Sexual Sexual ReproductionReproduction

Cellular ReproductionCellular Reproduction

There are 2 types ofThere are 2 types of reproduction: reproduction:

Asexual ReproductionAsexual Reproduction

Sexual ReproductionSexual Reproduction

Cellular ReproductionCellular Reproduction

1.1. Asexual Reproduction (5 phases)Asexual Reproduction (5 phases)

1 1 mother cell divides intomother cell divides into 2 2 daughter daughter cells cells

Daughter cell is Daughter cell is identiidenticalcal to its mother to its mother Interphase + MitosInterphase + Mitosisis AllAll cells cells havehave 4646 chromosomes called chromosomes called

““DIPLODIPLOIID D cellscells”” Produce Produce SOMATISOMATIC cellsC cells ((not sexual cellsnot sexual cells))

Cellular ReproductionCellular Reproduction

22. . Sexual Reproduction (9 phases)Sexual Reproduction (9 phases)

11 mother cell divides intomother cell divides into 44 daughter daughter cellscells

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

Interphase + MInterphase + Meeiosiosisis I + M I + Meeiosiosisis II II CCrossing overrossing over of genetic material often of genetic material often

occurs.occurs. SEXUSEXUAL cellsAL cells ( (eggegg and sperm) and sperm) known as known as

“ga“gammeetestes””

Asexual Asexual ReproductionReproduction

Sexual ReproductionSexual Reproduction

ProduProducesces __ __ daughter daughter cellscells

ProduProducesces __ __ daughter daughter cellscells

ProduProduces cells which ces cells which are _____ to their are _____ to their mother cellmother cell

ProduProduces cells which ces cells which are _____ to their are _____ to their mother cellmother cell

MMotherother:__chromosome:__chromosomessDaughterDaughter :__chromo :__chromo

MMotherother:__chromosome:__chromosomessDaughterDaughter :__chromo :__chromo

Asexual Asexual ReproductionReproduction

Sexual ReproductionSexual Reproduction

Crossing overCrossing over??

YESYES NO NOCrossing overCrossing over??

YESYES NO NO

______________ cells cells ______________ cells cells

DIPLODIPLOIID HAPLOD HAPLOIIDD DIPLODIPLOIID HAPLOD HAPLOIIDD

__ phases:__ phases: __ phases:__ phases:

GamGameetes…tes…don’t forget!! don’t forget!!

~ ~ Another name for Another name for eggseggs and and spermsperm

~ ~ They areThey are haplo haploiid (23 chromosomes)d (23 chromosomes)

~ ~ They are They are sexusexualal cell cellss

~ ~ They areThey are produ produced by sexual ced by sexual reproductionreproduction

TheThe ““nn” value” value

nn = = the basic (smallest) number of the basic (smallest) number of chromosomeschromosomes

Interphase Interphase ofof M Meeiosiosisis (4n = 92) (4n = 92)

AAfterfter T Teelophase I (2n = 46) lophase I (2n = 46)

Gametes Gametes at the end of at the end of MMeeiosiosisis ~ ~ afterafter

TTeelophase II ~ (n = 23)lophase II ~ (n = 23)

There are 3 major steps:There are 3 major steps:

~ Interphase~ Interphase

~ M~ Meeiosiosisis I I

~ ~ MMeiosiseiosis II II

SexuSexualal Reproduction Reproduction

HomologHomologousous ChromosomesChromosomes

A pair of A pair of chromosomeschromosomes ( (maternmaternal al andand paternpaternalal)) that have similar/identical that have similar/identical shapeshapes s andand sizes.sizes.

Have Have ggeenesnes for the same for the same cchharactaracteeristiristics cs (ie: (ie: eye coloreye color))..

EachEach locuslocus (g(geenene position) position) contrcontroolls the s the same traitsame trait and is inand is in the same place the same place on on homologous chromosomes. homologous chromosomes.

VocabulaVocabularyry

Homologous Chromosomes

chromatids chromatidstetrad

VocabulaVocabularyry

Sperm + egg = zygoteSperm + egg = zygote

HomologHomologous ous ChromosomesChromosomes

Paternal Maternal

Eye colorEye color

Hair color Hair color

Locus

Remember!! Remember!!

InterphaseInterphase

ProphaseProphase

MetaphaseMetaphase

AnaphaseAnaphase

TelophaseTelophase

Remember!! Remember!!

InterphaseInterphase

Prophase IProphase IMetaphase IMetaphase IAnaphase IAnaphase ITelophase ITelophase IProphase IIProphase II

Metaphase IIMetaphase IIAnaphase IIAnaphase IITelophase IITelophase II

MeiosisMeiosis

4n=92

2n=46

2n=46

meiosis I

n=23

n=23

n=23

n=23meiosis II

4 haploid

gamètes (n)

AfterInterphase

diploid (2n)

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

Interphase (4n = 92)Interphase (4n = 92) Same as Interphase in Same as Interphase in MitosMitosisis

Chromosome reChromosome replicationplication, growth and , growth and preparation (chromatin rolls etc)preparation (chromatin rolls etc)

Each of the Each of the rreepliplicated cated chromosomeschromosomes poss possessesesses 22 chromatideschromatides which are which are attachattacheded at at theirtheir centromcentromeerere..

Interphase (4n = 92)Interphase (4n = 92) We can see the nucleolus and the We can see the nucleolus and the

nuclear membrane. nuclear membrane.

Nuclear membrane

Nucleolus

Cell membrane

Chromatine

There are 92 chromosomes (46 pairs!!)

MMeeiosiosisis I ( I (44 phases) phases)

~ Prophase I~ Prophase I

~ M~ Meetaphase Itaphase I

~ Anaphase I~ Anaphase I

~ T~ Teelophase Ilophase I

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

22 homolog homologousous chromosomes chromosomes combine. combine. This combination is called a This combination is called a TETRADTETRAD XXXX

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

TheThe nucnuclearlear memmembranebrane and theand the nuclnucleeololusus both disappear both disappear

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

centriolesSpindle fibers

Crossing OverCrossing Over DurDuringing Prophase IProphase I

One chromatid of One chromatid of eacheach chromosome chromosome crosses over crosses over with with the chromatid of the the chromatid of the other chromosome. other chromosome.

TheThe r reesultsult is an is an exexchangechange of their of their genetic materialgenetic material

Crossing OverCrossing OverThe exchange of sections of homologous chromosomes in a TETRAD.

Maternalchromo

Paternalchromo

MMeetaphase I (4n = 92)taphase I (4n = 92)

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

MMeetaphase I (4n = 92)taphase I (4n = 92)

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

TheThe tetrads tetrads sseeparparate and ate and homologhomologououss chromosomes chromosomes travel to the polestravel to the poles. .

HHomologues chromosomes omologues chromosomes are still attached by their are still attached by their centromcentromeeresres..

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

TTeelophase I/lophase I/CytokenisisCytokenisis (2n = 46)(2n = 46)

EachEach p poole le has a has a diplodiploiidd number of number of cchromosomes.hromosomes.

Cytokenisis Cytokenisis - - 22 diplo diploiids cells ds cells areare form formeded. .

Spindle fibers Spindle fibers and and centriolescentrioles disappear.disappear.

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

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

Cell divisionCell division

MMeeiosiosisis II ( II (44 phases) phases)~ Prophase II~ Prophase II

~ Metaphase II~ Metaphase II

~ Anaphase II~ Anaphase II

~ T~ Teelophase IIlophase II

MMeeiosiosisis II II

Interphase II Interphase II – – does not existdoes not exist

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

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

Same as Same as ProphaseProphase inin MitosMitosisis

MMeetaphase II (n = 46)taphase II (n = 46)

Same as Same as MMeetaphasetaphase inin MitosMitosisis

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

Same as Same as AnaphaseAnaphase inin MitosMitosisis DON’T FORGETDON’T FORGET! ! CChromosomes hromosomes are are

separated into chromatids.separated into chromatids.

Télophase II/Télophase II/CytokenisisCytokenisis (n = (n = 23)23)

Same as Same as TelophaseTelophase inin MitosMitosisisEXCEPT n = 23

The nucleolus and nuclear membrane The nucleolus and nuclear membrane reformreform

CytokenisisCytokenisis

Important: Important: 4 haplo4 haploiid gamd gameetes tes areare form formeded..

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

Meiosis– http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter28/animation__how_meiosis_works.html

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

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

MitosMitosisis vs M vs Meeiosiosisis

MitosMitosisis MMeieiososisis

ResultResult 2 diplo2 diploiid cells d cells (2n)(2n)

44 hahaploploiid cellsd cells (n)(n)

The cells areThe cells are iidentidenticalcal diffdiffeerentrent

Occurs inOccurs in somatisomaticc ccellules (all ellules (all cells in the cells in the body)body)

sexusexualal

CCellules ellules (sperm and (sperm and egg)egg)

Meiosis– United Streaming

Visual RepresentationsVisual Representations

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

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

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