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Higher biology > unit 1 > Flashcards

unit 1 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what does a nucleotide contain

A

phosphate group
deoxyribose sugar
base

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2
Q

what can be found at each prime end

A

5’ = phosphate
3’ = deoxyribose sugar

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3
Q

what makes the sugar phosphate backbone?

A

phosphate group
deoxyribose sugar

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4
Q

what bonds are base pairs held together by?

A

weak hydrogen bonds

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5
Q

what bonds hold together the sugar phosphate backbone?

A

sugar-phosphate bonds

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6
Q

the structure of DNA

A

nucleotides join together in an antiparallel structure to form a double stranded helix

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7
Q

what prime end can new nucleotides be added to?

A

3’ end

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8
Q

how can DNA be found?

A

linear chromosomes
circular chromosomes

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9
Q

prokaryotes DNA

A

No nucleus
Circular chromosomes (storied in cytoplasm)
Circular plasmids (carry non-essential genes)

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10
Q

eukaryotes DNA

A

Contains nucleus
Plant + animal cells
Linear chromosomes (storied in nucleus)
Mitochondria and chloroplasts = circular chromosomes
Yeast
Linear chromosomes (storied in nucleus)
Circular plasmids

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11
Q

what is DNA in eukaryotes tightly packaged around?

A

proteins called histones

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12
Q

stages of DNA replication

A

formation of the leading strand
formation of the lagging strand

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13
Q

leading strand stages

A

DNA unwinds and weak hydrogen bonds break
Primer attaches to the 3’ end of the template DNA strand
The enzyme DNA polymerase attaches free DNA nucleotides to the primer at the 3’ end
DNA polymerase then catalyses the sugar-phosphate bond between the nucleotides
Replication is continuous

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14
Q

lagging strand steps

A

Each fragment is primed
DNA polymerase binds nucleotides together in fragments from the primers 3’ end
Primer is then replaced by DNA
The enzyme ligase joins these fragments together
Replication is discontinuous

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15
Q

replication of DNA requirements

A

template DNA
primers
a supply of nucleotides
DNA polymerase
ligase
ATP supply

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16
Q

what is a primer?

A

attaches to the 3’ end of the template DNA
shows the start point of DNA replication

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17
Q

what does DNA polymerase do?

A

Attaches free DNA nucleotides to the primer at the 3’ end
Catalyses the sugar-phosphate bond between the nucleotides

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18
Q

what does ligase do?

A

Joins the fragments of DNA together in the lagging strand

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19
Q

what is the importance of DNA replication?

A

ensure an exact copy of DNA is passed onto each daughter cell

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20
Q

steps of PCR

A

DNA heated to break H bonds
cooled allowing primers to bind to target sequence
heated for heat-tolerant DNA polymerase to add nucleotides to the primers at the 3’ end of the original strand

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21
Q

temperatures in PCR

A

95 (92-98)
55 (50-65)
75 (70-80)

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22
Q

why does DNA polymerase have to be heat-tolerant in PCR?

A

ensures the enzyme does not denature

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23
Q

where does PCR take place?

A

thermocycler

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24
Q

requirements for PCR

A

DNA template strand
primers
supply of nucleotides
DNA polymerase

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25
Q

uses of PCR

A

paternity suits
help solve crime scenes
diagnose genetic disorders

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26
Q

genotype

A

determined by the sequence of bases in its genes

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27
Q

phenotype

A

determined by the proteins that are synthesised when genes are expressed
(physically look like)

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28
Q

mRNA

A

carries a copy of the genetic code from the nucleus to the ribosome

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29
Q

tRNA

A

each tRNA molecule carries its specific amino acid to the ribosome

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30
Q

rRNA

A

forms the ribosome with proteins

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31
Q

codon

A

each triplet on the mRNA molecule and codes for a specific amino acid

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32
Q

introns

A

non-coding regions of DNA

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33
Q

exons

A

coding regions of DNA `

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34
Q

where does transcription occur?

A

nucleus

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35
Q

how is mRNA formed?

A

RNA polymerase moves along gene unwinding the double helix - breaking H bonds
RNA polymerase synthesises a primary transcript from RNA nucleotides by complementary base pairing

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36
Q

how does RNA polymerase know when to form a mRNA primary transcript?

A

starts when it reads the start codon
ends with it reads the stop codon

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37
Q

how is the mature transcript formed?

A

splicing
introns are removed from the primary transcript and exons are spliced together to form the mature transcript
order of exons is unchanged

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38
Q

what occurs after splicing?

A

mature mRNA transcript leaves the nucleus into the cytoplasm at the ribosome

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39
Q

how can multiple genes be expressed from the one protein?

A

alternative splicing
different mature mRNA transcripts are produced depending on which exons are retained

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40
Q

where is tRNA found?

A

cytoplasm

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41
Q

structure of a tRNA molecule

A

one triplet of bases called an anticodon which is complementary to an mRNA codon
this is specific to an aimco acid which is found on the amino acid attachment site at the other end

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42
Q

where does translation occur?

A

ribosome

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43
Q

how does protein synthesis begin?

A

when the start codon is read

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44
Q

describe tRNA in translation

A

complementary tRNA anticodons attach to the mRNA strand bringing a specific amino acid

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45
Q

how is a protein formed in translation?

A

the amino acids which are brought by tRNA are bonded together by peptide bonds
tRNA then leaves once they are attached
this forms a polypeptide

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46
Q

how does protein synthesis stopped?

A

when the stop codon is reached

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47
Q

describe the structure of a polypeptide

A

folds to form a 3D shape of a protein
held together by hydrogen bonds and other interactions

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48
Q

what forms the ribosome?

A

proteins
rRNA

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49
Q

what is differentiation?

A

the process by which a cell expresses certain genes to produce a characteristic for the cell type

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50
Q

what do stem cells have the ability to do

A

differentiate to carry out specialised functions
self-renew

51
Q

embryonic stem cells differentiation abilities

A

Differentiate into all the cell types that make up the organism = pluripotent
All the genes in embryonic stem cells can be switched on

52
Q

where are embryonic stem cells found?

A

from the early stages of an embryo

53
Q

tissue stem cells differentiation abilities

A

They can differentiate into all cell types found in a particular tissue type = multipotent
Many genes are already switched off

54
Q

example of tissue stem cell

A

blood stem cells in bone marrow can give rise to all types of blood cell

55
Q

where are tissue stem cells found?

A

tissues throughout the body

56
Q

what are tissue stem cells involved in?

A

growth, renewal, repair

57
Q

therapeutic use of stem cells

A

involved in the repair of diseased or damaged organs
corneal repair
skin grafts

58
Q

research use of stem cells

A

provides information on cell processes = cell growth, differentiation and gene regulation
how diseases develop
drug testing

59
Q

ethical issues of embryonic stem cells

A

Can lead to effective treatments for disease and injury
Involves the destruction of the embryo
Reduces animal testing

60
Q

what is an organisms genome?

A

its entire hereditary information encoded in its DNA

61
Q

what is the genome made of?

A

DNA sequences that code for a protein (genes)
Non-coding DNA sequences

62
Q

function of coding sequences in the genome?

A

Code for amino acid sequences in proteins

63
Q

function of non-coding sequences in the genome?

A

regulate transcription by turning genes on/off
transcribed but not translated

64
Q

example of non-coding sequences transcribed but not translated

A

tRNA
rRNA

65
Q

what is a mutation?

A

changes in DNA that can result in no protein or an altered protein being synthesised

66
Q

how can mutations occur?

A

spontaneous
random
rarely

67
Q

how are mutations the driving factor of evolution?

A

normally have negative effects but occasionally mutation may be advantageous, increases variation

68
Q

single gene mutations

A

substitution
insertion
deletion

69
Q

substitution mutations

A

missense
nonsense
splice-site

70
Q

missense mutation

A

one amino acid changed for another
produces a non-functional protein

71
Q

nonsense mutation

A

premature stop codon produced
shorter protein

72
Q

splice-site mutation

A

some introns being retained and/or some exons not being included in the mature transcript

73
Q

type of insertion/deletion mutation

A

frameshift mutation

74
Q

frameshift mutation

A

All of the codons and all of the amino acids after the mutation are changed
Major effect on the structure of the protein and it is almost certain to be non-functional

75
Q

types of chromosome mutations

A

deletion
duplication
inversion
translocation

76
Q

deletion chromosome mutation

A

A section of a chromosome is removed when it breaks in two places and a segment in between becomes detached

Chromosome is short and lacks certain genes

77
Q

duplication mutation

A

A section of a chromosome is added from its homologous partner

78
Q

inversion mutation

A

The chromosome breaks in two places and the segment in between is reversed

79
Q

translocation mutation

A

One section of a chromosome breaks off and attaches to another chromosome that is not its homologous partner

80
Q

importance of duplication mutation

A

allows potential beneficial mutation to occur in duplicated gene whilst original gene still expresses its own protein
produces a second copy that is free from selection pressures

81
Q

what is evolution?

A

changes in organisms over generations as a result of genomic variation

82
Q

natural selection

A

non-random increase in the frequency of DNA sequences that increase survival and the non-random reduction in the frequency of deleterious sequences

83
Q

types of natural selection

A

stabilising
directional
disruptive

84
Q

stabilizing selection

A

An average phenotype is selected for and extremes of the phenotype are selected against
This means there is a smaller range of values so less variation in the population

85
Q

directional natural selection

A

One extreme of the phenotype range is selected for as it gives a selective advantage

86
Q

disruptive natural selection

A

Two or more phenotypes are selected for (not the average)
The population is split into two or more distinct groups with different characteristics

87
Q

types of gene transfer

A

vertical
horizontal

88
Q

vertical gene transfer

A

Occurs in eukaryotes and prokaryotes and involved genes being passed from parents to offspring

89
Q

how does vertical transfer occur?

A

through sexual or aesexual reproduction

90
Q

horizontal gene transfer

A

Prokaryotes can transfer genes between individuals of the same generation

91
Q

why do prokaryotes have faster evolutionary change?

A

they use vertical and horizontal transfer

92
Q

what is speciation?

A

generation of a new biological species by evolution

93
Q

types of speciation

A

allopatric
sympatric

94
Q

difference between allopatric and sympatric?

A

allopatric = gene flow is prevented by a geographical barrier
Sympatric = gene flow is prevented by an ecological or behavioural barrier

95
Q

speciation steps

A

population occupies the same environment
isolation barrier splits into sub-population
different mutations occur
natural selection occurs
barrier removed and they can no longer interbreed to product fertile offspring

96
Q

what does an isolation barrier do?

A

prevent gene flow between sub-populations

97
Q

isolation barriers

A

geographical
behavioural
ecological

98
Q

what is genomics?

A

the study of genomes

99
Q

what is genomic sequencing?

A

the sequence of nucleotide bases can be determined for individual genes are entire genomes

100
Q

what genomes have been sequenced?

A

Disease-causing organisms
Pest species
Species that are important model organisms for research

101
Q

reasons for genomic sequencing

A

accurate diagnosis
specific pest control
model organisms

102
Q

accurate diagnosis for genomic sequencing

A

Disease causing organisms have been sequenced to help with accurate diagnoses

103
Q

specific pest control for genomic sequencing

A

Pest species have been sequenced to develop more specific measures of control rather than using general pesticides

104
Q

model organisms for genomic sequencing

A

Model organisms (fruit flies) have been sequenced so they can be used in medical research in place of mammals, reducing ethical concerns and cost

105
Q

what is required for comparative genomics?

A

bioinformatics

106
Q

what are bioinformatics?

A

computer and statistical analysis

107
Q

what are special about computer programs?

A

can be used to identify base sequences by looking at sequences similar to known genes

108
Q

what has comparative genomics revealed?

A

genes are highly conserved

109
Q

what can highly conserved DNA be used for?

A

comparing the genomes of two species
- the greater number of conserved genes, the closer they are related

110
Q

what is phylogenetics?

A

the study of evolutionary history and relationships

111
Q

what is used to construct a phylogenetic tree?

A

comparative genomics

112
Q

what are requirements for the main sequence of events in evolution?

A

DNA sequence data
fossil records

113
Q

lineage

A

a sequence of species which have evolved from ancestry populations

114
Q

a sequence divergence

A

Describes when lineages diverged from a common ancestor

115
Q

main sequence of events on life list

A

Cells
Last universal ancestor
Prokaryotes
Photosynthetic organisms
Eukaryotes
Multicellularity
Animals
Vertebrates
Land plants

116
Q

molecular clocks

A

used to estimate when species diverged

117
Q

what is required for molecular clocks?

A

DNA sequence data
fossil records
mutation rate

118
Q

what is a molecular clocks disadvantage?

A

assumes a constant mutation rate

119
Q

how can you work out how long ago species diverged?

A

the number of nucleotide differences as nucleotide substitutions is regarded as being proportional to time

120
Q

what is personalised medicine?

A

individuals personal genome can be used to select the most effective drugs and dosage to treat their disease

121
Q

pros of personalised medicine

A

It can be used to predict a future disease diagnosis
There could be early intervention to take preventative measures
The ideal prescription and dosage of medication can be given

122
Q

cons of personalised medicine

A

Who should be allowed to access this information?
Could employers, life insurers or offspring be allowed to demand this information?

123
Q

what is pharmacogenetics?

A

the study of the genetic variation between individuals that affects their response to drugs/pharmaceuticals

124
Q

how can the cause of inherited diseases be found?

A

by comparing the DNA of affected and unaffected individuals to reveal the precise mutation which caused the mutation

Higher biology (3 decks)

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