1. EQ: How are sexual and asexual reproduction alike and different?
Reproducing a Species
EQ: How are sexual and asexual reproduction alike and different?

2. Two Kinds of Reproduction
Asexual
Sexual
Mitosis
Only one parent cell is needed
Division results in offspring genetically identical to the parents
Regeneration (starfish, worms)
Uniform offspring
Large numbers offspring produced quickly
Meiosis
Two parent cells join
Sex cells
Sperm= males
Eggs = females
Offspring share traits with traits with their parents, but are not exactly like their parents
Diverse offspring
Longer period of time for offspring production
Added from Meiosis 2014

3. Meiosis
In 1903, an American graduate student named Walter Sutton made an important observation.
While studying grasshopper cells, Sutton observed that chromosomes occurred in distinct pairs
And that during meiosis, the chromosome pairs split, and each chromosome goes to its own cell.

4. Meiosis
While mitosis was cell division for growth, meiosis is cell division for sexual reproduction.
Meiosis happens when it’s time to reproduce an organism
Added from Meiosis 2014

5. The Big Idea There are TWO cell divisions
Mitosis has one division, but meiosis has TWO
You still have to remember PMATI, but you have to go though it twice
Prophase-Metaphase-Anaphase-Telophase-Interphase
Four cells are created from one.
Start with one, get four!
Each cell has only HALF the amount of DNA needed by a cell

6. The Big Idea
The steps are very simple, when you break it down, it’s just two PMATIs in a row.
Scientists call it Meiosis I and Meiosis II, but it’s just two PMATIs
The interphase that happens between the two PMATIs is very short and the DNA is not replicated
The resulting cells (sperm and eggs) have half the number of chromosomes (23 in humans) and are referred to as haploid cells.
This is basically like the PMATI of regular mitosis.

7. Meiosis I --- Almost like mitosis
Pairs of chromosomes line up at the center of the cell and then are pulled to each side.
The genetic material duplicates, the cell divides and two cells result

8. A Short Interphase
Normally, the cell would go about its business of living during its interphase, and slowly duplicate its chromosomes getting ready for its next mitotic division
But since this is meiosis, there is a very short interphase and division begins again!

9. Meiosis II is a bit different from mitosis..
During Prophase II, a process called crossing-over occurs.
This crossing over is an exchange of genes.
This leads to the genes being mixed up, and the cell is not an exact duplicate like in mitosis
The rest of the steps (Metaphase, Anaphase, Telophase) follow the patterns of mitosis and meiosis I, but instead of starting with one cell and ending with two, one cell becomes four!

10. The Big Idea
Instead of two new cells being created with equal numbers of chromosomes like mitosis, the cell divides a second time after the first.
Genetic material is mixed up, and different eggs/sperm from the same person have different genetic make up
The resulting cells (sperm and eggs) have half the number of chromosomes of a normal (diploid) body cell
Haploid cells
When a sperm fertilizes an egg, the resulting zygote (fertilized egg) receives one copy of each gene from the mother and one copy from the father. Thus, each person receives half of his/her genes from mom and the other half from dad.
Heredity All About You – slide 8 chromosome defintion

11. Genes and Chromosomes
Walter Sutton used his observations of meiosis, and his understanding of the work of another scientist named Gregor Mendel which stated that an offspring receives half its genetic information from its father and the other half from its mother,
And some creative thinking,
Sutton proposed something very important:
Genes are located on chromosomes

12. Genes and Chromosomes
Through his work, Sutton was able to show that the steps of meiosis explained the results of a scientist named Gregor Mendel’s experiments with pea plants.
Meiosis explained how characteristics were inherited.

13. Genes and Chromosomes
Information on chromosomes determines many of our traits.
Sex chromosomes carry the genes that determine gender

14. Genes and Chromosomes
Sex chromosomes are described as either “X” or “Y”
In humans, females have the genotype of XX
Males have the genotype of XY

15. Genes and Chromosomes So how was your gender determined?
During meiosis, only one of each of the chromosome pairs ends up in a sex cell.
All female sex cells (eggs) have one “X” chromosome
However, male sex cells (sperm), will have either an “X” or “Y”

16. Genes and Chromosomes
If an egg is fertilized by a sperm with an “X” chromosome, the offspring will be a female
Genotype: XX
Girls are X-cellent!!!
If the egg is fertilized by a sperm with a “Y” chromosome, the offspring will be a male
Genotype XY

17. Genes and Chromosomes
The Y chromosome does not carry all of the genes an X chromosome
Males only have one copy of the X chromosome
Females have two X chromosomes, so they carry two copies of each gene carried on the X chromosome.
This makes a backup gene available if one becomes damaged.
Males do not have this back up!

18. Genes and Chromosomes Examples: Color Blindness Hemophilia Baldness
The genes for certain disorders are carried on the X chromosome.
These disorders are called sex-linked disorders.
Because the gene for such disorders is recessive, males are more likely to be affected

19. Genetic Counseling
Many genetic disorders can be traced through a family tree.
If a couple is worried that they might pass a disease to their children, they may consult a genetic counselor.
These counselors often make use of a diagram called a pedigree, which is a tool for tracing a trait through generations of a family.
By making this pedigree, a counselor can often predict if a person is a carrier of a hereditary disease.

20. Cystic Fibrosis Pedigree

22. Comparing Asexual and Sexual Reproduction
EQ: How are asexual and sexual reproduction alike and different?

23. It’s a matter of survival …
Organisms within a species must reproduce if their species is to survive.
There are two types of reproduction:
Asexual Reproduction
Sexual Reproduction

24. Two Kinds of Reproduction
Asexual Reproduction
Sexual Reproduction
Mitosis
Only one parent cell is needed
Division results in offspring genetically identical to the parents
Regeneration (starfish, worms)
Uniform offspring
Large numbers offspring produced quickly
Meiosis
Two parent cells join
Sex cells
Sperm= males
Eggs = females
Offspring share traits with traits with their parents, but are not exactly like their parents
Diverse offspring
Longer period of time for offspring production

25. Comparing Asexual and Sexual Reproduction
For today’s activity, you will be divided into two groups:
New Mexico Whiptails who reproduce asexually
Parthenogensis: eggs undergo a chromosome doubling after meiosis and developing into lizards without being fertilized.
Collard Lizards who reproduce sexually

26. Comparing Asexual and Sexual Reproduction
The New Mexico Whiptails will work individually
Why?
What might be an advantage of asexual reproduction

27. Comparing Asexual and Sexual Reproduction
The Collard Lizards will work in pairs
Why?
What are advantages of sexual reproduction?

28. Comparing Asexual and Sexual Reproduction
In this activity, all New Mexico Whiptails will be given a blue square of paper, and all new offspring will be represented by a blue square of paper.
Collard lizards and their offspring will be represented by different colored squares of paper picked randomly from a bowl.
How do the papers analogize to real-life?

29. Comparing Asexual and Sexual Reproduction
In this activity, a round will equal one year.
Each year, the New Mexico Whiptails will get a blue square and each set of Collard Lizard parents will get a square from chosen randomly from the bowl.
Round 1, Year 1
Why do the New Mexico Whiptails offspring look alike?
Why are the Collard Lizard offspring varied?
Fill in chart
Number of organisms before reproduction (both)
Number of new offspring (both)
Total number of organisms (both)
Round 2, Year 2
Round 3, Year 3

30. Comparing Asexual and Sexual Reproduction
PREDATOR ALERT!!!
A rattlesnake strikes, kills and consumes one offspring from each New Mexico Whiptail and each set of Collard Lizard parents

31. Comparing Asexual and Sexual Reproduction
Round 4, Year 4
Round 5, Year 5
DISEASE!!!
An intestinal parasite is running through the populations of both the New Mexico Whiptails and the Collard Lizards.
Half of the New Mexico Whiptails die, and all of the Collard Lizards with the blue squares die as well
Round 6, Year 6
Complete questions at the bottom as a group
Complete: Advantages/Disadvantages Table collaboratively

32. Comparing Asexual and Sexual Reproduction

33. Selective Breeding
In selective breeding, organisms with desirable characteristics are mated.
Plants and animals are often selectively bred for higher food quality.
Dogs, cats and other pets are also commonly bred selectively.