1. HW: IP: Sex-linked Traits Punnett Square quiz tomorrow!
Thursday
April 6, 2017
I can:
predict offspring ratio of sex-linked traits
Agenda
(10) Catalyst
(20) GN: Sex-linked Traits
(35) Relay Race: Punnett Square Medley
(15) IP: Sex-linked Traits
(5) Exit Ticket
Catalyst
How many copies of each chromosome do we have? What is a chromosome?
What are sex chromosomes?
What is the genotype for females? What is the genotype for males?
Which chromosome determines “maleness”?
HW: IP: Sex-linked Traits
Punnett Square quiz tomorrow!

2. Turned in STEM Survey (100% = party Thursday, 13th!)

3. Pre-  Mid-Benchmark Scores (Unit 1: Ecology)
Bio (energy flow): 33.3%  35.5%
Bio (adaptations): 37.5%  52.9%
Bio (interactions): 37.5%  62.8%
Bio (pop. growth): 43.8%  52.9%
Bio (envnt. impact): 59.4%  52.9%
Bio (natural resources): 43.8%  79.4%
Overall growth:
+14%!

4. Pre-  Mid-Benchmark Scores (Unit 2: Biochemistry)
Bio (organelles): 18.8%  58.8%
Bio (types of cells): 6.3%  52.9%
Bio (homeostasis): 34.4%  26.5%
Bio (enzymes): 25.0%  N/A
Bio (PS & CR): 12.5%  47.1%
Bio (active transport): 34.4%  50.0%
Overall growth:
+26%!

5. Pre-  Mid-Benchmark Scores (Unit 3: Genetics, Micro)
Bio (mitosis): 21.9%  41.2%
Bio (DNA): 25.0%  94.1%
Bio (trnx & translation): 37.5%  41.2%
Bio (mutations): 35.4%  73.5%
Bio (meiosis): 21.9%  52.9%
Overall growth:
+32%!

6. Pre-  Mid-Benchmark Scores (Unit 4: Genetics, Macro)
Bio (Punnett Squares): 37.5%  58.8%
Overall growth:
+21%!

8. What are chromosomes made up of? Where are chromosomes located?

9. Genes located on the X chromosome are said to be sex-linked.
Recall that humans have 23 pairs of chromosomes.
Genes located on the X chromosome are said to be sex-linked.
Most genes are located on one of the 22 pairs of autosomes.
The X and Y chromosomes are sex chromosomes.

10. 1 in 100 women are colorblind but 1 in 10 men are colorblind
Can you see these numbers? If not, you may be red-green colorblind.
Why is it that…
1 in 100 women are colorblind
but 1 in 10 men are colorblind

11. We have 2 copies of most of our genes…
X chromosomes are much larger than Y chromosomes and contain important genes.
Y chromosomes are very small and only contain a maleness-determining factor. We don’t need a Y chromosome to function.
We have 2 copies of most of our genes…
Since males only have 1 copy of each gene on the X-chromosome, all X-linked alleles are expressed in males, even if they are recessive. X Y

12. Some alleles are neither dominant nor recessive, and many traits are controlled by multiple alleles or multiple genes.
complete dominance
incomplete dominance
co-dominance
multiple alleles
sex-linked

13. Traits determined by genes located on the X chromosome are said to be sex-linked traits.
Some common sex-linked traits:
red-green colorblindness – can’t distinguish between shades of green and red
hemophilia – blood doesn’t clot properly
Duchenne muscular dystrophy – progressive weakness of the muscles; life expectancy: 25 years
These diseases are all caused by a recessive allele.

14. Genotype Notation for Sex-linked Traits
XHXh
XHY
Female genotypes always have 2 X chromosomes.
each X chromosome carries an allele
a heterozygous female is called a carrier because she can pass the trait on to her offspring
Male genotypes always have 1 X and 1 Y chromosome.
the X chromosome carries an allele
the male will show whatever allele is on the X chromosome

15. What is the gender and phenotype of the individual?
XH = normal phenotype
Xh = hemophilia
What is the gender and phenotype of the individual? ?
XhXh
female,
hemophilia

16. What is the gender and phenotype of the individual?
XH = normal phenotype
Xh = hemophilia
What is the gender and phenotype of the individual? ?
XHXh
female,
carrier (normal)

17. What is the gender and phenotype of the individual?
XH = normal phenotype
Xh = hemophilia
What is the gender and phenotype of the individual? ?
XHXH
female,
normal

18. What is the gender and phenotype of the individual?
XH = normal phenotype
Xh = hemophilia
What is the gender and phenotype of the individual? ?
XHY
male,
normal

19. What is the gender and phenotype of the individual?
XH = normal phenotype
Xh = hemophilia
What is the gender and phenotype of the individual? ?
XhY
male,
hemophilia

20. What is the gender and phenotype of the individual?
XD = normal phenotype
Xd = Duchenne M.D.
What is the gender and phenotype of the individual? ?
XdY
male,
Duchenne

21. What is the gender and phenotype of the individual?
XD = normal phenotype
Xd = Duchenne M.D.
What is the gender and phenotype of the individual? ?
XDXd
female,
carrier (normal)

22. What is the gender and phenotype of the individual?
XD = normal phenotype
Xd = Duchenne M.D.
What is the gender and phenotype of the individual? ?
XDY
male,
normal

23. What is the gender and phenotype of the individual?
XD = normal phenotype
Xd = Duchenne M.D.
What is the gender and phenotype of the individual? ?
XDXD
female,
normal

24. What is the gender and phenotype of the individual?
XD = normal phenotype
Xd = Duchenne M.D.
What is the gender and phenotype of the individual? ?
XdXd
female,
Duchenne

25. Solving a Sex-linked Trait Problem
The allele for colorblindness is recessive and sex-linked. A carrier female has a child with a normal man. What are the likely genotypes of their children?
XC = normal vision
Xc = colorblind
Solving a Sex-linked Trait Problem XC Y
1. Read the problem. Underline the known alleles. Identify the type of inheritance as sex-linked. XC Y XC XC XC
2. Choose a letter to represent each allele in the problem.
3. Circle and/or write down the genotypes of the parents. Each cross needs a mother (XX) and father (XY). XC Y Xc Xc Xc
4. Set up and solve Punnett Square.
5. Highlight and answer what the question is asking.
XCXC = 25%
XCY = 25%
XCXc = 25%
XcY = 25%
parents: XCXc x XCY

26. Punnett Square Relay Race
There will be an assortment of inheritance problems (complete dominance, incomplete dominance, co-dominance, sex-linked trait) on the board
I will read the question and you will write on your boards (one at a time)
Type of inheritance
Alleles
Parental genotypes
The answer to the question
You will have 30 seconds for questions 1-3 and 1 minute for question 4
You will get points for each correct answer
Winning team will get +2 on the quiz or candy!

27. Question 1
A man with type AB blood marries a woman with type O blood. What percent of their children will have type A blood?
Type of inheritance?
Alleles?
Parental genotypes?
Answer to question?
Co-dominance
IA = type A
IB = type B
i = type O IA IB
IAIB x ii
IAi
IBi
50% type A blood i
IAi
IBi i

28. Question 2
Snapdragons can be red, white or pink. If a red snapdragon is crossed with a white snapdragon, what percent of the offspring will be pink?
Type of inheritance?
Alleles?
Parental genotypes?
Answer to question?
Incomplete
R = red
W = white
RR x WW R R
100% pink RW RW W RW RW W

29. Question 3
Hemophilia (h) is a recessive genetic disorder carried on the X chromosome. If a man with hemophilia marries a woman who is a carrier, what percent of their daughters will have hemophilia?
Type of inheritance?
Alleles?
Parental genotypes?
Answer to question?
Sex-linked
XH = no hemophilia
Xh = hemophilia
XhY x XHXh Xh Y
50% daughter with
hemophilia
XHXh
XHY XH
XhXh
XhY Xh

30. Question 4
Green seeds (G) are dominant to yellow seeds (g) in peas. If a homozygous dominant plant is crossed with a plant with yellow seeds, what percent of the offspring will have yellow seeds?
Type of inheritance?
Alleles?
Parental genotypes?
Answer to question?
Complete
G = green
g = yellow
GG x gg G G
0% yellow Gg Gg g Gg Gg g

31. Question 5
Horses can be black, white or grey. If a black horse is crossed with a grey horse, what percent of the offspring will be black?
Type of inheritance?
Alleles?
Parental genotypes?
Answer to question?
Incomplete
B = black
W = white
BB x BW B B
50% black BB BB B BW BW W

32. Question 6
Hitchhiker’s thumb is dominant to no hitchhiker’s thumb in humans. If two people who are heterozygous for hitchhiker’s thumb have a baby, what is the chance that the baby will have hitchiker’s thumb?
Type of inheritance?
Alleles?
Parental genotypes?
Answer to question?
Complete
H = hitchhiker’s thumb
h = no hitchhiker’s thumb H h
Hh x Hh HH Hh
75% Hitchhiker’s
thumb H Hh hh h

33. Question 7
A white cow (WW) mates with a roan cow (RW). What is the probability that they will produce a roan cow?
Type of inheritance?
Alleles?
Parental genotypes?
Answer to question?
Co-dominance
W = white
R = red
WW x RW W W
50% roan (RW) RW RW R WW WW W

34. Question 8
Brown eyes (B) are dominant to blue eyes (b) in humans. If a homozygous recessive person is crossed with a heterozygous person, what percent of the offspring will have brown eyes?
Type of inheritance?
Alleles?
Parental genotypes?
Answer to question?
complete
B = brown
b = blue
bb x Bb b b
50% brown Bb Bb B bb bb b

35. Question 9
Color-blindness (h) is a recessive genetic disorder carried on the X chromosome. If a man with color-blindness marries a woman without it, what percent of their son will have color-blindness?
Type of inheritance?
Alleles?
Parental genotypes?
Answer to question?
Sex-linked
XH = normal
Xh = color-blind
XhY x XHXh or XHXH Xh Y Xh Y
XHXh
XHY
XHXh
XHY XH XH
50% color-blind
son
0% color-blind
son
XhXh
XhY
XHXh
XHY Xh XH