Week 3 Key Terms

Question 1

Allele

Answer 1

The variation or version of DNA sequences for a given section of a genomic location.

The expression of genes

Question 2

Autosomal dominant inheritance

Answer 2

A dominant mutated gene located on an autosome (non-sex gene)

You need only one changed gene to be affected by this type of disorder. A person with an autosomal dominant disorder has a 50% chance of having an affected child with one changed gene

Huntington’s Disease

Question 3

Autosomal recessive inheritance

Answer 3

To have an autosomal recessive disorder, you inherit two mutated genes from each parent (both parents must pass on allele). Their health is rarely affected because they have only one changed gene.

Two carriers have a 25% chance of having an unaffected child with two unaffected genes. They have a 50% chance of having an unaffected child who also is a carrier. They have a 25% chance of having an affected child with two changed genes.

Albinism, Sickle Cell Anemia

Question 4

Behavioral genetics

Answer 4

Field of study that examines how genes and experience combine to influence the diversity of human traits, abilities, and behaviors

Traits with strong genetic components are still modified by environmental influences

Question 5

Dizygotic (DZ) twins

Answer 5

Also know as a fraternal twin; occurs when two ova are released and each is fertilized by a different sperm; he resulting offspring share 50% of the genetic material

Question 6

DNA

Answer 6

Deoxyribonucleic Acid; the chemical structure, shaped like a twisted ladder, that contains all of the genes; 20K-25K genes reside within our chromosomes

Question 7

Down Syndrome

Answer 7

Also known as trisomy 21; a condition in which a third, extra chromosome appears at the 21st site. Down syndrome is associated with distinctive physical characteristics accompanied by developmental disability

Question 8

Epigenetic framework

Answer 8

A perspective stating that development results from reciprocal interactions between genetics and the environment such that the expression of genetic inheritance is influenced by environmental forces

The epigenome is a molecule that stretches along the length of DNA and provides instructions to genes, determining how they are expressed and whether they are turned on or off

Question 9

Fragile X Syndrome

Answer 9

An example of a dominant-recessive disorder carried on the X chromosome

1 in 20K males

Symptoms include cognitive impairment; attention problems; anxiety; unstable mood; long face; large ears; flat feet; and hyper extensible joints

Question 10

Gene

Answer 10

A basic unit of heredity composed of DNA

Question 11

Genetic counseling

Answer 11

A counseling session where a genetic defects and chromosomal abnormalities are determined through a family history of heritable disorders

Women over the age of 35, couples from the same ethic group, relatives have a genetic condition

Question 12

Genotype

Answer 12

An individual’s collection of genes that contain instructions for all physical and psychological characteristics, including hair, eye color, personality, health, and behavior

Question 13

Heritability

Answer 13

A measure of the event to which variation of a certain trait can be traced to genes

Heritability research examines the contributions of the genotype but also provides information on the role of experience in determining phenotypes

Selective breeding has revealed genetic contributions to many traits and characteristics, such as aggressiveness, emotionality, sex drive, and learning

Question 14

Heterozygous

Answer 14

Chromosomal pair consisting of two different alleles

Whether the trait is expressed depends on the relations among genes

(Aa, aA)

Question 15

Homozygous

Answer 15

Refers to a choromxomal pair consisting of two identical alleles

The inherited characteristic will be displayed in the offspring

(AA, aa)

Question 16

Huntington’s Disease

Answer 16

A degenerative brain disorder that affects muscular coordination and cognition

1 in 20K people;

Usually expresses after 30+ years

Chromosome 4 mutation: repeated material

Question 17

Incomplete dominance

Answer 17

A genetic inheritance pattern in which both genes are expressed in the phenotype

Question 18

Monozygotic (MZ) twins

Answer 18

Also known as identical twins; occurs when the zygote splits apart early in development. The resulting offspring share 100% of their genetic material

Question 19

Mutation

Answer 19

A sudden permanent change in the structure of genes

May be induced by exposure to environmental toxins such as radiation and agricultural chemicals in food

Question 20

Niche-picking

Answer 20

An active gene-environment correlation in which individuals seek out experiences and environments that complement their genetic tendencies

An example of an active gene-environment correlation when children actively create experiences and environments that correspond to and influence their genetic predispositions

Question 21

Phenotype

Answer 21

The observable physical or behavioral characteristics of a person, eye, hair color, or height

Question 22

Polygenic inheritance

Answer 22

Occurs when a trait is a function of the interaction of many genes, such as with height, intelligence, temperament, and susceptibility to certain forms of cancer

Question 23

Range of reaction

Answer 23

The concept that a genetic trait may be expressed in a wide range of phenotypes dependent on environmental opportunities and constraints

Although someone may have the genes to be tall, if they are malnourished, they will not fulfill their genetic potential

A genotype sets boundaries on the range of possible phenotypes, but the phenotypes ultimately displayed vary in response to different environments

Question 24

Sex-linked (or X-linked) traits

Answer 24

Genetic disorders that affect the sex chromosome: X

Males are more likely to be affected by X-linked genetic disorders because they only have one X chromosome

Color blindness, Duchenne muscular dystrophy, Hemophilia

Question 25

Sickle cell

Answer 25

Sickle cell alleles cause red blood cells to become crescent, or sickle, shaped

Cannot distribute oxygen effectively throughout the circulatory system