Transcript Chromosomes and Cell Reproduction The Cell Cycle The cell cycle

Chromosomes
and Cell
Reproduction
The Cell Cycle
The cell cycle is a repeating
sequence of cellular growth
and division during the life of
an organism.
A cell spends 90 percent of its
time in the first three phases of
the cycle.
G0
PHASE
DNA
SYNTHESIS
CELL
GROWTH
GROWTH &
PREP. FOR
MITOSIS
M PASE
A cell will enter the last two
phases of the cell cycle only if
it is about to divide.
key checkpoints at which
feedback signals from the cell
can trigger the next phase of
the cell cycle (green light).
Overview
of the cell cycle
Cell Cycle
Movie/
Game
Bacterial cells divide to
reproduce
Binary fission is a form of
asexual reproduction that
produces identical
offspring: Mitosis
Chromosome Structure
Chromosomes are the coiled
up version of DNA.
They consist of DNA and
proteins: histones and
nonhistones
How Chromosomes
Coil
Each half of a chromosome is
an exact copy called a
chromatid.
Chromatids are attached at the
center called a centromere.
A gene is a segment of DNA
that codes for a protein or RNA
molecule.
Cell Types
Somatic Cells
Gametes
Chromosome Numbers
Types: Autosomes and Sex
Chromosomes (XX or XY).
Humans: 22 pair of
homologous chromosomes
and 1 pair of sex
chromosomes.
Chromosome Numbers
All of the cells in the body,
other than gametes are Diploid
(2n=46 in humans).
Gametes contain only one set
of chromosomes: Haploid
(n=23 in humans).
Different species have
different numbers of
chromosomes.
Change in chromosome number
Humans who are missing even
one of the 46 chromosomes
usually do not survive.
Humans with more than two
copies of a chromosome, result
in a condition called trisomy.
Abnormalities in chromosome
number can be detected by
analyzing a karyotype.
Nondisjunction during the
production of gametes results in
gametes having more or less
chromosomes than normal.
Pictures called karyotypes can
detect problems after conception.
Karyotypes Explained
When control is lost: cancer
Cancer is the uncontrolled
growth of cells.
Mutations in genes that control
cell division may result in
cancer.
Cancer Biology
All the Details
The Phases of Mitosis
Interphase
Prophase
Metaphase
Anaphase
Telophase
The Jazzy
Version of
Mitosis
MITOSIS
Cytokinesis
I Prefer My Awesome Teacher…Cool!
Prophase
1. Chromosomes
coil and
become visible.
CENTRIOLES
MITOTIC
SPINDLE
NUCLEAR
ENVELOPE
2. Nuclear
envelope &
nucleolus
breaks down.
3. Mitotic Spindle
fibers begin to
form.
CENTROMERE
HOMOLOGUES
Metaphase
1. Chromosomes
line up along the
equator of the
cell.
2. Spindle fibers
attach to
kinetochore.
3. Centrioles
migrate to the
poles of the cell.
Anaphase
1. Spindle fibers
begin to shorten.
2. Chromatids
separate.
3. Chromatids
begin moving
toward the poles
of the cell.
1. Nuclear
envelope
reforms.
2. Cleavage
furrow forms
pinching the
cytoplasm.
3. Chromosomes
uncoil.
4. Cytokinesis
begins.
Telophase
Cytokinesis
During telophase, cytokinesis
occurs.
During cytokinesis, the
cytoplasm of the cell is divided
in half, and the cell membrane
grows to enclose each cell.
Cleavage
In
Action
Meiosis
USA 300,000,000 strong and growing
Meiosis produces gametes and
reduces the number in chromosomes
in half.
The following presents mitosis on the
left and the corresponding meiosis
phase on the right….notice the
differences.
First Link First
Prophase
Prophase I
GENTEIC
RECOMBINATION
INDEPENDENT
ASSORTMENT
SYNAPSIS
Metaphase
Metaphase I
Anaphase
Anaphase I
Telophase
& Cytokinesis
Telophase I
& Cytokinesis I
None
Prophase II
None
Metaphase II
None
Anaphase II
None
Telophase II
& Cytokinesis II
Formation of Gametes
Spermatogenesis
spermatids
Oogenesis
OVUM
Third Link
Comparison of
OOGENESIS
&
SPERMATOGENISIS
So How Do Mitosis and Meiosis
Compare?
.
Comparison of
Mitosis and Meiosis
Types of Reproduction
Sexual and Asexual