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Sexual Reproduction. Cellular Reproduction. There are 2 types of reproduction: Asexual Reproduction Sexual Reproduction. Cellular Reproduction. Asexual Reproduction (5 phases) 1 mother cell divides into 2 daughter cells Daughter cell is identi cal to its mother

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Cellular reproduction
Cellular Reproduction

There are 2 types of reproduction:

  • Asexual Reproduction

  • Sexual Reproduction


Cellular reproduction1
Cellular Reproduction

  • Asexual Reproduction (5 phases)

  • 1 mother cell divides into 2 daughter cells

  • Daughter cell is identical to its mother

  • Interphase + Mitosis

  • All human cells have46 chromosomes called “DIPLOID cells”

  • Produce SOMATIC cells(not sexual cells)


Cellular reproduction2
Cellular Reproduction

2. Sexual Reproduction (9 phases)

  • 1mother cell divides into4daughter cells

  • Daughter cells have ½ the chromosomes of their mother (23) “HAPLOID cells”

  • Interphase + Meiosis I + Meiosis II

  • Crossing over of genetic material often occurs.

  • SEXUAL cells (egg and sperm) known as “gametes”



Gam e tes
Gametes

~ Another name for eggsand sperm

~ They are haploid (In humans, that is 23 chromosomes)

~ They are sexual cells

~ They are produced by sexual reproduction


Homolog ous chromosomes
Homologous Chromosomes

  • A pair of chromosomes (maternal and paternal)that have similar/identical shapes andsizes.

  • Have genesfor the same characteristics (ie: eye color).

  • Eachlocus(geneposition) controls the same traitand is inthe same place on homologous chromosomes.


Vocabula ry

Homologous Chromosomes

chromatids

chromatids

Vocabulary

tetrad


Vocabula ry1
Vocabulary

Sperm + egg = zygote


Homolog ous chromosomes1

Eye color

Eye color

Hair color

Hair color

Paternal

Locus

Maternal

Homologous Chromosomes


Remember
Remember…

Interphase

Prophase

Metaphase

Anaphase

Telophase

Asexual

Reproduction

Mitosis


Sexu al reproduction
Sexual Reproduction

  • There are 3 major steps:

    ~ Interphase

    ~ Meiosis I

    ~ Meiosis II


Interphase

Prophase I

Metaphase I

Anaphase I

Telophase I

Prophase II

Metaphase II

Anaphase II

Telophase II

Sexual

Reproduction

Meiosis


Meiosis in humans

2n=46

4n=92

2n=46

meiosis I

Meiosis in Humans

n=23

AfterInterphase

n=23

4 haploid

gametes (n)

n=23

n=23

diploid (2n)

meiosis II


Video
Video

  • Meiosis


Interphase 4n 92
Interphase (4n = 92)

  • Same as Interphase in Mitosis

  • Chromosome replication, growth and preparation (chromatin rolls etc)

  • Each of the replicated chromosomes possesses2chromatideswhich are attachedat theircentromere.


Interphase 4n 921
Interphase (4n = 92)

  • We can see the nucleolus and the nuclear membrane.

There are 92 chromosomes (46 pairs!!)

Nuclear membrane

Chromatine

Cell membrane

Nucleolus


M e ios is i 4 phases
Meiosis I (4 phases)

~ Prophase I

~ Metaphase I

~ Anaphase I

~ Telophase I


Prophase i 4n 92
Prophase I (4n = 92)

  • 2 homologous chromosomes combine. This combination is called a TETRADXX

  • Spindle fibers grow, and attach to each side of the tetrad

  • Thenuclearmembraneand thenucleolusboth disappear


Prophase i 4n 921

Spindle fibers

centrioles

Prophase I (4n = 92)


Crossing over
Crossing Over

  • DuringProphase I

  • One chromatid of each chromosome crosses over with the chromatid of the other chromosome.

  • The result is anexchangeof their genetic material


Crossing over1
Crossing Over

The exchangeof sections ofhomologouschromosomes in aTETRAD.

Maternal

chromo

Paternal

chromo


M e taphase i 4n 92
Metaphase I (4n = 92)

  • Spindle fibers pull on the tetrads, and align them in the centre of the cell.


M e taphase i 4n 921
Metaphase I (4n = 92)


Anaphase i 4n 92
Anaphase I (4n = 92)

  • Thetetrads separate and homologouschromosomes travel to the poles.

  • Homologues chromosomes are still attached by their centromeres.



T e lophase i cytokenisis 2n 46
Telophase I/Cytokenisis(2n = 46)

  • Each pole has a diploidnumber of chromosomes.

  • Cytokenisis - 2 diploids cells are formed.

  • Spindle fibers and centriolesdisappear.

  • The nuclear membrane sometimes reforms, and the nucleolus does not reform at this point.


Telophase i 2n 46
Telophase I (2n = 46)

Cell division



M e ios is ii 4 phases
Meiosis II (4 phases)

~ Prophase II

~ Metaphase II

~ Anaphase II

~ Telophase II


M e ios is ii
Meiosis II

Interphase II – does not exist

** Don’t forget!! This process is now occurring in both daughter cells created during Meiosis I **


Prophase ii 2n 46
Prophase II (2n = 46)

  • Same as ProphaseinMitosis


M e taphase ii n 46
Metaphase II (n = 46)

  • Same as MetaphaseinMitosis


Anaphase ii 2n 46
Anaphase II (2n = 46)

  • Same as AnaphaseinMitosis

  • DON’T FORGET! Chromosomes are separated into chromatids.


Telophase ii cytokenisis n 23
Telophase II/Cytokenisis (n = 23)

  • Same as TelophaseinMitosisEXCEPT n = 23

  • The nucleolus and nuclear membrane reform

  • Cytokenisis

    Important: 4 haploid gametes areformed.


Telophase ii cytokenisis n 231
Telophase II/Cytokenisis (n = 23)


Animation!!

Meiosis– McGraw-Hill animation




Mitos is vs m e ios is
Mitosis vs Meiosis


Mitos is vs m e ios is1
Mitosis vs Meiosis




Attention
Attention!!!!!!!!!!!!!

  • Female meiosis is somewhat different. 4 gametes are initially created, but Cytokenisis is UNEQUAL. In this case, ONE GAMETE survives, and the other 3 are not viable.


Video!!

United Streaming- Cell Division



Visual representations

Mitosis vs. Meiosis

Visual Representations

http://www.cellsalive.com/meiosis.htm

http://www.csuchico.edu/~jbell/Biol207/animations/meiosis.html

http://www.sumanasinc.com/webcontent/animations/content/meiosis.html


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