LESSON 2 CH20
What are chromosomes? _______________________________________________________
What is the portion of chromosomes that makes each human unique to another? ________
 What is the shape of this structure? __________________________________
Chromosomes:
 How many pairs do you have? __________ How many total ____________
 What letter chromosome signifies a female __________ Male __________
 Which parent determines the gender of the fetus? ______________
Why__________________________________________________________________
What are the structures in the chromosomes that carry our genetic traits? _____________
 What are some examples of the genetic traits our genes deal with
_________________
__________________
___________________
 How does this process of creating traits come about? ___________________________
______________________________________________________________________
****For each trait there are 2 genes, they can be called _______________ or ______________
Dominant Gene: ______________________________________________________________
Recessive Gene: _______________________________________________________________
Example: Each parent offers a gene for eye color… Let’s say that mom offers a gene for blue eye color
and dad offers a gene for brown eye color. If the brown gene is dominant what color eyes would the
offspring have? _____________________________________
How would you figure out the chances (roughly) that your child could have blue/brown eyes? First you
would need to know what genes you carried for the trait (dominant/recessive homozygous/heterozygous…)
 In the area below take notes on homozygous/heterozygous for dominant or recessive
traits and pennant squares. You will need to know this for the test, keep in mind there is
actually much more that goes into deciding what traits an offspring has, this is the tip of
the iceberg…
Example: What are the chances these two have a child with brown eyes/Blue eyes?
MOM: Bb
DAD: BB
B: Dominant gene for brown eye color
b: Recessive gene blue eye color
Answer: _________________________________
________________________________________
________________________________________
Example: What are the chances these two have a child with brown eyes/Blue eyes?
MOM: Bb
DAD: bb
B: Dominant gene for brown eye color
b: Recessive gene blue eye color
Answer: _________________________________
________________________________________
________________________________________
***We also may use this to determine probabilities that the offspring may end up with genetic disorder
based on parent being a “carrier” of a recessive gene…
How do you check for genetic disorders?
1) Amniocentesis: __________________________________________________________
________________________________________________________________________
________________________________________________________________________
2) Ultrasound: ______________________________________________________________
________________________________________________________________________
________________________________________________________________________
3) Chorionic Villi Sampling: __________________________________________________
________________________________________________________________________
________________________________________________________________________
Genetic Disorders: page 465/466 in your text.
Sickle Cell Anemia: ___________________________________________________________
_____________________________________________________________________________
Phenylketonuria: _____________________________________________________________
_____________________________________________________________________________
Tay-Sachs Disease: ____________________________________________________________
_____________________________________________________________________________
Cystic Fibrosis: _______________________________________________________________
_____________________________________________________________________________
Down Syndrome: _____________________________________________________________
_____________________________________________________________________________
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