Honors Biology Chapter 12 Notes
12.1
Pedigrees

A diagram that traces the inheritance of a particular trait through several generations
Inferring Genotypes

Knowing physical traits can determine what genes an individual is most likely to have.
Predicting Disorders

Record keeping helps scientists use pedigree analysis to study inheritance patterns, determine phenotypes, and
ascertain genotypes.
Recessive Genetic Disorders
A recessive trait is expressed when the individual is homozygous recessive for the trait
Cystic Fibrosis

Affects the mucus-producing glands, digestive enzymes, and sweat glands

Chloride ions are not absorbed into the cells of a person with cystic fibrosis but are excreted in the sweat.

Without sufficient chloride ions in the cells, a thick mucus is secreted.
Albinism

Caused by altered genes, resulting in the absence of the skin pigment melanin in hair and eyes

White hair

Very pale skin

Pink pupils
Tay-Sachs Disease

Caused by the absence of the enzymes responsible for breaking down fatty acids called gangliosides
Gangliosides accumulate in the brain, inflating brain nerve cells and causing mental deterioration
Galactosemia
Recessive genetic disorder characterized by the inability of the body to digest galactose
Dominant Genetic Disorders

Huntington’s disease affects the nervous system.

Achondroplasia is a genetic condition that causes small body size and limbs that are comparatively short.
12.2 Notes
Incomplete Dominance
The _______________________ phenotype is an ________________________ phenotype between the two
homozygous phenotypes (both alleles are ____________________)
Codominance
Both alleles are _______________ in the _________________ condition (both alleles are seen at the same time)
Sickle-cell Disease
Changes in __________________ cause ______ blood cells to change to a _________ shape
People who are ___________________ for the trait have both normal and sickle-shaped cells
Multiple Alleles

Blood groups in __________________

_________ blood groups have _________ forms of _______________.
Coat Color of Rabbits

_____________________ alleles can demonstrate a hierarchy of ___________________.

In rabbits, ___________ alleles code for coat color: C, cch, ch, and c.
Sex Determination

Sex chromosomes determine an individual’s _________________.
Sex-Linked Traits

Genes located on the ___ chromosome

______________________ color blindness

_______________________
Polygenic Traits

____________________ traits arise from the interaction of __________________ pairs of genes.
Environmental Influences

___________________________ factors

_____________ and exercise

_______________ and water

_________________________
Twin Studies

Helps scientists separate genetic contributions from environmental contributions

Traits that appear frequently in identical twins are at least partially controlled by heredity.

Traits expressed differently in identical twins are strongly influenced by environment.
Karyotype Studies

________________—micrograph in which the pairs of homologous chromosomes are ______________ in
____________________ size.

Images of _____________________ stained during __________________
Chromosomes are arranged in decreasing size to produce a micrograph