Bootcamp Heredity Study Guide –
Genetics, Mendelian Inheritance, DNA
& Trait Transmission (Complete
Review 2026)
a _____ is a distinct unit or sequence of genetic material that codes for a trait
gene
a _____ is the location of a gene on a chromosome
locus
an _____ is one variation of a gene that has different forms
E.g. brown or blue coded at the eye color gene locus
allele
a _____ allele is the 'normal' copy of an allele
wild type
a _____ allele has an altered DNA sequence that can affect a gene's phenotype
mutant
the _____ refers to the actual DNA sequence of a gene
genotype
the _____ refers to the observable characteristics of a gene's expression
phenotype
_____ are a pair of chromosomes (one maternal and one paternal) that contain all
the same gene loci
homologous chromosomes
homologous chromosomes have the same gene loci, but they do not have to
have the same _____
alleles
humans have 22 pairs of _____ chromosomes and 1 pair of _____ chromosomes
autosomal; sex
(True/False) the sex chromosomes of a female are homologous because they are
XX (genotype)
true
(True/False) the sex chromosomes of a male are homologous because they are
XY (genotype)
false
They are not homologous because men are hemizygous
an organism is considered to be _____ for a given gene if an identical allele is
present on each homologous chromosome
homozygous
,how many copies of the dominant allele do homozygous-dominant individuals
carry?
2 (ex: BB)
how many copies of the recessive allele do homozygous-dominant individuals
carry?
0 (ex: BB)
how many copies of the dominant allele do heterozygous individuals carry?
1 (ex: Bb)
how many copies of the recessive allele do heterozygous individuals carry?
1 (ex: Bb)
what is the phenotype of a heterozygous individual?
dominant
how many copies of the dominant allele do homozygous-recessive individuals
carry?
0 (ex: bb)
how many copies of the recessive allele do homozygous-recessive individuals
carry?
2 (ex: bb)
what is the phenotype of a homozygous-recessive individual?
recessive
_____ refers to the condition of having a single copy of a gene instead of 2
hemizygous
men have 2 different sex chromosomes (XY), so they are _____ for genes on each
chromosome
hemizygous
the law of _____ says that homologous chromosomes separate during _____ (cell
phase), so each parent only passes 1 of their alleles to their offspring
segregation; anaphase I of meiosis
the law of _____ says that 1 chromosome does not affect another as they
separate during _____ (cell phase)
independent assortment; anaphase I of meiosis
the law of dominance says that _____ alleles will mask the effect of _____ alleles
dominant; recessive
a monohybrid cross mates individuals that are _____ for _____ gene(s)
homozygous; a single
what is the phenotypic ratio for a monohybrid cross?
3:1
what is the genotypic ratio for a monohybrid cross?
1:2:1 for XX : Xx : xx
a dihybrid cross mates individuals that are _____ for _____ gene(s)
heterozygous; 2
what is the phenotypic ratio of a dihybrid cross?
9:3:3:1
what is the label for the parental generation in a cross?
P = parental
what is the label for the first generation of offspring in a cross?
, F1 = filial 1 hybrid = offspring of parental generation
what is the label for the second generation of offspring in a cross?
F2 = filial 2 hybrid = offspring of F1 generation
what are the three important single allele crosses?
homozygous x homozygous = 1/1 AA, Aa or aa
homozygous x heterozygous = 1⁄2 AA (or aa) and 1⁄2 Aa
heterozygous x heterozygous = 1⁄4 AA; 1⁄2 Aa; 1⁄4 aa (1:2:1 monohybrid ratio)
what is the simplest way to calculate the probability of a specific dihybrid cross?
multiply the heterozygous x heterozygous single allele cross probabilities together
(ex: Aabb = 1/2 x 1/4 = 1/8)
in a dihybrid cross, gene loci must be on separate _____
chromosomes
_____ is the pattern of inheritance in which the expression of alleles is blended,
producing a unique heterozygous phenotype
incomplete dominance
Mnemonic: INcomplete dominance is the INtermediate
_____ is the pattern of inheritance in which both alleles (for the same gene)
are completely expressed at the same time
codominance
Mnemonic: Codominance is NO dominance
_____ is the pattern of inheritance in which more than two alleles exist for a given
gene
multiple alleles
what is an example of multiple alleles in humans?
the ABO blood typing. A person can be type A, AB, B, or O
_____ is the pattern of inheritance in which 1 gene affects the phenotypic
expression of a second, separate gene
epistasis
_____ is the pattern of inheritance in which a single gene has more than 1
phenotypic expression
pleiotropy
what is an example of pleiotropy in humans?
cystic fibrosis. A single gene will lead to the expression of different symptoms in
different tissues
_____ is the pattern of inheritance in which multiple genes affect one phenotype
with continuous variation
polygenic inheritance
(ex: height or skin color)
_____ genes are genes that reside on a sex chromosome
sex-linked
(ex: color blindness)
in _____, a specific allele is expressed (or not) depending on whether it is
inherited from the mother or father
Genetics, Mendelian Inheritance, DNA
& Trait Transmission (Complete
Review 2026)
a _____ is a distinct unit or sequence of genetic material that codes for a trait
gene
a _____ is the location of a gene on a chromosome
locus
an _____ is one variation of a gene that has different forms
E.g. brown or blue coded at the eye color gene locus
allele
a _____ allele is the 'normal' copy of an allele
wild type
a _____ allele has an altered DNA sequence that can affect a gene's phenotype
mutant
the _____ refers to the actual DNA sequence of a gene
genotype
the _____ refers to the observable characteristics of a gene's expression
phenotype
_____ are a pair of chromosomes (one maternal and one paternal) that contain all
the same gene loci
homologous chromosomes
homologous chromosomes have the same gene loci, but they do not have to
have the same _____
alleles
humans have 22 pairs of _____ chromosomes and 1 pair of _____ chromosomes
autosomal; sex
(True/False) the sex chromosomes of a female are homologous because they are
XX (genotype)
true
(True/False) the sex chromosomes of a male are homologous because they are
XY (genotype)
false
They are not homologous because men are hemizygous
an organism is considered to be _____ for a given gene if an identical allele is
present on each homologous chromosome
homozygous
,how many copies of the dominant allele do homozygous-dominant individuals
carry?
2 (ex: BB)
how many copies of the recessive allele do homozygous-dominant individuals
carry?
0 (ex: BB)
how many copies of the dominant allele do heterozygous individuals carry?
1 (ex: Bb)
how many copies of the recessive allele do heterozygous individuals carry?
1 (ex: Bb)
what is the phenotype of a heterozygous individual?
dominant
how many copies of the dominant allele do homozygous-recessive individuals
carry?
0 (ex: bb)
how many copies of the recessive allele do homozygous-recessive individuals
carry?
2 (ex: bb)
what is the phenotype of a homozygous-recessive individual?
recessive
_____ refers to the condition of having a single copy of a gene instead of 2
hemizygous
men have 2 different sex chromosomes (XY), so they are _____ for genes on each
chromosome
hemizygous
the law of _____ says that homologous chromosomes separate during _____ (cell
phase), so each parent only passes 1 of their alleles to their offspring
segregation; anaphase I of meiosis
the law of _____ says that 1 chromosome does not affect another as they
separate during _____ (cell phase)
independent assortment; anaphase I of meiosis
the law of dominance says that _____ alleles will mask the effect of _____ alleles
dominant; recessive
a monohybrid cross mates individuals that are _____ for _____ gene(s)
homozygous; a single
what is the phenotypic ratio for a monohybrid cross?
3:1
what is the genotypic ratio for a monohybrid cross?
1:2:1 for XX : Xx : xx
a dihybrid cross mates individuals that are _____ for _____ gene(s)
heterozygous; 2
what is the phenotypic ratio of a dihybrid cross?
9:3:3:1
what is the label for the parental generation in a cross?
P = parental
what is the label for the first generation of offspring in a cross?
, F1 = filial 1 hybrid = offspring of parental generation
what is the label for the second generation of offspring in a cross?
F2 = filial 2 hybrid = offspring of F1 generation
what are the three important single allele crosses?
homozygous x homozygous = 1/1 AA, Aa or aa
homozygous x heterozygous = 1⁄2 AA (or aa) and 1⁄2 Aa
heterozygous x heterozygous = 1⁄4 AA; 1⁄2 Aa; 1⁄4 aa (1:2:1 monohybrid ratio)
what is the simplest way to calculate the probability of a specific dihybrid cross?
multiply the heterozygous x heterozygous single allele cross probabilities together
(ex: Aabb = 1/2 x 1/4 = 1/8)
in a dihybrid cross, gene loci must be on separate _____
chromosomes
_____ is the pattern of inheritance in which the expression of alleles is blended,
producing a unique heterozygous phenotype
incomplete dominance
Mnemonic: INcomplete dominance is the INtermediate
_____ is the pattern of inheritance in which both alleles (for the same gene)
are completely expressed at the same time
codominance
Mnemonic: Codominance is NO dominance
_____ is the pattern of inheritance in which more than two alleles exist for a given
gene
multiple alleles
what is an example of multiple alleles in humans?
the ABO blood typing. A person can be type A, AB, B, or O
_____ is the pattern of inheritance in which 1 gene affects the phenotypic
expression of a second, separate gene
epistasis
_____ is the pattern of inheritance in which a single gene has more than 1
phenotypic expression
pleiotropy
what is an example of pleiotropy in humans?
cystic fibrosis. A single gene will lead to the expression of different symptoms in
different tissues
_____ is the pattern of inheritance in which multiple genes affect one phenotype
with continuous variation
polygenic inheritance
(ex: height or skin color)
_____ genes are genes that reside on a sex chromosome
sex-linked
(ex: color blindness)
in _____, a specific allele is expressed (or not) depending on whether it is
inherited from the mother or father
