Task 2 PEAS, GENES, AND A POST-MORTEM WEDDING

Question 1

Homozygous

Answer 1

The case in which the plant has two copies of the same Allele (e.g. AA or aa)

Question 2

Heterozygous

Answer 2

One copy of each of the two different alleles (e.g. Aa)

Question 3

Probability of passing on alleles

Answer 3

it is always 50/50 which allele is passed on

Question 4

Dominant

Answer 4

as long there is a least one copy of A the corresponding characteristic gets developed

Question 5

Recessive

Answer 5

Both copies of the Gene has to be a to be expressed

Question 6

Co-dominant

Answer 6

heterozygotes fully express the phenotype of both of their homozygotes parents

Question 7

Incomplete dominance

Answer 7

means that the phenotype of the heterozygotes is intermediate in form between those of the two homozygotes (white + red flower= pink flowers which still can have white or red offspring) (only the phenotype changes not the genetic material)

Question 8

Independent segregation

Answer 8

means that phenotypic traits controlled by different genes can become separated from each other through generations

Question 9

Inbreeding

Answer 9

makes it more likely to become two diseases because of the recessive alleles

Question 10

Genetic drift

Answer 10

in smaller populations it could happen that the recessive allele will not be expressed so allele frequency fluctuates
o The more people there are in a population the less likely it is that the gene reaches Fixation
o Fixation: The point where everybody in the population carries the gene

Question 11

Law of segregation

Answer 11

the two alleles for a heritable character segregate (separate from each other) during gamete formation and end up in different gametes (if same allele thus true-breeding: allele present in all gametes)

Question 12

Mendelian disease

Answer 12

A disease that is transferred by one single gene (e.g. Huntington)

Question 13

Neutral theory of molecular evolution

Answer 13

The amount of divergence between the DNA sequences of any two populations or species basically reflects the time since their common ancestor.

Question 14

Hardy Weinberg equilibrium

Answer 14

displays the distribution of alleles in a population without environmental influence
o Without natural selection alleles won’t become more rare and the distribution of hetero and homozygotes will stay the same
p^2 (AA) + 2pq(Aa) + p^2 (aa) = 1

Question 15

Heritability

Answer 15

the proportion of the observed phenotypic variation that can be accounted for genetic variation in a particular population and time (difference
o Maximum heritability is 1 that means all phenotypic variation is related to genotypic variation and heritability of 0 would mean none of it is
o a heritability of 0 means that environmental effects account for all of the variation in the characteristic.

Question 16

´Coefficient of relatedness

Answer 16

between a man and his father is one-half
o (r) – probability that any particular allele in individual A (dark blue) is identical by descent (derived from same immediate source) as the allele in individual B (any of the light blue ones)

Question 17

Twin studies

Answer 17

o Shared environment: parental social class, parental behaviour, diet available, school, town etc. they will influence both kinds of twins in the same way
o Non-shared environment: childhood diseases or accidents that affect one twin but not the other. No kind of twins shares these factors by definition

Question 18

Falconers estimate of heritability

Answer 18

if the height of MZ twins correlates at 0.9, and the heights of DZ twins correlate at 0.5, then the estimated heritability is (0.9 — 0.5) x 2 = 0.8.

Question 19

ACE models

Answer 19

A (the heritability) C (the effect of the shared environment) E (the effect of the non-shared environment)
o Allows us to identify its relative strength
o Called narrow sense heritabilities because they don’t consider the dominance and epistatic effect

Question 20

Problems with twin studies

Answer 20

o For MZ the rivalry in the placenta which they have to share
o MZ twins are treated more alike than DZ twins

Question 21

Coefficient of additive genetic variance

Answer 21

is an estimate of the amount of genetic variation in a population relevant to a particular trait, independent of the amount of environmental variation.

Question 22

Dominance effect

Answer 22

Effects on heritability that are due to the interaction between the pair of alleles at a locus

Question 23

Epistatic effect

Answer 23

Effects on heritability that are due to the interactions between alleles at different loci

Question 24

Polygeneic inheritance

Answer 24

additive effect of multiple genes on a single phenotypic character
• E.g. AABBCC darkest  AaBbCc middle  aabbcc lightest (majority in the middle)

Question 25

Quantitative genetics

Answer 25

When one characteristic is influenced by multiple genes

Question 26

Identical descent

Answer 26

derived from the same immediate source

Question 27

Monozygotic

Answer 27

Twins from the same egg

Question 28

Dizygotic

Answer 28

Twins from different eggs

Question 29

All psychological traits show significant and substantial genetic influence

Answer 29

 Traits such as political beliefs, religiosity, altruism, and food preferences also have shown significant genetic influence
 They differ in how much influence genetic has

Question 30

No traits are 100% heritable

Answer 30

 Typically between 30% and 50%

 Physical traits are more reliably measured than psychological

Question 31

Heritability is caused by many genes of small effect

Answer 31

 Many genes influence complex traits

 There is no single effect that is higher than 1%

Question 32

Phenotypic correlations between psychological traits show significant substantial genetic mediation

Answer 32

 Phenotypic covariance between traits is significantly and substantially caused by genetic covariance, not just environmentally driven covariance.
 Some genes effect several traits

Question 33

The heritability of intelligence increases throughout lifetime

Answer 33

 The inheritance of the states of intelligence through a lifetime

Question 34

Age-to-Age stability is mainly due to genetics

Answer 34

trait across age), whereas age-to-age change is primarily the provenance of environmental factors

Question 35

Most measures of the environment shows significant genetic influence

Answer 35

 humans select, modify, and create environments correlated with their genetic behavioural propensities such as personality and psychopathology

Question 36

Most associations between environmental measures and psychological traits are significantly mediated genetically

Answer 36

 if these correlations are mediated genetically, interpretations that assume environmental causation are wrong
 genetically sensitive designs can be used to identify causal effects of the environment free of genetic confound
 genetic mediation of the association between environmental measures and behavioural traits is not just a nuisance that needs to be controlled

Question 37

Most environmental factors are not shared by children growing up in the same family

Answer 37

 for most behavioural dimensions and disorders, it is genetics that accounts for similarity among siblings
 The message is not that family experiences are unimportant but rather that the relevant experiences are specific to each child in the family

Question 38

Abnormal is normal

Answer 38

 People with mental diseases are the extremes of the distribution of genes
 Everybody carries some kind of abnormalities which don’t have to be expressed

Question 39

Linkage

Answer 39

when two genes lie on the same chromosome
 Closer together = greater linkage (lower probability of crossover)
 Parental type frequency greater than 50%

Question 40

Pleiotropy

Answer 40

one gene can have multiple phenotypic effects