Welcome! 3/16/15
OBJECTIVE—Students will:
 Finish analyzing pedigrees
 Review sex-linked traits and pedigrees
 Show understanding on Quiz 5.3
CATALYST—
1. Is the pedigree dominant
or recessive?
2. Is it autosomal or sex-linked?
3. What is the genotype of III.1?
HOMEWORK/REMINDERS— Sex-linked HW
DUE Today; ISN Check TOMORROW; All
missing work DUE 3/27/15
Catalyst
Determining the genotypes in a
pedigree for Sex-Linked Traits
HINT: Sex linked traits often show
passing from MOTHER TO SON.
 More MALES are affected than
females.

Determining the genotypes in a
pedigree for Autosomal Traits

What trait is colored in?
◦ Dominant usually appears more often
◦ Recessive will appear less often


Look at the parents…
Look at the kids…
◦ If both parents do NOT show the trait, but a
child does…the trait is RECESSIVE


Sometimes you might not be able to determine
if a dominant genotype is BB or Bb
If it is an autosomal trait, it will usually affect
males and females equally.
Your Turn!


Goal: Create a pedigree to show the passing of hitchhiker’s thumb.
(HINT: the “affected” individuals will have a hitchhiker thumb).
Directions:
1. Read the following family clues out loud as a group.
2. Review the key for making pedigrees...
3. Draw the pedigree for this family on a piece of chart paper.
DRAW IN PENCIL FIRST. You may also want to make a rough draft
on a piece of scratch paper.
4. Read the following description and color in the squares or circles
for the affected individuals.
5. Once you’re pedigree has been approved by Mrs. Reigel, you can
make a final draft on your chart paper, add colors and a KEY!
Don’t forget to add Roman Numerals for each generation, and
numbers to each person in a generation.
6. Now look back at your pedigree, add GENOYPES to each person!
(If an individual is dominant, you might have to write “Rr or RR”)
*** BONUS: If you finish early, complete the analysis questions found
on the back of your directions.***
Gallery Walk
With you group, go to another group’s
pedigree.
 Answer the analysis questions about their
pedigree in your notebook.
 You will have 5 minutes with your group
at each pedigree.

Sex-Linked Review

The 44 non sex chromosomes are called
autosomes
◦ Genes found on these chromosomes are called
autosomal traits

The other 2 chromosomes are sex
chromosomes
◦ They are X and Y females are XX and males
are XY
Sex-Linked Review

The genes found on the sex
chromosomes are called sex-linked
◦ They are found on the X chromosome

Females have 2 copies of these alleles,
males only have 1
◦ This is how females can be a carrier of
recessive sex-linked disorders
Sex-linked Punnett Squares: I DO
Xh = Hemophilia
 XH = Normal
 So…a carrier female mates with
a normal male…
What are the genotypes for the parents?
BE CAREFUL

Sex-linked Punnett Squares: I DO
XH
XH
Y
Xh
Sex-linked Punnett Squares: I DO
“Drop it
like it’s
hot!”
XH
Y
XH
Xh
XH
Xh
XH
Xh
Sex-linked Punnett Squares: I DO
“Do the
Cupid
Shuffle…to XH
the right, to
the right!”
Y
XH
Xh
XHXH
XhXH
XHY
Xh Y
Sex-linked Punnett Squares: I DO
XH
Y
XH
Xh
XHXH
XhXH
XHY
XhY
What is the chance that:
•The sons will have hemophila?
•The daughters will have hemophilia?
•Their children will have hemophilia?
Complete Practice Problems!
Look for clues about the parents and
children
 Remember that if it is sex-linked you
must use XX and XY
 Dominant and recessive stay the same
 “Carrier” means heterozygous

Quiz Review
Complete the Quiz Review handout.
 If you get stuck, use your notes, ask a
partner
 We will check the answers in 20 minutes

Quiz 5.3 Sex-Linked & Pedigrees
Look for key words
 Annotate!
 Underline genotypes/phenotypes
 For the pedigree, make sure you decide if
it is autosomal/sex-linked and
dominant/recessive BEFORE you write
any genotypes.

Wrap Up
Quiz Review handout on Page 65
 HW 5.3 will go on page 64 (update your
table of contents)
 Update Table of Contents
 Turn in WWO
 ISN DUE Tomorrow for ISN Check #5
