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Cell Reproduction

Cell Reproduction. Chapter 8. Table of Contents. Section 1 Chromosomes Section 2 Cell Division Section 3 Meiosis. Section 1: Chromosomes Objectives. Describe the structure of a chromosome.

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Cell Reproduction

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  1. Cell Reproduction Chapter 8

  2. Table of Contents Section 1 Chromosomes Section 2 Cell Division Section 3 Meiosis

  3. Section 1: ChromosomesObjectives • Describe the structure of a chromosome. • Identify the differences in structure between prokaryotic chromosomes and eukaryotic chromosomes. • Compare the numbers of chromosomes in different species. • Explain the differences between sex chromosomes and autosomes. • Distinguish between diploid and haploid cells.

  4. DNA • Recall: • DNA stands for Deoxyribonucleic acid. • DNA stores genetic information, synthesizes proteins, and controls cellular activities. • DNA is a polymer. Its monomer is a nucleotide.

  5. DNA • DNA is a long thin molecule. • It is organized into long structures called chromosomes. • DNA is packed and coiled in a complicated but organized manner.

  6. Chromosome structure • Chromosomes are rod-shaped structures made of DNA and protein. • In eukaryotes, DNA wraps around proteins called histones to help maintain the compact structure of chromosomes and aid in the tight packaging of DNA. • Nonhistone proteins are involved in controlling specific regions of the DNA.

  7. Chromosome Structure

  8. Chromosome Structure • Between cell divisions, DNA isn’t so tightly coiled into chromosomes. • Regions of DNA uncoil in between cell divisions so they can be read. • The less tightly coiled DNA-protein complex is called chromatin.

  9. Parts of a chromosome

  10. Parts of a chromosome • ..\..\Abir School CD copy\Biology\Teacher's one stop\Powernotes presentations\ch_ppts\Ch08\60116.html

  11. Chromosome Structure • Chromosomes in prokaryotes are simpler in structure than chromosomes in eukaryotes. • DNA of most prokaryotes consists of only one chromosome, which is attached to the inside of the cell membrane. • Prokaryotic chromosomes consist of a circular DNA molecule.

  12. Chromosome Numbers • Each species has a characteristic number of chromosomes in each cell.

  13. Chromosome Numbers Chromosome numbers of various organisms

  14. Chromosome Numbers • Sex Chromosomes and Autosomes • Sex chromosomes are chromosomes that determine the sex of an organism. • All of the other chromosomes in an organism are autosomes.

  15. Chromosome Numbers • Every cell of an organism produced by sexual reproduction has two copies of each autosome. • The organism receives one copy of each autosome from each parent. • The two copies of each autosome are called homologous chromosomes or homologues. • Homologous chromosomes are the same size and shape and carry genes for the same traits.

  16. Sex Chromosomes and Autosomes • ..\..\Abir School CD copy\Biology\Teacher's one stop\Powernotes presentations\ch_ppts\Ch08\60121.html

  17. Karyotype • Karyotypes are used to examine an individual’s chromosomes. • Karyotypes are made from a sample of person’s Blood. • WBCs are treated chemically to stimulate then arrest mitosis in Metaphase. • The chromosomes are photographed, cut out, and arranged by size and shape into pairs.

  18. Karyotype

  19. Chromosome Numbers • Diploid and Haploid Cells • Cells having two sets of chromosomes are diploid (2n). • Haploid cells (1n) have only one set of chromosomes.

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