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Genetics Notes Handout – Section 7
DEFINITION
EXAMPLE
VOCABULARY
Phenotype
(see)
Physical
The physical
characteristics of
an individual
expressed using
______
words .
• dimples
• blue eyes
Genotype
(alleles)
Genes
genetic
The ___________
constitution of an
individual, written
into the DNA.
• Dd
• bb
Think.Pair.Share: If an individual born with brunette hair
dyes her hair blonde, does this alter the phenotype,
genotype, or both? Explain your reasoning.
Genetics Notes Handout – Section 7
ALLELES
DOMINANT
RECESSIVE
• The trait that is
• The letters used to • The trait that is
represent your
always expressed.
covered unless
genes
__________.
there are two
• There are 2
different forms of
each allele.
• Examples:
B
_____
b
_____
stronger
• The___________
of the two alleles.
B
• Example: _____
forms of the
recessive allele.
weaker
• The __________
of the two alleles.
b
• Example: _____
Genetics Notes Handout – Section 7
HOMOZYGOUS
(aka. pure, purebred,
true breeding)
(aka. hybrid)
Gene combinations of
the _______
same alleles.
Gene combinations of
different
____________
alleles.
Examples:
BB or _____
bb
_____
HETEROZYGOUS
Bb
Example: _____
Genetics Notes Handout – Section 8
Complete #1 in Section 8 of the notes.
Check your answers.
AA ____
AA:
Ho
Ee ____
Ee:
He
Ii ____
Ii:
He
Mm ____
Mm:
He
Bb ____
Bb:
He
ff ____
ff:
Ho
Jj ____
Jj:
He
nn ____
nn:
Ho
Cc ____
Cc:
He
Gg ____
Gg:
He
kk ____
kk:
Ho
oo ____
oo:
Ho
Genetics Notes Handout – Section 6
•
•
•
Now you will go back and write your possible
genotype(s) for each trait.
If you exhibit the recessive trait, your genotype must
be homozygous recessive for the trait.
If you exhibit the dominant trait, your genotype is
either homozygous dominant or heterozygous for the
trait.
Punnett Square Practice Worksheet
1.
2.
3.
4.
5.
6.
7.
Dominant allele:
s
R
c
T
a
L
Recessive allele:
l
c
T
M
y
g
True breeding trait:
SS
Tt
Gg
TT
cc
Mm
Hybrid trait:
Rr
Tt
GG
aa
ii
Cc
Homozygous dominant (pure dominant trait):
Ss
Bb
LL
GG
aa
gg
Homozygous recessive (pure recessive trait):
ll
TT
SS
Gg
yy
tt
Heterozygous:
Yy
RR
Ss
Tt
ff
Aa
f
G
A
t
Aa
bb
Ll
nn
AA
Cc
BB
ii
bb
PP
Punnett Square Practice Worksheet
•
Fill out the GENOTYPE AND PHENOTYPE chart for
rabbit fur color using your notes.
Homozygous
Dominant
Heterozygous
Homozygous
Recessive
GENOTYPE
PHENOTYPE
BB
Black
Bb
Black
bb
White
Warm-up
The genotype of an organism describes the –
a.
b.
c.
d.
codons that make up the genes of the organisms.
number of genes on the organism’s chromosomes
genetic make up of a trait
type of chromosomes present in the nucleus
_______________________
Genotype/Phenotype Practice
EARLOBES
• Do you have attached or detached earlobes?
• Ask your neighbor to check if you’re not sure.
• Make a key for the possible genotypes.
– Typically the letter for the dominant trait is used.
• Predict your genotype using the key you just created.
Dominant: Detached
Recessive: Attached
GENOTYPES
Detached: DD or Dd
Attached: dd
Spongebob Practice #1
Ho
He
He
Ho
Ho
He
He
Ho
Ho
Ho
Ho
Ho
Homozygous (Ho)
Heterozygous (He)
Spongebob Practice #2
yellow
square
yellow
square
blue
round
Spongebob Practice #3
TT or Tt
PP or Pp
pp
tt
How To Fill Out a Punnett Square
• The big letter is always
PUNNETT SQUARE:
written FIRST.
_____
B _____
b
• Try to complete as many
problems as you can on _____
B
BB Bb
the front of you Punnett
Square Exercises
b
_____
bb
Bb
without talking.
• Raise your hand if you
have a question.
We Do – Spongebob Practice #4
Genotypes: Ss and ss
Step 1
ALLELE KEY:
SS
____ = homo. square
Ss
____ = heterozygous
ss
____ = round
Step 2
PARENT GENOTYPE:
Ss X _____
ss
_____
(male)
(female)
2
round
2
4
4
50
50
Step 3
PUNNETT SQUARE:
s
s
_____
_____
S
_____
Ss
Ss
s
_____
ss
ss
Phenotypes: Square and
Step 4
GENOTYPIC RATIO:
0/4 = SS
_____
2/4 = Ss
_____
2/4 = ss
_____
Step 5
PHENOTYPIC RATIO:
50 % tall
_____
50 % short
_____