1. This is a chromosome.

2. The DNA has been replicated (copied) and now there are 2 identical chromatides that are attached at the centromere. During anaphase these two identical chromatides are pulled apart so the new cell that is being formed will be identical to the initial cell. They will have the same DNA– genetic information. Making more cells identical to each other -- this is 1 way an organism grows This is also a chromosome

3. These two previously called chromatides have been split, no longer attached so we don’t call them chromatides anymore, they are called chromosomes once again. Humans have 46 chromosomes total. They exist in pairs, so 23 pair.

4. Humans have 46 chromosomes total. They exist in pairs, so 23 pair. How many from Mom = 23 How many from Dad = 23 So even though you are getting chromosomes/genetic information that is unique from mom and getting chromosomes/genetic information that is unique from dad you need information from both in order to have a complete set, all the information you need to give you the characteristics that make you – unique YOU

5. Humans have 46 chromosomes total. They exist in pairs, so 23 pair. How many from Mom = 23 How many from Dad = 23 Study Question # 9 The last page closely resembles an actual photograph of a set of replicated human chromosomes. You cut out the chromosomes we will get to what you need to do with them in just a bit....on the back of your lab. Then at the bottom of the page explain your pattern of choice.

6. Humans have 46 chromosomes total. They exist in pairs, so 23 pair. Mom gives 23 and Dad gives 23 The chromosome that each one pairs up with are called homologous chromosomes. Not only do they contain information regarding the same characteristics but they are also Not the same exact information-- one is from mom and one is from dad so it isn’t the same – but it is about the same thing –same characteristic. Homologous chromosomes have a corresponding chromosome from each parent

7. Humans have 46 chromosomes total. They exist in pairs, so 23 pair. Mom gives 23 and Dad gives 23 The chromosome that each one pairs up with are called homologous chromosomes. Not only do they contain information regarding the same characteristics but they are also the same length, and they have the same centromere position. Homologous chromosomes have a corresponding chromosome from each parent A cell that contains both sets of homologous chromosomes is called diploid, diploid = 2N, in humans 2N is 46.

8. Mitosis is what occurs for asexual reproduction. -Assists in the growth and repair of an organism. Meiosis is what occurs for sexual reproduction. The two have a few similarities, the basic structures chromatides, chromosomes, centrioles, spindle fibers, etc. *mitosis has 1 division *meiosis has 2 divisions *mitosis results in 2 cells that are genetically identical *meiosis results in 4 cells that are genetically unique

9. In interphase of meiosis 1, DNA is replicated (copied), and then the 2 identical chromatides attach at the centromere, this is just like mitosis. But then The now replicated identical chromatides find their homologous pair They are positioned next to each other.... so the duplicated homologous chromosomes are now hanging out together

10. In interphase of meiosis 1, DNA is replicated (copied), and then the 2 identical chromatides attach at the centromere, this is just like mitosis. But then The now replicated identical chromatides find their homologous pair Then the homologous pairs are separated from each other, but the attached duplicated chromosomes stay together. This assures that a member of each pair of homologous chromosomes goes into two separate cells.

11. In interphase of meiosis 1, DNA is replicated (copied), and then the 2 identical chromatides attach at the centromere, this is just like mitosis. But then The now replicated identical chromatides find their homologous pair Then the homologous pairs are separated from each other, but the attached duplicated chromosomes stay together. This assures that a member of each pair of homologous chromosomes goes into two separate cells. That means that the new cells that are being made, no matter what the chromosomes say the color of hair and eyes are –at least will have some information about hair and eye color.

12. In interphase of meiosis 1, DNA is replicated (copied), and then the 2 identical chromatides attach at the centromere, this is just like mitosis. But then The now replicated identical chromatides find their homologous pair Then the homologous pairs are separated from each other, but the attached duplicated chromosomes stay together. This assures that a member of each pair of homologous chromosomes goes into two separate cells. So now we will have 2 cells but they ARE NOT IDENTICAL like in mitosis.

13. Page 276 –Telophase 1 and Cytokinesis This completes the 1 st division, it is called Meiosis 1. Meiosis 1 results in 2 daughter cells where each do not contain both sets of chromosomes. They have half the number of chromosomes sets as the original. Containing only 1 set of chromosomes, half as many as the original –this is called haploid (N). Remember diploid (2N)

14. Both of these cells now begin a 2 nd division= BUT No DNA replication occurs beforehand =This is different!!! The chromosomes still line up in the middle, centrioles and spindle fibers are attached – metaphase. They are pulled apart – anaphase Telophase occurs too Cytokinesis also occurs But end result is 4 daughter cells, each are haploid (N) they have half as many chromosomes sets represented compared to the original cell.

15. Meiosis produces 4 genetically different haploid cells. How are each of them genetically unique??? These haploid cells are called gametes. In males gametes are sperm In females a gamete is an egg. Male gamete formation results in 4 equal sized sperm. In many female animals, the formation of a gamete results in only 1 large egg. Because during both divisions one cell receives most of the cytoplasm, this is the one that results in a successfully formed gamete.

16. Sexual reproduction results in offspring with greater genetic variation....... Meiosis provides a mechanism that prevents doubling and re-doubling of chromosome number with every generation, and also provides a mechanism that adds to variation with every generation. 2 ways this occurs is through Recombination of chromosomes and crossing over....

17. As homologous chromosomes pair up in meiosis 1 they exchange portions of their chromatids. This process of exchange is called crossing over.

18. Meiosis produces 4 genetically different haploid cells. These haploid cells, these are called gametes. In males gametes are sperm In females a gamete is an egg. Male gamete formation results in 4 equal sized sperm. In many female animals, the formation of a gamete results in only 1 large egg. 4 gametes are made but only 1 survives. During the formation of a female egg, in both divisions one cell receives most of the cytoplasm, this is the one that results in a successfully formed gamete. The other 3 are called polar bodies

19. You can now complete study questions 4-8. They are asking about Meiosis.