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Biology Chapter 7 Notes on Mendelian Genetics
7.1 Chromosomes and Phenotype
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KEY CONCEPT
The chromosomes on which genes are located can affect the expression of traits.
Two copies of each autosomal gene affect phenotype.
An _________________________________ is a gene located on a numbered chromosome and usually
affects males and females in the same way.
_________________________ is the physical and psychological characteristics of an organism from both
genetics and environment.
Mendel studied autosomal gene traits like ________________________________,
______________________________, __________________________ thumb, ____________ attachment,
etc...
Widow’s peak
Mendel’s rules of inheritance apply to autosomal genetic ________________________.
 An organism's ___________________________ represents the two alleles inherited for a given trait
such as CC or cc. For an organism to be a ____________________, the genotype must include one
copy of a recessive allele (Ex. Bb). Carriers ____________________ exhibit the physical trait, but
have a _____________chance of passing the gene on to an offspring.
 Disorders caused by dominant alleles are ______________________.
Males and females can differ in sex-linked traits.
 Genes on sex chromosomes are called sex-linked genes.
- Y chromosome genes in mammals are responsible
for male characteristics.
- X chromosome genes in mammals affect many traits.
(domin
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Male mammals have an _________ genotype.
– ___________ of a male’s sex-linked genes are expressed.
– Males have no __________________________ of sex-linked genes.
Female mammals have an _________ genotype.
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Expression of sex-linked genes is similar to _________________________ genes in females.
X chromosome inactivation randomly _______________________ one X chromosome.
7.2 Complex Patterns of Inheritance
KEY CONCEPT
Phenotype is affected by many different factors.
*Phenotype can depend on interactions of alleles.
 In _____________________ dominance, neither allele is completely dominant
nor completely recessive.
– _________________________ means that an organism has two different
alleles of a gene (_________________).
– _________________________ means that the organism has two copies of
the same allele for a gene (_______________).
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________________________ alleles will both be
completely expressed.
– Codominant alleles are neither dominant
nor recessive.
– The __________ blood types result from
codominant alleles.
Many genes have more than ________ alleles.
Many genes may interact to produce one trait.
 ______________________ traits are produced by two or more genes (at least 3 genes and 6 alleles).
__________________ in addition to __________, __________, and __________ color are examples.
 Order of dominance for eye color: brown > green > blue.
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An _____________________ gene can interfere with other genes.
It ___________________ the output of a gene or genes.
Examples are __________ hair and ___________________.
The environment interacts with genotype (Ex. Bb or BB).
 Phenotype is a combination of _________________ and
__________________________.
 The sex of sea turtles depends on both genes and the environment; _____________________ develop with ____________________ temperatures (~88°F) whereas
__________________ develop in slightly _______________________ temperatures (~83°F).
 _____________________ is an example of a phenotype strongly affected by factors in the
environment such as _________________________ and ________________________.
7.3 Gene Linkage and Mapping
KEY CONCEPT
Genes can be mapped to specific locations on chromosomes.
Gene linkage was explained through fruit flies.
 Nobel prize winner Thomas Hunt Morgan found that linked traits are on the ____________________
__________________________ based on experiments with fruit flies.
 __________________________, not genes, assort independently or _____________________ during
meiosis.
 ________________________________ are not inherited together every time.
 Chromosomes exchange homologous genes (HH or hh) during _____________________.
Linkage maps estimate distances between genes.
 The ________________ together two genes are, the _________________________ they will be
inherited together.
 Cross-over ______________________ are related to ________________________ between genes.
 Linkage maps show the relative locations of genes.
 Cross-over frequencies can be converted into map units.
– gene A and gene B cross over _____ percent of the time
– gene B and gene C cross over ________ percent of the time
– gene A and gene C cross over ________ percent of the time
7.4 Human Genetics Pedigrees
KEY CONCEPT
A combination of methods is used to study human genetics.
Human genetics follows the ____________________ seen in other organisms.
 The basic principles of genetics are the same in all ______________________________________
___________________________.
– Inheritance of many human traits is ____________________________.
– Single-gene traits are important in understanding human genetics.
Females can carry sex-linked genetic disorders.
 __________________ (XY) express all of their sex linked genes.
 ________________________ of the disorder depends on which ____________________ carries
the allele and the ____________/____________________ of the child.
A ______________________ is a chart for tracing ________________________________.
Phenotypes are used to infer genotypes on a pedigree.
Autosomal genes show different patterns on a pedigree than sex-linked genes.
 If the phenotype is more common in ___________, the gene is likely ______________________.
Several methods help map human chromosomes.
 A ______________________ is a picture of all chromosomes in a cell.
 Karyotypes can show ___________________ in chromosomes.
– _____________________ of part of a chromosome or _____________ of a chromosome
– __________________ changes in chromosomes
– _____________________ chromosomes or duplication of ____________ of a chromosome