Name ____________________________________________ date _______ hour ______
10.2 Guided Reading Activity! Meiosis
Page 269
1. What is the electron microscope picture showing? ______________
Genes, Chromosomes, and Numbers
2. Where are genes located? _______________
3. How many are on each of the structures from question 2? _____________________
Diploid and haploid cells: pages 269-270
4. Pea plants have 14 chromosomes and therefore have _________ pairs.
Humans have 46 chromosomes and therefore have ________ pairs
5. One chromosome from the pair comes from your _________ and the other comes from your ________.
6. A cell with 2 of each kind of chromosome is called _____________ (2n)
One allele is located on each _____________________.
7. When an organism produces gametes (sex cells like sperm and egg) they contain _____ chromosome from each pair.
A cell with one of each kind is called ______________ (n)
Diploid (2n) number for humans = 46 (think di=2)
Haploid (n) number for humans = 23 (think hap = half)
8. Examine table 10.1 on page 270
Dad
23 chromosomes
in gametes
Mom
23 chromosomes
in gametes
You
46!
a. What is the diploid number of chromosomes for a dog?
__________ How about haploid? _____
b. What type of cell has a diploid number of chromosomes?
______________
c. What type of cell has a haploid number of chromosomes?
___________
How many chromosomes are in
your gametes? ____________
Homologous Chromosomes pages 270-271
9.
10.
11.
12.
Homologous chromosomes are __________chromosomes.
Each pair has genes for the __________________________.
Are the homologous chromosomes identical? ______________
Genes are arranged in the __________________ order.
13. Complete the Problem solving Lab 10-2
1. _________________________________________________________________________
2. _________________________________________________________________________
3. _________________________________________________________________________
4. _________________________________________________________________________
5. _________________________________________________________________________
14. Examine Figure 10.10
a. What would be the overall genotype of this set of homologous chromosomes? ___Aa__, ______and _______
b. What would be the overall phenotype for these traits? ________________________, _____________________,
________________________.
c. Allele Review: “a” is an allele for the trait of flower position. What is the other allele? _____
Page 271 - 272: Why Meiosis?
15. In mitosis, when a cell divides, the new cells have exactly the _______________________________________
_____________________________________________________________as the original cell.
16. Why do gametes have half the chromosomes as the other “body cells”? (Body cells can be heart cells, skin cells, etc.)
17. What is meiosis?
18. Meiosis consists of ______ separate divisions known as __________________ and _________________.
19. Meiosis begins with one ____________ and by the end there are ______________________________.
20. These haploid cells are ______________.
21. When a sperm fertilizes an egg, the resulting cell is called a ______________________.
22. How many chromosomes does it have now? ___________________________________
23. The zygote then develops by ________ into multicellular organisms.
24. The fusion of haploid sex cells is called _________________________________.
Pages 272-275: The Phases of Meiosis!!!!!!!!!!!!!!!
These are going to be more general questions to get you started on learning about meiosis.
25. First paragraph: What does the book suggest is a major difference between Mitosis and Meiosis?
26. Beginning with interphase, list the phases of meiosis in order. Page 273 is helpful for this.
I _________________________
Stages of Meiosis
P________________________
27. In the diagram, you begin with one cell, how many does it end with? _______
(look closely!)
28. Describe how interphase in meiosis is similar to interphase in mitosis.
M________________________
A_________________________
T_________________________
29. What is a tetrad?
P________________________
M________________________
A________________________
T_______________________
30. What is crossing over?
Phases of Meiosis – not including interphase
Write in the correct phase for each description, and then do the same for the pictures
Name of Phase
Description
1.
Spindles form in two new cells, and attach to chromosomes, - the chromosomes
here are made up of 2 sister chromatids.
2.
Spindle fibers move homologous chromosomes to opposite sides
3.
Spindle breaks down, nuclear membrane reforms, cytoplasm divides, 4 daughter
cells formed
4.
Chromosomes consisting of sister chromatids line up in the middle, just like in
mitosis
5.
Chromosomes coil up, spindle forms, homologous chromosomes come together to
form tetrad, crossing over occurs
6.
Sister chromatids separate and move to opposite ends.
7.
Spindle attaches to centromeres of each chromosome, and pull the tetrad to the
middle.
8.
Spindle breaks down, chromosomes uncoil, cytoplasm divides, 2 daughter cells are
formed
Don’t
forget the
back!
Don
Page 275-277: Meiosis Provides Genetic Variation
31. First paragraph: How is genetic produced?
32. Examine figure 10.13: What is different about the original chromosomes compared to the gametes?
What is this process called? (You have already written down the definition in another question!))
33. What is the definition of genetic recombination?
34. Examine “Genetic Recombination” on page 277. What analogy is used about crossing over? (read through steps 1-4)
Pages 278-279: Mistakes in Meiosis
35. What is nondisjunction?
36. How are trisomy, monosomy, and triploidy similar?