1. Science March 7, 2016 Genetics Day 9
Write in your agenda. Quiz – March 16 and Test – March 18.
1. Why do sex-linked disorders show up more in males? See # 25 on study guide.
2. Write the matching bases for: AAC GTG CCA
T TG CAC GGT
3. An allele whose trait always shows up when the allele is present.
4. Having two different alleles for a trait.
5. The process that occurs in sex cells by which the number of chromosomes is reduced by half.

2. Punnett Square Practice
We will pass out the Punnett square.

3. Review An allele that is masked when a dominant allele is present.
Recessive
A change in a gene or a chromosome.
Mutation
The different forms of a gene.
alleles
The scientific study of heredity.
Genetics

4. 5. Male sex chromosomes. XY
6. A mutation can occur if a nitrogen base is put in place of another. What is this called?
substitution
7. What are the sides of the DNA ladder made of?
Phosphates and sugars/deoxyribose

5. 8. Name the nitrogen bases.
Adenine
Thymine
Cytosine
Guanine

6. 9. Draw a Punnett square for this problem
9. Draw a Punnett square for this problem. Cross a homozygous yellow seed color with a homozygous green seed color.
Y= dominant yellow and y = recessive green Y Y y Yy y

7. Answer the Punnett square questions.
10. In which box is Tt? (Write the letter of the box.) b
11. In which box is TT? (Write the letter of the box.) a
12. In which box is tt? (Write the letter of the box.) c
T t T t a b c

8. Question 13. How does DNA relate to you? Chromosomes are made of DNA
Genes are on our chromosomes which determine traits we inherited.
DNA makes us who we are.

9. Humans have 46 chromosomes in body cells. We have always.
14. Why must the quality and quantity of DNA in cells remain the same from generation to generation?
Humans have 46 chromosomes in body cells. We have always.
Our great grandparents had 46 chromosomes in body cells. Future generations will.
Quality and quantity must remain the same for us to be healthy humans.

10. 6. List the parents.
A and B, C and D, F and G, H and I
7. List the carriers.
A, N
8. How many girls did parents C and D have?
two
Is this a sex linked trait?
Yes, because there are no male carriers X Y

11. Review 1. Write the matching bases for the DNA sequence. CCG ACG TCA
GGC TGC AGT
2. Mendel concluded from his experiments with pea plants that each trait he studied had two sets of instructions, one from each ___
Parent

12. 3. The number of chromosomes we have in our sex cells is ____.23
4. The number of chromosomes we have in our body cells is ____. 46
5. The process of selecting a few organisms with desired traits to serve as parents of the next generation.
Selective breeding

13. 6. One parent and the offspring are genetically identical to the parent. Binary fission, budding and mitosis are examples of this.
Asexual reproduction
Binary Fission Budding Budding
Yeast Cell Hydra

14. 7. Two parents and the offspring are genetically different from both parents. Egg and sperm cells.
Sexual reproduction
8. A chart or diagram used to trace a trait through generation of a family. A circle represents a female and a square represents a male.
Pedigree

15. 9. Male = XY Female = XX What kind of chromosomes are these?
Sex chromosomes
10. Why do sex linked disorders occur more often in males? Males have only ______________ and their Y chromosome has no allele to mask the recessive sex linked allele.
One X chromosome
11. The process that occurs in sex cells by which the number of chromosomes is reduced by half.
meiosis