Mutations, Alleles, and Mutagens

Mutation & Alleles

• Mutation results in the genetic variation between species and individuals
• Mutations are changes in DNA, not faults or disease
• Types of mutations include neutral (no effect), beneficial (increases survival), and harmful (decreases survival)
• Mutagens are physical or chemical agents that alter an organism's DNA
• Mutagens can be human-made, natural, carcinogenic (cancer-causing), or teratogenic (cause birth defects)

Mutagen Operation

• Mutagens alter DNA, encompassing physical, chemical, and biological agents
• Physical mutagens include radiation, X-rays, and UV radiation
• Chemical mutagens include cigarette smoke, nitrates, and benzoyl peroxide
• Biological mutagens include infectious agents like Human Papillomavirus(HPV) and Helicobacter pylori

Electromagnetic Radiation

• EM radiation is carried by waves, where high frequency EM waves are known as ionizing radiation
• Ionizing radiation causes mutations and forms ions by removing electrons from atoms/molecules
• EM radiation can cause mutation via dimerizing (direct) or oxidative (indirect) mechanisms

Dimerizing & Oxidative Mutation

• Dimerizing mutations directly cause cross-links between adjacent nucleotide bases, which prevents complementary pairing
• Oxidative mutations, caused by free radicals produced by ionizing radiation, break DNA bonds, preventing oxidized bases from pairing during DNA replication
• Antioxidants aid in the decomposition of free radicals
• Constant exposure to lower frequencies like radio waves or TV can induce mutation, but requires much higher levels than ionizing radiation

Chemical Mutagens

• Chemical mutagens cause changes in DNA that alter protein production, function, and cell function
• Mutagenic chemicals structurally resemble nitrogenous bases, leading to their mistaken incorporation into the DNA sequence during replication
• Examples of chemical mutagens include alcohol and tobacco
• Chemicals like 5-BRU can be incorporated into DNA transcription as it mimics thymine

Naturally Occurring Mutagens

• Mutation can be caused by naturally occurring mutagens
• Biological mutagens include fungi, bacteria, and viruses that insert their DNA sequence into bases, altering gene function
• HPV can induce cervical cancer, acting as a carcinogen
• Non-Biological mutagens include non-living substances emitting radiation, like uranium in rocks and soil
• Spontaneous mutations stem from errors in DNA replication, like the deamination of cytosine to uracil

Types of Mutation

• Point mutations are induced by external stimuli, affecting a single nucleotide
• Chromosomal mutations are spontaneous, affecting multiple genes

Key differences in mutations

• Point mutations involve a single nucleotide change, while chromosomal mutations involve multiple genes
• Point mutations can be somatic, whereas chromosomal mutations can be germ-line and heritable
• Point mutations are alterations of a single nucleotide

Substitution & Inversion Mutations

• In substitution mutations, one nucleotide base is replaced by another
• Inversion mutations involve nucleotide pairs switching positions

Effects of mutations

• Nonsense mutations change amino acids to STOP codons
• Missense mutations change amino acids in the polypeptide chain
• Silent mutations have no effect on the amino acid
• Point mutations can have nonsense, missense, or silent effects

Frameshift Mutations & their effects

• Frameshift mutations stem from insertions or deletions, shifting the polypeptide chain
• Insertions add a base into the polypeptide sequence
• Deletions remove a base from the polypeptide sequence
• Frameshift mutations are insertions or deletions, shifting the polypeptide chain altering every amino acid
• Point mutations lead to changes in amino acids, stop codons, or no change at all

Chromosomal Mutations

• Chromosomal mutations affect large chromosome sections, typically multiple genes, or they alter the number of chromosomes in a cell, occurring in meiosis, caused by mutagens
• Duplication involves copying chromosome sections multiple times, which results in increased size
• Inversion occurs when a chromosome section breaks, rotates 180°, and re-attaches
• Deletion involves the loss of a chromosome section
• Insertion involves a chromosome section detaching and reattaching to another chromosome
• Translocation occurs when a whole chromosome or chromatid attaches to or exchanges with a different chromosome

Chromosomal Abnormalities

• Chromosomal abnormalities include aneuploidy (involving a whole chromosome) or polyploidy (involving a number of chromosomes) and are detectable via karyotyping
• Aneuploidy involves abnormal numbers of a particular chromosome, like Down syndrome, Turner's syndrome or Klinefelter syndrome
• Polyploidy is a condition where cells and organisms have more than two full chromosome sets, and diploid gametes don't survive

Somatic Cell & Germ-Line Mutations

• Somatic mutations occur in non-reproductive cells due to replication errors during mitosis
• Somatic mutations pass to daughter cells, causing localized phenotypic changes in tissue
• Somatic mutations can change proto-oncogenes into oncogenes, which results in a neoplasm
• Damage to tumour-suppressor genes leads to uncontrolled cell division
• Somatic mutations increase susceptibility to neoplasm as we age
• Damaged proto-oncogenes or tumour-suppressor genes can be inherited, leading to a family’s predisposition to cancers
• Mosaicism is a condition where somatic mutagens survive to create daughter cells, where the individual holds 2 genomes

Germ-Line Mutations

• Germ-line mutations occur in reproductive cells (gametes) during meiosis
• Germ-line mutations are inherited by offspring and can cause cancer, such as retinoblastoma
• Cancer development needs alleles from both parents to mutate
• Huntington's Disease needs only one allele to mutate since it is autosomal dominant

Non-Disjunction

• Non-disjunction occurs when chromosomes do not separate properly, either in Meiosis I or Meiosis II
• Trisomy 21 has 3 Chromosome 21s
• Transposable elements are short DNA sequences that move around the genome, causing errors in replication, interfering with gene function, and causing chromosome duplication

Coding & Non-coding Mutations

• Exons are coding regions producing polypeptide chains comprise 2% of DNA
• Other 98% are made up of introns (regulate polypeptide production and tRNA and rRNA activity), regulatory elements (start, enhance or inhibit DNA transcription), RNA molecules, and transposons(sequences that move throughout genome)
• Telomeres are repetitive DNA at the end of chromosomes that provide protection from deterioration during replication
• Non-coding mutations prevents frameshift mutations affecting the whole chromosome
• STRs/Short Tandem Repeats highlight genetic similarity between individuals

Intron Mutations & Effects of Genes

• Introns' transcription requires 3 spliceosome binding sites (5’ Junction, 3’ Junction and Branch point)
• Intron mutation can cause range of genetic disoders
• Mutations to promoter and terminator regions genes affect transcription and produced excess or shortage of gene product
• Mutation to telomeres or centromeres may inhibit the function of mitosis/meiosis
• Mutations in non-coding regions can lead to aggressive bone caner and susceptibility to ewing sarcoma

Junk DNA & Investigating Effects

• Mutations of areas of 'junk DNA' will have negligible and no effect on organism
• Mutations of exons will alter amino acids produced and proteins of a polypeptide
• Mutations to exon regions also affect organisms phenotype and cell function/ or have no effect at all
• Sickle cell aneamia caused by the mutation to codes that codes haemogloblin
• Sperm that fertilises egg is random

Meiosis, Variability & Mutation

• Meiosis recombs of genetic material through crossing over
• Crossing over: segment of dna from one chromosome is exchanged with anther. This increased variabillity with gametes
• Segregation of Chromomosomes: 2 alleles separate and offspring may inherit blonde or brom hair
• Independent assortment : seperstion od alleles on 1 gene is indpendent tp thay of another
• Mutations that increase in trait that aide survival will overcome population

Population genetics, gene pool, polygenic, natural selection and genetic drift

• Population Genetics: is the study of populations an dtheir changes due to environmental pressures
• Gene pool: Genes in population
• polygenic: number of genes that prevent for height
• Natural selection: Due to appeal for sexual reproduction and survical
• Genetic drift: Causes change frequency

Effects of mutation, founder effect and bottleneck

• Founder effect; small group branches off from population and colonises new area
• Bottleneck effect: Catastrophic event occurs

Factor, Gene Flow, Biotech

• Selective pressures that make individuals well suited with genes increases
• Mating is non random
• Leads to formation of new Gene Flow: leads to individuals integrating entering emigrating
• biotechnology is te use of living/ biological process/ products

Factors that define biodiversity Biotechnology and the Past

• Total variety and variability: Variety
• Biodiversity in: Agricultural, production medicine

Bio Technology today, future and the analyses

• Biotechnology uses genetic engineering to meet modern and new DNA
• Reproduction: IVF forms in a lab
• AI: Spreads 1 Genome
• AP: Produces desiralble amount that produce yield
• cloning: Same genetical makeup

Future Bio, gene therpay, transgenic

• CATTLE assisted with marker can prevent de-herning
• Gene slicing treats disease
• Transgenic: transfrom of herbiable
• transgenic salmon grow faster and oysteris are resistant

GMO and Ethics

• Bt catton ethics
• Cross contaminations of bacteria which animals can ingest
• reduces Bio diverity and becomes dominant crop

Spider silk, Knock out Mice and privacy

• Spider silk = range of properties
• Knock out mice : improves cancer rates
• Privaxy increased

Transgenic views, Medical Biotech and views

• Governming body, philosphy religious views and animal welfare
• Medical = Nanomedicine using polymers
• Bioremidiation: bacteria
• Industrial enzymes to cut

Bio benefits society

• Make crops nutritous
• Prevent through mutation
• Develop mosquito to cut

Genetric Techniques and biodiversity

• GM crops selective that deacrese gene pool
• Bio increase through bio and bio fuels

Genetic Change

• Articificial is to change