THE GENETIC CODE AND THE CELL CYCLE Flashcards
1
Q
3 aspects of nucleotide structure
A
- pentose sugar
- phosphate group
- organic base
2
Q
bond between sugar and phosphate in polynucleotide
A
phosphodiester
3
Q
pentose sugar type on RNA
A
ribose
4
Q
pentose sugar type on DNA
A
deoxyribose
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
6
Q
bonds between complimentary bases in DNA
A
hydrogen
7
Q
number of bonds between C and G
A
3
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
9
Q
number of bonds between A and T
A
2
10
Q
chromosomes in eukaryotes vs prokaryotes
A
eu = wound tightly around histone proteins to make chromosomes pro = coiled tightly NOT associated with histones
11
Q
shape of DNA in eukaryotes vs prokaryotes
A
eu = long and linear pro = short and circular
12
Q
semiconservative replication
A
one strand from old in each of the new strands
13
Q
DNA helicase function
A
at replication fork - splits double helix by breaking H bonds between bases
14
Q
DNA polymerase function
A
forms phosphodiester bonds in the backbone on the LEADING STRAND via condensation reaction
15
Q
DNA ligase function
A
joins Okazaki fragments on LAGGING STRAND via condensation reaction to make phosphodiester bonds and form backbone
16
Q
replication on leading strand
A
continual, 5 to 3 direction
17
Q
replication on lagging strand
A
in Okazaki fragments, joined by DNA ligase
18
Q
prophase
A
- chromosomes shorten and thicken (visible under microscope)
- nuclear membrane disappears
19
Q
metaphase
A
- centrioles migrate to the poles of the cell
- spindle fibres pull chromosomes to align at the equator of the call
20
Q
anaphase
A
- spindle fibres pull chromatids to poles of the cell
centromeres split in 2
21
Q
telophase
A
- cytokinesis - cytoplasm and membrane split into 2, forming 2 discreet daughter cells
22
Q
interphase
A
- chromosomes replicate - now made up of 2 chromatids joined by a centromere
23
Q
purine bases
A
A T U
24
Q
pyramidine bases
A
C G
25
tRNA features 4
- 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)
26
reaction type forming a dinucleotide
condensation reaction
27
organic bases in RNA
C, G, A, U
28
DNA function
passing genetic information between cells
29
stages of DNA replication (4)
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
30
requirements of semiconservative replication (4)
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
31
differences between eukaryotic and prokaryotic DNA (2)
- 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
32
codon
3 nucleotides which code for an amino acid
33
degenerate
some amino acids are coded for by more then 1 codon
34
regions of non coding DNA
introns
35
charge carried by nucleic acid molecules
negative
36
purines
types of organic bases made up of 2 rings of carbon and nitrogen atoms
37
pyrimidines
types of organic bases made up of a single ring of carbon and nitrogen atoms
38
product of transcription
a mRNA copy of part of DNA
39
translation
process by which amino acids are assembled using code carried by mRNA
40
types of mutation (6)
- substitution
- deletion
- addition
- translocation
- inversion of bases
- duplication
41
interspecific variation
one species differs from another
42
intraspecific variation
members of the same species differ from eachother
43
first name in binomial system
genus
44
second name in binomial system
species
45
how do courtship behaviours increase chance of successful mating? (4)
- 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
2 main forms of classification
- artificial
| - phylogenetic
47
artificial classification
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
phylogenetic classification
- 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
characteristics which artificial classification is based on
analogous - same function but not same evolutionary origins
50
characteristics which phylogenetic classification is based on
homologous - similar evolutionary origins regardless of function
51
taxon
group within phylogenetic classification
52
3 domains
Archea, bacteria and eukarya
53
bacteria
group of single celled prokaryotes
54
features of bacteria (5)
- 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
Archea
group of single celled prokaryotes
56
how do archea differ from bacteria (4)
- 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
eukarya
group of organisms made up of 1+ eukaryotic cells
58
features of eukarya (4)
- 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
4 kingdoms of eukarya
- protoctista
- fungi
- plantae
- Animalia
60
classification rank
domain>kingdom>phylum>class>order>family>genus>species
61
why may it be difficult to separate individuals into different species (5)
- 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
species
individuals which can breed to produce live, fertile offspring
63
4 methods of investigating biodiversity
- observable characteristics
- comparing dna base sequences
- comparing mRNA base sequences
- comparing amino acid sequences in proteins
64
genome
the complete set of genes in a cell
65
proteome
the full range of proteins a cell can produce
66
RNA structure
single polynucleotide strand containing uracil instead of thymine
- pentose sugar - ribose
- phosphate group
67
what stage of protein synthesis is mRNA made in?
transcription
68
what stage of protein synthesis is tRNA made in?
translation
69
codon
3 adjacent bases on mRNA strand
70
function of tRNA
carries amino acids used to make proteins to the ribosomes
71
tRNA structure
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
transcription
producing an mRNA copy of a gene from DNA (in nucleus in eukaryotes)
73
translation
polypeptides made at ribosomes by the joining of amino acids, following codon sequence carried by mRNA
74
why is the code 'non-overlapping'?
each base only read once
75
why is the code 'universal'?
with few exceptions, each triplet codes for same amino acid in all organisms
76
homologous pair
a pair of chromosomes, one maternal and one paternal which have the same gene loci and therefore determine the same features
77
structure of mRNA
long strand in single helix
| - base sequence determined by base sequence of DNA
78
anticodon
sequence of 3 organic bases on tRNA molecule, complimentary to a particular codon on mRNA molecule
79
2 factors increasing frequency of mutation
- x rays
| - benzene
80
3 differences between tRNA and mRNA
- mRNA has no base pairing, tRNA does
- mRNA linear, tRNA is clover shaped
- mRNA has no binding site for amino acids
81
3 possible results of substitution mutation
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
deletion mutation
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
addition mutation
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
duplication mutation
causes frame shift to right
85
inversion of bases mutation
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
translocation of bases
- 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)
