1. Meiosis and Reproduction

2. Types of Reproduction
Asexual Reproduction – production of offspring that requires only one parent; all the genetic materials come from the one parent, so offspring are identical
Sexual Reproduction – production of offspring (kids) that requires one male and one female parent; chromosomes come from both parents

3. Meiosis Meiosis – the process by which sex cells are made
So we’re not talking about our body cells any more they get Mitosis were talking about GAMETES.
What is a
Gamete?

4. GAMETES Gametes – sex cells
Male sex cell is sperm; female sex cell is egg
The male and female sex cells unite (come together) in sexual reproduction to produce an organism, this process is called fertilization

5. Lets Label the Pictures
Egg
Sperm
Fertilization

6. Important Chromosome Information
Chromosomes are thread-like structures found in the nucleus that contain DNA (genetic material)
Chromosomes occur in Pairs
Homologous Chromosomes – chromosomes that have the same shape and size and carry information for the same traits (genes)
- For every chromosome an organism has, there is another one just like it

8. Replication
This one is from Pa
And this one is from Ma

9. Important Info Continued
Humans have 46 total chromosomes
Humans have 23 different chromosomes (since they all have a matching pair)
In all of our body cells (ex. skin cells, heart cells, liver cells, ect.) we have 46 total chromosomes
The chromosomes that we have 1/2 came from our mom and 1/2 came from our dad

10. Chromosomes in Gametes (Sex Cells)
If we make egg and sperm with 46 chromosomes each, how many chromosomes would our kids have when the sperm and egg unite? 92
What must we do with the number of chromosomes in our gametes (sperm and egg) to make sure our kids only have 46 chromosomes?
Cut the number in half

11. How many chromosomes are in the parent cell? 2  (Look here)
Where have I seen this?
chromosomes do not line up single file in the middle, homologous pairs line up side-by-side
How many chromosomes are in the daughter cells (sex cells)? 1
How many daughter cells (sex cells) are produced? 4

12. Mitosis vs. Meiosis occurs in body cells occurs in sex cells
involves only one division
Daughter cells look Identical to parent cells
have same # of chromosomes in daughter cells as parent
2 daughter cells produced
occurs in sex cells
involves two divisions
Daughter cells are NOT identical to parent cells
have half # of chromosomes in daughter cells as parent
4 daughter cells are produced

13. Reproduction The Process of Organisms making more organisms like themselves
2 Types
Asexual Reproduction – production of offspring that requires only one Parent
Sexual Reproduction – Production of offspring that requires 2 parents one Male and one Female Parent

14. Asexual Reproduction Offspring are Identical to the Parent
- Involves only one parent
Parent goes through the Cell Cycle and end up with offspring (kids)
Offspring are Identical to the Parent
Involves only the process of Mitosis

15. Asexual reproduction in single-celled organisms
Occurs by process of cell division and offspring are genetically identical to parent cell

16. Ex. of Cell Division
Binary Fission – when a cell divides into two identical cells that are equal in size
Occurs in bacteria

17. Ex. of Cell Division
Budding – when a cell divides into two identical cells that are unequal in size
Occurs in Yeast

18. This is Cloning NOT Budding

19. Asexual reproduction in Multi-cellular organisms
Some multi-cellular organisms can reproduce asexually by breaking off a body part. The body part then develops into a new organism
The new organism is genetically identical to the parent organism

20. Example
Plant Propagation – when parts on a plant (such as leaves or roots) are used to grow another plant

21. Example
Regeneration – when part of an animal is used to develop into an entire new animal
Ex. Sea Stars

22. Sexual Reproduction requires 2 parents
Offspring are NOT genetically identical to parent
½ genetic material comes from male and ½ comes from female
DAD
MOM

23. Necessary Requirements
In order for sexual reproduction to be successful, organisms need to make gametes that have half the # of chromosomes as a normal cell
 reason: the gamete will combine with another gamete to make an organism

24. Gametes Sex cells (cells involved in sexual reproduction)
Sperm in male & Egg in female
They only have 23 chromosomes in each. They are no longer paired

25. How are gametes made?
By a process called Meiosis

26. Meiosis
Parent Cell 4
Gametes