Chromosomes and Cell Reproduction Chapter 6 & 7. I. Chromosomes A. Chromosome- made of 2 exact copies of DNA coiled around proteins (*this is after replication.

Chromosomes Chromosomes and Cell and Cell

ReproductionReproductionChapter 6 & 7Chapter 6 & 7

I. ChromosomesI. Chromosomes

A.A. Chromosome- made of Chromosome- made of 2 2 exact exact copies of copies of DNADNA coiled around coiled around proteins proteins

(*this is after (*this is after replicationreplication but before but before cell divisioncell division))

B.B. Chromatid- each copy of the Chromatid- each copy of the DNADNA on a on a chromosomechromosome

C.C. Centromere- place where the Centromere- place where the chromatidschromatids attachattach to make a to make a chromosomechromosome

D.D. Genes- Segments of Genes- Segments of DNADNA on a on a chromosomechromosome that code for a that code for a specific specific protein/traitprotein/trait

*Draw a chromosome and label chromatids, centromere and gene

II. Chromosome NumberII. Chromosome Number

A.A. Each human Each human somaticsomatic cell (body cell (body cell) has cell) has 22 copies of copies of 2323 different different chromosomes for a chromosomes for a totaltotal of of 4646 chromosomeschromosomes

B.B. We inherit We inherit 11 of each chromosome of each chromosome from from mommom and and 11 from from daddad

C.C. Homologous Chromosomes- similar Homologous Chromosomes- similar in in size, shape and genetic contentsize, shape and genetic content

D. D. DiploidDiploid cells- contain cells- contain 2 sets2 sets of of chromosomes, all chromosomes, all somaticsomatic cells are cells are diploiddiploid

(ex. Somatic cells in (ex. Somatic cells in humanshumans have a have a total of total of 46 46 chromosomes)chromosomes)

E. E. HaploidHaploid Cells- contain only Cells- contain only 11 set of set of chromosomes, only chromosomes, only gametesgametes can be can be haploidhaploid

(ex. Gametes in (ex. Gametes in humanshumans have have 2323 chromosomes)chromosomes)

III. III. KaryotypesKaryotypes

A.A. A A picturepicture of the of the chromosomes chromosomes of an of an organism arranged by organism arranged by sizesize

B.B. Used to examine an individuals Used to examine an individuals chromosomeschromosomes::

C.C. Karyotypes can determine only Karyotypes can determine only 22 things about the organism:things about the organism:

1.1. SexSex of individual of individual

2.2. Any Any abnormalitiesabnormalities in the in the chromosomeschromosomes (number or shape(number or shape

C. C. HumansHumans have have 1 pair1 pair of sex of sex chromosomes and chromosomes and 22 pairs22 pairs of autosomal of autosomal chromosomes (non sex chromosomes)chromosomes (non sex chromosomes)

D. Sex Chromosomes-D. Sex Chromosomes-XX= FemaleXX= Female XY= MaleXY= Male

((the sex chromosomes are the last pair of the sex chromosomes are the last pair of chromosomes shown in a karyotypechromosomes shown in a karyotype))

Trisomy – when there is three of a certain chromosome instead of the normal 2

IV. Cell CycleIV. Cell Cycle

A.A. G1 Phase- period of cell growthG1 Phase- period of cell growth

B.B. S Phase- when DNA replication S Phase- when DNA replication occursoccurs

C.C. G2 Phase- cell growth and G2 Phase- cell growth and preparation for mitosispreparation for mitosis

D.D. Mitosis- division of the nucleus Mitosis- division of the nucleus

E.E. Cytokinesis- division of the Cytokinesis- division of the cytoplasmcytoplasm

Cell Cycle AnimationsCell Cycle Animations

http://www.cellsalive.com/http://www.cellsalive.com/cell_cycle.htmcell_cycle.htm

http://iknow.net/http://iknow.net/cell_div_education.htmlcell_div_education.html

V. MitosisV. Mitosis

A.A. The division of the nucleus in The division of the nucleus in somatic cellssomatic cells

B.B. Chromosomes have replicated prior Chromosomes have replicated prior to the start of mitosisto the start of mitosis

C.C. Produces 2 identical daughter cellsProduces 2 identical daughter cells

D.D. 4 phases4 phases

1.Prophase-

chromatin coils into chromosomes

Nuclear envelope dissolves

Spindle fibers form

2. Metaphase (middle)

Chromosomes line up in the middle of the cell

Centrioles move to opposite poles

Spindle fibers attach to chromosomes

3. Anaphase (apart)

Spindle fibers shorten and pull chromatids toward opposite poles

4. Telophase (opposite of prophase)

Nuclear envelope forms around chromatids

Chromatids uncoil

Cleavage is formed

Spindle fibers dissolve

E. Cytokinesis

Occurs after Mitosis

Cytoplasm is divided in half

Cell membrane encloses each cell**New cells are now in interphase and the cell cycle starts over.

Mitosis AnimationMitosis Animation

http://iknow.net/http://iknow.net/cell_div_education.htmlcell_div_education.html

http://www.loci.wisc.edu/outreach/bioclips/CDBio.htmlhttp://www.loci.wisc.edu/outreach/bioclips/CDBio.html

VI. MeiosisVI. Meiosis

A.A. Two divisions of the nucleusTwo divisions of the nucleus

B.B. Results in the formation of 4 Results in the formation of 4 gametes (egg, sperm)gametes (egg, sperm)

C.C. Halves the number of Halves the number of chromosomes (in humans from 46 chromosomes (in humans from 46 to 23)to 23)

Stages of Meiosis IStages of Meiosis I11.*Prophase I-.*Prophase I- crossing over occurs, crossing over occurs, (portions of one chromosome are broken (portions of one chromosome are broken and exchanged with portions of the other and exchanged with portions of the other homologue)**results in genetic variabilityhomologue)**results in genetic variability2. 2. Metaphase I-Metaphase I- homologous chromosome homologous chromosome pair up together at the equatorpair up together at the equator3. 3. Anaphase I-Anaphase I- centromeres do not divide centromeres do not divide4. 4. Telophase ITelophase I and and CytokinesisCytokinesis

Meiosis IIMeiosis II

1. Prophase II1. Prophase II

2. Metaphase II2. Metaphase II

3. Anaphase II3. Anaphase II

4. Telophase II & Cytokinesis4. Telophase II & Cytokinesishttp://www.tokresource.org/tok_classes/biobiobio/biomenu/meiosis/

Interphase

P 1 M 1 A 1 T1 & C

P 2 M 2 A 2 T 2 Cytokinesis

Females- called oogenesis, forms 1 Females- called oogenesis, forms 1 ovum and 3 polar bodiesovum and 3 polar bodies

Males- called spermatogenesis, forms Males- called spermatogenesis, forms 4 sperm cells4 sperm cells

http://www.biologyexams4u.com/2013/06/difference-between-spermatogenesis-and.html

Meiosis AnimationsMeiosis Animations

Meiosis AnimationMeiosis Animation

Meiosis Square Dance VideoMeiosis Square Dance Video