Name ____________________________________
Mrs. Geithner-Marron Bio 200
Date __________
Period _________
Unit 8: Genetics & Heredity & Unit 9: Human Genetic Disorders
Ch. 26: Inheritance of Traits & Ch. 27: Human Genetics
Genetics & Heredity
•
What is genetics?
– The study of _________________________
– ____________________________________________ from parents to offspring
Chromosomes in Cells
•
Remember…
– Body cells are ________________________________
•
_________ of each chromosome
–
1 from mom & 1 from dad
– Gametes (sperm & eggs) are ______________________
•
_________________ of each chromosome
–
Why? _________________________________________________
Genes
•
Why is your combination of genes unique?
– _______________ … don’t know ______________________________________
•
get ½ of your chromosomes from mom & ½ from dad
•
____________________________
–
crossing over during _______________________________________
–
“independent assortment” of chromosomes based on alignment during
___________________________________
Genes & Alleles
•
What is a gene?
– section of ________________________________________________________
(ex. hair color, eye color, ear shape, etc.)
– genes are ________________________________________________________
•
different forms of genes for the same trait are called “________________”
Name ____________________________________
Mrs. Geithner-Marron Bio 200
Date __________
Period _________
Dominant & Recessive Alleles
•
Each parent contributes __________________________________________________
•
Can be:
– ______________________________________________
•
prevents expression of (“masks”/“hides”) recessive trait
– ______________________________________________
•
•
seen only when pure (homozygous) for trait
Represented with _____________________________________
– usually first letter of _____________________________
•
same letter used for _________________________
–
CAPITAL = ___________________________
–
lowercase = ___________________________
Allele Combinations
•
If both alleles are:
– the same
•
________________________________________ (pure) dominant (ex. AA)
•
________________________________________ (pure) recessive (ex. aa)
– different
•
________________________________________ (hybrid) (ex. Aa)
Genotype vs. Phenotype
•
__________________________________ = actual genetic make-up of individual (alleles)
– codes for phenotype (trait)
– represented by ____________________________________________________
•
represent alleles from mom & dad
–
•
ex. ___________________________________________________
________________________________ = outward (physical) expression of the genotype
– trait we _____________________
•
(due to) the protein that is produced
– usually represented by an ____________________________________________
•
ex. ________________________________________________________
Name ____________________________________
Mrs. Geithner-Marron Bio 200
Date __________
Period _________
Genotype is Expressed as a Phenotype
•
Ex. Let P = purple & p = white
– homozygous (pure) dominant
•
genotype _________
•
phenotype = _________
– heterozygous (hybrid)
•
genotype _________
•
phenotype = _________
–
___________ trait "masks/
hides" ____________ trait
– homozygous (pure) recessive
•
genotype _________
•
phenotype = _________
Predicting Traits in Offspring
•
Punnett Squares
– Help predict ______________________________________________________
•
Letters along top & side represent _________________________________
___________________________________________________________
•
Boxes represent ______________________________________________
___________________________________________________________
–
Can be used to determine ___________________________________
Name ____________________________________
Mrs. Geithner-Marron Bio 200
Date __________
Period _________
Making a Punnett Square
1. Determine the genotypes of
the parent organisms.
2. Write down your "cross"
(mating).
Making a Punnett Square
• Parents are Tt & tt genotypes…
– So… Tt x tt is our cross
3. Draw a Punnett square.
4. "Split" the letters of the
genotype for each parent & put
them "outside" the Punnett
square (one on left & one on top)
to represent the possible alleles
in the gametes.
5. Determine the possible
genotypes of the offspring by
filling in the Punnett square.
6. Summarize results (genotypes & phenotypes of offspring)

Parent Pea Plants ("P" Generation)
o Genotypes: __________________________
o Phenotypes: __________________________

Offspring ("F1" Generation)
o Genotypes: __________________________
o Phenotypes: __________________________
Passing Traits to Offspring & Probability
•
Probability
– ________________________________________________________________
– What is the chance of getting heads? _______________ Tails? _______________
•
If you flip two coins, of getting 2 heads? __________ 2 tails? ___________
•
What is the chance of a couple having a boy? ________ A girl? ___________
Of having four boys? _________________ Five girls? _________________
Name ____________________________________
Mrs. Geithner-Marron Bio 200
Date __________
Period _________
Passing Traits to Offspring & Ratios
•
_____________________________ = probable ratio
of genotypes in offspring of a cross
– Ex. If cross Pp & Pp
•
•
_______________________________
___________________ = probable ratio of phenotypes
resulting from the genotypic ratio
•
•
Ex. If cross Pp & Pp
•
_______________________________
___________________________ = ratio expected based on
probability (Punnett Square)
•
_____________________________ = what actually occurs
•
Why would these be different?
– __________________________________________
– __________________________________________
Passing Traits to Offspring
•
If one parent is homozygous dominant & other is homozygous recessive
– each parent can only produce gametes with _______________________________
– All offspring will always have:
•
____________________________________________________ genotype
–
•
_________________________________ phenotype
–
•
ex. ______________________
ex. ___________________________________________________
If both parents are heterozygous
– each parent can produce gametes with ___________________________________
– Offspring will always have:
•
________________________________________________ genotype ratio
–
•
ex. ___________________________________________________
_______________________________________________ phenotype ratio
–
ex. ___________________________________________________
Name ____________________________________
Mrs. Geithner-Marron Bio 200
Date __________
Period _________
– the Father of Genetics (1822-1884)
Mendel’s Experiments
•
Studied garden pea plants
– 7 different traits with clearly different forms
•
•
Tried to determine how these traits were passed from parent to offspring
Mated pure purple parent (_____) & pure white parent (_____)
– All offspring had:
•
______________________ phenotype
•
_______________________________ genotype
–
•
___________
Heterozygous (hybrid) offspring allowed to self- pollinate
– So… ______________________
•
New offspring ______________________________
Mendel’s Principle of Dominance
•
Mendel noted that one form dominates over the other
– dominant trait ____________________________________________________
•
Ex. In peas, purple x white gives all purple offspring
–
PUPRLE = ____________________
–
white = ______________________
Dominant/Recessive is Not Always the Mode of Inheritance
•
Traits are not always as clearly defined as the 7 pea plant traits Mendel studied
– Examples of non-dominant/recessive inheritance
•
________________________________________
•
________________________________________
•
________________________________________
•
________________________________________
Name ____________________________________
Mrs. Geithner-Marron Bio 200
Date __________
Period _________
Sex Determination
•
humans have ________ chromosomes (in body cells)
– ______________
•
•
Pairs 1 – 22 = _________________________________________________
•
23rd pair determines gender = ____________________________________
–
__________ = female
–
__________ = male
Which parent’s chromosomes determines if the offspring will be a
boy or girl???? _____________ Why? ___________________
_________________________________________________
Sex-linked Inheritance
•
X & Y chromosomes _____________________________________________________
– ______ is bigger & carries more genes
•
Males will have only 1 allele for traits carried only on X
– called ___________________________________________________________
•
Ex.:
–
In Drosophila (fruit flies) _________________________________
–
In humans  ____________________________________________
– X-linked traits & disorders are more common in males
•
Why??? ____________________________________________________
Sex-linked Inheritance
___________________________________________________________
•
Predictions made using ___________________________________________________
• Predictions made using Punnett square
Consider
the sex
Y) & genes
– Consider the sex chromosomes (X–or
Y) & genes
theychromosomes
carry (shown (X
as or
superscript/
exponent) together as a unit…
•
they carry (shown as superscript/exponent)
together as a unit…
• ex. XG (= dominant gene), Xg (= recessive gene), Y (= no
ex. ________________________________________________________
gene)
– If a female is _____________________________,
If adisorder,
female isbut
heterozygous,
she does not show the trait/have –
the
is a
she does not show the
_________________________________________
•
trait/have the disorder,
can __________________________________
but is a carrier
• can pass gene
to offspring
XG female Xg
XG X G
XG X g
XG Y
Xg Y
XG
Male
Y
Name ____________________________________
Mrs. Geithner-Marron Bio 200
Sex-linked Inheritance (cont'd)
•
Ex. In Drosophila (fruit flies)  ______________________
– What are the sex, genotype, & phenotype of each offspring?
•
Top picture: ______________________________
________________________________________
–
Are there any female carriers for the white eye
gene? _______________________________
•
Bottom picture: ______________________________
________________________________________
–
Are there any female carriers for the white eye
gene? _______________________________
Codominance
•
heterozygote (hybrid)
________________________________________________
– shown by ____________________________________
•
Ex. Roan cow
–
phenotype = ________________________
_________________________________
–
genotype = _________________________
Multiple Alleles
•
______________________ different forms of an allele exist
– but individual ________________________________
•
Ex. _____________________________________________
–
exhibits _________________________________ (3)
•
________________
•
________________
•
________________
– also exhibits ________________________
•
____________ (A & B are ________________________)
–
____ (o is ________________________)
– So… (________ = ________) > ________
Date __________
Period _________
Name ____________________________________
Mrs. Geithner-Marron Bio 200
Date __________
Period _________
Human Genetic Disorders
•
Due to DNA mutation (usually recessive) or chromosome abnormalities (in # or structure)
– Causes production of ________________________
•
Examples:
–
–
Autosomal recessive disorders (***most genetic disorders)
•
________________________________
•
________________________________
•
________________________________
Autosomal dominant disorders
•
–
–
________________________________
Sex-linked disorders
•
________________________________
•
________________________________
Chromosomal abnormality disorders
•
________________________________
•
________________________________
Autosomal Recessive Disorders
•
To be affected, must be __________________________________________________
– Cystic Fibrosis
– Sickle-cell Anemia
– Tay-Sachs Disease
Autosomal Dominant Disorders
•
To be affected, can be _____________________________
_______________________________________________
– Huntington’s Disease
Name ____________________________________
Mrs. Geithner-Marron Bio 200
Date __________
Period _________
Sex-linked Disorders
•
_____________________ is X-linked recessive
– If mother is carrier & father has hemophilia:
•
genotypic ratio? _____________________________
_________________________________________
•
phenotypic ratio? ____________________________
_________________________________________
– If mother is carrier & father is normal:
•
Make a Punnett square (to the right)
–
genotypic ratio? _________
_____________________
______________________
–
phenotypic ratio? _________
______________________________________________________
•
_________________________ is X-linked recessive
– In this Punnett square, what are the genotypes &
phenotypes of the parents?
•
•
genotypes:
–
mom = _____________
–
dad = ______________
phenotypes
–
mom = _____________
–
dad = ______________
Chromosomal Abnormalities in Number
•
abnormal number of chromosomes:
– Caused by ________________________
•
failure of paired chromosomes to
___________________________
during meiosis 1 or meiosis 2
Name ____________________________________
Mrs. Geithner-Marron Bio 200
Date __________
Period _________
Chromosomal Abnormality Disorders
•
_______________________________________ (trisomy 21)
– person has ____________________ of chromosome # 21
•
•
Caused by _______________________________
Klinefelter’s Syndrome
– ____________________________________ disorder
•
Males have extra copy of ________ chromosome
–
•
XXY (or 47, XXY b/c 47 total chromosomes)
cause by ______________________________
Chromosomal Abnormalities in Structure
•
abnormal structure of chromosomes:
− ___________________________________________
___________________________________________
Detecting Abnormalities
•
____________________________________________________________________
– “picture of human chromosomes” (as seen above for Down Syndrome & Klinefelter’s
Syndrome)
•
From blood sample
–
•
Can detect extra chromosomes or chromosomal abnormalities
____________________________________________
– sample of fluid surrounding fetus
•
•
can detect Down Syndrome
____________________________________________
– sample of cells from chorion