1. 7.4 Human Genetics and Pedigrees
Set up Cornell Notes on pg. 81
Topic: 7.4 Human Genetics and Pedigrees
Essential Questions:
1. NO EQ
7.4 Human Genetics and Pedigrees
2.1 Atoms, Ions, and Molecules
KEY CONCEPT A combination of methods is used to study human genetics.

2. KEY CONCEPT A combination of methods is used to study human genetics.

3. Inheritance of many human traits is complex
The basic principles of genetics are the same in all sexually reproducing organisms.
Inheritance of many human traits is complex
Single-gene traits are important in understanding human genetics.
Ex: widow’s peak
Widow’s peak

4. A pedigree is a chart for tracing genes in a family.
Phenotypes are used to infer genotypes
Please copy on Pg. 80
Pedigree Key:
Boxes = males
Circles = females
Shaded = they show the trait
White = does not show trait
Half shaded = carrier
(Carrier= Only for recessive disorders)

5. How many females are in this family?
How many carriers?
How many children were in generation two?
How many offspring in generation three are affected by the trait?
Pg. 80
Generation 1
Generation 2
Generation 3
Generation 4

6. How many females are in this family? 11 How many carriers? 7
How many children were in generation two? 5
How many offspring in generation three are affected by the trait? 2
Generation 1
Generation 2
Generation 3
Generation 4

7. Autosomal Dominant Trait- Many family members will show the trait in the pedigree
Widow’s peak
No Widow’s peak

8. On pg. 81, please create this pedigree and answer the following questions:
 Jamie and Joe married in Joe was homozygous dominant for a Widow’s Peak, while Jamie did not have a Widow’s Peak. They had two children: A son named Kyle and a daughter named Marie.
Kyle married a woman who had no Widow’s Peak.
Marie never married.
Kyle and his wife had three children: Two boys and a girl.
Do Kyle and Marie have Widow’s Peaks?
What percent of Kyle’s children can we expect to have Widow’s Peaks?
What percent of Kyle’s children can we expect to have NO Widow’s Peaks?

9. ? ? ? Joe Jamie LL x ll 100% Ll LL ll Marie Kyle Ll ll Ll Ll x ll
50% Ll and 50% ll ? ? ?
Yes, Kyle and Marie have Widow’s Peaks
50% should have Widow’s Peaks
50% should have NO Widow’s Peaks

10. Autosomal Recessive Disorders will show up if carriers mate, may skip a few generations before reappearing. Only a few, will show the trait/disorder
On pg. 81, Fill in the genotypes of this incomplete pedigree. Shade if necessary. aa

11. On pg. 81, Fill in the genotypes of this incomplete pedigree
On pg. 81, Fill in the genotypes of this incomplete pedigree. Shade if necessary. aa

12. Albinism is an autosomal recessive disorder.
Fill in the genotypes. Shade if necessary Aa aa
Prob. ? Aa aa Aa Aa
Aa or AA Aa ? ? aa aa Aa
AA or Aa

13. Pg. 80
Mary and Joe were married in Both Mary and Joe were carriers for a fatal recessive disorder called Cystic Fibrosis. They had three children: A son named Pete who was a carrier, a son named Charles who was not a carrier and did not have the disease, and a girl named Isabel who died from Cystic Fibrosis. Pete married a woman who was homozygous dominant. Pete and his wife are worried about having a child with Cystic Fibrosis. Should they worry? What are the chances of any of their children having Cystic Fibrosis? Carriers?

14. ? ? ? Joe Mary Ff Ff Isabel Charles Pete Ff FF FF ff FF x Ff
O%- No chance of any of their children having the disorder
50% will be carriers ? ? ?

15. Females can carry sex-linked genetic disorders.
Males (XY) express all of their sex linked genes.
Expression of the disorder depends on which parent carries the allele and the sex of the child. X Y

16. Sex-linked traits: More males will show their sex-linked traits because they do not have another X to mask the disorder Ex: Color blindness
males
females

17. X-linked Color Blindness- Recessive XMXM= Normal XMXm= carrier
XmXm= CB
XMY= Normal
XmY= CB
XmY
XMXm
XMXm
XMXm
XMXm
XMY
XmY
On pg. 80, Fill in the genotypes of this incomplete pedigree. Shade if necessary. ?
XmY
XmY
XMXM or XMXm

18. A karyotype is a picture of all chromosomes in a cell.
X Y

19. Karyotypes can show changes in chromosomes.
deletion of part of a chromosome or loss of a chromosome
large changes in chromosomes
extra chromosomes or duplication of part of a chromosome

20. In down syndrome a person has an extra copy of chromosome 21.
In Klinefelter’s syndrome a male has an extra X (XXY).