TOPIC 8 : THE CONTROL OF GENE EXPRESSION Flashcards

1
Q

Gene mutation

A

change in base sequence of
DNA
occurs during DNA replication
includes addition, deletion,
substitution, inversion,
duplication and translocation
of bases

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2
Q

Mutagenic
agents

A

chemical or radiation that
increases mutation rate

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3
Q

Addition
mutation

A

One extra base is added to the
DNA sequence
causes all subsequent codons
to be altered (frameshift)

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4
Q

Deletion
mutation

A

One base is deleted in the DNA
sequence.
causes all subsequent codons
to be altered (frameshift)

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5
Q

Substitution
mutation

A

One base in the DNA sequence
is changed
no frameshift
only one codon changes
may have no impact due to
degenerate genetic code

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6
Q

Frameshift

A

A change in all the codons after
the point of mutation
each base shifts left or right one
position

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7
Q

Inversion
mutation

A

A section of bases detach from
the DNA sequence and re-join
inverted
results in different amino acids
being coded for in this region

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8
Q

Duplication
mutation

A

One base is duplicated at least
once in the sequence
causes a frameshift to the right

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9
Q

Translocation of
bases
mutation

A

A section of bases on one
chromosome detaches and
attaches to a different
chromosome

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10
Q

Non-functioning
protein

A

a protein with a different
primary and tertiary structure
therefore the shape is changed
it cannot carry out its function

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11
Q

Tumour

A

a mass of cells as a result of
uncontrolled cell division
can be benign or malignant

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12
Q

Benign
tumour

A

non-cancerous tumour
grows large but at a slow rate
produce adhesive and are
surrounded by a capsule so they
cannot spread

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13
Q

Malignant
tumour

A

cancerous tumour
grows rapidly
can become unspecialised
can metastasise
grow projections
develop own blood supply

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14
Q

Cancer

A

Malignant tumours that form
due to uncontrolled cell division

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15
Q

Metastasis

A

cancer cells breaking off from the
tumour
spreading to form secondary
tumours in different tissues or
organs

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16
Q

Oncogene

A

a mutated version of a protooncogene
results in constant initiation of
DNA replication and mitotic cell
division
causes tumour formation

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17
Q

Tumour
suppressor genes

A

genes that produce proteins to
slow down cell division and
cause cell death if DNA copying
errors are detected

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18
Q

Epigenetics

A

the heritable change in gene
function
without changing the DNA base
sequence
caused by changes in the
environment
can inhibit transcription

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19
Q

Hypermethylation

A

an increased number of methyl
groups attached to a gene
results in the gene being
deactivated
results in cancer if happens to a
tumour suppressor gene

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20
Q

Methylation
of DNA

A

inhibits transcription
methyl groups attach to the
cytosine base on DNA
prevents transcriptional factors
from binding
condenses the DNA-histone
complex

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21
Q

How can oestrogen
increase the risk of
breast cancer?

A

Oestrogen is a steroid hormone
it binds to a receptor site on a
transcriptional factor
causing a change in shape
so it can bind to the DNA to
initiate transcription
can result in uncontrolled cell
division

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22
Q

Stem cell

A

undifferentiated cells that can
continually divide and become
specialised

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23
Q

Totipotent
stem cell

A

can differentiate into any body
cell
occur for a limited time in early
mammalian embryos

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24
Q

Pluripotent
stem cell

A

can differentiate into almost
any body cell
occur in embryos

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25
Q

Multipotent
stem cell

A

can differentiate into a limited
number of cells
found in mature mammals e.g
in bone marrow

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26
Q

Unipotent
stem cell

A

can differentiate into one type
of cell
found in mature mammals

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27
Q

Induced
pluripotent
stem cell

A

produced from adult somatic
cells
using protein transcriptional
factors
overcomes ethical issues of
using embryonic stem cells

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28
Q

Transcriptional
factor

A

proteins that can bind to
different base sequences on
DNA
initiate transcription of genes

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29
Q

What is a vector?

A

a DNA molecule used as a
vehicle to carry a DNA fragment
e.g. plasmids/viruses

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30
Q

Acetylation of
histones

A

Decreased acetylation inhibits
transcription
removing acetyl groups makes
the histones more positive
this attracts the negative
phosphate group on DNA
making it harder for the
transcriptional factors to bind

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31
Q

RNA
interference

A

inhibition of the translation of
mRNA
the mRNA gets destroyed so it
cannot be translated

32
Q

siRNA

A

small interfering RNA
destroys mRNA molecules to
prevent translation

33
Q

Recombinant
DNA technology

A

combining different organisms’
DNA
enable scientists to manipulate
and alter genes to improve
industrial processes and
medical treatment

34
Q

Sequencing
projects

A

Reading the full genome of
organisms
provides opportunities to
screen DNA to identify potential
medical problems

35
Q

How can you
create a DNA
fragment?

A

Reverse transcription with
reverse transcriptase
restriction endonucleases
gene machine

36
Q

Gene machine

A

creates DNA fragments using a
computerised machine

37
Q

Reverse
transcriptase

A

An enzyme that makes cDNA
single-stranded copies of DNA
from mRNA

38
Q

Restriction
endonucleases

A

Enzymes that cut up DNA to
create fragments
cut at specific
recognition/restriction
sequences
results in sticky ends

39
Q

In vivo cloning

A

Creating DNA fragments using
bacteria
involves restriction
endonulcease enzymes

40
Q

In vitro cloning

A

Using PCR to create a large
number of copies of a DNA
fragment

41
Q

Uses of PCR

A

Used widely in gene technology
to make large numbers of
copies of DNA fragments
e.g. forensics, genotyping,
cloning, paternity tests,
microarrays

42
Q

Describe the PCR
process

A

increase temperature to 95C to
break hydrogen bonds & split
DNA into single strands
temperature is decreased to 55C
so primers can attach
DNA polymerase joins
complementary nucleotides &
makes a new strand
temperature increased to 72C
(optimum for Taq DNA
polymerase)

43
Q

Uses of genetic
fingerprinting

A

Forensic science
medical diagnosis
plant/animal breeding
paternity tests

44
Q

What is gel
electrophoresis

A

Separation of DNA samples
using an electrical voltage
different lengths of DNA VNTRs
are separated

45
Q

Why does the
DNA move in gel
electrophoresis?

A

DNA is negatively charged and
moves towards the positive end
of the gel
the shorter the piece of DNA, the
faster and further it moves

46
Q

What is genetic
screening?

A

Testing DNA to identify the
presence of alleles that can
cause/increase the risk of
developing a disease

47
Q

What is genetic
counselling?

A

a type of social work giving
people advice and information
following the screening of
disease causing alleles

48
Q

What is cDNA?

A

Complementary, singlestranded
DNA strands
created by reverse transcriptase

49
Q

What are the
advantages of
using the gene
machine?

A

Very quick
accurate
create intron-free DNA

50
Q

What are the
advantages of using
reverse
transcription?

A

Creates intron-free cDNA

51
Q

What are the
advantages of using
restriction
endonculeases?

A

Creates sticky ends on DNA to
enable the DNA fragments to
join with complementary base
pairs

52
Q

Oligonucleotides

A

Short DNA molecules
used in gene machines to create
DNA fragments

53
Q

Sticky ends

A

Exposed staggered ends of
bases
palindromic base sequences
created by restriction
endonuclease enzymes

54
Q

Palindromic
sequence

A

sequences of bases that read
the same forwards as they do
backwards

55
Q

Blunt end

A

When a restriction
endonuclease cuts the DNA
double-strand in the same
position
there is no overhang of bases

56
Q

What are the two
methods to amplify
DNA?

A

In vivo
in vitro (PCR)

57
Q

Promoter region

A

a sequence of DNA that is the
binding site for RNA polymerase
to enable transcription to occur

58
Q

Terminator
region

A

added at the end of the gene
it causes RNA polymerase to
detach and stop transcription
to ensure one gene is copied
into mRNA at a time

59
Q

Plasmid

A

a small loop of bacterial DNA
contains only a few genes
contains the genes for
antibiotic resistance

60
Q

Recombinant
plasmid

A

a small loop of bacterial DNA
with the DNA from another
organism inserted into it

61
Q

Transformation

A

the process of getting a plasmid
to re-enter a bacterium
involves calcium ions and
temperature shocking

62
Q

How can
transformed cells
be identified?

A

using marker genes
antibiotic resistance genes
genes coding for fluorescent
proteins
genes coding for enzymes

63
Q

What is a
marker gene?

A

genes on the plasmid used to
identify which bacteria
successfully took up the
recombinant plasmid

64
Q

DNA probe

A

short, single-stranded pieces of
DNA
labelled radioactively or
fluorescently so that they can
be identified

65
Q

DNA
hybridisation

A

DNA is heated to separate the
double helix into single strands
it is then mixed with
complementary sequences of
single-stranded DNA
it is then cooled so
complementary strands will
anneal

66
Q

Personalised
medicine

A

screening for the presence of
particular alleles
to select medicines and
personalise health advice based
on your genotype

67
Q

VNTRs

A

variable number tandem
repeats sequences of bases in
introns
unique to each person

68
Q

How can DNA
samples be
collected?

A

From blood, body cells or hair
follicles

69
Q

How is DNA
extracted from cells
so that it can be
examined?

A

cell fractionation and
ultracentrifugation

70
Q

How is DNA
digested in genetic
fingerprinting?

A

Restriction endonucleases are
added to cut the DNA into
smaller fragments
enzymes that cut close to the
target VNTRs are added

71
Q

Why can the genome not
be easily translated into
the proteome in complex
organisms?

A

due to the presence of noncoding
DNA and regulatory
genes

72
Q

What is the role of
DNA ligase in
making
recombinant DNA?

A

used to stick the DNA fragment
to create recombinant DNA

73
Q

Outline the process to decrease blood glucose levels

A

Blood glucose levels rise
Detected by B cells of the pancreas
Produces insulin
Increased cellular respiration
Conversion of glucose to glucagon
Convert glucose to fat
Absorb glucose into cells
Blood glucose levels fall

74
Q

Outline the process by which blood glucose levels increase

A

Blood glucose levels fall
Defected by the Alpha cells of the pancreas Produce glucagon
Conversion of glucagon to glucose
Conversion of amino acids to glucose
Uncontrolled quantity of glucose enters from the intestine
Blood glucose levels rise

75
Q

Define type 1 diabetes

A

Diabetes mellitus- insulin dependant diabetes
Happen suddenly in childhood
Body doesn’t produce its own insulin as the immune system attacks the insulin, producing beta cells

76
Q

Define type 2 diabetes

A

Insulin independent
Occurs <40
Glycoprotein receptors loose their responsiveness to insulin/ inadequate supply of insulin from the pancreas