Download Welcome! 3/12/14

Welcome! 3/12/14
OBJECTIVE—Students will analyze and interpret
Punnett Squares and Pedigrees of autosomal and
sex-linked traits by showing 80% mastery on
Quiz 5.3
CATALYST—
Aliens from Mars have 2 eyes (dominant) or 4
eyes (recessive). This gene is carried on the Xchromosome. Show the cross of a heterozygous
2-eyed female with a 4-eyed male.
HOMEWORK/REMINDERS—
All missing work DUE 3/28/14 END OF 3rd
Quarter
Let’s 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 Yà females are XX and males
are XY
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
Review Practice
—  Hemophilia
is a sex-linked recessive
disorder.
◦  What is the genotype of a male with
hemophilia?
◦  What is the genotype of a female carrier?
◦  SHOW the cross (Punnett Square)
Pedigrees
• Pedigrees
are maps of
inheritance
•  Help us determine if a trait is
dominant, recessive, or sexlinked.
• Pedigrees are just like maps and
can trace the path of a trait
through many generations and
marriages.
#1-2
—  Generations
numerals
are noted with Roman
◦  The generations start at the top and go down.
—  Each
individual in a generation is labeled
with a regular number
—  How
many
generations are in
this pedigree?
I
II
III
IV
#3
— 
— 
— 
In a pedigree, males are
represented by squares
◦  If a square is colored in, it means that
male has the trait that is being
discussed
How many males are there on your
worksheet? ____
How many of the males have
hemophilia?____
#4
—  Females
are represented by circles
◦  If a circle is colored in, the female has the trait
◦  SOMETIMES, the circles will be half coloredin. This means that the female is a CARRIER,
she is heterozygous for the trait.
#4 Carriers
—  Many
times, Pedigrees will make it easy
and show the carriers by giving them a
half colored-in circle on the pedigree.
—  How
many females are there on your
pedigree? __
—  How many have hemophilia? __
—  How many of the females are carriers? __
#5 Helpful hint
—  If
there are more affected individuals than
unaffected, the trait in question is
DOMINANT!
—  If there are fewer affected individuals, the
trait is RECESSIVE! (Carriers are not
affected)
—  Is the trait on our pedigree dominant or
recessive?
#6
—  Marriages
are noted by a
horizontal line connecting a
circle and a square
◦  How many marriages are there
in your pedigree?
#7
—  A
line perpendicular to a marriage line
indicates the offspring.
— 
ON YOUR PEDIGREE:
◦  How many children did the first couple in generation I
have? ____
◦  How many children did the couple in generation III have?
____
Determining the genotypes in a
pedigree for Sex-Linked Traits
—  Determining
genotypes from pedigrees is
EASY
—  Sex-linked traits:
◦  Step 1: Determine the genotypes of the
males first.
–  Determine if the trait is dominant or recessive,
then give the appropriate allele to their X
chromosome.
— 
Step 2: Determine the female’s genotypes
◦  If the trait is recessive, any female with the trait
must have 2 recessive alleles attached to her X
chromosomes
◦  How many females have genotype XnXn ?_____
◦  If the female has the dominant trait, she can either
be homozygous dominant, or a carrier
(heterozygous)
–  The easiest way to determine this, is to look at her
offspring. If ANY offspring have the trait, male or female, the
mother MUST be a carrier, WHY?
◦  What is the genotype of individual III.4? ___
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?
—  Look
—  Look
at the parents…
at the kids…
◦  Dominant usually appears more often
◦  Recessive will appear less often
◦  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.
Pedigree Practice
—  Complete
Pedigree Practice.
—  Stay focused!
—  Look for clue words.
—  Ask yourself
◦  Is it showing the dominant or recessive?
◦  Is it sex-linked or autosomal?
◦  Who does it affect? More males or females?
◦  Whose genotype is easiest to figure out?
Pedigree Practice
Pedigree Practice
Pedigree Practice
Pedigree Practice
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. 
2. 
3. 
Read the following family clues out loud as a group.
Review the key for making pedigrees...
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.***
Quiz 5.3—Sex Linked Traits and
Pedigrees
—  Stay
focused
—  ANNOTATE genotypes and phenotypes
—  Eliminate answers
—  Ask yourself
◦  Is it dominant or recessive?
◦  Is it sex-linked or autosomal?
◦  Who does it affect?
◦  Whose genotype is easiest to figure out?
Exit Slip
1. 
2. 
3. 
How many school days until the HSA?
When does 3rd Quarter end?
What do YOU need to do before the
end of 3rd Quarter to make sure you are
on track? (List at least 3 things)