Download Reviewing Genotypes and Phenotypes Genotype is the alleles, or

Reviewing Genotypes and Phenotypes
Reviewing Genotypes and Phenotypes
Genotype is the alleles, or variations, of a gene that are carried by an organism.
Organisms inherit one copy of each gene from each parent.
Genotypes are represented using letters for each allele. Capital letters represent the
dominant allele, lower case letters represent the recessive allele. GG, Gg and gg all
represent different genotypes for the same trait. The capital or lower case g’s represent
the different alleles for the gene.
Genotype is the alleles, or variations, of a gene that are carried by an organism.
Organisms inherit one copy of each gene from each parent.
Genotypes are represented using letters for each allele. Capital letters represent the
dominant allele, lower case letters represent the recessive allele. GG, Gg and gg all
represent different genotypes for the same trait. The capital or lower case g’s represent
the different alleles for the gene.
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
E=Freckles
e=no freckles
Phenotype
bb
cc
Phenotype
BB
Detached ear lobe
Freckles
Genotype
Aa
Phenotype
bb
cc
No Freckles
Genotype
AA
E=Freckles
e=no freckles
Detached ear lobe
Freckles
No Freckles
dd
Freckles, Detached ear lobe
dd
Freckles, Detached ear lobe
Cc
Brown Eyes
Cc
Brown Eyes
Genetics and Natural Selection
 Traits are controlled by genes, which are inherited during reproduction.
 A population of organisms can be thought of as a gene pool.

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. Selection
pressures are external agents that affect an organism’s ability to survive in a
given environment. Selection pressures can be negative (decreases the
occurrence of a trait) or positive (increases the proportion of a trait)
Genetics and Natural Selection
 Traits are controlled by genes, which are inherited during reproduction.
 A population of organisms can be thought of as a gene pool.

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. Selection
pressures are external agents that affect an organism’s ability to survive in a
given environment. Selection pressures can be negative (decreases the
occurrence of a trait) or positive (increases the proportion of a trait)