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MISS ESTRUCH FLASHCARDS > TOPIC 4: GENETIC INFORMATION, VARIATION, AND RELATIONSHIPS BETWEEN ORGANISMS > Flashcards

TOPIC 4: GENETIC INFORMATION, VARIATION, AND RELATIONSHIPS BETWEEN ORGANISMS Flashcards

1
Q

Gene

A

a section of DNA that contains a
code for making a polypeptide
and functional RNA

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2
Q

Locus

A

the location of a particular gene
on a chromosome

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3
Q

Allele

A

a different version of the same
gene

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4
Q

Chromosome

A

threadlike structure
composed of tightly coiled DNA
wrapped around histones (if it
is a eukaryotic cell)

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5
Q

Homologous
chromosome

A

a pair of chromosomes that
have the same genes
therefore, they are the same
size

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6
Q

Eukaryotic
DNA

A

DNA is stored as chromosomes
inside the nucleus
linear chromosomes
DNA is tightly coiled and
wrapped around proteins called
histones

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7
Q

Prokaryotic
DNA

A

DNA molecules are shorter and
circular
DNA is not wound around
histones. Instead, it supercoils
to fit in the cell

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8
Q

Codon

A

3 bases on mRNA that code for
an amino acid

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9
Q

Start codon

A

3 bases at the start of an mRNA
sequence which help to initiate
translation

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10
Q

Stop codon

A

3 bases at the end of every gene
that do not code for an amino
acid
this causes ribosomes to
detach
and therefore stops translation

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11
Q

Genetic code

A

an amino acid is coded for by 3
DNA bases which are described
as the “triplet code”

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12
Q

What is meant by
‘the genetic code
is degenerate?

A

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

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13
Q

What is the advantage
of the genetic code
being degenerate?

A

if a substitution mutation
occurs, the new triplet of bases
may still code for the same
amino acid
therefore the mutation will have
no impact on the final protein
produced

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14
Q

What is the advantage
of the genetic code
being universal?

A

genetic engineering is possible
a human gene can be inserted
into another organism
e.g human gene for insulin
inserted into bacteria to make
insulin

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15
Q

What is the advantage
of the genetic code
being nonoverlapping?

A

if a point mutation occurs, it
will only affect one codon and
therefore one amino acid

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16
Q

Triplet code

A

an amino acid is coded for by 3
bases

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17
Q

Mutation

A

a change in the DNA
can be a gene or chromosome
mutation

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18
Q

What is meant by
‘the genetic code
is universal?

A

the same triplet of bases codes
for the same amino acid in all
organisms

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19
Q

What is meant by
‘the genetic code is
non-overlapping?

A

each base in a gene is only part
of one triplet of bases that
codes for one amino acid
therefore each codon is read as
a discrete unit

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20
Q

Introns

A

non-coding sequence of DNA

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21
Q

Exons

A

sequences of DNA that code for
amino acids

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22
Q

What is
splicing?

A

post-transcription modification
removing introns

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23
Q

Genome

A

the complete set of genes in a
cell

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24
Q

Proteome

A

The full range of proteins that a
cell is able to produce

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25
Q

Anticodon

A

3 bases on the tRNA which are
complementary to the codon on
mRNA.

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26
Q

mRNA
structure

A

single-stranded
made up of codons
a copy of one gene

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27
Q

tRNA
structure

A

single-stranded, folded to
create a cloverleaf shape
held in place by hydrogen bonds
has an anticodon and amino
acid binding site

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28
Q

mRNA
function

A

a copy of a gene from DNA
created in the nucleus, and it
then leaves the nucleus
to carry the copy of the genetic
code of one gene to a ribosome
in the cytoplasm

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29
Q

tRNA
function

A

a specific amino attaches at the
binding site
transfers this amino acid to the
ribosome to create the
polypeptide chain

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30
Q

Transcription

A

the first stage in protein
synthesis
one gene in DNA is copied into
mRNA
occurs in the nucleus

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31
Q

Translation

A

the second stage in protein
synthesis
the polypeptide chain is
created using both the mRNA
base sequence and the tRNA
occurs on ribosomes in the
cytoplasm

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32
Q

Which enzymes are involved in transcription?

A

DNA helicase
RNA polymerase

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33
Q

DNA
helicase

A

catalyses the breaking of
hydrogen bonds between the
two strands of DNA

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34
Q

RNA
polymerase

A

joins adjacent RNA nucleotides
together
forming a phosphodiester bond

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35
Q

pre-mRNA

A

mRNA in eukaryotes that still
contains the introns

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36
Q

How is premRNA
modified?

A

the introns are removed by a
protein called a spliceosome
this leaves just the exons

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37
Q

What is ATP
used for in
translation?

A

forming the peptide bond
between amino acids

38
Q

Haploid

A

one copy of each chromosome
in a cell

39
Q

Diploid

A

two copies of each chromosome
in a cell

40
Q

Meiosis

A

cell division that creates
genetically different gametes
there are two nuclear divisions
in this process
results in four haploid daughter
cells

41
Q

Independent
segregation

A

homologous pairs of
chromosomes randomly line up
opposite each other at the
equator of the cell
when they separate it creates a
large number of possible
combinations of chromosomes
in the daughter cells produced

42
Q

Crossing over

A

homologous pairs of
chromosomes line up opposite
each other at the equator in
meiosis 1
parts of the chromatids twist,
break and recombine with
another chromatid
results in new combinations of
alleles in the gametes

43
Q

Gametes

A

sex cells (sperm and egg)

44
Q

How does meiosis
introduce
variation?

A

crossing over
independent segregation

45
Q

Types of gene
mutations

A

deletion
substitution

46
Q

What is a
frameshift?

A

the removal of one base
changes all of the subsequent
codons
all the bases shift back one
position

47
Q

Chromosome
mutation

A

change in the number of
chromosomes
occurs during meiosis

48
Q

Deletion
mutation

A

a gene mutation
a base is removed from a
sequence
causes a frameshift

49
Q

Substitution
mutation

A

a gene mutation
a base is swapped for a
different one

50
Q

Non-disjunction

A

the chromosomes or
chromatids do not split equally
during anaphase

51
Q

Polyploidy

A

changes in whole sets of
chromosomes
e.g. when organisms have three
or more sets of chromosomes
mainly occurs in plants

52
Q

Aneuploidy

A

a change in the number of
individual chromosomes
e.g 3 copies of chromosome 21

53
Q

Down’s
syndrome

A

causes by a chromosome
mutation
an example of aneuploidy
3 copies of chromosome 21

54
Q

Genetic
diversity

A

the number of different alleles
in a population

55
Q

Natural
selection

A

the process that leads to
evolution in populations
results in species becoming
better adapted to their
environment

56
Q

Gene pool

A

all the genes and alleles in a
population at a particular time

57
Q

Allele
frequency

A

the proportion of organisms
within the population carrying a
particular allele

58
Q

Evolution

A

the change in allele frequency
over many generations in a
population

59
Q

Selection
pressure

A

factors that affect the survival
of an organism
the driving force of natural
selection

60
Q

Types of
selection

A

stabilising
directional

61
Q

Directional
selection

A

one of the extreme traits has a
selective advantage
occurs when there is a change
in the environment
the modal trait changes

62
Q

Stabilising
selection

A

the middle (median) trait has a
selective advantage and
continues to be the most
frequent in the population
represented by a normal
distribution graph
range decreases as the extreme
traits are lost over time

63
Q

An example of
directional
selection

A

antibiotic resistance

64
Q

An example of
stabilising
selection

A

human birth weight

65
Q

Definition of a
species

A

a group of similar organisms
that can breed to make fertile
offspring

66
Q

Binomial
system

A

a universal naming system
individuals are named after
their genus and species
e.g. Homo sapiens

67
Q

Courtship
behaviour

A

different sequences of
behaviours that animals
demonstrate to attract a mate
each species demonstrates its
own unique behaviour
essential for successful mating

68
Q

Importance of
courtship

A

helps to synchronise mating
behaviour so that the animals
are more likely to mate when
the female is releasing eggs
increases the likelihood of
successful mating
enables individuals to
recognise members of the same
species and opposite sex

69
Q

What is meant
by a hierarchy?

A

smaller groups arranged within
larger groups
there is also no overlap between
groups

70
Q

Phylogenetics

A

the study of species’
evolutionary origins and
relationships

71
Q

Common
ancestor

A

the species from which another
species evolved

72
Q

Taxon

A

the term for each group in
classification

73
Q

What are the taxa in
the Linnaeus
classification
system?

A

domain
kingdom
phylum
class
order
family
genus
species

74
Q

Species
diverstity

A

the number of different species
and the number of individuals
within each species in a
community

75
Q

Species
richness

A

the number of different species
in a particular area at the same
time

76
Q

Index of diversity

A

a measure of species diversity
a calculation to measure the
relationship between the
number of species in a
community and the number of
individuals in each species

77
Q

Community

A

all the species in a particular
area at a particular time

78
Q

Environment

A

the abiotic (non-living) factors
in an area

79
Q

Habitat

A

The range of physical, biological
and environmental factors in
which a species can live

80
Q

Which farming
techniques reduce
biodiversity?

A

destruction of hedgerows
selective breeding
monocultures
over-grazing
filling in ponds and draining
wetlands

81
Q

Biodiversity

A

a measure of the range of
habitats
from a small local habitat to the
entire Earth
a measure of species diversity
a measure of genetic diversity

82
Q

How is standard
deviation more
useful than a mean?

A

it gives you the spread of data
(variance) around the mean\
overlaps in standard deviation
indicate no significant
difference in the means

83
Q

How do you make
sure your sampling is
representative of the
population?

A

take a large sample (at least
30)
randomly sample to avoid bias

84
Q

How can you
measure genetic
diversity?

A

by comparing the base
sequence of DNA, mRNA and the
amino acid sequence of the
proteins

85
Q

Genetic
diversity

A

the mesure of how many
different alleles there are for
each gene

86
Q

Formula for
Index of Diversity

A

D=N(N-1)/E n(n-1)
N= the total number of organisms of all the species
n=the population size of one species
D=simpson’s index of diversity

87
Q

Compare the DNA in
chloroplast/
mitochondria to
prokaryotic DNA

A

the DNA is similar to
prokaryotic DNA, in that it is:
short
circular
not histone bound

88
Q

How does
transcription differ
between prokaryotes
and eukaryotes

A

Transcription in prokaryotic
organisms results in mRNA
that requires no modification
because prokaryotic DNA does
not contain any introns
eukaryotic transcription results
in pre-mRNA that needs introns
removed

89
Q

What is the role
of ribosomes in
translation?

A

it holds two tRNA molecules
to enable peptide bonds to form
between the amino acids

90
Q

What is the role
of tRNA in
translation?

A

it carries a specific amino acid
anticodons align opposite
complementary codons on the
mRNA

91
Q

Gene
mutations

A

a change in the base sequence
of DNA
substitution or deletion

92
Q

When in the cell
cycle do gene
mutations occur?

A

interphase (s phase)
this is when DNA is replicated

MISS ESTRUCH FLASHCARDS (8 decks)

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