chromosomes and cell reproduction

8/8/2019 Chromosomes and Cell Reproduction

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Chromosomes and CellChromosomes and Cell

ReproductionReproduction


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Cell Cycle

Cell cycle- cycle of cell growth

Interphase -

G1- rapid cell growth

S- DNA synthesis

G2- final growth phase

Mitosis - nucleus division (PMAT)

Cytokinesis - dividing of cytoplasm and cell

membrane

Interphase- first three phases


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Phases of Cell Cycle


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Control of the Cell cycle


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Cancer Canceris the uncontrollablegrowth of cells

One of the genes atcheckpoints in cell cycle is

mutated, so cancer cells

keeps dividing

Usually bodys immunesystem destroys cancer cells,

if not forms a tumor

Older individuals have a

higher likelihood of cancerdue to many mutations over

time


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Prokaryotic (Bacterial) Division

Prokaryote cells are much smaller/simpler

Divide more quickly

Contain a single circular DNA molecule Go through a process ofBinary Fission

form of asexual reproduction that produces

offspring identical to parent (clones)


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Process of Binary Fission

1) DNA is copied soeach cell is identical

2) Cell membrane

pinches off between

copies

3) Results in 2

identical cells

http://www.youtube.com/watch?v=4lmwbBzClAc&feature=related

http://www.youtube.com/watch?v=gEwzDydciWc


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Bacteria Reproduction


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Eukaryotic Division

Information in DNA is

organized in genes

Gene - segment of

DNA that codes for

protein

Genes determine how

a persons body will

develop and function

Genes are onchromosomes


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Chromosome number

Different species havedifferent numbers of

chromosomes in their

nuclei

No particular pattern tochromosome numbers


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Human chromosomes

All human somatic

(body) cells contain

two sets/pairs of23 chromosomes

(total of46)

This is a karyotype.


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Chromosome number (cont.)Two types of cells:

1) Haploid cells (1n) - one

set of chromosomes

(gametes - sperm andegg)

2) Diploid cells (2n) - two

sets of chromosomes

(somatic cells - all othercells)


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Is this a boy or girl?

Of the 23 pairs ofchromosomes, 22 areautosomal

They have no effect ongender. They are thesame in males &females.

Sexchromosomes - thelast set determines

genderXX- female

XY- male


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When things go wrong

Changes in chromosome #

or structure can cause

abnormal development

Trisomy 21 - three copies of

chromosome #21 aka Downs syndrome

Karyotype - photo that

shows chromosomes

Used to determineabnormalities/mutations

Mutations -change in

chromosome structure


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Chromosome Mutations

12 3 4 5 6

12 3 4 5 6

Deletion something is missing (1 2 3 4 6)

Inversion - reversed (1 2 4 3 5 6)

Translocation - from another location(1 2 9 3 4 5 6)

Duplication - doubled (11 2 2 3 4 5 6)

Nondisjunction - failure to separate These will either be totally missing or an

entire extra copy will be present

chromosomes and cell reproduction

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