Task 2

Question 1

What are single gene characteristics?

Answer 1

The difference in a phenotype is determined by which allele the individual has at just one genetic locus

Question 2

What are polygenic characteristics?

Answer 2

Characteristics where variation in the phenotype is related to which allele is present across a number of genes (e.g. height)

Question 3

What two approaches are there to hunt genes?

Answer 3

1. Linkage studies

2. Association studies

Question 4

What is the Huntington’s disease?

Answer 4

Incurable neurological condition, which leads to the gradual loss of coordination and cognitive abilities
-> single gene disease

Question 5

How did Mendel’s experiment look like?

Answer 5

1. He established pure yellow- and pure green podded lines of pea plants
2. He then crossbred both traits which led to the so called F1 generation
3. After carefully examining their phenotypes he interbred the F1’s which led to a new generation called F2 whose phenotypes he again carefully recorded

Question 6

What were the results of Mendel’s pea experiments?

Answer 6

The F1 generation were all yellow! In the F2’s 3/4 were yellow and 1/4 was green.
3:1 ratio

Question 7

What did Mendel conclude from his experiments?

Answer 7

1. Each individual must be carrying two particles of heredity from each parent
2. These particles can either be “green” or “yellow” in form

Question 8

What are the four points that make up Mendel’s Model?

Answer 8

1. Alleles - alternative versions of genes account for variations in inherited characters
2. For each character an organism inherits two alleles, one from each parent
3. Dominant and recessive alleles
4. Law of segregation

Question 9

What is Segregation?

Answer 9

Seperation of an individuals two genes at a locus into its offspring

Question 10

What is independent segregation?

Answer 10

Phenotypic traits cotrolled by different genes can become separated from each otherthrough generations; therefore, under independent segregation novel combinations of phenotypes are generated even though those traits were not visible in F1
-> when two genes reside on different chromosomes

Question 11

What is dependent segregation?

Answer 11

When the loci are linked on the same chromososme, they do not segregate independently

Question 12

What does the law of segregation state?

Answer 12

During gamete formation (meiosis), the alleles for each gene segregate from each other so that each gamete carries only one allele for each gene.

Question 13

What does the law of independent assortment state?

Answer 13

Each pair of alleles segregates independently of each other pair of alleles during gamete formation

Question 14

What does the law of dominance state?

Answer 14

Some alleles are dominant while others are recessive

Question 15

What are the four exceptions of Mendelian law?

Answer 15

1. Co-dominance
2. Incomplete dominance
3. Mutliple alleles
4. Pleitropy

Question 16

How does co-dominance build an exception to the Mendelian law?

Answer 16

Heterozygotes fully express the phenotype of both of their homozygous parents (e.g. human blood groups AB)

Question 17

What does incomplete dominance show?

Answer 17

The phenotype of the heterozygote is intermediate in form between those of the two homozygotes (e.g. pink flowers)

Question 18

What is Pleiotropy?

Answer 18

One gene is able is able to affect multiple phenotypic characters (e.g. cystic fibrosis and sickle-cell disease)

Question 19

What did Hardy-Weinberg show?

Answer 19

1. The population frequencies of alleles do not change over the generations, even though sexual reproduction is constantly shuffling the combinations up
2. As long as mating is largely random, the expected frequency of homozygotes and heterozygotes is predictable from the frequency of the allele in general

Question 20

What does the Hardy Weinberg equilibrium show?

Answer 20

allele and genotype frequencies in a population will remain constant from generation to generation in the abscence of other evolutionary influences

Question 21

What are the ideal conditions for the Hardy Weinberg equilibrium?

Answer 21

1. No mutations
2. Random mating
3. No natural selection
4. Extremely large population
5. No gene flow

Question 22

What is the Genetic Drift?

Answer 22

In smaller populations random events are more likely and the allele frequencies will fluctuate from generation to generation, even in absence of natural selection due to change;

Question 23

What is the Neutral Theory of Molecular Evolution?

Answer 23

Holds that at the molecular level most evolutionary changes and most of the variation withing and between species is not caused by natural selection but by genetic drift of mutant alleles that are neutral

Question 24

What does the Molecular clock show?

Answer 24

The more difference there is between DNA sequence of two animals the greater time since their common ancestor

Question 25

What are quantitative genetics?

Answer 25

The study of the inheritance of traits that show a continuous distribution in the population. Such traits are not either/or but continuous.

Question 26

What are continuous characters?

Answer 26

Characteristics that vary continuously, and every individual in the population differs slightly from every other individual

Question 27

What is the central idea of quantitative genetics?

Answer 27

Some of the variance in the phenotypic characteristics is due to the influence of the environment and some is due to the influence of genotype

Question 28

What is the total phenotypic variation?

Answer 28

Sum of the genetic variation + environment variation

Question 29

How can we calculate heritability?

Answer 29

Divide by 2 each generation in diploid organisms

Question 30

What are the three parameters of the ACE model?

Answer 30

``` A= Heritability C= Shared environment influences E= Non-shared environmental influences ```

Question 31

What are the four problems with twin studies?

Answer 31

1. The environment might not be 100% identical 2. Parents might treat their MZ twins more similarly than they do their DZ twins and this could cause the MZ twins to become similar 3. The prenatal environment of MZ twins (shared placenta) could be more shared on average than that of DZ twins (C is often underestimated in a twin study) 4. After birth MZ twins are usually more dissimilar because they had to compete for nourishment in the womb.

Question 32

What are the three problems with adoption studies?

Answer 32

1. Children are often selectively placed in families which could affect the generalizability of C 2. Adoption agencies tend to place children in families that seem similar to the child or its biological parents 3. If adoption occurs immediately after birth, the prenatal environment is of often underestimated and A is overestimated

Question 33

What are dominance effects?

Answer 33

Effects are due to interaction between the pair of alleles at the locus

Question 34

What are epistatic effects?

Answer 34

Effects due to interaction between alleles at different loci

Question 35

What six explanations does the article by Maher give for the 'missing heritability'?

Answer 35

1. Right under our Nose 2. Out of Sight 3. In the Architecture 4. In Underground Networks 5. The Great Beyond 6. Lost in Diagnosis

Question 36

Explain the first 'right under our Nose' point out of the Maher article

Answer 36

The GWAS are limited -> they only identify Single Nucleotide Polymorphism that occur in a disease or trait in many individuals - SNPs represent a much bigger block of genetic material

Question 37

Explain the second 'out of sight' point out of the Maher article

Answer 37

Screening for common variation delivered less than hoped -> some might be rare not to be found at some point

Question 38

Explain the third 'in the architecture' point out of the Maher article

Answer 38

Copy-Number Variations (CNVs) could account for the differences between individuals with a disorder and missing heritability; such variations can be base pairs that are deleted or duplicated

Question 39

Explain the fourth 'in underground networks' point out of the Maher artile

Answer 39

Most genes work together, and it is possible that effects of one on heritability cannot be found without knowing the effects of the other -> Epistasis

Question 40

Explain the fifth 'the great beyond' point out of the Maher article

Answer 40

Environmental factors that could for example contribute to height are sometimes overlooked (ex: nutrients or toxins)

Question 41

Explain the sixth 'lost in diagnosis' point out of the Maher article

Answer 41

Medicine tries too hard to squish together a complex collection of symptoms

Question 42

What are the top 10 replicated findings from behavioral genetics acording to Plomin?

Answer 42

1. All psychological traits show significant and substantial genetic influence 2. No traits are 100% heritable 3. Heritability is caused by many genes of small effect 4. Phenotypic correlations between psychological traits show significant and substantial genetic mediation 5. The heritability of intelligence increases throughout development 6. Age-to-age stability is mainly due to genetics 7. Most measures of the “environment” show significant genetic influence 8. Most associations between environmental measures and psychological traits are significantly mediate genetically 9. Most environmental effects are not shared by children growing up in the same family 10. Abnormal is normal