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Human Genomics
Higher Human Biology
Learning Intentions
• Explain what is meant by human genomics
• State that bioinformatics can be used to
identify DNA sequences
Human Genomics
• The genome is the whole
hereditary information of an
organism that is encoded in
the DNA.
• Human genomics is the study
of the human genome
• It involves determining the
sequence of the nucleotide
base molecules along the
DNA.
Human Genomics
• The sequence of bases can be determined for
individual genes and entire genomes
• This genetic information can be used to find
the function of different genes.
• Entire genomes can be compared using single
nucleotide polymorphisms (SNPs). (These are
differences between individuals due to base
substitutions. )
SNPs
The Human Genome Project
• The human genome project began in 1990
and was completed on 14th April 2003.
• The main aims of the project were:
– To identify the approximate 100,000 genes in the
human DNA.
– Determine the sequences of the 3 billion bases
that make up human DNA.
genome sequencing animation
Bioinformatics
• Is the use of computer
technology to identify
DNA sequences
• The enormous amount of
data produced by DNA
and protein sequencing
can be managed and
analysed using computer
technology and shared
over the internet
Bioinformatics
• Computer programs can be used to
identify
– Gene sequences by looking for
coding sequences similar to
know genes
– Start sequences (there is a good
chance that each of these will
be followed by a coding
sequence
– Sequences lacking stop codons
(a protein coding sequence is
normally a very long chain of
base triplets containing no stop
codon except the one at its end
Bioinformatics
• Computer programmes can also be used to
search for base sequences that code for
specific amino acid sequences of known
proteins.
• This can be useful in medicine, for example in
genetic screening for diseases.
Videos
• BBC documentary (1 hour)
https://www.youtube.com/watch?v=FgqXoyorWY
• Ethics of genome project (5 mins)
http://www.bbc.co.uk/learningzone/clips/ethi
cs-of-the-human-genome-project/8732.html
Learning Intentions
• Describe what is meant by systematics
• Explain the role of genomics in personalised
medicine
• Explain what pharmacogenetics is and how it
is used
Systematics
• Systematics is the study of a
group of living things with
respect to their diversity,
relatedness and classification.
• It compares human genome
sequence data and genomes
of other species to provide
information on evolutionary
relationships and origins
Video
Systematics
• Systematics has been used to examine genetic
differences between populations of humans.
• It shows that the biggest genetic variation
occurs in populations in Africa.
• This has led scientists to put forward the ‘out
of Africa’ theory, which suggests that modern
humans originated in Africa.
Personalised Medicine
• Personalised medicine is
based on an individuals
genome.
• It would allow scientists to
predict an individuals
susceptibility to disease,
select treatment that is
more likely to be successful,
and avoid adverse reactions
to medication.
Video
Personalised Medicine
• To make use of this technique, scientists need
to:
– Locate mutant variants in the genome
– Distinguish between harmful and neutral variants
– Establish a link between the mutation and a
disease
• The nature of the disease might depend on
genetic and environmental factors.
Pharmacogenetics
• Pharmacogenetics is the study of how
people's genetic makeup affects their
responses to drugs.
• If a drug is known to produce side effects in
some people, pharmacogenetic testing may
help identify at-risk patients.
Rational drug design
• Drugs work by
interacting with target
molecules (receptors)
in our bodies and
altering their activities
in a way that is
beneficial to our
health.
Pharmacogenetics
• Once DNA sequencing
has identified the genes
involved in a specific
disease and established
the structure of the
protein expressed, the
Pharmacogenetisists try
to synthesise a specific
drug.
Pharmacogenetics
• The drug produced will
– bind to proteins involved or
– prevent their synthesis by
binding to a specific region of
the DNA preventing
transcription of abnormal
mRNA
or
– by binding to the abnormal
mRNA preventing translation
The Future
• In the future, genomics could be used to
predict risk of disease.
• What are some ethical issues of sequencing
individuals genomes?
• Would you have your genome sequenced?
On each card is a statement covering an issue related to
personal genomics. Each of these ethical issues need to be
considered when discussing whether or not personal
genomics is a good thing and should be an area of scientific
development. Arrange the cards into a diamond with the
statement they agree with most at the top and least at the
bottom.
Strongly agree
Strongly disagree
Learning Intention
• Describe the steps involved in PCR
PCR
• PCR (polymerase chain reaction) is a
technique that replicates short sections of
DNA quickly.
• This amplification of DNA is an in vitro
(outside the body) process.
Primers
• Amplification of DNA using PCR involves the
use of primers.
• The primer is a piece of single stranded DNA
complementary to a specific target sequence
at the 3’ end of the strand to be replicated.
PCR Steps
1. DNA is heated to separate the DNA strands
(by breaking the hydrogen bonds).
2. DNA is cooled to allow the primers to bind to
target sequences of DNA.
3. Heat tolerant DNA polymerase adds
nucleotides to the primers at the 3’ ends of
original DNA strands.
PCR Steps
4. Repeated cycles of heating and cooling
amplify the region DNA.
5. In one hour, a short length of DNA can
become a million.
pcr animation
pcr glow
PCR game
pcr song
DNA Microarray
• This is an arrangement of thousands
of different DNA probes as tiny spots
attached to a glass slide.
• It is used to detect a specific
sequence of nucleotide bases in a
sample of DNA.
• This is how the DNA to be amplified
can be identified.
DNA Probe
• A DNA probe is a short single stranded piece
of DNA that is complementary to a specific
sequence.
• A fluorescent label is attached to the probe to
allow detection.
SQA Notes
• Polymerase Chain Reaction (PCR) : amplification of DNA using
complementary primers for specific target sequences.
• DNA heated to separate strands then cooled for primer
binding.
• Heat-tolerant DNA polymerase then replicates the region of
DNA.
• Repeated cycles of heating and cooling amplify this region of
DNA.
• Primers are complementary to specific target sequences at
the two ends of the region to be amplified.
Learning Intention
• Give some applications of DNA profiling.
DNA Profiling
• DNA profiling allows the identification of
individuals by comparing regions of the
genome with highly variable number of
repetitive sequences of DNA.
• This can be used forensically, for example to
identify criminals and in paternity testing, or
medically, for example to analyse disease risk.
Glow
DNA Profiling
Which child is the mother’s from a previous marriage?
Which child is adopted?
DNA Profiling
Which suspect
committed the
crime?