View
1
Download
0
Category
Preview:
Citation preview
QUIZ SESSION 3Punnett squares
Prof. Sabrina Pricl A.Y. 2020-2021
In rabbits, white fur (B) is dominant to black fur (b).
Q1. If you cross a BB male (P1) with a Bb female (P2), what are the possible genotypes (G) and phenotypes (P) of the 1st gen offspring? What is the percentage of each? Explain.
A1. 1. Fill the relevant G/P Punnett square
2. Fill in the Table
Quiz #1 – Punnett squares (Lesson 15)
2
B B
B
b
BBwhite
BBwhite
Bbwhite
Bbwhite
P1
P2
BB
Bb
white
white
50%
50%
Genotype ratio 1:1 Phenotype ratio: - (100% white)
Elements of Chemical and Molecular Biology – QUIZ SESSION 3
In cabbage butterflies, white wings (W) are dominant to yellow wings (w).Q2. If a Ww butterfly (P1) is crossed with a ww butterfly (P2), what are the possible genotypes (G) and phenotypes (P) of the 1st gen offspring? What is the percentage of each?A2. 1. Fill the relevant G/P Punnett square
2. Fill in the Table
Quiz #2 – Punnett squares (Lesson 15)
3
W w
w
w
Wwwhite
wwyellow
P1
P2
Wwww
whiteyellow
50%50%
wwyellow
Wwwhite
Genotype ratio 1:1 Phenotype ratio: 1:1
Elements of Chemical and Molecular Biology – QUIZ SESSION 3
In dogs there is a hereditary type of deafness caused by a recessivegene (d). Two dogs who carry the gene for deafness but have normal hearing are mated.Q3a. What is the genotype of the two mating dogs?A3a. Both dogs must have genotype Dd
Quiz #3 – Punnett squares (Lesson 15)
4Elements of Chemical and Molecular Biology – QUIZ SESSION 4
In dogs there is a hereditary type of deafness caused by a recessive gene (d). Two dogs who carry the gene for deafness but have normal hearing are mated.Q3b. what are the possible genotypes (G) and phenotypes (P) of the 1st gen offspring? What is the percentage of each?A3b. 1. Fill the relevant G/P Punnett square
2. Fill in the Table
Quiz #3 – Punnett squares (Lesson 15)
5
D d
D
d
DDnormal
Ddnormal
P1
P2
DD
dd
normal
deaf
25%
25%dddeaf
Ddnormal
Dd normal 50%
Genotype ratio 1:2:1 Phenotype ratio: 1:2:1Elements of Chemical and Molecular Biology – QUIZ SESSION 3
Quiz #4 – Punnett squares gets more complicatedIn rabbits, white fur (B) is dominant to black fur (b) and long ears (E) is dominant to short ears (e). Q4. If a breeder mates two rabbits heterozygous for both traits, which is the probability for the 1st generation offspring to be black with long ears?A4. 1. Write the genotypes of the mating rabbits à BbEe
2. Write the crossing à BbEe x BbEe3. Fill in the Punnett square for the corresponding
genotype4. Look for black fur and long ear rabbits and
remember:- to be black (recessive) genotype MUST be…(bb)- to have long ears (dominant) genotype must be…either (EE) or (Ee)
6
BE bEBe beP1
P2
BE
Be
bE
be
BBEE BBEe BbEE BbEe
BBEe BBee BbEe Bbee
BbEE BbEe bbEE bbEe
BbEe Bbee bbEe bbee
Elements of Chemical and Molecular Biology – QUIZ SESSION 3
Quiz #4 – Punnett squares gets more complicated4. Look for black fur and long ear rabbits and remember:
- to be black (recessive) genotype MUST be…(bb)
- to have long ears (dominant) genotype must be…either (EE) or (Ee)
5. There are 16 possibilities in total- you must discard all the genotypes that contain the
dominant allele B (otherwise white fur)- you must discard the genotype bbee (otherwise
short ears)- you are left with:
one genotype bbEE with probability 1/16one genotype bbEe with probability 2/16
Therefore, the probability to have a black rabbit with long ears by mating two rabbits with heterozygous genotypes for both traits is 3/16
7
BE bEBe beP1
P2
BE
Be
bE
be
bbEE
BBEE BBEe BbEE BbEe
BBEe BBee BbEe Bbee
BbEE BbEe
BbEe Bbee
bbEe
bbEe bbee
Elements of Chemical and Molecular Biology – QUIZ SESSION 3
Co-dominant traits
8Elements of Chemical and Molecular Biology – QUIZ SESSION 3
Quiz #5 – Punnett squares (Lesson 15)
9
Colors in some cows shows codominance. The genotypes for black and white cows are (BB) and (WW), respectively, while black and white cows are heterozygous (BW).
Q5. What are the possible genotypes (G) and phenotypes (P) of the 1st gen offspring obtained by crossing two black and white cows? What is the percentage of each?
A5. 1. Fill the relevant G/P Punnett square
2. Fill in the TableB W
B
W
BBblack
BWblack and
white
P1
P2
WWwhite
BWblack and
white
BB
WW
black
white
25%
25%
BW black and white 50%
Genotype ratio 1:2:1 Phenotype ratio: 1:2:1
Elements of Chemical and Molecular Biology – QUIZ SESSION 3
Incomplete dominant traits
10Elements of Chemical and Molecular Biology – QUIZ SESSION 3
Quiz #6 – Punnett squares (Lesson 15)
11
Colors in flowers shows incomplete dominance. The genotypes for red and white flowers are (RR) and (ww), respectively, while pink flowers are heterozygous (Rw).
Q6. What are the possible genotypes (G) and phenotypes (P) of the 1st gen offspring obtained by crossing two pink flowers? What is the percentage of each?
A6. 1. Fill the relevant G/P Punnett square
2. Fill in the TableR w
R
w
RRred
Rwpink
P1
P2
wwwhite
Rwpink
RR
ww
red
white
25%
25%
Rw pink 50%
Genotype ratio 1:2:1 Phenotype ratio: 1:2:1
Elements of Chemical and Molecular Biology – QUIZ SESSION 3
A fundamental example of co-dominance:The blood group genes
12Elements of Chemical and Molecular Biology – QUIZ SESSION 3
The human blood group genes
13Elements of Chemical and Molecular Biology – QUIZ SESSION 3
The human blood group genes
14Elements of Chemical and Molecular Biology – QUIZ SESSION 3
Quiz #7 – Punnett squares & blood groups
15
A male with blood type AB mates with a woman who is heterozygous for type A blood.
Q7. What are the possible genotypes (G) and phenotypes (P) of the 1st gen blood groups? What is
the percentage of each? Explain
A4. 1. The male G is (AB), the woman G is (AO)
2. Fill the relevant G/P Punnett square
3. Fill in the TableA B
A
O
AAA
ABAB
P1
P2
BOB
AOA
AA, AO
BO
A
B
50%
25%
AB AB 25%
Genotype ratio 1:1:1:1 Phenotype ratio: 2:1:1
Elements of Chemical and Molecular Biology – QUIZ SESSION 3
Sex-linked recessive traits
16Elements of Chemical and Molecular Biology – QUIZ SESSION 3
Sex-linked recessive traits• Sex-linked diseases are passed down through families through one of the X
or Y chromosomes (sex chromosomes)
• Dominant inheritance occurs when an abnormal gene from one parent causes disease, even though the matching gene from the other parent is normal• The abnormal gene dominates
• In recessive inheritance, both matching genes must be abnormal to cause disease• If only one gene in the pair is abnormal, the disease does not occur or it is mild
• Someone who has one abnormal gene (but no symptoms) is called a carrier• Carriers can pass abnormal genes to their children
17Elements of Chemical and Molecular Biology – QUIZ SESSION 3
Sex-linked recessive traits• The term sex-linked recessive most often refers to X-linked recessive• X-linked recessive diseases most often occur in males• Males have only one X chromosome. A single recessive gene on that X
chromosome will cause the disease• The Y chromosome is the other half of the XY gene pair in the male• The Y chromosome does NOT contain most of the genes of the X
chromosome• Because of that, it does not protect the male from the disease
• Diseases such as hemophilia and Duchenne muscular dystrophy occur from a recessive gene on the X chromosome• X-linked diseases are rare in women
18Elements of Chemical and Molecular Biology – QUIZ SESSION 3
X-linked recessive traits – Quiz #8
19
Human colorblindness is a typical human X-linked recessive trait.
Q7. If a man (P1) with colorblindness marries a woman (P2) who is not colorblind but carries the recessive allele, what can we say about the 1st gen offspring?
Xr Y
Xr
XR
P1
P2
XrXr
f,CBXrY
m,CBXRY
m,NCBXRXr
f,NCB
25% female with disease25% healthy female25% male with disease25% healthy male
Elements of Chemical and Molecular Biology – QUIZ SESSION 3
Recommended