hsc biology - mod 6 genetic change

mutation

a change in the nucleotide base sequence in the DNA of a genome

genetic variation

the frequency and variety of alleles in a population

genetic disorder

a condition caused by an abnormality (mutation) in the DNA sequence

proto-oncogenes

genes responsible for cell growth and division

oncogenes

a mutated form of the cells responsible for cell growth and division. causes uncontrolled cell division and cancer.

tumour suppressor genes

genes that code for proteins that slow cell division and growth. a mutation results in a TUMOUR! and uncontrolled growth

mutagen

a mutation causing agent. can be naturally occurring or not. involves naturally occurring biological + non-biological, chemical, radiation. random and quirky

chemical mutagen

ingested chemicals and heavy metals that break the sugarphosphate backbone of DNA and inhibit DNA repairing enzymes. they are INSERTED INTO NUCLEOTIDES DURING REPLICATION.

• arsenic, mercury

• alcohol, tobacco

radiation mutagen

ionising radiation that breaks or changes the structure of DNA bases.

• uv, gamma rays.

deaminating agent

changes the molecular structure of nucleotide bases —> substitution

ionising radiation

radiation that has the ability to move electrons from their valence fields.

uv radiation

causes chemical damage to the DNA by breaking the hydrogen or sugar phosphate backbone of DNA so it no longer pairs with the corresponding base

• thymine dimers

gamma rays

emit radiation that pass through cells and release free radicals

free radicals

has valence electrons meaning high reactivity

naturally occurring biological mutagen

a microbe that inserts its own DNA into a genome

• a virus, bacteria, fungi

naturally occurring non-biological mutagen

heavy metals. sausage burnt

• nitrates and amines combine to form CARCINOGENIC NITROSAMINES

transposon

DNA that randomly fragments and relocates into chromosomal DNA to disrupt function

somatic mutations

mutations that occur in the body cells excluding germline cells. result of DNA replication error

germline mutations

mutations that occur in gametic cells before specialised cell division in the embryo. affects all body cells. can be inherited by offspring.

chromosome mutations

whole fragments of chromosomes are affected by a mutation. can be a change in the arrangement or number of chromosomes. effects are usually more severe, causing genetic disorders or lethality

translocation

segments of a chromosome are relocated to another chromosome

transversion

segments of DNA in a chromosome fragment are placed in reverse order and read backwards.

duplication

parts of a chromosome are copied and can be read multiple times

deletion

• in a chromosome: whole segment of chromosome is removed

• in a point mutation: one nucleotide base is removed

insertion

• in chromosome: extra segment of a chromosome is added into a chromosome

• in point mutation: a nucleotide base is added to the DNA strand

point mutation

mutation involving only 1 nucleotide

• insertion, deletion or substitution

nonsense mutation

a point mutation in the form of a substitution leads to the coding of a stop codon

• premature termination of a protein

missense mutation

a point mutation in the form of a substitution leads to the coding of the incorrect amino acid in a polypeptide chain

silent mutation

a point mutation in the form of a substitution leads to nothing

gene flow

the addition or subtraction of alleles from a population caused by individuals leaving or joining a population.

• change in variation + frequency = ____

• change in frequency over generations = evolution

• new variations lead to Darwins Theory

genetic drift

when the frequency in alleles in a population shifts as a result of a random event.

• doesn’t involve selective advantages

• floods, fires etc.

bottleneck effect

when a population’s alleles are reduced as a result of natural disaster. the individuals are the only ones that survived

founder effect

when a population’s allele frequency changes as a result of individuals being isolated from the original population, forming their own gene pool

meiosis

process of gamete formation. methods that create genetic variation:

• crossing over, random segregation, independent assortment all randomise the genetic combinations in gametes

• fertilisation randomly selects regg and sperm making it more random

introns

non-coding dna

• mutations affect regulatory proteins

exons

coding dna

• mutations may affect phenotype

biotechnology

the use of biological material to fulfil human needs. used to increase yield + quality however reduces genetic diversity

past: fermentation, selective breeding
present: transgenic organisms
future: CRISPR

plant hybridisation

artificial pollination of plants for improved yield, nutrience and environmental resistance.

biodiversity

the variety of all living things

gene technology

manipulation of DNA material

• genetic engineering, gene cloning, genetic screening, gene therapy, recombinant DNA technology

transgenic organism

organism that has had a gene from another species cut, copied and pasted into their genome to give them a desired feature.

• e.g. salmon antifreeze gene in strawberries to grow in cold climates.

• can be used in medicine. e.g. bacteria with human insulin gene.

role of fertilisation

to shuffle DNA from the mother and father. result is a recombination of the parent DNA.

artificial pollination

the intentional transfer of pollen from one flower to another to facilitate fertilization by humans.

• results in new breeds and varieties of plants, higher yield + quality

• decreases genetic diversity

cloning

the process of creating a genetically identical copy of an organism or cell

• more organisms with desired traits

• reduced genetic diversity

Bt cotton

GMO made by inserting the gene from a Bacillus thurigiesis that kills a specific caterpillar that targets cotton plants.

• only affects pests, doesnt affect adjacent beneficial insects or affect soil + water

past biotechnologies

• fermentation

• antibiotic production: alexander fleming discovered fungus penicilin

• selective breeding

• higher yield/better quality

• reduced genetic variation

present biotechnologies

accelerated greatly after the discover of DNA manipulation. there has been a shift from selective breeding to genetic manipulation

• pcr, dna profiling, dna sequencing used in research of inheritance

• genetic technologies

genetic technologies

manipulation of DNA to make specific proteins and regulation of cell processes used for medicine.

• genetic engineering

• gene cloning

• genetic screening

• gene therapy

• recombinant DNA technology

genetic engineering

A technique that involves directly manipulating an organism's DNA to alter its characteristics, often used to produce desired traits or improve health outcomes.

gene cloning

replicating a gene multiple times through pcr.

genetic screening

The process of testing individuals to identify genetic disorders or predispositions to certain diseases by analyzing their DNA.

gene therapy

modifying a person’s DNA to fight against disease

recombinant DNA technology

combining DNA from multiple organisms to create new DNA to fight environmental adversity or disease

• e.g. modified bacteria to produce human insulin

• restriction enzymes cut DNa from human, inserted into bacteria. bacteria produces desired

genetically modified organisms

organisms with a newly constructed genome. also known as a transgenic species

industrial biotechnology

• enzyme engineering

• bio-nanotechnology

• synthetic biology

• biochemical

• bio-material

aneuploidy

loss or gain of an entire chromosome: monosomy and trisomy

uv radiation

mutagen radiation from sunlight or __ lamps. photons are absorbed by DNA bases, especially thymine. forms thymine dimers

thymine dimers

covalent bond between adjacent thymine on the same strand. they distort the DNA helix and interfere with replication and transcription. result of UV radiation

ionising radiation

mutagen caused by x rays and gamma rays. penetrates tissues and interacts with molecules to produce free radicals which break DNA strands, modify bases by oxidation and crosslink DNA with proteins. DNA breaks can be misrepaired, resulting in mutations like deletions, insertions or translocations causing cancer.

somatic cell nuclear transfer

the process by which a whole organism is cloned.

• egg cell is enucleated then the nucleus of a somatic cell is transferred into the enucleated egg and implanted intot he womb of a parent organism

gene cloning

the process of replicating human genes by incorporating it into a plasmid, inserting the plasmid into a vector which replicates creating many copies of a gene.