Genetic Change: Mutation and Biotechnology

This module explores the process of mutation and how it introduces new alleles into populations. It also delves into the uses and applications of biotechnology, past, present, and future. The module discusses the effects of genetic techniques on Earth's biodiversity and evaluates the potential of artificial manipulation of DNA to change populations permanently. It also examines the social, ethical, and economic implications of biotechnology.

MODULE 6: GENETIC CHANGE
1: Mutation – How does mutation introduce new
alleles into a population?
 Mutations: A mutation is a permanent change in the base sequence
of DNA.
They can be spontaneously caused by replication errors or induced
by external elements.
They can be harmful (disease/disorders), neutral (non-coding DNA)
or beneficial.
They create variations of genes and introduce new alleles into
populations.
 How a range of mutagens operate
o Mutagens: A mutagen is an environmental agent that induces
mutations. Introducing a mutagen is known as mutagenesis.
o Electromagnetic radiation sources: Radiation coming from
e.g. visible light, gamma rays, X-rays, etc.
Radiation is the transfer of energy and includes heat and
ionising radiation. Ionising radiation can break chemical bonds
in DNA and create free radical (which break DNA strands), and
comes from UV radiation, X-rays and gamma rays.
E.g. UV radiation from sunlight damages the cell cycle by
connecting adjacent base pairs so they cannot pair with the
complementary base.
o Chemicals: Mutagenic chemicals are usually similar to DNA
bases and get incorporated into DNA, leading to incorrect
nucleotides being paired—mispairing
Can come from: alcohol, cigarette tar, asbestos, pesticides,
cleaning products
o Naturally occurring mutagens: Chance of mutation
increases with frequency and exposure.
 Biological mutagens: This includes microbes (viruses,
bacteria, fungi) such as Hepatitis B and HPV, which
cause mispairing; metabolism end-products; and
transposons—DNA fragments that spontaneously

relocate/multiply/fragment, disrupting DNA functioning
and triggering cancers.
 Non-Biological mutagens: E.g. mercury and cadmium.
 Causes, processes and effects of different types of
mutation
o Point mutations: Involve changes to the
sequence of one base. Occurs during transcription
and changes the amino acid sequence and
possibly the protein.
 Substitution: Replacing one base with
another—effect varies
 Insertion/deletion: Adding or deleting a
base. Causes frameshift mutations—the
entire sequence after the mutated base,
leading to a major change in the amino acid
sequence.
 Inversion: Two bases are swapped
 Silent: Does not alter the amino acid
sequence—no effect (e.g. codons code for
same amino acid—both GUA and and GUG
code for valine)
 Nonsense: Creates a premature stop codon
and ends sequence (causes e.g. cystic
fibrosis)—serious effect
 Missense: Alters one amino acid (causes e.g. sickle cell
anaemia)—effect varies
 Neutral: Missense, results in an amino acid of the same
type as the original—no significant effect.
o Chromosomal mutation: Changes to a series of bases.
 Chromosome structure
 Duplication: Part of the chromosome is copied =
duplicate segments and genes. Effect depends on
size and location.
 Inversion: Segment is removed, flipped and
replaced. (causes e.g. haemophilia)
Base
V
Codon
V
Amino acid
V
Polypeptid
e
V
Protein

 Translocation: Segments of two chromosomes are
exchanged. (causes e.g. down syndrome)
 Deletion: Segment and its genes are lost. (causes
e.g. cat cry syndrome)
 Chromosome number (aneuploidy): An abnormal
number of chromosomes, caused by e.g. chromosomes
not separating in meiosis (non-disjunction)
 Trisomy: An extra chromosome, causes e.g. down
syndrome.
 Deletion: A missing chromosome
 Polyploidy: Genome duplication—extra complete
sets of chromosomes. Fatal to humans and most
animals, but can make plants more robust.
o Mutations can also be:
 Somatic or germline: Occurring in somatic (body) cell or
reproductive (germline) cell.

 Spontaneous or induced: Random as a result of a
natural process, or caused by an environmental agent.
 Harmful, neutral or (rarely) beneficial
 Distinguish between somatic mutations and germ-line
mutations and their effect on an organism
o Somatic: Usually caused by environmental factors or
replication errors, occur in a diploid body cell and cannot be
inherited, therefore only affect individuals.
Most have no effect, but if the mutated cell divides by mitosis,
the mutation is passed onto other cells, amplifying the error.
E.g. if a tumour suppression gene is mutated, this can cause
uncontrolled cell growth -> cluster of mutated cells (tumour) -
> cancer
o Germline: Occur in sexual reproductive cells that give rise to
haploid gametes, and can be passed on to offspring with a
harmful, neutral, or beneficial effect.
When a mutated gamete fuses with another gamete, the
mutation is replicated in every cell of the created zygote as it
divides and grows = huge effect on child.
The inheritance of mutations contribute to the gene pool and
can influence whole populations.
 Assess significance of coding and non-coding DNA in
the process of mutation
o Coding DNA: (exons) Directly codes for proteins (and
therefore genes), and is less than 2% of human DNA.
Therefore mutations here directly affect protein production.

o Non-coding DNA: (introns) Contains regulatory genes that
control when and where different genes are expressed. Also
produces tRNA, mitochondrial RNA and other RNA responsible
for gene and chromosomal repair, structure and regulation.
Mutations here are linked to birth defects and abnormalities,
and predisposition to diseases.
o Junk DNA: Non-coding DNA without a known function (neither
protein-coding or regulatory)
 Investigate causes of genetic variation relating to
fertilisation, meiosis and mutation
 Fertilisation: Can maintain or change gene frequency
depending on the combinations of genes passed onto
the offspring.
 Meiosis: In prophase I, crossing over occurs and
homologous chromosomes exchange genetic material,
leading to four genetically different chromatids. They
may have a combination of DNA from both homologous
chromosomes, meaning they are recombinant and have
unique gene combination -> can increase genetic
variation by creating different allele combinations.
Non-disjunction can also cause chromosomal mutations
and change the gene pool.
 Mutation: Can change gene frequency in a population
by altering, creating or deleting genes (by changing the
proteins produced)
 Evaluate effect of mutation, gene flow and genetic drift
on the gene pool of populations
o Mutation: New genes arrive due to errors in replication,
adding new genes to the pool. Most are not beneficial and are
removed, but neutral/beneficial ones are kept and increase
genetic variation.
o Gene flow: Change to gene pool due to individuals leaving
(emigrating) or entering (immigrating) a population. More
noticeable in small populations, stabilises the gene pool.
o Genetic drift: Change to due chance events (e.g. natural
disaster) that lead to individuals being killed or isolated.
Decreases genetic diversity, more noticeable in small
populations.
o Sexual selection: When certain individuals are more attractive
and breed more. Means that alleles of those with mating
success become higher in frequency.
o Selective pressure: Certain allele/genes increase the chance
of surviving certain environmental pressures. Individuals with

these genes survive to pass them on and they increase in
frequency.
o Other situations:
 Population bottleneck: Genetic drift where natural/man-
made events reduce a population by over 50%.
Decreases genetic variation. When members
repopulate, gene pool no longer resembles original.
 Founder effect: When a small group breaks away from a
population and colonises somewhere else. Has lower
genetic diversity and is more vulnerable. As it increases
in numbers, it no longer resembles the original gene
pool.
2: Biotechnology – How do genetic techniques
affect Earth’s biodiversity?
 Uses and applications of biotechnology (past, present
and future)
o Past: food production (bread, cheese, wine), medicine,
domestication, selective breeding, antibiotics.

Present: DNA manipulation (splicing, amplification,
recombinant DNA technology), DNA analysis/visualisation (gel
electrophoresis, DNA sequencing and profiling), biofuels—
renewable and produces less pollution
Gel electrophoresis: DNA fragments placed on a single track
on the gel, a current is applied along the gel. Magnetic
currents cause the DNA to separate according to size. The gel
is then stained to highlight the fragments.
Future: (see ‘Future directions’)
o Social implications and ethical uses, with animal and
plant examples
 Non-harm, ethical decisions, individual rights and
autonomy, equity and justice, privacy.
 E.g. Dolly the Sheep: Cloned via SCNT. Raised questions
about cloning of humans and poor health of cloned
animals (Dolly only lived half her expected lifespan).
 E.g. Bt cotton: Uses the Bt bacterium toxin gene to
provide immunity to pests, decreases biodiversity,
meaning a whole crop could be wiped out by
environmental change/insects more likely to develop
immunity -> social and economic problems.
o Future directions: More widespread use of cloning and
recombinant DNA technology. E.g. gene therapy
(inserting/replacing/inactivating genes to prevent/treat
disease).
o Potential benefits for society: Gene therapy—treat human
disease, genetically modified food—alleviate hunger, plant
banks/animal cryopreservation—maintain biodiversity and
conservation, plant/algae based resources—biofuels
o Changes to the Earth’s biodiversity due to genetic
techniques
 Short-term: New gene combinations = increased
biodiversity
 Long-term: Selective breeding of certain genes =
decreased biodiversity
3: Genetic technologies – Does artificial
manipulation of DNA have the potential to
change populations forever?
 Uses and advantages of current genetic technologies
that induce genetic change
o Artificial selection (AI and AP): Used to create organisms with
desired characteristics. Makes fertilisation easier, transfers
desired characteristics and allows consistency.

o Whole-organism cloning: Involves putting the nucleus of a
body cell into an enucleated egg cell, then putting that into a
foster/surrogate mother to develop. Allows desired
characteristics to be copied, time efficiency and can be used
in conservation.
o Recombinant DNA technology: Transferring genes between
organisms/species, moving/deleting/modifying genes. Can
increase genetic diversity, produce organisms quickly, and
develop medicine.
 Gene cloning: Involves cutting a desired gene from a
chromosome and a plasmid from a bacterium using a
restriction enzyme. A sector is removed from the
plasmid and replaced by the gene, the plasmid is
reinserted and the bacterium multiplies. Can be used in
medical applications (e.g. insulin)
 Transgenic organisms: Putting genes from other species
into an organism, e.g. Bt cotton. Allows advantageous
traits to be transferred.
 Compare processes and outcomes of reproductive
technologies
Artificial insemination Artificial pollination
Inseminates a female with
male semen from the same
species
Involves dusting pollen w/
desired genes onto stigma of
plant
= offspring with desired
characteristics
= offspring with desired
characteristics
Reduces genetic variation Can create hybrids = short-
term genetic variation. Long
term = decreased variation.
 Assess the effectiveness of cloning
Whole organism cloning Gene cloning
Produces organism with
identical genotype to
original organism
Produces copies of a single
gene
Uses SCNT Uses recombinant DNA tech
To produce clones To transfer genes between
organisms/species
E.g. Dolly the Sheep E.g. human insulin cloning
 Techniques and applications used in recombinant DNA
technology

o Transgenic organisms for agricultural and medical
applications
 Agricultural: Bt cotton—created through recombinant
DNA technology, by inserting toxin gene from bacterium
Bt into cotton plants = resistance to pests.
Decreases the need for pesticides, improving safety, soil
quality and yield, but also decreases biodiversity = risk
of crops wiped out in environmental change, risk of
pests developing resistance
 Medical: Transgenic mice—receive human genes so
they can be used to replicate human conditions and
serve as models to test drugs/medicines, insulin cloning
—done through recombinant DNA technology.
 Benefits of genetic technologies in agricultural, medical
and industrial applications
o Agricultural: DNA marker test -> breed naturally hornless
beef cattle and prevent injury, Bt cotton -> less pesticide use
and increased yield/profit, AI/AP/cloning -> desired
characteristics passed on
o Medical: Transgenic organisms (transgenic mice as disease
models, cloning of insulin) -> larger volumes at lower cost,
vaccines (made by cloning antigens of weak/dead pathogenic
cells), hormones/proteins made through genetic modification,
gene therapy
o Industrial: Biofuel (production improved by altering bacteria
and fermentation), cleaning up pollution (genetically modified
bacteria to clean up crude oil), producing renewable
resources/biodegradable materials
 Effect of biotechnology in agriculture on biodiversity:
Reproductive and recombinant DNA technologies create more
genetically similar offspring, decreasing genetic variation and the
gene pool within the population. Widespread use of these
technologies = decreased biodiversity = higher risk of extinction
due to environmental change (disease, pests, etc.)
 Assess the influence of social, economic and cultural
context on biotechnologies
o Cultural context: values and beliefs -> opinions and uses of
biotech
o Social context: needs of a society determine what biotech is
used
o Economic context: GMOs can be expensive -> possible
unequal distribution of wealth and opportunity