Download Sexual Reproduction

REPRODUCTION
2 Kinds of Reproduction
Asexual -- One parent
Sexual -- Two parents
Specifically-Sperm and Egg
Chromosomes and Cell Division
Chromosomes – Structures in a cell’s
nucleus that contain genes.
Genes – Found on chromosome in cell.
Gives living thing a certain trait and tells a
cell how to grow/develop.
How do all forms of asexual
reproduction end in an organism?
Through the process of
MITOSIS!
(Form of reproduction requiring only one parent.)
Why do organisms go
through asexual
reproduction??
1. Grow
2. Repair
3. Replacement
Cell Division — 6 phases
Mitosis — 4 phases
1. Interphase —normal life functions
Toward the end—chromosomes duplicate
Once duplicated- 92
Humans- 46
Sister chromatids held together- centromere
2. Prophase-- Mitosis begins
Nuclear membrane breaks down
Centrioles begin to move & Spindle forms between
3. Metaphase- Centromeres line up in the MIDDLE
4. Anaphase-- Centromeres split—move
to opposite sides
5. Telophase-- Mitosis is complete!
Nuclear membrane appears
6. Cytokinesis-- Cytoplasm divides
End result==2 NEW DAUGHTER CELLS
Exactly like the parent cell!
Is this a problem?? Why?
Cell Division/MITOSIS!!
Interphase
I
Prophase
Painted
Metaphase
Anaphase
My
Aunt’s
Toes
Telophase
Cytokinesis
Crimson!
Actual “Mitosis” only happens in phases 2-5!
Sexual Reproduction
Production of new organism from 2 parents,
a male and a female.
Process called
MEIOSIS
Results in the formation of 4 daughter cells
called GAMETES (sex cells)
Gametes—reproductive cells that have
only half the number of chromosomes as
the parent cell
What is the name of the gametes in humans?
SPERM & EGG
23
23
chromosomes
chromosomes
46
chromosomes
- New person not exactly like each parent.
2 complete cells join, new baby has twice the chromosomes as
each parent.
Prophase 1—chromosome
number is doubled
Metaphase 1--line up in the
middle
Anaphase 1—sister chromatids
begin pulling apart
Telophase/Cytokinesis 1-Two new daughter cells
NO PROPHASE!!!!
Metaphase 2—Line up
in the middle
Anaphase 2 &
Telophase 2—Pulls
apart and separates
End Result—4 new
cells with half of
the number of
chromosomes as
the parents
Let’s Compare!!
Number of
parents
Type of cell
division
Number of
daughter cells
produced
Genetic Makeup
of offspring
Asexual
Reproduction
Sexual
Reproduction
1
2
Mitosis
Meiosis
2
4 (gametes)
Identical to the
parent
Unique; different
from parents
Meiosis
(Process that produces sex cells with ½ number of
chromosomes of parent cell.)
46
24
46 chromosomes
Sperm or Egg Cells
23
23
46
23
Sperm or Egg Cell
23
Let’s watch meiosis in action!
Advantages/Disadvantages of
Asexual/Sexual Reproduction
Asexual Reproduction
Sexual Reproduction
Organism
does not
need a mate
to produce
offspring.
Gives
species
variation.
Offspring
exactly
like parents.
2 parents
needed
for
reproduction.
Species
(Group of similar organisms that can mate with one
another and produce fertile offspring.)
Why mitosis and meiosis?