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Chromosomes

Chromosomes

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Chromosomes

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  1. Chromosomes • What is a Chromosome • Terminology • Chromosomal Mutations • Differences among species • Karyotypes

  2. What is a chromosome? • Chromosome- coils of DNA and proteins • Chromatid- two exact copies of DNA that make up a chromosome • Centromere- where the two chromatids attach Chromosome

  3. Terminology • Gene- segment of DNA that codes for a protein or RNA molecule • Units of information

  4. Terminology • Homologous chromosomes- are chromosomes that are similar in shape, size and genetic content

  5. Terminology • Somatic cell- any cell other than a sperm or egg cell • Cheek, blood, brain, bone, liver, kidney • 46 chromosomes in human somatic cells • 23 pairs • One set comes from the mother, the other from the father • A diploid (2n) cell contains two sets of chromosomes, like the somatic cell

  6. Terminology • Gamete- sperm or egg cell • Carries one set of chromosome (has 23 total chromosomes) • A haploid (n) cell contains only one set of chromosomes, like the gamete cell

  7. Terminology • Fertilization- fusion of two gametes (fusion of sperm and egg) • Zygote- fertilized egg cell • The first cell of a new individual

  8. Terminology Haploid (n) Diploid (2n) n = 23 Sperm 23 chromosomes n Egg + 23 chromosomes + n Total 46 chromosomes 2n (diploid)

  9. Differences among species • Each organism has a characteristic number of chromosomes • The number is constant with the species • Potatoes, plums, and chimpanzees all have 48 chromosomes

  10. Karyotypes • A karyotype is a picture of an organisms chromosomes • It allows us to study the difference of shape, structure and size of each chromosome

  11. Karyotypes • Humans have 23 pairs of chromosomes • Sex chromosomes- the last pair (#23) on a karyotype that determine the sex of an individual • Females (XX) • Males (Xy) • Autosomes- are all other chromosomes

  12. Karyotypes • During mitosis, a picture is taken • The chromosomes are sorted into identical pairs and arranged from biggest to smallest • The 2 sex chromosomes are put at the end (pair 23)