Cell Reproduction

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Cell Reproduction

• Chapter 8

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8-1 Chromosomes
Cell Reproduction
8-2 Cell Division
8-3 Meiosis
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DNA Chromosomes
Centromere

• DNA
• Nucleotides
• Genes
• Forms In Eukaryotes
• Chromosome
• Coiled DNA
• Histone proteins
• Nonhistone proteins
• Centromere
• Chromatin
• Loose storage
• Prokaryotes
• Single circular molecule

Chromatid
Copy Chromatid
Chromosome
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Chromosome Structure Numbers
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Types Organization of Chromosomes

• Sex Chromosomes
• 2 chromosomes
• Determines gender
• XX female
• XY male
• Carries some genes
• Autosomes
• 44 chromosomes
• All other chromosomes
• Homologous Chromosomes
• Pairs carrying genes for same trait
• Karyotype
• 22 pairs homologous autosomes
• 2 sex chromosomes

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Cells Chromosomes

• Diploid (2N)
• Both chromosomes in homologous pair
• All cells except reproductive cells
• Human
• 46 chrom. 22 autosome pairs2 sex chrom
• Haploid (1N)
• One set of chromosomes from pair
• Reproductive Cells sperm egg gametes
• Sperm Egg zygote (2N)
• Human
• 23 chrom 22 autosomes 1 sex chrom

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Cell Division Prokaryotes

• Binary Fission
• 2 new genetically identical offspring
• 3 stages
• Chromosome copies itself
• Cell wall forms between chromosomes
• Cell splits

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Cell Division Eukaryotes

• 2 Types
• Mitosis genetically identical, 2N
• Meiosis genetically different gametes, 1N
• Cell Cycle
• Interphase
• G1 (Gap 1) Phase
• S Phase
• G2 Phase
• Or G0 Phase after G1, exit cell cycle, no
  division
• Mitosis (M phase)
• Cytokinesis

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Cell Cycle
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Mitosis Phases

• Prophase
• Chromosomes form
• Nucleolus nuclear envelope disappear
• Centrosomes (contain centrioles) separate to
  opposite poles of cell
• Spindle fibers make mitotic spindle
• Kinetochore fibers attach to kinetochore in
  chromosome
• Polar fibers

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Mitosis Phases

• Metaphase
• Chromosomes line up on midline
• Anaphase
• Chromatids separate? chromosomes
• Telophase
• Spindle fibers disappear
• Chromosomes? chromatin
• Nucleolus and nuclear envelope reforms
• Cytokinesis
• Cytoplasm divides in telophase
• Cleavage furrow in cell membrane
• Cell plate plant cells

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Cytokinesis Cleavage Furrow Cell Plate
1
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Mitosis Diagram
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Meiosis Reproductive Cells Only

• Forms gametes (1N) from diploid cells (2N)
• 4 genetically different haploid cell
• Meiosis I haploid cells form by end
• Prophase I
• Synapsis? tetrad
• Crossing over? genetic recombination
• Metaphase I
• Anaphase I
• Independent assortment
• Telophase I
• Meiosis II
• Prophase, Metaphase, Anaphase, Telophase II

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Spermatogenesis

• In testes
• Produces 4 genetically different haploid
  spermatids
• Spermatids mature into sperm

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Oogenesis

• In ovaries
• Produces
• 1 Egg
• 3 Polar Bodies

Unequal Cytoplasm Division
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Asexual Sexual Reproduction

• Asexual
• Offspring from 1 parent
• Unicellular? mitosis or budding
• Multicellular? budding
• Always genetically identical to parent
• Sexual
• Offspring results from union of gametes zygote
• Offspring genetically different from parents due
  to meiosis recombining genes
• Allows specie adaptation more quickly