Chapter 3 Gene Enviroment and Development

Question 1

What much of human DNA is identical fro person from person.

Answer 1

99%

Question 2

Darwins Theory

Answer 2

There is genetic variation among members within a species
Some genes contribute more to adaptation and survival than others
Natural selection—those genes that more heavily promote adaptation & survival are more likely to be passed to future generations
Kettlewell’s (1959) moths—highlights the interaction of genes/environment.

Question 3

Degrees of Genetic Similarity

Answer 3

Parent/Child:
50% of genes in common
Siblings:
On average have 50% of genes in common

Monozygotic (identical) twins
Develop from the division of one fertilized egg
Identical genetic makeup
About 1 in every 250 births

Dizygotic (fraternal) twins
Most common multiple birth
Results from the fertilization of 2 separate ova
Genetically, no more alike than non-twin siblings
About 1 in 125 births
Increased probability:
Increased maternal age
In vitro fertilization
Fertility drugs

Question 4

Zygote

Answer 4

Cell that results following the union of sperm & ovum at conception
Contains 23 pairs of chromosomes

Question 5

Genes

Answer 5

Segment of DNA along the length of a chromosome

Contribute directly to physical traits, but only indirectly to psychological traits

Question 6

Chromosomes

Answer 6

Threadlike structures within nucleus of cells that contain genes
46 in each human cell (23 pairs)

Question 7

DNA

Answer 7

Series of proteins that contain genetic blueprints for development and functioning

Question 8

Gamates

Answer 8

sex cells
Sperm & ova
Produced through meiosis
Contains 23 chromosomes which are passed on to offspring

Question 9

Sex Chromosomes

Answer 9

23rd pair of chromosomes

Determines sex of offspring (X- or Y-bearing sperm)

Question 10

Karyotype

Answer 10

is an organized profile of chromosomes that allows us to view the number and shape of each set of chromosomes.

Question 11

Genotype

Answer 11

Genetic makeup a person inherits

Question 12

Phenotype

Answer 12

Directly observable characteristics of the person

Question 13

Single Gene-Pair Inheritance

Answer 13

Influence of only 1 pair of genes on a given characteristic
People display a particular trait or they don’t
Dominant gene = dominant trait
Displayed more frequently across generations
E.g., brown eyes, tongue curling
Recessive genes
Weaker gene that cannot dominate
E.g., blue eyes, non-curling tongue

Question 14

Sex- linked characteristcs

Answer 14

Influenced by single genes located on sex chromosomes
Actually X-linked
Because females have 2 X-chromosomes, any recessive allele has a good chance of being suppressed

Question 15

Polygenic Inheritance

Answer 15

Traits that are influenced by multiple pairs of genes & typically interact with multiple environmental factors
Accounts for the great individual differences in these traits
Many, including height, intelligence, disease susceptibility
These traits are normally distributed

Question 16

Studying Genetic & 
Environmental Influences:Behavioral genetics

Answer 16

Scientific study of the extent to which genetic and environmental differences among people or animals a

Question 17

Studying Genetic & 
Environmental Influences:Heritibility estimates

Answer 17

Extent to which individual differences in complex traits are due to genetic factors
Obtained from kinship studies, so estimates vary from study to study

Question 18

Concordance rates

Answer 18

Percentage of pairs of people studied in which, if one member of a pair displays a specific trait, so does the other one
Higher percentages among genetically closer individuals imply greater genetic influence
Sometimes, correlation coefficients are used instead

Question 19

Gene-Environment Interactions

Answer 19

The effects of our genes depend on what kind of environment we experience, and how we respond to the environment depends on what genes we have.

Question 20

Gene-Environment Correlations

Answer 20

Ways in which a person’s genes & environmental experiences are interrelated
Based on correlations
Passive G-E correlation
Type of environment provided by parents
Evocative G-E correlation
Types of reactions a person’s behavior triggers in others
Active G-E correlation
Types of environments we actively seek out

Question 21

Epigenesis & Epigenetic Effect

Answer 21

The process by which nature and nurture interact to produce our developmental outcomes
Environmental influences impact whether or not a gene (set of genes) will be expressed, and also to what extent
Genes do not dictate our developmental patterns!
Prominent during the prenatal period, but influential throughout life
Fraga & colleagues (2005) data comparing similarity in younger vs. older twins.