Chapter 8 the cellular basis of reproduction and inheritance
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CHAPTER 8 The Cellular Basis of Reproduction and Inheritance. Modules 8.12 – 8.18. MEIOSIS AND CROSSING OVER. 8.12 Chromosomes are matched in homologous pairs. _____ cells of each species contain a specific number of chromosomes

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Chapter 8 the cellular basis of reproduction and inheritance

CHAPTER 8The Cellular Basis of Reproduction and Inheritance

Modules 8.12 – 8.18


8 12 chromosomes are matched in homologous pairs

MEIOSIS AND CROSSING OVER

8.12 Chromosomes are matched in homologous pairs

  • _____ cells of each species contain a specific number of chromosomes

    • Human cells have 46, making up 23 pairs of ________ chromosomes

Chromosomes

Centromere

Sister chromatids

Figure 8.12


Karyotype cells haploid cells
Karyotype______CellsHaploidCells


8 13 gametes have a single set of chromosomes
8.13 Gametes have a single set of chromosomes

  • Cells with two sets of chromosomes are said to be ______

  • Gametes are ______, with only one set of chromosomes


Chapter 8 the cellular basis of reproduction and inheritance

  • At fertilization, a sperm fuses with an egg, forming a diploid ______


Chapter 8 the cellular basis of reproduction and inheritance

Haploid gametes ( mature adultn = 23)

Egg cell

  • The human life cycle

Sperm cell

MEIOSIS

FERTILIZATION

Diploidzygote (2n = 46)

Multicellulardiploid adults (2n = 46)

Mitosis anddevelopment

Figure 8.13


8 14 meiosis reduces the chromosome number from diploid to haploid
8.14 Meiosis reduces the chromosome number from diploid to haploid

  • Meiosis, like mitosis, is preceded by chromosome duplication

    • However, in meiosis the cell divides ____ to form _____ daughter cells


Chapter 8 the cellular basis of reproduction and inheritance

  • While they are paired, they haploid____ ___ and exchange genetic information

  • The homologous pairs are then separated, and two daughter cells are produced

  • In the first division, meiosis I, homologous chromosomes are _____


Chapter 8 the cellular basis of reproduction and inheritance

9 haploid


Chapter 8 the cellular basis of reproduction and inheritance

MEIOSIS haploidI: Homologous chromosomes separate

INTERPHASE

PROPHASE I

METAPHASE I

ANAPHASE I

Centrosomes(withcentriolepairs)

Microtubules attached tokinetochore

Metaphaseplate

Sister chromatidsremain attached

Sites of crossing over

Spindle

Nuclearenvelope

Sisterchromatids

Tetrad

Centromere(with kinetochore)

Homologouschromosomes separate

Chromatin

Figure 8.14, part 1


Chapter 8 the cellular basis of reproduction and inheritance

  • The sister haploid______ of each chromosome separate

  • The result is four haploid daughter cells

  • Meiosis II is essentially the same as ______


Chapter 8 the cellular basis of reproduction and inheritance

MEIOSIS haploidII: Sister chromatids separate

TELOPHASE IAND CYTOKINESIS

TELOPHASE IIAND CYTOKINESIS

PROPHASE II

METAPHASE II

ANAPHASE II

Cleavagefurrow

Sister chromatidsseparate

Haploiddaughter cellsforming

Figure 8.14, part 2


8 15 review a comparison of mitosis and meiosis
8.15 Review: A comparison of mitosis and meiosis haploid

  • For both processes, chromosomes replicate only once, during interphase


Chapter 8 the cellular basis of reproduction and inheritance
8.16 Independent orientation of chromosomes in meiosis and random fertilization lead to varied offspring

  • Each chromosome of a homologous pair comes from a different parent

    • Each chromosome thus ____ at many points from the other member of the pair

    • Cross-Over (Does it happen) and where cross-over Occurs


Chapter 8 the cellular basis of reproduction and inheritance

  • The large number of possible random fertilization lead to varied offspring_______ of chromosome pairs at metaphase I of meiosis leads to many different combinations of chromosomes in gametes

  • _____ fertilization also increases variation in offspring


Chapter 8 the cellular basis of reproduction and inheritance

POSSIBILITY 1 random fertilization lead to varied offspring

POSSIBILITY 2

Two equally probable arrangements of chromosomes at metaphase I

Metaphase II

Gametes

Combination 1

Combination 2

Combination 3

Combination 4

Figure 8.16


Chapter 8 the cellular basis of reproduction and inheritance

Tetrad random fertilization lead to varied offspring

Chaisma

Centromere

Figure 8.18A