Today’s Objectives:
• Explain the difference between chromosomes and genes.
• Describe the process of the sperm cell and egg cells uniting and how the number of chromosomes form.
• Describe the difference between dominant and recessive traits.
• Identify and describe 2 common human genetic disorders.
Lesson 2: Heredity and Genetics
Big Idea: Certain traits, such as ________________ and __________________ color, come from both parents.
Heredity

Main Idea: Heredity is the passing of __________________ traits from parents to their children.
o
All the characteristics you have, such as your eye color, the amount of ____________ in your hair, and your height,
are determined by your ________________ code.

_____________________ members often share similar physical traits.

Most of the cells in the human body contain _________ chromosomes that are arranged in ________ pairs.
o
Def: _________________ - like structures found within the ________________ of a cell that carry the
_________________ for inherited traits.

Genes are ___________________ of chromosomes that occur in __________________. One gene from each
______________ is inherited from each __________________.
o

Def: The basic units of heredity
DNA
o
All living things are made of _________________, or deoxyribonucleic acid.

o
Def: The _________________ unit that makes up chromosomes
DNA like this _______________ helix, looks like a long twisted __________________.
Genetic and Fetal Development

Main Idea: Chromosomes from a ___________ and an ____________ unite to carry the hereditary traits from parents.
o
Passing on traits from parent to child involves genetics.

Most human cells have __________ chromosomes, or 23 ________________.

However, egg and sperm cells have half that number—_________ chromosomes.

When a sperm and egg unite during _________________, the resulting zygote will have __________________
chromosomes:

o
23 from the ________________ egg and
o
23 from the ________________ sperm.
Dominant and Recessive Genes
o
Some genes are _____________________, while others are _______________________.
o
The traits of recessive genes usually _______________ only when the dominant genes are not present.
o
Because females have only ________ chromosomes, their egg cells contain only an X chromosome.
o
Sperm contain either an ______ or a ______ chromosome. Thus, the sperm from the male determines the
______________ of a child.
Genetic Disorders

Main Idea: Genetic disorders are caused by _________________ in genes.
o

Most genetic disorders cannot be cured, but some can be treated.
A person can inherit genes that contain a ___________________, or abnormality.

The mutation may have little or no effect. It also may result in a _______________ defect or may increase the person’s
likelihood of developing a ____________________.

Some genetic disorders are _______________ at birth.
o

Def: Disorders caused ____________ or ______________ by a defect in genes
_________________________ is used to test for genetic disorders.
o
A procedure in which a ______________ is inserted through a pregnant female’s ____________________ wall to
remove a sample of the amniotic fluid surrounding the developing _______________________.

Common Human Genetic Disorders
o
____________ __________ Anemia - Red blood cells have a sickle shape and clump together; may result in severe
___________ and _________________ pain, weakness, kidney disease, restricted blood flow
o
Tay-Sachs Disease - Destruction of _______________ system; blindness; paralysis; death during early
_________________.
o
Cystic Fibrosis - Mucus _____________ many organs, including _____________, liver, and pancreas; nutritional
problems; serious ________________ infections and congestion
o
Down Syndrome - Varying degrees of _______________ retardation, short stature, round __________________
with eyelids that cover inner corners of the eyes
o

Hemophilia - Failure of blood to _________________.
______________ ____________ sampling is used to test for genetic disorders.
o
Def: A procedure in which a small piece of ____________________ is removed from the chorion, a layer of tissue
that develops into the placenta
Battling Genetic Diseases

Main Idea: Research is ongoing to correct genetic disorders.
o
Research into the human _____________ has given scientists a greater understanding of how genetic diseases
__________________.

Gene therapy is an experimental treatment for correcting genetic disorders.
o Def: The process of inserting _______________ genes into human cells to _________________
genetic disorders

Genetic Counseling
o
Genetic counselors can guide families of children with genetic disorders on ____________________ options.
o
Through genetic engineering, some _________________ that can prevent disease have been produced.