Download of the cell

Cell Reproduction
The Cell Cycle
Interphase
 Divided into 3 phases:
 G1 = First Gap Phase – Cells grow and develop
 S = Synthesis Phase - DNA replication occurs
(i.e. chromosomes copied) in preparation for
making new cells during mitosis
 G2 =Second Gap Phase = centrioles replicate,
cell prepares for cell division, makes new cell
parts
Mitosis



Mitosis- the process of producing body cells
Cells produced are IDENTICAL to parent
cell- have same number of chromosomes of
parent cell
Four phases




Prophase
Metaphase
Anaphase
Telophase
Prophase
 Chromatin- shortens and
thickens, chromosomes
become visible
 Nuclear membrane and
nucleoli dissolves
 Spindle fibers form
 Centrioles move to
poles
Prophase





Centriole
Centromere
Spindle
Chromosome
(chromatids)
Aster
Metaphase
 Chromosomes
line-up in the
middle (equator)
of the cell
Anaphase
 Chromosomes
divide and are
pulled to opposite
poles
Telophase
 Chromosomes reach
the poles begin to
uncoil forming chromatin
 Nuclear membrane and
nucleoli form around the 2
new nuclei
 Spindle fibers disappear
 Cytokinesis begins
Cytokinesis
 The cytoplasm
distributed equally
between the 2 new
cells
 In animals, a
cleavage furrow
forms from outside in
 In plants, a cell
plate forms from
inside out
Animal
Plant
Cytokinesis in plants
A cell plate made up of cell-wall
components gradually forms in the middle
of the cell.
Cytokinesis in animals
A cleavage (or division) of the animal cell.
The membrane pinches together forming 2
cells
figure 09-08b.jpg
Figure 9.8
– Part 2
Figure 9.8 – Part 2
Mitosis consists of several different phases.
Can You Identify the Stages of Mitosis?
Put the
following
mitosis
stages in the
correct
sequence
Mitosis vs Meiosis
Characteristic
Mitosis
Cells produced Body cells
(somatic cells)
Chromosome
Same as
number
parent cell
Diploid 2N
Number of
1
divisions
Number of
2
cells produced
Meiosis
Sex cells
(gametes)
Half number of
parent cell
Haploid N
2
4
The Results
Products of Mitosis: 2 - 2n cells
2n
2n
2n
Diploid
Products of Meiosis: 4 - n cells
2n
n
n
n
n Haploid
Meiosis- forming sex cells
Process in which haploid cells are formed from diploid
cells
 In humans:
Parent 46
46 Parent
Diploid (2N)
Diploid (2N)

Chromosome number cut in half
Ovum23
Haploid (N)
23 Sperm
Haploid (N)
Fertilization
Zygote 46
Diploid (2N)
Chromosome Number Questions
1.If a horse retina cell has 36
chromosomes, how many
does a horse sperm cell have?
2.If the n = 4 for fruit flies, how
many chromosomes does a
wing cell have?
Chromosome Number Questions
3. In streptomycin fungus n = 11. What is
the diploid number for this species?
4. If n = 16 for goldfish how many
chromosome in a fin cell?
5. If 2n = 108 for black spruce trees then
what is the haploid number?
Meiosis
Meiosis I
Meiosis II
Crossing Over

Crossing Overexchange of
genetic
information by
non- sister
chromatids
during meiosis
Mistakes in Meiosis




Nondisjunction- failure of
chromosomes to separate properly
during meiosis
Trisomy- inherits an extra
chromosome
Monosomy- is missing a chromosome
Triploidy- inherits an extra set of
homologous chromosomes
Downs Syndrome
 Trisomy 21


Wide variety of problems

Developmental delays

Heart defects

Immune problems

Vision, hearing respiratory issues
Can also be very talented
Turner’s Syndrome
 Monosomy X
 Problems include
 Short stature
 Lack of ovarian
development
 Prone to kidney,
cardiovascular, and
thyroid problems
 Difficulties with spatial
orientation &
awareness