Transcript Reproduction

Topic: Reproduction and
Development
Aim: How do cells divide?
Do Now: Explain the differences between sexual
and asexual reproduction. What types of things
reproduce sexually? Asexually?
HW: PAGE 96-97 10 MAIN POINTS & FINISH HANDOUT
What are the two types of
reproduction?
• Asexual reproduction
MITOSIS
• Sexual reproduction
MEIOSIS
What is ASEXUAL Reproduction?
• Requires one parent
that divides
– Asexual
“A”parent
• Offspring are identical
to parents
• Same # of chromosomes
How does ASEXUAL reproduction occur?
• MITOSIS – cell division
• One cell divides into two
identical daughter cells
(same # of chromosomes as
parent)
• Occurs in all body cells
EXCEPT sex cells
What are the steps of Mitosis?
•
•
•
•
•
Interphase
Prophase
Metaphase
Anaphase
Telophase
– Cytokinesis
Interphase
CHROMATIN
The mass of DNA
inside the nucleus
during interphase is
known as CHROMATIN.
Prophase
Metaphase
Anaphase
Telophase
What are the steps of Mitosis?
1. INTERPHASE: cell grows to mature size
2.
3.
4.
5.
and chromatin replicate (makes copy of
DNA)
PROPHASE: chromatin forms
chromosomes, nuclear membrane
disappears and spindle fibers form
METAPHASE: chromosomes line up in
the Middle of the cell
ANAPHASE: chromosomes separate and
move Away from each other
TELOPHASE: nuclear membrane starts
to form
What is Cytokinesis?
• Part of telophase
• Cell membrane pinches in
(cytoplasm separates) resulting
in 2 new cells
CYTOKINESIS
How is mitosis different in plant cells?
1. Cell membrane DOES NOT pinch in
• Instead a CELL PLATE forms
between 2 new cells
2. Plant cells do not have
centrioles (animal cells do)
CELL PLATE
Cytokinesis – Animal and Plant
What is Cancer?
• Abnormal and uncontrolled cell division
What are the different types of
ASEXUAL Reproduction?
1. Binary Fission – one celled organism
divides into two identical cells (mitosis)
•
•
Binary Fission means “equal division”
Examples: ameba and paramecia
2. Budding – unequal division of
organisms
•
Examples: hydra, yeast
3. Sporulation – spores (specialized cells)
develop into new organisms (mitosis)
•
Examples: mold, mushrooms
What are the different types of
ASEXUAL Reproduction?
4. Vegetative Propagation – Asexual
reproduction used by plants
a. Runners (strawberries)
b. Buds (potatoes)
c. Grafting (roses)
d. Bulbs (onions)
Binary Fission & Budding
BINARY FISSION
BUDDING
Sporulation
Vegetative Propagation
RUNNERS
GRAFTING
BUDS
BULBS
Topic: Reproduction and
Development
Aim: What is sexual
reproduction?
Do Now: Why does sexual
reproduction require two parents?
What is sexual reproduction?
• Requires 2 parent cells, each with half the
normal number of chromosomes
• Involves sex cells
• Human: sperm + egg → zygote
23 + 23 → 46
What is meiosis?
• Cell division occurs only in sex organs to
produce sex cells (sperm and egg)
• Produces 4 daughter cells with half the
number of chromosomes as parent cell
(23 in humans)
• 2 divisions (1 → 2 → 4)
Meiosis
How does meiosis occur in males?
• Occurs in testes to produce sperm
• Produces 4 new sperm cells
How does meiosis occur in
females?
• Occurs in ovaries
• Produces 1 egg cell and 3 polar bodies
What is fertilization?
• Union of egg and sperm to form a zygote
• Two types:
• Internal fertilization: occurs inside the
female (humans)
• External fertilization: occurs outside the
female (frogs); can occur on land or in
water
What happens to the zygote after
fertilization?
•
Zygote divides by MITOSIS to form 3
layers that will develop into different
parts of the embryo
1. Outer layer: forms the skin and nerves
2. Middle layer: forms muscles
3. Inner layer: forms heart and stomach
Outer layer
Middle layer
Inner layer