MODULE 6 Genetics, Evolution and Ecosystems TOPIC 1 ○ Repressor breaks away from operator Types of Gene Mutations ○ RNA polymerase can bind to promoter • Homeobox genes • Types of gene mutations ○ Regulate body part development ○ Substitution ○ Grouped in hox clusters – Nucleotide replaced ○ Precisely conserved due to importance ○ Insertion ○ Expressed anterior posterior – Causes frameshift ○ Determine where limbs branch off ○ Deletion • Apoptosis = programmed cell death in multicellular – Causes frameshift organisms • Consequences of gene mutations ○ Enzymes break down cytoskeleton and DNA ○ Neutral ○ Remaining parts phagocytosed ○ Harmful ○ Controlled by complex cell signals ○ Beneficial ○ Causes limbs to separate • Point mutation • Transcription factors ○ Only one base is affected ○ Proteins/ noncoding RNA ○ Silent mutation ○ Attach/detach from DNA – No change in amino acid sequence • Introns = unexpressed DNA (don’t code for genes) ○ Missense mutation • • Exons = expressed DNA Monohybrid = genetic diagram with just 1 gene – 1 amino acid is changed in sequence • Dihybrid = genetic diagram with 2 genes ○ Excess amino acids deaminated in liver ○ Nonsense mutation • Linkage = when 2 or more gene loci are on the same ○ Converted into ammonia then urea – Triplet becomes stop codon chromosome ○ Urea excreted in urine by kidney • Gene expression regulation ○ Autosomal linkage = when the two genes are on ○ Some genes constantly expressed TOPIC 2 non-sex chromosomes ○ Others expressed only when needed Patterns of Inheritence ○ Sex linkage = when the two genes are on sex – E.g. lac operon chromosomes – Presence of lactose and absence of glucose • Genotype = genetic makeup of an individual – More likely to be on X chromosome triggers synthesis of enzymes that break down • Phenotype = observd/ expressed characteristics of an • Epistasis = interaction of non-linked genes where one lactose individual masks the other • Lac operon = section of E.coli DNA ○ Result of genotype and environment • Recessive epistasis • ○ Structural part codes for enzyme Genetic factors contributing to phenotypic variation ○ Homozygous recessive alleles mask expression of ○ Operon part switches structural genes on/off ○ Genetic random mutations another allele at different locus ○ Promoter region = region where RNA polymerase – Mutagenic agents ○ E.g. flower colour in Salvia binds to begin transcription – Chromosomal mutations • Codominance = when two different alleles at the same • Lac operon in absence of lactose – Aneuploidy/ polyploidy locus are both expressed – Variation from sexual reproduction ○ Regulator gene expressed ○ E.g. human blood group type • Environmental factors contributing to phenotypic ○ Repressor protein synthesised and binds operator • Chi-squared test region variation ○ Determine whether expected vs observed allele Environment alone (e.g. limb loss in accident) ○ RNA polymerase cannot bind promoter region ○ frequency differences are due to chance • Lac operon in presence of lactose ○ Environment affecting gene expression ○ Use when... ○ Epigenetics ○ Lactose changes shape of repressor – Data variation is discrete • Genetic diagrams – Large sample size Super concise & exam board specific videos, notes & summaries by A* students at snaprevise.co.uk MODULE 6 Genetics, Evolution and Ecosystems This summary is intentionally blurred, to view more sign up for free now! Super concise & exam board specific videos, notes & summaries by A* students at snaprevise.co.uk MODULE 6 Genetics, Evolution and Ecosystems This summary is intentionally blurred, to view more sign up for free now! Super concise & exam board specific videos, notes & summaries by A* students at snaprevise.co.uk MODULE 6 Genetics, Evolution and Ecosystems This summary is intentionally blurred, to view more sign up for free now! Super concise & exam board specific videos, notes & summaries by A* students at snaprevise.co.uk MODULE 6 Genetics, Evolution and Ecosystems This summary is intentionally blurred, to view more sign up for free now! Super concise & exam board specific videos, notes & summaries by A* students at snaprevise.co.uk.