what determines who we are?

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What determines who we are?. Genes and Chromosomes. Evolution. Evolution is the process by which species change over time. This is done by natural selection: random changes to an animal are passed on if those changes help the animal survive and reproduce. - PowerPoint PPT Presentation


  • What determines who we are?Genes andChromosomes

  • EvolutionEvolution is the process by which species change over time.This is done by natural selection: random changes to an animal are passed on if those changes help the animal survive and reproduce.These random changes are called mutations. How do they happen?

  • MutationsMutations are random changes to the genetic information of a plant or an animal and can cause the animal to grow in a new and different way.Most mutations are neutral they do not affect an animals fitness positively or negatively.Some mutations are negative such as deformed limbs or malfunctioning organs.Some mutations are positive such as larger brains, webbed feet, or better camouflage.

  • GenesGenes hold your personal informationThey control hereditary traits like eye colour and body functionGenes are segments of DNADNA makes up your chromosomesEach human cell has 23 pairs of chromosomes

  • ChromosomesThere are 22 autosome pairs and one pair of sex chromosomes Sex chromosomes control genderFemales have 2 X chromosomes and males have an X and a Y chromosomeAutosomes determine other traits

  • So what does this have to do with mutation?Mutation happens at the genetic levelThis happens when the information in the genes gets mixed upWe know certain syndromes come from mutations in specific chromosomes: -for example Downs Syndrome comes from having an extra chromosome 21One possible mutation:

  • Recap (1)Cells contain chromosomesEach chromosome is made up of DNAA segment of DNA which controls a trait or body function is called a geneWhen the information in genes is mixed up it is called mutationMutations may or may not change an individual for better or for worse

  • Recap (2)When the mutation helps, the individual is more likely to reproduce and pass on the mutation to future generations.When the mutation is harmful, the individual is less likely to reproduce.This process is called evolution by natural selection and allows species to change over long periods of time.

  • Dominant vs. Recessive GenesWe get one set of 23 chromosomes from each parentWhen the gene from one set overrules the gene from the other set, that gene is called dominant.The other gene is called recessive.The gene for brown eyes is dominant.

  • Bibliography of imageshttp://www.oncolink.org/library/images/id818-1.gifhttp://ghr.nlm.nih.gov/handbook/illustrations/chromosomes.jpghttp://www.biology-online.org/images/gene_inversion.gifhttp://www.ashg.org/images/dominant.jpghttp://www.detectingdesign.com/images/DefiningEvolution/defini8.jpghttp://evolution.berkeley.edu/evosite/evo101/images/drosophila_experiment.gif