Download Aim #57 - Manhasset Schools

Date: February 29, 2016
Aim #57: How are traits inherited?
Do Now: Warm-Up Notebook
Date
Title of Activity
**No Warm-Up Today  **
Page #
HW:
1) Human Fetus Development Lab due Wednesday
2) Human Phys. Unit 7a Packet due next Friday (March 4th)
Aim #57: How are traits inherited?
1) Traits
Traits are a person’s physical
characteristics. Ex: Eye color,
hair color, etc…
2) What determines our traits?
Genes appear as dark
bands on the
chromosome.
Genes found on chromosomes (DNA)
determine your traits.
3) Chromosomes
•46
AUTOSOMES
SEX CHROMOSOMES
•Why do we have two
of each chromosome?
HOMOLOGOUS
CHROMOSOMES –
pairs of chromosomes,
one from each parent.
Inheritance
• During Fertilization each parent’s sex
cell contributes half the chromosomes.
23
23
23
23
4) Results of Fertilization
Offspring will
receive two copies of
each chromosome,
one from dad and
one from mom.
Gregor Mendel
• “Father of Genetics”
• Characteristics of
offspring were the
result of inheriting
“factors” from parents
Used pea plants because…
• Easy to grow
• Quick germination
time
• Can control
pollination
• Traits are easy to
observe
5) Alleles
• The different forms of a gene.
They can be dominant or
recessive
GENE FOR PEA COLOR
HAS TWO ALLELES:
GREEN & YELLOW
6) Genes can be DOMINANT &
recessive
Dominant genes are indicated with a
CAPITAL (RR) letter, while recessive genes
are indicated with lowercase (rr) letters.
Dominant
alleles will be
seen over the
recessive
genes.
7) Genes come in different forms
Mom
Dad
Traits
Hair Color
B = Black Hair
b = Red Hair
Which gene is dominant?
Black Hair
B
+
B
Black
b
+
b
Red
B
+
b
Black
R = red
r = white
Dominant or recessive?
RR – (Dominant)
Rr – (Dominant – R show through)
rr – (recessive)
8) Genotype determines phenotype
Genotype: actual
types of genes on
the chromosomes
(RR, Rr, rr)
Phenotype: physical
appearance
9) When will the recessive allele show in the
phenotype?
• Two recessive
alleles must come
together (one from
each parent). In
other words, a
recessive trait will
only appear when
two lowercase
letters are together.
10) Heterozygous vs. Homozygous
Homozygous- the two alleles are the same
RR or rr
Heterozygous- the two alleles are different
Rr
Date: March 1, 2016
Aim #57: How are traits inherited?
Do Now: Warm-Up Notebook
Date
Title of Activity
3/1
Know Your Genetics Vocabulary
Page #
98
HW:
1) Complete Worksheet??
2) Human Fetus Development Lab due Wednesday
3) Human Phys. Unit 7a Packet due next Friday (March 4th)
Basic Rules for Genetics:
1) Two alleles (mom & dad) code for one
trait.
2) DOMINANT alleles will be seen over
recessive alleles.
3) DOMINANT alleles are written with capital
letters.
4) Recessive alleles are written with
lowercase letters.
11) Mendel’s Laws
1) Law of Dominance- dominant alleles will be seen over
recessive alleles.
2) Law of Segregation- during the formation of gametes,
the two alleles responsible for a trait separate from each
other.
3) Law of Independent Assortment- alleles for different
traits are sorted independently from each other.
Law of Dominance
• Heterozygous
individuals will express
the phenotype of the
dominant allele
• Example: Tt will be a
tall plant
Law of Segregation and
Recombination
Tt
Segregation
(Meiosis)
Tt
T
t T
t
TT
Tt Tt
tt
Recombination
(Fertilization)
Law of Independent Assortment
• Traits are inherited
independently of each other if
they are on different
chromosomes
• Example: seed color and
seed shape
Punnett Squares
Male
Female
b = white fur
How can we predict genotypes and
phenotypes of offspring?
AA
Aa
Aa
aa
Amoeba Sisters
Monohybrid Cross (Mendelian)
https://www.youtube.com/watch?v=i-0rSv6oxSY
Summary
Find the percentages for genotypes and phenotypes for each cross.
1. In guinea pigs, black coat color is dominant over to brown
coat color. Cross a black male guinea pig (Bb) with a brown
female (bb).
Summary
Find the percentages for genotypes and phenotypes for each cross.
2. Cross a black male (Bb) with a black female (BB).
Summary
Find the percentages for genotypes and phenotypes for each cross.
3. Cross 2 tall pea plants with the genotypes TT and Tt.
Summary
1. In guinea pigs, black coat color is dominant over
brown coat color. The genotype of a guinea pig is
BB. What color is the coat color of the mom and
dad?
b) If the genotype of the guinea pig is bb, what is the
coat color of the mom and dad?
Monohybrid Cross Vs. Dihybrid Cross
Rr x Rr
RrTt x RrTt
12) Testcross
You breed an individual
of unknown genotype,
but dominant phenotype
with a homozygous
recessive individual
P = purple
p = white
13) Exceptions: Codominance
• Both alleles are
expressed in the
phenotype.
• Example:
Blood Type
Heterozygotes will
express both traits
14) Exceptions: Intermediate Inheritance
The heterozygotes have a
phenotype that is
intermediate between the
phenotypes of the two
homozygotes
P = Parent
F1 = 1st generation
F2 = 2nd generation