Chapter 3 - Hereditary Influences on Development

Question 1

What is the nature vs. nurture debate?

Answer 1

nature = biological predispositions are most important

nurture = environmental influences are most important

actually interaction of biology and environment

Question 2

What is a chromosome?

Answer 2

threadlike DNA structure made of genes (which hold the DNA)

come in matching pairs (23 x 2)

Question 3

What is the result of conception?

Answer 3

fathers sperm + mothers ovum = zygote

46 chromosomes total, 23 from each parent

Question 4

When does mitosis begin? What is it?

Answer 4

after fertilization

cell duplicates its chromosomes and then divides, producing 2 complete, identical daughter cells

continues throughout life, replacing old or damaged cells

Question 5

What is meiosis?

Answer 5

parent’s original germ cells split into 4 separate gametes with half the chromosomes of parent cell

Question 6

Which parent determines the sex of the child?

Answer 6

father

females (XX) donating an X chromosome either way

males (XY) could donate an X or a Y, deciding gender

Question 7

What are genes?

Answer 7

hereditary instructions for development transmitted generation to generation

direct production of AA to form new cells

turning on and off regulate timing of development

Question 8

What is a genotype?

Answer 8

inherited genetic endowment

Question 9

What is a phenotype?

Answer 9

the way someone’s genotype is expressed in observable characteristics and behaviours

Question 10

What are the 2 types of twins?

Answer 10

monozygotic

• zygote divides in 2 and forms 2 genetically identical individuals
• 1 in 250

dizygotic

• 2 ova are released simultaneously, both fertilized by different sperm
• fraternal
• 1 in 125

Question 11

What is H?

Answer 11

heritability coefficient

how strong the contribution of heredity is to a trait

H = (r identical - r fraternal) x 2

Question 12

What is the heritability of IQ?

Answer 12

moderate

higher concordance with identical than fraternal

Question 13

What are concordance rates?

Answer 13

percentage of cases in which a particular attribute is present for both members of a twin/parent-child pair

Question 14

What is twin design looking at?

Answer 14

are identical twins or fraternal twins more similar when both reared together?

Question 15

What is adoption design looking at?

Answer 15

are adopted children more similar to biological or adopted parents?

Question 16

What are the 2 types of environmental influences involved in determining heritability?

Answer 16

non-shared environmental influences
- unique to each individual, not shared by other members of the family in the same environment

shared environmental influences
- experiences common to all family members in the same environment

Question 17

What is the heritability of personality?

Answer 17

genes moderate at best

shared environment decreases over time, non-shared environment must be important

Question 18

What does the heritability of mental illness demonstrate about inheritance?

Answer 18

genetics have some role, but inheriting genes does not guarantee expression of these genes
- environment influences expression

Question 19

What is the canalization principle?

Answer 19

genes restrict development to a small range of outcomes

ex. babbling is a highly canalized attribute

Question 20

What is the range of reaction principle?

Answer 20

genes set boundaries for range of phenotypes, environment decides where in the range they will fall

not as rigid as canalization

Question 21

Describe simple dominant recessive inheritance?

Answer 21

dominant alleles are stronger, will be expressed if they are present

recessive alleles will only be expressed if both copies are excessive

ex. dark hair is dominant, blonde hair is recessive

Question 22

What are congenital problems?

Answer 22

present at birth
- but may not always be apparent

could be due to environmental or hereditary causes

Question 23

What causes chromosomal abnormalities?

Answer 23

uneven distribution of chromosomes during meiosis

could also occur through mutation

most abnormalities are lethal

Question 24

What are 2 abnormalities of sex chromosomes in females?

Answer 24

Turner syndrome

• XO
• small, underdeveloped, sterile

Poly-X syndrome

• XXX
• fertile, developmental delays

Question 25

What are 2 abnormalities in the sex chromosomes in males?

Answer 25

Klinefelter syndrome

• XXY
• extremely tall, sterile
• some female secondary sex characteristics

Supermale syndrome

• XYY
• significantly taller, large teeth. severe acne

Question 26

What are autosomes?

Answer 26

the first 22 pairs of chromosomes

everything but the sex chromosomes

Question 27

What is the cause of Down syndrome?

Answer 27

extra 21st chromosome (trisomy 21)

risk increases with age of mother

Question 28

What are some examples of genetic abnormalities associated with recessive traits?

Answer 28

cystic fibrosis
diabetes
hemophilia

Question 29

What is epigenetics?

Answer 29

genetic endowment that an individual inherits

Question 30

What makes the shape of DNA?

Answer 30

stretches of DNA are made of 2 complementary strands that twist into double helix

Question 31

What are germ cells?

Answer 31

cells that produce gametes (sperm/ova)

Question 32

What are gonads?

Answer 32

sexual organs that produce germ cells

testes in mails, ovaries in females

formed through meiosis

Question 33

What is crossing over?

Answer 33

process in which genetic material is exchanged between maternal and paternal homologues to create new and unique hereditary combinations
- each parent alone can produce more than 8 million different genetic combinations

Question 34

What is independent assortment?

Answer 34

when paternal and maternal chromosomes independently segregate

Question 35

What is the genome?

Answer 35

complete set of our genes

Question 36

What are experience-expectant and experience-dependent interactions?

Answer 36

experience-expectant = effects of environment experienced by all humans

experience-dependent interactions = effects of environment only experienced by some people

Question 37

What is codominance?

Answer 37

two heterozygous but equally powerful alleles produce a phenotype in which both genes are fully and equally expressed

Question 38

What is sex-linked inheritance?

Answer 38

determined by recessive gene that appears on an X chromosome

more likely to characterize males (since they only have one X, can’t have another gene to counteract it)

Question 39

What is polygenetic inheritance?

Answer 39

traits influenced by the action of many genes

observe patterns of continuous variation with few people having traits at extreme ends and most having traits in the middle of the distribution

Question 40

What is epigenetics?

Answer 40

influences whether genes are expressed, partially expressed, or not expressed without changing DNA sequences

can’t influences subsequent generations

Question 41

What is amniocentesis?

Answer 41

acquire sample of amniotic fluid to determine presence of chromosomal abnormalities and genetic disorders

Question 42

What is selective breeding?

Answer 42

a method of studying genetic influences by determining whether traits can be bread in animals through selective mating

Question 43

What is kinship?

Answer 43

the extent to which 2 people have the same genes

Question 44

What are passive gene-environment interactions?

Answer 44

notion that the rearing environments biological parents provide are influenced by parent’s own genes

Question 45

What are evocative gene-environment interactions?

Answer 45

notion that our heritable attributes affect others behaviour towards us and thus influence the social environment in which development takes place

Question 46

What are active gene-environment interactions?

Answer 46

notion that our genotypes affect the types of environments that we prefer and seek out