Download Cell Reproduction

Cell Rep. 1
Cell Reproduction
I. Chromosomes (Eukaryotic Cells)
*Recall…DNA molecules are long, thin, and made of six
billion pairs of nucleotides (DNA double helix)(twisted stair
case)
A. CHROMOSOME STRUCTURE
1) Chromosomes coiled DNA with proteins and rod
shaped
2) Histones the proteins that DNA wraps around
3) 2 identical Chromatids make up a Chromosome
4) Chromatids held together by a Centromere
5) Centromere the constricted area of the
chromosome
B. CHROMOSOME NUMBERS
* Each species has a specific # of chromosomes
1) Sex Chromosomes and Autosomes
a) Sex Chromosomesdetermine sex of organism
1) XYmale…XXfemale
b) Autosomesall the other chromosomes
c) Humans 46 chromosomes (23 from each
parent)2 of 46 Sex Chr.44 are autosomes
d) Homologous Chromosomes chromosomes
(2) that are same shape, size, and have the
same genes (autosomes)
II. Cell Division
*Cells come from cellscell division is the process of cell
reproduction.
A. CELL DIVISION IN PROKARYOTES
1) Binary fission division of prokaryotic cell into 2
Offspring
B. CELL DIVISION IN EUKARYOTES
*Mitosis result1 cell makes 2 genetically
identical cells (unicellular and tissues in Multicell.)
Cell Rep. 2
* Meiosisreduces chromosome # by ½.
new cell joins with another organisms cell
…ex.-->sperm(23) and egg (23)
…which gives a new cell with (46)
1) The Cell Cycle
a) a repeating set of events that make up the life of
a cell
b) Interphase the time between cell divisions
 DNA is copied
3) Mitosis
a) division of nucleushappens during cell
division
b) continuous process
c) 4 steps of mitosis (in the following order)
1)Prophase (2)Metaphase (3)Anaphase
(4) Telophase
d) Prophase copied DNA coils into
chromosomes.
e) Metaphase chromosomes line up along
midline of dividing cell
f) Anaphasechromatids move towards opposite
ends (poles)(centrosomes) of cell.
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g) Telophase chromosomes reach poles and
cytoplasm divides…then cell divides
(Cytokinesis)
III. MEIOSIS (gives haploid reproductive cells)
*A process of nuclear division that reduces the number of
chromosomes in new cells to half the number in the original
cell.
*Humansmeiosis…producesgametes(haploid)(23chr.)
(egg)(sperm)zygote46chr.
A. STAGES OF MEIOSIS (Meiosis I and Meiosis II)
1) Meiosis I
a) Synapsis homologous chromosomes pair up
one is paternal (your dads)one is
maternal (your moms)
b) Tetrad pair of homologous chromosomes
c) Crossing over homologous chromosomes
Cell Rep. 4
switch chromatid pieces (during synapsis)
genetic material is exchanged between
maternal and paternal chromosomes
this produces new mix of genetic
material (genetic recombination)
d) End of Meiosis I2 cells w/half the number
of chromosomes (23)
2) Meiosis II
a) Each cell after MeiosisI goes through MeiosisII
b) so2 cells give 4cells(sperm cells)or
(egg cell)
d) End of Meiosis II4 cells each w/ (23 chrom.)
4) Asexual and Sexual Reproduction
a) Asexual Reproduction offspring produced
from 1 parent (binary fission (unicellular))or
(mitosis)
Parents AND offspring genetically
IDENTICAL
b) Sexual Reproduction (meiosis)…
(sperm + egg)=offspring
Parents AND offspring genetically
DIFFERENT