Meiosis

Figure 13.2

(a) Hydra (b) Redwoods

Bud

Parent

0.5 mm

Figure 12.7a

G2 of Interphase Prophase Prometaphase

Centrosomes(with centriole pairs)

Chromatin(duplicated)

NucleolusNuclearenvelope

Plasmamembrane

Early mitoticspindle

Aster

Centromere

Chromosome, consistingof two sister chromatids

Fragments of nuclearenvelope

Nonkinetochoremicrotubules

Kinetochore Kinetochoremicrotubule

Figure 12.7b

Metaphase

Metaphase plate

Anaphase Telophase and Cytokinesis

Spindle Centrosome atone spindle pole

Daughterchromosomes

Cleavagefurrow

Nucleolusforming

Nuclearenvelopeforming

Figure 13.3a

Figure 13.3b

Pair of homologousduplicated chromosomes

Centromere

Sisterchromatids

Metaphasechromosome

5 m

Figure 13.3c

5 m

Figure 13.4

Sister chromatidsof one duplicatedchromosome

Key

Maternal set ofchromosomes (n 3)Paternal set ofchromosomes (n 3)

Key

2n 6

Centromere

Two nonsisterchromatids ina homologous pair

Pair of homologouschromosomes (one from each set)

Figure 13.6aKey

Haploid (n)Diploid (2n)

Gametes

MEIOSIS FERTILIZATION

Zygote

MitosisDiploidmulticellularorganism

(a) Animals

n

2n

n

n

2n

Figure 13.6b

2n2n

n

MEIOSIS FERTILIZATION

Mitosis Mitosis

Mitosis

GametesSpores

Zygote

Haploid multi-cellular organism(gametophyte)

Diploidmulticellularorganism(sporophyte)

(b) Plants and some algae

n n n n

Haploid (n)Diploid (2n)

Key

Figure 13.6cKey

Haploid (n)Diploid (2n)

2n

n n

n

n

n

MEIOSIS FERTILIZATION

Mitosis Mitosis

Gametes

Zygote

Haploid unicellular ormulticellular organism

(c) Most fungi and some protists

Figure 13.6

KeyHaploid (n)

Diploid (2n)

Gametes

MEIOSIS FERTILIZATION

Zygote

MitosisDiploidmulticellularorganism

(a) Animals

n

n

n

2n 2n 2n2n

2n

n n

n

n n

nn

n

n

nMEIOSIS

MEIOSIS

FERTILIZATION

FERTILIZATION

Mitosis Mitosis

Mitosis

Mitosis Mitosis

GametesSpores

Gametes

Zygote

Zygote

Haploid multi-cellular organism(gametophyte)

Diploidmulticellularorganism(sporophyte)

Haploid unicellular ormulticellular organism

(b) Plants and some algae (c) Most fungi and some protists

Figure 13.7-3

Pair of homologouschromosomes indiploid parent cell

Duplicated pairof homologouschromosomes

Chromosomesduplicate

Sisterchromatids Diploid cell with

duplicatedchromosomes

Homologouschromosomes separate

Haploid cells withduplicated chromosomes

Sister chromatidsseparate

Haploid cells with unduplicated chromosomes

Interphase

Meiosis I

Meiosis II

2

1

Figure 13.8a

Prophase I Metaphase I Anaphase I Telophase I andCytokinesis

Centrosome(with centriole pair)

Sisterchromatids

Chiasmata

Spindle

Homologouschromosomes

Fragmentsof nuclearenvelope

Duplicated homologouschromosomes (red and blue)pair and exchange segments;2n 6 in this example.

Centromere(with kinetochore)

Metaphaseplate

Microtubuleattached tokinetochore

Chromosomes line upby homologous pairs.

Sister chromatidsremain attached

Homologouschromosomesseparate

Each pair of homologous chromosomes separates.

Cleavagefurrow

Two haploid cells form; each chromosomestill consists of two sister chromatids.

Figure 13.8b

Prophase II Metaphase II Anaphase II Telophase II andCytokinesis

Sister chromatidsseparate

Haploid daughtercells forming

During another round of cell division, the sister chromatids finally separate;four haploid daughter cells result, containing unduplicated chromosomes.

Human gametogenesisSpermatogenesis Oogenesis

Primaryspermatocyte

Primaryoocyte

Secondaryspermatocytes

Secondaryoocyte

Polar body

Spermatids

Sperm

Polar body

Fertilized egg

2n 2n

n

n

n

n

n n

n n n n

n n n n

Figure 46.UN01

Figure 13.9a

Prophase

Duplicatedchromosome

MITOSIS

Chromosomeduplication

Parent cell

2n 6

Metaphase

AnaphaseTelophase

2n 2n

Daughter cellsof mitosis

MEIOSIS

MEIOSIS I

MEIOSIS II

Prophase I

Metaphase I

Anaphase ITelophase I

Haploidn 3

Chiasma

Chromosomeduplication Homologous

chromosome pair

Daughter cells of

meiosis I

Daughter cells of meiosis II

n n n n

Figure 13.9b

SUMMARY

Property Mitosis Meiosis

DNAreplication

Number ofdivisions

Synapsis ofhomologouschromosomes

Number of daughter cellsand geneticcomposition

Role in the animal body

Figure 13.10-1

Possibility 1 Possibility 2

Two equally probablearrangements ofchromosomes at

metaphase I

Figure 13.10-2

Possibility 1 Possibility 2

Two equally probablearrangements ofchromosomes at

metaphase I

Metaphase II

Figure 13.10-3

Possibility 1 Possibility 2

Two equally probablearrangements ofchromosomes at

metaphase I

Metaphase II

Daughtercells

Combination 1 Combination 2 Combination 3 Combination 4

Figure 13.11-1Prophase Iof meiosis

Nonsister chromatidsheld togetherduring synapsis

Pair of homologs

Figure 13.11-2Prophase Iof meiosis

Nonsister chromatidsheld togetherduring synapsis

Pair of homologs

Chiasma

Centromere

TEM

Figure 13.11-3Prophase Iof meiosis

Nonsister chromatidsheld togetherduring synapsis

Pair of homologs

Chiasma

Centromere

TEM

Anaphase I

Figure 13.11-4Prophase Iof meiosis

Nonsister chromatidsheld togetherduring synapsis

Pair of homologs

Chiasma

Centromere

TEM

Anaphase I

Anaphase II

Figure 13.11-5Prophase Iof meiosis

Nonsister chromatidsheld togetherduring synapsis

Pair of homologs

Chiasma

Centromere

TEM

Anaphase I

Anaphase II

Daughtercells

Recombinant chromosomes