Download Daysheet 48 - We Read. We Write. We Work.

UNIT 4: DNA, Chromosomes, and Cell Division
DAYSHEET 48: Meiosis and Sexual Reproduction
Name _____________________________________
Biology I
Date: __________
Catalyst/Bellringer: Use your reading strategies as you read the article below about cancer.
Then answer the questions at the bottom.
Purpose: To find out what causes cancer
Activate Prior Knowledge: What do you already know about cancer?
CANCER
Cancer is a family of diseases that are caused by genetic mutations, or mistakes in DNA.
Mutations can be caused by many things, including exposure to UV rays or contact with certain
chemicals (like those found in cigarettes). Mutations can also occur by random chance when the DNA
is replicating. Usually mistakes are caught by the cell, but if they’re not the cell could become
cancerous.
The mutations that cause cancer all have one thing in common – they make the cell and grow
and divide uncontrollably. In cancer cells, mitosis happens at a very fast rate. If one cell grows and
divides uncontrollably, it can form a mass of cells called a tumor. The tumor can suck nutrients and
oxygen away from nearby cells in the body, causing healthy cells to die.
NORMAL
CELLS
CANCER
CELLS
Many tumors are benign (not dangerous). The tumor can be removed and the person can
continue to live a healthy life. But sometimes the cells in a tumor can begin to spread to other parts of
the body. When cancer cells spread, the cancer is said to be malignant. If this happens, the person may
need to get surgery, chemotherapy, or radiation treatment to try to kill the cancer cells.
1. What is a mutation? __________________________________________________________
2. What are some things that can cause mutations? ____________________________________
3. What type of mutation causes cancer? ____________________________________________
4. What is a tumor? ____________________________________________________________
5. What does it mean when a tumor is malignant? ____________________________________
Activity 1: Cornell Notes
Biology Objective / Essential Question:
Main Ideas / Questions:
1. What are the differences
between sexual and asexual
reproduction?
Notes:
Characteristic
Asexual Reproduction Sexual Reproduction
Bacteria – Binary Fission
Example
Yeast - Budding
# of Parents
Offspring
Where does the
DNA come from?
Advantages
Disadvantages
Asexual Reproduction: ______________________________________
_________________________________________________________
Sexual Reproduction: _______________________________________
_________________________________________________________
2. What cells are involved
in sexual reproduction?
How are they made?
 The sperm and egg are called ________________ and only have
_________ as much DNA has the other cells in our body. We say
these cells are ________________, and use the symbol _____
when talking about these cells.
 These cells are made by a process called ______________. During
this process, DNA from different chromosomes gets mixed up in a
process called __________________________________________.
This creates new combinations of genes and results in offspring
that are genetically unique.
Activity 1 Continued: Cornell Notes
Main Ideas / Questions:
Notes:
3. What about the other
cells in our body?
 The rest of our body cells (such as our skin cells, hair cells, brain
cells, cheek cells, etc.) are called ________________ cells. These
cells have _________________ the DNA, so we say they are
________________, and use the symbol ______ when talking
about these cells.
4. What are the steps of
sexual reproduction?
Summary
1N
2N
Steps to Calculating Chromosome Number
HAMMER out the question
Use your 1N and 2N columns to figure out what you have and what you are trying to find
Use the following rules to calculate chromosome number:
1N
2N
MULTIPLY BY 2
2N
1N
DIVIDE BY 2
Teacher Example:
1. A human skin cell has 46 chromosomes. How many chromosomes will be in a human egg cell
2. An egg cell of a cockroach has 5 chromosomes. How many chromosomes will be in the fertilized
zygote?
Your Turn:
3. A squirrel tail cell has 50 chromosomes. How many chromosomes are present an unfertilized
squirrel egg cell?
Activity 2: Time to Practice!
SOMATIC CELLS vs. GAMETES
Determine if the cells below are SOMATIC (BODY) CELLS or GAMETES. If the cell is a
SOMATIC CELL, write an S in the blank. If the cell is a GAMETE, write a G in the blank.
EXAMPLE: __S_ Eye cell
1. ____Cheek cell
2. ____Heart cell
3. ____Sperm cell
4. ____Skin cell
5. ____Nerve cell
6. ____Muscle cell
7. ____Egg cell
8. ____Lung cell
9. ____Liver cell
10. ____Hair cell
11. ____Stomach cell
12. ____Kidney cell
DIPLOID vs. HAPLOID
Determine if the cells below are HAPLOID or DIPLOID. If the cell is HAPLOID, write an H in the
blank. If the cell is DIPLOID, write a D in the blank.
EXAMPLE: __D_ Eye cell
1. ____Cheek cell
2. ____Heart cell
3. ____Sperm cell
4. ____Skin cell
5. ____Zygote
6. ____Muscle cell
7. ____Egg cell
8. ____Lung cell
9. ____Liver cell
10. ____Hair cell
11. ____Gametes
12. ____Kidney cell
SENTENCE COMPLETION
Circle the answer that best completes the sentences below.
1. Human skin cells are (HAPLOID / DIPLOID)
Human skin cells contain (23 / 46) chromosomes
Human skin cells are (SOMATIC / GAMETE) cells
2. Human egg and sperm cells are ( HAPLOID / DIPLOID)
Human egg and sperm cells contain (23 / 46) chromosomes
Human egg and sperm cells are (SOMATIC / GAMETE) cells
3. After the sperm fertilizes the egg, the resulting zygote has (23 / 46) chromosomes.
CALCULATING CHROMOSOME NUMBER
Use the steps listed below to solve the following problems
HAMMER out the question
Use your 1N and 2N columns to figure out what you have and what you are trying to find
Use the following rules to calculate chromosome number:
1N
2N
MULTIPLY BY 2
2N
1N
DIVIDE BY 2
1. A mosquito zygote contains 12 chromosomes. How many chromosomes are in a mosquito sperm
cell?
A. 0
B. 6
C. 12
D. 23
2. If a somatic cell in a snake contains 24 chromosomes, how many chromosomes would be in the
snake sperm cell?
A. 3
B. 6
C. 12
D. 24
E. 4
3. If a gamete in the common garden pea plant contains 7 chromosomes, how many chromosomes
would a garden pea plant’s leaf cell contain?
A. 0
B. 7
C. 14
D. 28
4. An orangutan zygote contains 48 chromosomes. How many chromosomes does an orangutan
zygote receive from the mother’s egg?
A. 0
B. 23
C. 46
D. 92
5. If the sperm cells of a fish contain 12 chromosomes, how many chromosomes would be found in
the diploid cells of that fish?
A. 3
B. 6
C. 12
D. 24
6. If an organism has a diploid number of 28, how many chromosomes would be found in one of its
unfertilized egg cells?
A. 7
B. 14
C. 28
D. 56
7. After a mouse egg cell containing 30 chromosomes is fertilized, how many chromosomes will be in
the zygote?
A. 0
B. 15
C. 45
D. 60
8. Horses have 64 chromosomes in each hair cell. How many chromosomes should be in each horse
gamete?
A. 16
B. 32
C. 64
D. 96
9. The bromeliad flower has 100 chromosomes in each haploid pollen cell. How many chromosomes
will be a bromeliad root cell?
A. 25
B. 50
C. 100
D. 200
10. The species Ursus maritimus has 70 chromosomes in each somatic cell. How many chromosomes
do Ursus maritimus receive from their father?
A. 15
B. 35
C. 70
D. 140
INTERPRETING DATA
TABLE 6-1 Chromosome Number of Various Organisms
Organism
2N Number of Chromosomes
Penicillium
4
Saccharomyces (yeast)
18
Mosquito
6
Housefly
12
Garden Pea
14
Corn
20
Fern
1,262
Frog
26
Human
46
Orangutan
48
Dog
78
Use Table 6-1 to answer the questions below. Assume that the chromosome numbers in the table for
each organism is 2n.
1. How many chromosomes would a DOG’S skin cell contain?____________________
How many chromosomes would a male DOG’S sperm cell contain?_____________
2. How many chromosomes would a FROG’S tongue cell contain?________________
How many chromosomes would a female FROG’S egg cell contain?_____________
3. How many chromosomes would a MOSQUITO wing cell contain?________________
How many chromosomes would a male MOSQUITO sperm cell contain?_________
4. Which organism has the MOST chromosomes? _____________________________
5. Which organism has the LEAST chromosomes? _____________________________
6. Do you think organism complexity is related to chromosome number? Why or why not?
Activity 3: Modeling Crossing Over
When sperm and egg are produced by the process of meiosis, new genetic combinations are
created through a process called crossing over. In crossing over, pairs of chromosomes get together and
exchange genes - pieces of DNA – creating new genetic combinations that never existed before! This is
the reason why even siblings with the same two parents usually look very different!
Directions: In order to create a model of crossing over follow the steps below:
1. Ask your teacher for a chromosome cut-out paper
2. Cut out the original chromosomes and paste them in the box labeled “Origin Chromosomes”
3. Cut out the crossing over chromosomes
4. Cut off a piece of the white chromosome, and a piece of the black chromosome and switch them!
5. Glue your new chromosome combinations in the box labeled “Crossed Over Chromosomes”
ORIGINAL CHROMOSOMES
CROSSED OVER CHROMOSOMES
HW48: Meiosis and Sexual Reproduction
Biology I
Name: _______________________________
Date: ____________________________
Below are the chromosome numbers for some common organisms. Fill in the blanks on the chart and
then answer the questions.
ORGANISM
SOMATIC CELL (2n)
GAMETE (n)
Human
46
23
Garden Pea
14
Fruit Fly
4
Tomato
24
Dog
78
Chimpanzee
Leopard frog
Corn
24
26
10
1. What is the diploid number of chromosome in corn? ______________
2. What is the haploid number of chromosome in corn? ______________
3. What is number of chromosome in tomato somatic cell? ______________
4. What is the number of chromosome in a leopard frog gamete? ______________
5. Which cells in the human contain only 23 chromosomes? ______________
6. What is the number of chromosomes in a human zygote? ______________
Calculating Chromosome Number:
1. Each giraffe somatic cell contains 20 chromosomes. How many chromosomes does a giraffe
sperm cell contain?
(A) 0
(B) 10
(C) 20
(D) 40
2. An elephant egg cell contains 15 chromosomes. How many chromosomes are found in the
fertilized elephant zygote?
(A) 0
(B) 7.5
(C) 15
(D) 30