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Fun fact: Humans are made up of about 7 octiliion atoms (that's 7,000,000,000,000,000,000,000,000,000 atoms)

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Catalyst Try and answer these questions without your notes: 1. How many chromosomes does a sperm cell have? 2. Whats the difference between homologous chromosomes and sister chromatids? 3. What are the products of mitosis? 4. What process in meiosis allows for gametes to be genetically unique?

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Catalyst 1. How many chromosomes does a sperm cell have?

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Catalyst 1. How many chromosomes does a sperm cell have? Answer: 23 Remember: Sperm cells are gametes, and are thus haploid. Haploid cells have only 1 copy of each chromosome.

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Catalyst 2. Whats the difference between homologous chromosomes and sister chromatids?

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Catalyst Remember: Sister chromatids are two parts of the same chromosome. Homologous chromosomes are two chromosomes (1 from mom, 1 from dad) that are the same length, have the same centromere position and same traits. Sister chromatidsHomologous chromosomes

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Catalyst 3. What are the products of mitosis?

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Catalyst Answer: 2 genetically identical diploid cells Remember: Unlike meiosis, the products of mitosis are genetically identical to the parent cell. Mitosis occurs in somatic, or body cells.

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Catalyst 4. What process in meiosis allows for gametes to be genetically unique?

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Catalyst Answer: Crossing Over Remember: Crossing over occurs during Prophase 1 of meiosis, and creates genetic variation because sister chromatids are no longer identical.

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Lets Review

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Gregor Mendel: father of genetics Austrian Monk 1822-1884 Worked with pea plants

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Mendel Mendel worked with pea plants. Why?

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Mendel Mendel worked with pea plants because they reproduce quickly, making it easier to study. They take about 2-3 months to mature.

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Mendel Mendel worked with pure-breds that self-pollinated for many generations to become genetically uniform.

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Mendel He observed 7 either-or traits to limit confusion when looking at results.

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Vocabulary Locus: Specific location of a gene on a chromosome Traits: distinguishing characteristics that are inherited (e.g. eye color, height, hair color) Alleles: Alternative forms of a gene (e.g. brown hair, black hair, blue eyes, grey eyes, tall, short)

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Law of Segregation Organisms inherit 2 copies of each gene, one from each parent Organisms donate only one copy of each gene tp their gametes, so the copies separate during gamete formation (meiosis)

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