Download Reviewing Genotypes and Phenotypes Genotype describes the

Reviewing Genotypes and Phenotypes
Reviewing Genotypes and Phenotypes
Genotype describes the genes/alleles an organism has inherited from its parents.
Organisms inherit one copy of each gene from their parents. Genotypes are represented
using letters for each allele (one from each parent.) An allele is a form of a gene. (Ex: G
and g are two alleles of a gene. GG, Gg, and gg are the different genotypes for this trait).
Capital letters represent the dominant allele, lower case letters represent the recessive
allele.
Genotype describes the genes/alleles an organism has inherited from its parents.
Organisms inherit one copy of each gene from their parents. Genotypes are represented
using letters for each allele (one from each parent.) An allele is a form of a gene. (Ex: G
and g are two alleles of a gene. GG, Gg, and gg are the different genotypes for this trait).
Capital letters represent the dominant allele, lower case letters represent the recessive
allele.
Phenotype describes how the genotype is expressed in an organism. Phenotype is
how an organism looks (physical traits) based on the genotype. Different genotypes can
produce different phenotypes for a trait.
Phenotype describes how the genotype is expressed in an organism. Phenotype is
how an organism looks (physical traits) based on the genotype. Different genotypes can
produce different phenotypes for a trait.
Review Activity:
Below are the alleles for 5 traits. Use this to complete the data table below.
A=right handed B=brown eyes C=curly hair
D=detached ear lobe
a=left handed
b= blue eyes c=straight hair d=attached ear lobe
Review Activity:
Below are the alleles for 5 traits. Use this to complete the data table below.
A=right handed B=brown eyes C=curly hair
D=detached ear lobe
a=left handed
b= blue eyes c=straight hair d=attached ear lobe
Genotype
Aa
Phenotype
BB
Genotype
AA
Phenotype
bb
ccdd
Freckles, Detached ear lobe
AaCC
Genetics and Natural Selection
 Traits are controlled by genes, which are inherited during reproduction.
 A population can be thought of as a gene pool.

Phenotype
Evolution through Natural Selection acts on an organism’s phenotype
(traits or characteristics) not its genotype. As a result, it influences the
frequency of genotypes. For many traits, the homozygous genotype (AA, for
example) has the same phenotype as the heterozygous (Aa) genotype. If both
an AA and an Aa individual have the same phenotype, the environment will not
distinguish between them.
Some alleles (forms of a gene) can increase or decrease based on changing
selective pressures from the environment. (New disease, predator, climate shift)
Genotype
AA
Phenotype
Curly hair, attached ear lobe
Freckles
No Freckles
Eedd
AACc
E=Freckles
e=no freckles
bb
ccdd
No Freckles
Eedd

Genotype
Aa
BB
Curly hair, attached ear lobe
Freckles
AACc
E=Freckles
e=no freckles
Freckles, Detached ear lobe
AaCC
Genetics and Natural Selection
 Traits are controlled by genes, which are inherited during reproduction.
 A population can be thought of as a gene pool.

Evolution through Natural Selection acts on an organism’s phenotype
(traits or characteristics) not its genotype. As a result, it influences the
frequency of genotypes. For many traits, the homozygous genotype (AA, for
example) has the same phenotype as the heterozygous (Aa) genotype. If both
an AA and an Aa individual have the same phenotype, the environment will not
distinguish between them.

Some alleles (forms of a gene) can increase or decrease based on changing
selective pressures from the environment. (New disease, predator, climate shift)
http://www.pbs.org/wgbh/evolution/change/family/
http://www.pbs.org/wgbh/evolution/educators/lessons/lesson3/in
dex.html
Single Gene traits
Polygenic traits
May have 2 or 3 phenotypes
that can shift in frequency
based on environmental
pressure
Blood type, # of fingers, snail
shell pattern (p485)
Has a wide range of
phenotype expression that
can distribute in a bell shaped
pattern
Height, birth weight, skin
color,
http://www.pbs.org/wgbh/evolution/educators/lessons/index.html
http://www.pbs.org/wgbh/evolution/darwin/origin/index.html