Table of Contents
Chapter: Cell Reproduction
Section 1: Cell Division and Mitosis
Section 2: Sexual Reproduction
and Meiosis
Section 3: DNA
Cell Division and Mitosis
1
Why is cell division important?
• Multicellular organisms need cell division to
grow and replace dead cells
• Unicellular organisms divide to reproduce
Cell Division and Mitosis
1
Cell Division and Mitosis
1
Interphase
• Hereditary material copies
• Organelles grow
and duplicate
Cell Division and Mitosis
1
Mitosis
• Mitosis - nucleus divides to form two
identical nuclei.
• Steps of mitosis - prophase, metaphase,
anaphase, and telophase.
P M A T
Cell Division and Mitosis
1
Steps of Mitosis
• Chromosome - structure
in the nucleus that
contains hereditary
material.
Cell Division and Mitosis
1
Steps of Mitosis
• Chromatids- 2 tightly coiled thickened,
identical strands
Cell Division and Mitosis
1
Steps of Mitosis
• Prophase
• Pairs of chromatids
visible
• Nucleolus and
nuclear membrane
disintegrate
• Centrioles move to
opposite ends of cell
• Spindle fibers form
Cell Division and Mitosis
1
Steps of Mitosis
• Metaphase
• Spindle fibers
attach to
centromere of
chromatid
• Chromatids
line up across
Middle
Cell Division and Mitosis
1
Steps of Mitosis
• Anaphase
• Spindle fibers
shorten
• Chromatids
separate and move
to opposite ends
• Each chromatid
now called a
chromosome
Cell Division and Mitosis
1
Steps of Mitosis
• Telophase
• Spindle fibers
start to
disappear
• Chromosomes
start to uncoil
• New nucleus
forms.
Cell Division and Mitosis
1
Division of the Cytoplasm
• After mitosis the entire cell splits
• Plant cells – cell
plate appears
Click box to view movie.
Cell Division and Mitosis
1
Results of Mitosis
• 2 identical nuclei
• 2 cells instead of 1
Cell Division and Mitosis
1
Asexual Reproduction
• Asexual
reproduction - new
organism with
identical genes
(sometimes more
than one) is
produced from one
organism.
Cell Division and Mitosis
1
Cellular Asexual Reproduction
• Fission – cells
without a
nucelus copy
gentetic
material and
divide
Cell Division and Mitosis
1
Budding and Regeneration
• Budding – bud
develops and
breaks away as a
new organism
Cell Division and Mitosis
1
Budding and Regeneration
• Regeneration uses cell division
to regrow body
parts
• Examples:
sponges,
planaria,
seastars
Section Check
1
Question 1
Many-celled organisms grow by _______.
Answer
The answer is cell division. Cell division
increases the total number of cells in an
organism.
Section Check
1
Question 2
What is the longest part of the cell cycle?
Section Check
1
Answer
The answer is interphase. Interphase is the
period of growth and development in a
eukaryotic cell.
Section Check
1
Question 3
_______ is the process in which the nucleus
divides to form two identical nuclei.
Answer
The answer is mitosis. Each new nucleus that
is produced is identical to the original nucleus.
Sexual Reproduction and Meiosis
2
Sexual Reproduction
• Sexual
reproduction two sex cells
come together.
• Sperm - formed in
testes
• Eggs - formed in
ovaries
Sexual Reproduction and Meiosis
2
Sexual Reproduction
• Fertilization - joining of an egg and a sperm
• Zygote – cell made when they join
Sexual Reproduction and Meiosis
2
Diploid Cells
• Diploid - cells
with pairs of
similar
chromosomes
• Humans – 23
pairs, 46 total
chromosomes
Sexual Reproduction and Meiosis
2
Haploid Cells
• Haploid – cells that do not have pairs of
chromosomes
Sexual Reproduction and Meiosis
2
Meiosis and Sex Cells
• Meiosis - produces haploid sex cells.
Sexual Reproduction and Meiosis
2
Meiosis I and Meiosis II.
Sexual Reproduction and Meiosis
2
Meiosis I
Sexual Reproduction and Meiosis
2
Meiosis I
• Prophase I –
pairs of
chromosome
s come
together
Sexual Reproduction and Meiosis
2
Meiosis I
• Metaphase I - pairs
of duplicated
chromosomes line
up in the center of
the cell.
Sexual Reproduction and Meiosis
2
Meiosis I
• Anaphase I - 2 pairs
of chromatids
separate
Sexual Reproduction and Meiosis
2
Meiosis I
• Telophase I
• Cytoplasm
divides
• 2 new cells
form
Sexual Reproduction and Meiosis
2
Meiosis II
Sexual Reproduction and Meiosis
2
Meiosis II
• Prophase II
• Duplicated
chromosomes
and spindle
fibers reappear
Sexual Reproduction and Meiosis
2
Meiosis II
• Metaphase II
• Duplicated
chromosomes
move to the
middle
Sexual Reproduction and Meiosis
2
Meiosis II
• Anaphase II
• Centromere divides
• Chromatids move to
opposite ends of the
cell.
Sexual Reproduction and Meiosis
2
Meiosis II
• Telophase II
• Spindle fibers
disappear
• Nuclear
membranes
form
Sexual Reproduction and Meiosis
2
Summary of Meiosis
Click box to view movie.
Sexual Reproduction and Meiosis
2
Mistakes of Meiosis
Section Check
2
Question 1
_______ is the joining of an egg and a sperm.
Answer
The answer is fertilization. Fertilization
occurs during sexual reproduction.
Section Check
2
Question 2
_______ and _______ are the two types of
cells your body forms.
A. body and sex
B. egg and sperm
C. meiosis and mitosis
D. zygote and embryo
Section Check
2
Answer
The answer is A. Egg cells and sperm cells are
both types of sex cells.
Section Check
2
Question 3
Which best
describes
the sperm
and egg?
Section Check
2
A. typical body cells
B. haploid cells
C. zygotes
D. diploid cells
Section Check
2
Answer
The answer is B. Sperm and eggs are sex cells
that do not have pairs of chromosomes.
What is DNA?
http://www.comedycentral.com/motherload/index.jhtml?ml_video=91511
DNA
3
What is DNA?
• DNA – contains
the cell’s
hereditary material
• Found in
nucleus
• Passes
information to
offspring
DNA
3
DNA’s Structure
• Watson & Crick
(1953) made a model
of a DNA molecule.
DNA
3
A DNA Model
DNA
3
A DNA Model
• Nitrogen bases
• Adenine
• Thymine
• Guanine
• Cytosine
AT Grannies Cabin
DNA
3
A DNA Model
• A–T
• G–C
• A always
pairs with T
and G with C
DNA
3
Copying DNA
DNA
3
Genes
• Gene - a section of DNA on a chromosome
that codes to make a specific protein
DNA
3
Genes
• Genes say what order
to put amino acids to
make a specific
protein.
• RNA – carries codes
for making proteins to
the ribosomes
DNA
3
Ribonucleic Acid
• RNA has the same bases as DNA except
Thymine (T) is replaced with Uracil (U)
• 3 kinds
• messenger RNA
(mRNA)
• ribosomal (rRNA)
• transfer RNA (tRNA).
DNA
3
Ribonucleic Acid
• Ribosomes - made of rRNA.
• tRNA - bring amino acids to these
ribosomes.
• mRNA codes for a
specific tRNA
molecule to attach
amino acids
• Proteins are
made!
DNA
3
Mutations
• Mutations - any permanent change in the
DNA sequence of a gene or chromosome
• Caused by:
• X-rays
• Sunlight
• Chemicals
DNA
3
Results of a Mutation
• Can be good – add diversity to species
Section Check
3
Question 1
_______ is the chemical code that is stored in
the cell’s hereditary material.
Answer
The answer is deoxyribonucleic acid, or DNA.
DNA contains information for an organism’s
growth and function.
Section Check
3
Question 2
Which is not a nitrogen base of DNA?
A. adenine
B. guanine
C. kerosene
D. thymine
Section Check
3
Answer
The answer is C. The forth kind of nitrogen
base is cytosine.
Section Check
3
Question 3
This illustration represents the production of
_______?
A. DNA
B. genes
C. proteins
D. RNA
Section Check
3
Answer
The answer is C. Cells need DNA, RNA, and
amino acids to make proteins.
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