10.10 Darwin's Missing Mechanism Flashcards
1
Q
What is required for natural selection?
A
- Variability, not exact copies
- Heritability, offspring tend to look more like parents than other individuals.
- Differential reproduction, offspring with slight ‘edge’ will contribute more to next generation.
2
Q
Lamarck’s mechanism for evolution
A
- Individuals acquire characteristics useful to their mode of life.
- Acquired traits passed onto offspring via inheritance.
- Species persist indefinitely, but are constantly evolving.
3
Q
“Pangenesis” hypothesis of heritability
A
- Whole body of parents contributes to “gemmules” that carry hereditary information.
- Represents a Lamarckian view of heritability.
- “If I work out and get big biceps, my offspring will have big biceps”.
4
Q
“Blending inheritance”
A
- Predicts that trait/heredity factor is diluted in hybrids.
- BAsed on observation of hybrids.
- E.g. Red + White flower = Mix.
5
Q
Gregor Mendel
A
- Austrian monk
- Interested in heritability.
- Raised > 29,000 pea plants, closely controlled reproduction and kept notes generation by generation.
6
Q
Phenotype
A
physical expression of traits
7
Q
Mendelian genetics
A
- Phenotypes determined by units of heredity called genes.
- Each gene composed of two alleles.
- Some alleles are dominant, and some recessive.
8
Q
Principle of segregation
A
Each parent contributes one randomly chosen allele from each gene to each offspring.
9
Q
Principle of independent assortment
A
Allele pairs behave independently from other allele pairs.
10
Q
Heterozygous
A
2 different alleles for the same gene.
11
Q
Homozygous
A
2 alleles that are identical.
12
Q
Non-mendelian genetics
A
- When one or more key assumptions of Mendelian genetics are violated.
13
Q
Examples of Non-mendelian genetics
A
- Incomplete dominance of alleles. Eg Flowers.
- Co-dominance of alleles. E.g. Blood, A and B is dominant.
- This is why some hybrids show intermediate form/blending inheritance.
14
Q
Pleiotropism
A
- Example of Non-mendelian genetics.
- When one gene has multiple different effects.
- Eg gene for albinism related to having crossed eyes and larger body size.
15
Q
Epistasis
A
Non-mendelian genetics
non-additive gene interactions contribute to phenotype.
e.g. milk production in cows determined by several different complex gene interactions.
