Ch. 2: Genetic Basis of Child Development

Question 1

Gametes (sperm/egg cells) have _____ each. When combined, they provide _____.

Answer 1

23 chromosomes; 23 pairs of chromosomes.

Question 2

The first 22 pairs of chromosomes are _____ and the 23rd pair is _____.

Answer 2

Autosomes; sex chromosomes.

Question 3

The best known technique for couples who cannot conceive via intercourse is what?

Answer 3

In vitro fertilization: mixing sperm and egg in laboratory dish, then placing fertilized eggs in mother’s uterus.

Question 4

Each chromosome is made up of _____. Genes are sections of the _____.

Answer 4

DNA; DNA strands.

Question 5

Genetic instructions, in conjunction with environmental influences, produce a _____.

Answer 5

Phenotype.

Question 6

What does it mean if an allele is either dominant or recessive?

Answer 6

Determines whether chemical instructions are followed.

Question 7

In incomplete dominance, the phenotype that results often does what?

Answer 7

Falls between the phenotype associated with either allele.

Question 8

Individuals with one dominant and one recessive allele have what?

Answer 8

Sickle-cell trait.

Question 9

Many disorders are triggered when a child inherits what?

Answer 9

Two recessive alleles.

Question 10

People with Down Syndrome usually have what?

Answer 10

An extra 21st chromosome.

Question 11

Turner’s Syndrome, Klinefelter’s Syndrome, XYY complement, XXX Syndrome are disorders caused by what?

Answer 11

Missing or extra sex chromosomes.

Question 12

Relatively few serious disorders are caused by dominant alleles. Why?

Answer 12

Individuals affected by the disorder typically don’t live long enough to reproduce, so the dominant alleles that cause the disorder vanish from the species.

Question 13

A serious disorder caused by dominant alleles is Huntington’s disease. How is it inherited?

Answer 13

By the time symptoms appear, adults who are affected may already have reproduced.

Question 14

The complete set of genes that make up a person’s heredity is known as the person’s _____.

Answer 14

Genotype.

Question 15

Turner’s Syndrome is characterized by having just one _____ chromosome and is most common in _____.

Answer 15

X chromosome; girls.

Question 16

List three new medical and surgical techniques performed on fetuses in the uterus.

Answer 16

Delivery of drugs or hormones.

Bone marrow transplants.

Surgically repairing genetically transmitted defects of the heart, neural tube, urinary tract, and respiratory system

Question 17

What is the risk of repairing the urinary tract of a fetus in the uterus?

Answer 17

5-10% chance of miscarriage.

Question 18

Why is hemophilia considered a sex-linked disorder? Is it more commonly expressed in males or females?

Answer 18

Gene is carried on the X chromosome.

More commonly expressed in males.

Question 19

The branch of genetics that deals with the inheritance of behavioural and psychological traits is what?

Answer 19

Behavioural genetics.

Question 20

Phenotypes often reflect the combined activity of many separate genes. What is this known as?

Answer 20

Polygenic inheritance.

Question 21

Identical twins are known as what and why? What about fraternal twins?

Answer 21

Identical: monozygotic. Come from a single fertilized egg that splits in two.

Fraternal: dizygotic. Come from two separate eggs fertilized by two separate sperm.

Question 22

Behavioural geneticists often use what types of studies?

Answer 22

Twin studies and adoption studies.

Question 23

New techniques allow researchers to isolate particular segments of DNA in human chromosomes. What is the benefit to this?

Answer 23

Serve as markers for identifying alleles.

Question 24

If one identical twin is depressed, the other twin has roughly a _____ chance of being depressed. For fraternal twins, the odds are approximately _____.

Answer 24

50%; 25%

Question 25

A study on heredity and environmental bases of aggressive behaviour concluded what?

Answer 25

Strong genetic component to physical aggression, but more environmental explanation for social aggression.

Question 26

What is reaction range?

Answer 26

The same genotype can produce a range of phenotypes in reaction to environment.

Question 27

The continuous interplay between genes and multiple levels of the environment that drives development is known as what?

Answer 27

Epigenesis.

Question 28

Behavioural geneticists often use correlations in twin and adoption studies to calculate what?

Answer 28

Heritability coefficient: estimates extent to which differences between people reflect heredity.

Question 29

What is an example of gene-environment interaction regarding depression and stress and the 5-HTTLPR gene?

Answer 29

Individuals with short version of 5-HTTLPR genotype have an elevated risk of developing depression only if they also have stressful lives.

Question 30

What is the epigenetic view?

Answer 30

Our experiences are influenced by the timing of when our genes are expressed throughout our lifespan. The timing of genetic expression can be influenced by our experiences.

Question 31

A study regarding cannabis and psychosis found what two things about the COMT gene?

Answer 31

COMT moderated the influence of adolescent cannabis use on developing adult psychosis.

Carriers more likely to exhibit psychotic symptoms and to develop schizophreniform disorder if they used cannabis as adolescents.

Question 32

Early life experiences can produce what changes in gene expression?

Answer 32

Heritable changes that are not coded in the DNA itself.

Question 33

A study by Meaney et al. pertaining to “low licking” rat mothers found what?

Answer 33

“Low licking” rat mothers provide experiences that alter brain structure and lead to epigenetic alterations in the stress response.

Question 34

Children exposed to maltreatment early in life may have what epigenetic alterations?

Answer 34

Regulatory changes in areas of the brain responsible for the HPA axis, intensifying the stress response.

Question 35

Epigenetic changes influence the present experience and may do what to offspring?

Answer 35

Changes may be passed down through the sperm and eggs of the parents, shaping neural structure in offspring.

Question 36

Deliberately seeking environments that fit one’s heredity is known as what?

Answer 36

Niche-picking.

Question 37

Environmental forces that make siblings different from one another are known as what? Provide an example.

Answer 37

Non-shared environmental influences.

E.g., parents more affectionate with one child than another.