Inheritance,Variation and Evolution

• Chromosomes are really long molecules of DNA
• DNA is a polymer of nucleotides and forms a double helix shape
• A gene is a code for a specific protein
• Every organism has a genome which is the entire set of genetic material in an organism
• Understanding the genome is important for inherited disease cause and treatments and population migrations
• DNA is made up of nucleotides that consist of a base, sugar and phosphate
• A and T and C and G pairings are called complimentary base pairings
• Non-coding parts of DNA switch genes on and off
• mRNA carries genetic code to the ribosomes to be translated into a protein
• mRNA is made by copying DNA and acts as a messenger between DNA and ribosomes
• Proteins have many functions including enzymes, hormones and structural proteins such as collogen
• Mutations are random changes to the genetic code
• Mutation chances are increased when exposed to certain types of radiation or substances
• Most mutations have little effect on the gene
• If there is a mutation within non-coding parts of genes, it can alter how genes are expressed
• There are 3 different kinds of mutations: Insertions, Deletions and Substitutions
• Insertion is where a new base has been inserted into the genetic code which changes the way the code is read
• Bases code in threes
• Deletion is where one or more bases are removed from the genetic code
• Substitution is where a base has been swapped out for another
• Induced mutations are caused by external factors such as radiation or chemicals
• Spontaneous mutations happen when errors occur during DNA replication
• Sexual Reproduction produces genetically different offspring
• Each gamete in humans contains 23 chromosomes
• Asexual Reproduction produces genetically identical cells
• In Asexual Reproduction there is only 1 parent
• Asexual Reproduction is the division of cells by mitosis
• Gametes are produced by meiosis
• The cell produced by a gamete fusion replicates itself
• Sexual Reproduction increases variation in a population
• Selective Breeding can be used to speed up natural selection
• Asexual Reproduction only needs one parent therefore uses less energy, is faster and produces more offspring, which are all genetically identical
• Some organisms can reproduce both sexually and asexually
• Malaria parasites reproduce sexually in the mosquito and asexually inside the human host
• Strawberry plants reproduce asexually through runners
• Males have XY chromosomes and females have XX chromosomes
• All eggs have one X chromosome
• Genetic Diagrams show possible gamete and allele combinations
• Some characteristics are controlled by a single gene
• All genes exist in different versions called alleles