into DNA on another chromosome
    = significant affect on GENE EXPRESSION = abnormal phenotype (development of certain cancers and infertility)

AL. AQA Biology (18 decks)

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