UNIT 7: MEIOSIS AND SEXUAL REPRODUCTION

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• UNIT 7 MEIOSIS AND SEXUAL REPRODUCTION

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• EQ 1 . Compare and contrast mitosis and
  meiosis and relate to the process of sexual and
  asexual reproduction and their consequences for
  genetic variation.

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KEY CONCEPT Gametes (sex cells) have H___ the
number of chromosomes that body cells have.
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You have body cells and gametes.

• Body cells are also called somatic cells.
• Gametes are Sex Cells E___ and S____..
• Gametes have DNA that can be passed to offspring.

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DONT COPY. JUST READ THIS SLIDEYour cells have
autosomes and sex chromosomes.

• Your body cells have 23 pairs of chromosomes.
• 22 pairs of Autosomes are Homologous pairs of
  chromosomes, which means that have the same
  structure.
• For each homologous pair, one chromosome comes
  from each parent.
• 1 pair of Sex chromosomes, X and Y, determine
  gender in mammals.

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Body cells are diploid gametes are haploid.

• Diploid (2n) cells have T___ copies of every
  chromosome.
• Body cells are diploid.
• Half the chromosomes come from each parent
• (½ in egg ½ in sperm 1 full set in offspring)

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• Haploid (n) cells have one copy of every
  chromosome.

• Gametes are haploid..

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• Chromosome number must be maintained in animals.

• Mitosis and meiosis are types of nuclear division
  that make D_____ types of cells.
• Mitosis
• makesmore diploid cells.
• All cells in mitosis
• are identical to the
• parent cell.
• is only used for reproduction in Bacteria other
  1-cell organisms.

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• Meiosis

• makes H_______ cells from diploid cells.
• Meiosis occurs in sex cells.
• Meiosis produces gametes.
• Is employed for sexual reproduction

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• EQ 2How does reduction division results in the
  formation of haploid gametes or spores?

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KEY CONCEPT During meiosis, diploid cells
undergo T___ cell divisions that result in
haploid cells.
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Cells go through two rounds of division in
meiosis.VIDEO Round 1 Meiosis IRound 2
Meiosis II

• Meiosis reduces C__________ number and creates
  genetic D__________.

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• Meiosis I and meiosis II each have four phases
  (PMAT), similar to those in M___________.

• Pairs of homologous chromosomes separate
  inmeiosis I.
• Homologous chromosomes are S_____ but not
  identical.
• Sister chromatids divide in meiosis II.
• Sister chromatids are copies of the same
  chromosome. (identical!)

homologous chromosomes
sister chromatids
sister chromatids
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• Meiosis I occurs after DNA has been replicated.

• Meiosis I divides homologous chromosomes in four
  phases.

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Crossing over during meiosis increases genetic
diversity.

• Crossing over is the exchange of chromosome
  segments between homologous chromosomes.
• occurs during prophase I of meiosis I
• results in new combinations of genes

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• Meiosis II divides S______ chromatids in four
  phases.

• DNA is not replicated between meiosis I
  andmeiosis II.

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• EQ 3 How do independent assortment crossing
  over increase genetic diversity?

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INDEPENDENT ASSORTMENT increases offspring
diversity.

• The 4 gametes formed from 1 cell have different
  G___.
• This process is called INDEPENDENT ASSORTMENT
  because the genes separate differently each time
  gametes are formed.
• Since the gametes formed by an individual are
  D_______ each time, the offspring have increased
  genetic diversity.

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• Meiosis differs from mitosis in significant ways.

• Meiosis has two cell divisions while mitosis has
  one.
• In mitosis, homologous chromosomes never pair up.
• Meiosis results in haploid cells mitosis results
  in diploid cells.