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biology > genetic information, variation and relationships between organisms > Flashcards

genetic information, variation and relationships between organisms Flashcards

1
Q

prokaryotic cell DNA

A
  • short
  • circular
  • not associated with histones
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2
Q

eukaroytic cell DNA

A
  • long
  • linear
  • associated with histones
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3
Q

proteins associated with eukaryotic DNA

A

histones

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4
Q

gene

A

base sequence of DNA that codes for an amino acid in a polypeptide or a functional RNA

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5
Q

fixed position of a gene on a particular DNA molcule

A

locus

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6
Q

triplet

A

sequence of three DNA bases

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7
Q

role of triplet

A

codes for a specific amino acid

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8
Q

genetic code

A

non-overlapping, universal and degenerate

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9
Q

non-overlapping code

A

each base is read as a discrete unit of 3

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10
Q

universal code

A

the same codons code for the same amino acids in all organisms

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11
Q

degenerate code

A

each amino acid is coded for by more than one triplet of bases

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12
Q

exons

A

coding areas of DNA

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13
Q

introns

A

non-coding areas of DNA only found in eukaryotes between exons in genes

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14
Q

splicing

A

introns are removed from pre-mRNA and exons are joined together

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15
Q

genome

A

complete set of genes in a cell

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16
Q

proteome

A

full range of proteins that a cell is able to produce

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17
Q

mRNA

A

messenger RNA

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18
Q

tRNA

A

transfer RNA

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19
Q

structure of mRNA

A
  • short
  • single stranded
  • codons
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20
Q

structure of tRNA

A
  • three bases called anticodon
  • amino acid binding site
  • clover shaped formed from hydrogen bonds
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21
Q

transcription

A

production of mRNA from DNA

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22
Q

process of transcription

A
  • DNA helicase unwinds comp. base paires between DNA helix
  • one strand acts as a template
  • free mRNA molecules in nucleus align by comp. base pairing (A-U and C-G)
  • RNA polymerase catalyses condensation reaction between adjacent RNA nucleotides
  • creating PPD bonds
  • pre-mRNA can then be sliced
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23
Q

RNA polymerase

A

catalyse condensation reaction between adjacent RNA nucleotides to form phosphodiester bonds

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24
Q

prokaryote transcription

A

transcription results directly in the production
of mRNA from DNA

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25
eukaryote transcription
transcription results in the production of pre-mRNA; this is then spliced to form mRNA
26
translation
production of polypeptides from the sequence of codons carried by mRNA
27
process of translation
- mRNA attaches to ribosome - tRNA anticodons bind to complementary mRNA codons - tRNA brings specific amino acids - amino acids form peptide bonds with the use of ATP - tRNA is then released - ribosome moves along mRNA to form polypeptide
28
ribosome structure
rRNA and protein
29
rRNA
ribosomal RNA
30
gene mutation
change in the base sequence of DNA
31
spontaneous mutation arises from...
DNA replication
32
deletion mutation
when one nucleotide is removed from a codon causing a frame shift
33
addition mutation
when one nucleotide is added to a codon causing a frame shift
34
substitution mutation
one nucleotide is replaced with another this can result in 3 different mutations: silent, nonsense and missense
35
silent mutation
different codon codes for the same amino acid because the genetic code is degenerate
36
missense mutation
new codon codes for a different amino acid
37
nonsense
new codon codes for a stop codon
38
not all mutations cause a change in the sequence of encoded amino acids because...
- genetic code is degenerate - mutation may be in the introns
39
mutagenic agents
increase the rate of mutation (e.g carcinogens and radiation)
40
mutation in meiosis is caused by...
chromosome non-disjunction
41
chromosome non-disjunction
chromosomes or chromatids fail to split equally during meiosis
42
chromosome
a structure consisting of a long, coiled molecule of DNA and its associated proteins, by which genetic information is passed from generation to generation
43
homologous chromosome
two chromosomes with the same gene loci but different alleles, one inherited from each parent, joined by a centromere
44
chromosome structure
- two sister chromatids - joined by a centromere
45
polyploidy
change in whole sets of chromosome where organisms have three of more sets of chromosome rather than two
46
aneuploidy
change in individual number of chromosomes so there will be one more or one fewer chromosome
47
process of meiosis
meiosis I - DNA condenses - homologous chromosome pairs line up along equator - chromosomes pulled to opposite poles - centromeres do not divide cytokinesis meiosis II - chromosomes line up at equator - chromatids at opposite poles cytokinesis
48
divisions and products of meiosis
- two divisions - 4 haploid cells - genetically different daughter cells - production of gametes - used in sexual reproduction
49
possible number of different combinations of chromosomes following meiosis, without crossing over
2n
50
genetic diversity
number of different alleles of genes in a population
51
how is variation introduced in meoisis?
crossing over and independent segregation
52
crossing over
- chromatids become twisted casuing a part to break - this recombines with the other chromatid - creates a new combination of alleles
53
independent segregation of homologous chromosomes
- homologous chromosomes line up at equator in random order - creates many combinations of alleles
54
allele
different version of a gene found at the same locus
55
natural selection leads to...
evolution
56
evolution
change in allele frequency over many generations of a population
57
process of natural selection
- random mutation causes new alleles for a gene - new allele increases chances of survival - more likely to reproduce and pass on beneficial allele to new generation - over time there is an increase in allele frequency
58
types of selection
directional and stabilisng
59
directional selection
occurs when there is a change in the environment and one extreme trait has a selective advantage which mean favours (e.g. antibiotic resistance)
60
stabilising direction
no change in the environment so modal trait has the selective advantage (e.g. human birth weight)
61
how is variation introduced?
- crossing over - independent segregation - random fertilisation
62
organisms in the same species...
reproduce to produce fertile offspring
63
courtship behaviour
sequence of actions unique to each species, more similar courtship behaviour, the more closely related a species
64
advantages of courtship behaviour
- recognise sexually mature members of own species of the opposite sex - synchronise mating - form pair bond - successful breeding
65
hierachy
smaller groups arranged within larger groups with no overlap
66
classification system order
domain kingdom phylum class order family genus species
67
binominal system
each species is universally identified using the binomial, the first name is the genus and the second is the species. the names must be italicised and the genus captalised.
68
biodiversity
variety of living organisms
69
ecosystem diversity
range of different habitats
70
species diversity
number of different species and individuals in each species within a community
71
species richness
number of different species
72
species eveness
number of individuals in each species
73
index of diversity
D=N(N-1)/∑ n(n-1) N- number of organisms n- number of individuals in one species
74
balances of farming and conservation examples
- hedgerows - selective breeding - monocultures - overgrazing
75
genetic diversity can be made by comparing...
- observable characteristics - base sequence of DNA - base sequence of mRNA - amino acid sequence of proteins

biology (21 decks)

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