Download Document

Set
CornellGenetics
Notes on pg.
7.4 up
Human
and Pedigrees
81
7.4
Human
Genetics and Pedigrees
2.1
Atoms,
Ions,
and Molecules
•Topic: 7.4 Human
Genetics and Pedigrees
KEY CONCEPT
A combination of methods
•Essential Questions:
is used to study human
1. NO EQ
genetics.
7.4 Human Genetics and Pedigrees
KEY CONCEPT
A combination of methods is used to study human
genetics.
7.4 Human Genetics and Pedigrees
• 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
7.4 Human Genetics and Pedigrees
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)
7.4 Human Genetics and Pedigrees
1.
2.
3.
4.
How many females are in this family?
Pg. 80
How many carriers?
How many children were in generation two?
How many offspring in generation three are affected by the trait?
Generation 1
Generation 2
Generation 3
Generation 4
7.4 Human Genetics and Pedigrees
1. How many females are in this family? 11
2. How many carriers? 7
3. How many children were in generation two? 5
4.
How many offspring in generation three are affected by the trait? 2
Generation 1
Generation 2
Generation 3
Generation 4
7.4 Human Genetics and Pedigrees
Autosomal Dominant Trait- Many family members will show the
trait in the pedigree
Widow’s peak
No Widow’s
peak
On
81, please
create thisand
pedigree
and answer the following
7.4pg.
Human
Genetics
Pedigrees
questions:
Jamie and Joe married in 1912. 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?
7.4 Human Genetics and Pedigrees
Joe
Jamie
LL x ll
• 100% Ll
ll
LL
ll
Kyle
Marie
Ll
Ll
Ll x ll
?
?
?
• 50% Ll and 50% ll
1. Yes, Kyle and Marie have Widow’s Peaks
2. 50% should have Widow’s Peaks
3. 50% should have NO Widow’s Peaks
7.4 Human Genetics and Pedigrees
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
7.4 Human Genetics and Pedigrees
On pg. 81, Fill in the
genotypes of this
incomplete pedigree.
Shade if necessary.
aa
7.4 Human Genetics and Pedigrees
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
7.4 Human Genetics and Pedigrees
Pg. 80
Mary and Joe were married in 1950.
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?
7.4 Human Genetics and Pedigrees
FF
?
?
Joe
Mary
Ff
Ff
Pete
Charles
Isabel
Ff
FF
ff
?
FF x Ff
• O%- No chance of
any of their children
having the disorder
• 50% will be carriers
7.4 Human Genetics and Pedigrees
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.
Y
X
7.4 Human Genetics and Pedigrees
• 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
7.4 Human Genetics and Pedigrees
XMXM= Normal
XMXm= carrier
XmXm= CB
XMY= Normal
XmY= CB
X-linked Color Blindness- Recessive
XmY
XmY
XMXm
On pg. 80, Fill in the
genotypes of this
incomplete pedigree.
Shade if necessary.
XMXm
XMXm
XMXm
XMY
?
XmY
XmY
XMXM or XMXm
7.4 Human Genetics and Pedigrees
• A karyotype is a picture of all chromosomes in a cell.
XY
7.4 Human Genetics and Pedigrees
• 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
7.4 Human Genetics and Pedigrees
• In down syndrome a
person has an extra copy
of chromosome 21.
• In Klinefelter’s syndrome
a male has an extra X
(XXY).