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What determines who we are?

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.

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What determines who we are?

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  1. What determines who we are? Genesand Chromosomes

  2. 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. • These random changes are called mutations. How do they happen?

  3. Mutations • Mutations 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 animal’s 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.

  4. Genes • Genes hold yourpersonal information • They control hereditarytraits like eye colourand body function • Genes are segmentsof DNA • DNA makes up yourchromosomes • Each human cell has23 pairs of chromosomes

  5. Chromosomes • There are 22autosome pairsand one pair ofsex chromosomes • Sex chromosomescontrol gender • Females have 2 X chromosomes and males have an X and a Y chromosome • Autosomes determine other traits

  6. So what does this have to do with mutation? • Mutation happens at the genetic level • This happens when the information in the genes gets mixed up • We know certain syndromes come from mutations in specific chromosomes:-for example Down’s Syndrome comes from having an extra chromosome 21 • One possible mutation:

  7. Recap (1) • Cells contain chromosomes • Each chromosome is made up of DNA • A segment of DNA which controls a trait or body function is called a gene • When the information in genes is mixed up it is called mutation • Mutations may or may not change an individual for better or for worse

  8. 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.

  9. Dominant vs. Recessive Genes • We get one set of 23 chromosomes from each parent • When the genefrom 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.

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

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