genetic change Flashcards
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.
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.
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.
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.
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.
EXAMPLE- 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).
EXAMPLE - 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).
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)
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.)
o Artificial selection (AI and AP):
Used to create organisms with desired characteristics. Makes fertilisation easier, transfers desired characteristics and allows consistency.
effectiveness of cloning
Whole organism cloning Produces organism with identical genotype to original organism Uses SCNT To produce clones eg. Dolly the Sheep
Gene cloning To transfer genes between organisms/species Produces copies of a single gene E.g. human insulin cloning Uses recombinant DNA tech
Mutagens:
A mutagen is an environmental agent that induces mutations. Introducing a mutagen is known as mutagenesis.
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.
