Download 7.1 Study Guide

Name ______________________________ Class ___________________ Date __________________
Section 1: Chromosomes and Phenotype
Study Guide A
KEY CONCEPT
The chromosomes on which genes are located can affect the expression of traits.
VOCABULARY
carrier
sex-linked gene
X chromosome inactivation
MAIN IDEA: Two copies of each autosomal gene affect phenotype.
Fill in the blank or circle the word or phrase that best completes the sentence.
1. Sex chromosomes determine an organism’s _______________. All other
chromosomes, which do not directly affect an organism’s sex, are called
_______________.
2. A person who is a carrier differs from a person who has a genetic disorder. A
carrier does / does not show symptoms of a disorder but can / cannot pass the
disorder to offspring.
3. Complete the two Punnett squares below to compare autosomal recessive
disorders with autosomal dominant disorders.
Fill in the possible genotypes for offspring, and write in the phenotype
(no disorder, carrier, or disorder) for each.
Autosomal Recessive
D
Autosomal Dominant
d
D
D
D
d
d
d
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide A
0
Extending Mendelian Genetics
Section 1: Chromosomes and Phenotype
Name ______________________________ Class ___________________ Date __________________
Study Guide A continued
MAIN IDEA: Males and females can differ in sex-linked traits.
4. Sex-linked genes are located on the _____________________.
5. Fill in the Punnett square below to show the pattern of inheritance for sex
chromosomes. Write in the phenotype (male or female) for each.
Sex Chromosome Inheritance
X
X
X
Y
Circle the word or phrase that best completes the statement.
6. In humans, a gamete from a male determines the sex of the offspring, because
a male can pass on only X / only Y / either X or Y chromosomes. In contrast, a
female passes on only X / only Y / either X or Y chromosomes.
7. The genes on the Y chromosome are responsible for male / female
characteristics.
8. Place a check mark in the appropriate boxes to show how sex-linked genes are
expressed in the phenotypes of males and females.
Males
Females
Show phenotypes from all sex-linked genes.
Show phenotypes similarly to autosomal gene expression.
Vocabulary Check
Circle the word or phrase that best completes the statement.
9. The verb carry means “to transport.” This meaning is related to the term
carrier in genetics, because a carrier is a person who “transports” a
disease-causing allele to offspring / parents.
10. With X chromosome inactivation, which occurs in males / females, one of the
two X chromosomes in every cell is randomly “turned off” / “turned up.”
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide A
1
Extending Mendelian Genetics
Section 1: Chromosomes and Phenotype
Name ______________________________ Class ___________________ Date __________________
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide A
2
Extending Mendelian Genetics
Section 3: Gene Linkage and Mapping
Name ______________________________ Class ___________________ Date __________________
© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
Study Guide A
3
Extending Mendelian Genetics
Section 4: Human Genetics and Pedigrees