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