Biology 8.2

The alleles for ABO blood type are the A, B, AB and O alleles.

False - A, B, and O

Triple X syndrome results in XYXX males.

False - XXX females

Pleiotropy is when a more than one gene affects a single trait.

False - a single gene affects more than one trait

Widow's peak and hitchhiker's thumb are multiple allele traits.

False - autosomal traits

Amniocentesis can be used to see if the mother has any genetic abnormalities.

False - fetus

Characteristics that are encoded in DNA are called genetic diseases.

False - genetic traits

Most genetic disorders are controlled by dominant alleles.

False - recessive

the inheritance of traits controlled by a single gene with two alleles

Mendelian inheritance

Explain what causes chromosomal disorders.

Mistakes may occur during meiosis that result in nondisjunction. This is the failure of replicated chromosomes to separate during meiosis II. Some of the resulting gametes will be missing a chromosome, while others will have an extra copy of the chromosome.

Because it is a polygenic trait, human height can be represented by a bell-shaped graph.

True

Down syndrome is also known as trisomy 21.

True

Epistasis is when one gene affects the expression of another gene.

True

Most human traits have more complex modes of inheritance than simple Mendelian inheritance.

True

Single-gene X-linked traits have a different pattern of inheritance than single-gene autosomal traits.

True

Sex-linked traits are usually associated with genes on the _____ chromosome.

X

An example of a recessive _____ trait would be red-green color blindness.

X-linked

red-green color blindness

X-linked trait

Hemophilia A results in reduced activity of a protein needed for blood _____.

clotting

shows how a trait is passed from generation to generation within a family

pedigree

when a single gene affects more than one trait

pleiotropy

Human height is an example of a _____ trait.

polygenic

Hemophilia A is due to _____.

reduced activity of a protein needed for blood clotting

trait controlled by genes on the sex chromosomes

sex-linked trait

What are the signs and symptoms of sickle cell anemia?

sickle-shaped red blood cells that clog tiny blood vessels, causing pain and damaging organs and joints

A mother has red-green color blindness. Her husband is not affected.

All of their sons will have red-green color blindness.

Which of the following statements concerning genetic disorders is correct? (1) Many genetic disorders are caused by mutations in one or a few genes. (2) Some genetic disorders are caused by abnormal numbers of chromosomes. (3) Most genetic disorders are caused by dominant alleles. (4) Chromosomal disorders result from nondisjunction during mitosis.

1 and 2

ABO blood type is a multiple allele trait. Which of the following are possible ABO blood type phenotypes? (1) A, (2) B, (3) AB, (4) O, (5) AO, (6) BO

1, 2, 3, and 4

Why are few genetic disorders controlled by dominant alleles?

A mutant dominant allele is expressed in every individual who inherits even one copy of it. If it causes a serious disorder, affected people may die young and fail to reproduce. Therefore, the mutant dominant allele is likely to die out of the population.

an example of a multiple allele trait

ABO blood type

_____ is caused by an extra copy of chromosome 21.

Down syndrome

A karyotype is a picture of a cell's chromosomes.

True

A mutant recessive allele is not expressed in people who inherit just one copy of it.

True

A recessive X-linked allele is always expressed in males.

True

the failure of replicated chromosomes to separate during meiosis

nondisjunction

trait controlled by a gene on one of the 22 human autosomes

autosomal trait

when one gene affects the expression of another gene

epistasis

Describe the cause and symptoms of Down syndrome.

extra copy (complete or partial) of chromosome 21 developmental delays, distinctive facial appearance, and other abnormalities

involves inserting normal gene into cells with mutant genes

gene therapy

Mendelian inheritance refers to the inheritance of traits controlled by a single _____ with two _____.

gene; alleles

characteristics (traits) encoded in DNA

genetic trait

Down syndrome is due to _____.

nondisjunction of chromosome 21

Sickle cell anemia results in an abnormal _____ protein in red blood cells.

hemoglobin

Single-gene X-linked traits have a different pattern of inheritance than single-gene autosomal traits because _____.

males have just one X chromosome

Nondisjunction occurs during _____.

meiosis

traits controlled by a single gene with more than two alleles

multiple allele trait

ABO blood type is a _____ trait.

multiple-allele

Traits controlled by a single gene with more than two alleles are called _____ traits.

multiple-allele

Many genetic disorders are caused by _____ in one or a few genes.

mutations

What two main ways cause genetic disorders?

mutations in one or a few genes abnormal numbers of chromosomes

Characteristics that are encoded in DNA are called genetic _____.

traits

In a polygenic trait, such as adult height, most people _____.

will have a phenotype close to the average