Chapter 3

Question 1

What are Mendel’s 3 principles of genetic transmission?

Answer 1

1. principle of dominance
2. Principle of segregation
3. principle of independent assortement

Question 2

the case in which a trait is determined by a number of genes

Answer 2

polygenic inheritance

Question 3

the case in which a dominant gene does not completely suppress the effect of a recessive gene, which is then somewhat expressed in the phenotype

Answer 3

incomplete dominance

Question 4

the case in which both alleles are dominant and each is completely expressed in the phenotype

Answer 4

codominance

Question 5

the case in which the allele from one parent is biochemically silenced and only the allele from the other parent affects the phenotype

Answer 5

genomic imprinting

Question 6

Name the hereditary disorders

Answer 6

• PKU - tay sachs -down syndrome -hemophilia
• turner syndrome -kleinfelter syndrome -huntington disease -fragile x syndrome -duchenes muscular dystrophy -cystic fibrosis -sickle cell anemia

Question 7

Which hereditary disorders are dominant?

Answer 7

• Huntington disease

- neurofibromatosis

Question 8

Which hereditary disorders are recessive?

Answer 8

• PKU
• Cystic fibrosis
• Tay sachs
• sickle-cell anemia

Question 9

What are hereditary disorders resulting from structural defects in the chromosomes?

Answer 9

• autosomal disorders: trisomy 21 but also 13 and 18, deletion of part of chromosome 5=cris du chat syndrome
• disorders of sex chromosomes: 45, X=turner, 47 XXY=kleinfelter, 47, XYY

Question 10

How do we study the effect of gene on behaviour/phenotype?

Answer 10

1. family studies (lineage studies)
2. Adoption studies (Colorado Adoption Project)
3. twin studies
4. combined twin-study and adoption-study (Minesota studies of twins reared appart)

Question 11

What is the Colorado adoption project?

Answer 11

It is a longitudinal study that evaluated families with adopted children vs families with biological children. Teenagers who portrayed antisocial behaviours and who were adopted at birth were more likely to have had parents who suffered from psychiatric conditions. The children inherited their behaviour problems from biological parents, the knowledge of problems by adoptive parents incited harsh discipline and these practices served to maintain the children’s problem behaviours

Question 12

What is the Minnesota study of twins reared appart?

Answer 12

It is a study that looked at behaviour, personality, intelligence and their genetic contribution in twins who had been reared appart and thus theoretically had different environments.

Question 13

What is behaviour genetics?

Answer 13

the field of study that explores the role of genes in producing individual difference in behaviour and development

Question 14

What are the models of gene-environment interaction?

Answer 14

1. Gottesman’s limit-setting model
2. Scarr’s Niche-picking model
3. Plomin’s environmental genetics model
4. Bronfenbrenner and Ceci’s ecological model

Question 15

Model in which genes interact with the environment by setting the upper and lower limits of our development. Our environment and experiences then determine where we end up in this genetically determined reaction range.

Answer 15

Gotteman’s limit-setting model

Question 16

Range of ability or skill that is set by the genes. the value achieved within this range is determined by the environment.

Answer 16

Reaction range
e.g. genes have set limit of basketball skills such that very short children will not become proficient in these skills, while tall children have the greatest opportunity to benefit from a more supportive environment.

Question 17

Model in which genes play a role in determining the kind of environment the child experiences. Child’s gene assures that both genes and environment push development in the same direction.

Answer 17

Scarr’s niche-picking model

Question 18

concept of Scarr’s Niche-picking model, situation in which genes and environment affect development similarly because genes the child receives from the parents are compatible with the environment the parents provide. E.g. musically inclined parents are more likely to give birth to musically inclined children and to provide a musical home environment.

Answer 18

Passive gene-environment correlation

Question 19

concept of Scarr’s Niche-picking model, situation in which genes and environment affect development similarly because genetically set predispositions of the child elicit compatible experience from the environment. E.g a child who speaks and reads early may prompt parents to provide a rich language environment, including books, storytelling and educational games.

Answer 19

Evocative gene-environment correlation

Question 20

concept of Scarr’s Niche-picking model, situation in which genes and environment affect development similarly because children seek out experiences that are compatible with their genetic predispositions. E.g. children who are very active may seek environments (niche) that best fit their interests and talents-such as the gym, parks, etc…

Answer 20

Active gene-environment correlation

Question 21

Like scarr’s model this model believes that simillarities that we see in siblings result mostly from the genetic influence than from environmental influences. Genetic influence grows in importance as siblings get older. Children’s developmental outcomes are related to their family environments forr 2 reasons:

1. children share genes with their parents, who in turn provide environment for their children
2. children evoke from their parents the sorts of responses and surroundings that suit their genes.

Answer 21

Plomins’ environmental genetics model

Question 22

a concept used in behaviour genetics to refer to presumed aspects of the environment that children experience differently

Answer 22

non-shared environment

Question 23

Model in which we assign much more importance to the environment, genes can only exert their influence when certain experiences activate them. Theses experiences=proximal processes

• stable environment rich with ressources–>children develop to the fullest their abilities
• disorganized and disadvantaged (poor neighborhoods)–>proximal process can help prevent undesirable outcomes that might have occurred (agression, violence)

Answer 23

Bronfendbrenner and Ceci’s bioecological model
-child’s biology and ecology contribute more equally and in greater interaction in this model than in either the more strongly genetics or strongly environmental approaches.