unit 8 Flashcards
KILL YOURSELF FATTY
Gene mutation
change in base sequence of
DNA
occurs during DNA replication
includes addition, deletion,
substitution, inversion,
duplication and translocation
of bases
Mutagenic
agents
chemical or radiation that
increases mutation rate
Addition
mutation
One extra base is added to the
DNA sequence
causes all subsequent codons
to be altered (frameshift)
Deletion
mutation
ne base is deleted in the DNA
sequence.
causes all subsequent codons
to be altered (frameshift)
Substitution
mutation
One base in the DNA sequence
is changed
no frameshift
only one codon changes
may have no impact due to
degenerate genetic code
Inversion
mutation
A section of bases detach from
the DNA sequence and re-join
inverted
results in different amino acids
being coded for in this region
Frameshift
A change in all the codons after
the point of mutation
each base shifts left or right one
position
Duplication
mutation
One base is duplicated at least
once in the sequence
causes a frameshift to the right
Tumour
a mass of cells as a result of
uncontrolled cell division
can be benign or malignant
Translocation of
bases
mutation
A section of bases on one
chromosome detaches and
attaches to a different
chromosome
Non-functioning
protein
a protein with a different
primary and tertiary structure
therefore the shape is changed
it cannot carry out its function
Benign
tumour
non-cancerous tumour
grows large but at a slow rate
produce adhesive and are
surrounded by a capsule so they
cannot spread
Cancer
Malignant tumours that form
due to uncontrolled cell division
Malignant
tumour
cancerous tumour
grows rapidly
can become unspecialised
can metastasise
grow projections
develop own blood supply
Metastasis
cancer cells breaking off from the
tumour
spreading to form secondary
tumours in different tissues or
organs
Oncogene
a mutated version of a protooncogene
results in constant initiation of
DNA replication and mitotic cell
division
causes tumour formation
Tumour
suppressor genes
enes that produce proteins to
slow down cell division and
cause cell death if DNA copying
errors are detected
Epigenetics
he heritable change in gene
function
without changing the DNA base
sequence
caused by changes in the
environment
can inhibit transcription
Hypermethylation
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
Methylation
of DNA
inhibits transcription
methyl groups attach to the
cytosine base on DNA
prevents transcriptional factors
from binding
condenses the DNA-histone
complex
How can oestrogen
increase the risk of
breast cancer?
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
Stem cell
undifferentiated cells that can
continually divide and become
specialised
Totipotent
stem cell
can differentiate into any body
cell
occur for a limited time in early
mammalian embryos
Multipotent
stem cell
can differentiate into a limited
number of cells
found in mature mammals e.g
in bone marrow
Pluripotent
stem cell
can differentiate into almost
any body cell
occur in embryos
Unipotent
stem cell
can differentiate into one type
of cell
found in mature mammals
Induced
pluripotent
stem cell
produced from adult somatic
cells
using protein transcriptional
factors
overcomes ethical issues of
using embryonic stem cells
Transcriptional
factor
proteins that can bind to
different base sequences on
DNA
initiate transcription of genes
What is a vector?
a DNA molecule used as a
vehicle to carry a DNA fragment
e.g. plasmids/viruses
siRNA
small interfering RNA
destroys mRNA molecules to
prevent translation
RNA
interference
inhibition of the translation of
mRNA
the mRNA gets destroyed so it
cannot be translated
Acetylation of
histones
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
Recombinant
DNA technology
combining different organisms’
DNA
enable scientists to manipulate
and alter genes to improve
industrial processes and
medical treatment
Sequencing
projects
Reading the full genome of
organisms
provides opportunities to
screen DNA to identify potential
medical problems
How can you
create a DNA
fragment?
Reverse transcription with
reverse transcriptase
restriction endonucleases
gene machine
Gene machine
creates DNA fragments using a
computerised machine
Reverse
transcriptase
An enzyme that makes cDNA
single-stranded copies of DNA
from mRNA
Restriction
endonulceases
Enzymes that cut up DNA to
create fragments
cut at specific
recognition/restriction
sequences
results in sticky ends
In vivo cloning
Creating DNA fragments using
bacteria
involves restriction
endonulcease enzymes
In vitro cloning
Using PCR to create a large
number of copies of a DNA
fragment
Uses of PCR
Used widely in gene technology
to make large numbers of
copies of DNA fragments
e.g. forensics, genotyping,
cloning, paternity tests,
microarray
Describe the PCR
process
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)
Uses of genetic
fingerprinting
Forensic science
medical diagnosis
plant/animal breeding
paternity tests
What is gel
electrophoresis
Separation of DNA samples
using an electrical voltage
different lengths of DNA VNTRs
are separated
Why does the
DNA move in gel
electrophoresis?
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
What is genetic
screening?
Testing DNA to identify the
presence of alleles that can
cause/increase the risk of
developing a disease
What is genetic
counselling?
a type of social work giving
people advice and information
following the screening of
disease causing alleles
What is cDNA?
omplementary, singlestranded DNA strands
created by reverse transcriptase
What are the
advantages of
using the gene
machine?
Very quick
accurate
create intron-free DNA
What are the
advantages of using
reverse
transcription?
Creates intron-free cDNA
What are the
advantages of using
restriction
endonculeases?
Creates sticky ends on DNA to
enable the DNA fragments to
join with complementary base
pairs
Oligonucleotides
Short DNA molecules
used in gene machines to create
DNA fragments
Sticky ends
Exposed staggered ends of
bases
palindromic base sequences
created by restriction
endonuclease enzymes
Palindromic
sequence
sequences of bases that read
the same forwards as they do
backwards
What are the two
methods to amplify
DNA?
In vivo
in vitro (PCR)
Blunt end
When a restriction
endonuclease cuts the DNA
double-strand in the same
position
there is no overhang of bases
Terminator
region
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
Plasmid
a small loop of bacterial DNA
contains only a few genes
contains the genes for
antibiotic resistance
Promoter region
a sequence of DNA that is the
binding site for RNA polymerase
to enable transcription to occur
Recombinant
plasmid
a small loop of bacterial DNA
with the DNA from another
organism inserted into it
Transformation
the process of getting a plasmid
to re-enter a bacterium
involves calcium ions and
temperature shocking
How can
transformed cells
be identified?
using marker genes
antibiotic resistance genes
genes coding for fluorescent
proteins
genes coding for enzymes
What is a
marker gene?
genes on the plasmid used to
identify which bacteria
successfully took up the
recombinant plasmid
DNA probe
short, single-stranded pieces of
DNA
labelled radioactively or
fluorescently so that they can
be identified
Personalised
medicine
screening for the presence of
particular alleles
to select medicines and
personalise health advice based
on your genotype
DNA
hybridisation
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
VNTRs
variable number tandem
repeats sequences of bases in
introns
unique to each
How is DNA
extracted from cells
so that it can be
examined?
cell fractionation and
ultracentrifugation
How can DNA
samples be
collected?
From blood, body cells or hair
follicles
How is DNA
digested in genetic
fingerprinting?
Restriction endonucleases are
added to cut the DNA into
smaller fragments
enzymes that cut close to the
target VNTRs are added
Why can the genome not
be easily translated into
the proteome in complex
organisms?
due to the presence of noncoding DNA and regulatory
genes
what is the role of DNA ligase in making recombinant DNA
used to stick the DNA fragment to create recombinant DNA
