Lecture 4

Question 1

Genotype

Answer 1

genetic makeup of an organism
- aa, Aa, AA

Question 2

phenotype

Answer 2

a feature of an organism that is observed
size, fur, eye colour
shows how an organism varies physically

Question 3

Genome

Answer 3

the entirety of an organisms DNA that includes exons and introns

Question 4

Darwins Mechanisms of Natural Selection

Answer 4

1. Variation
2. Heredity
3. Differential fitness (some forms are more successful then other)

Question 5

What are the sources of genetic variation (increases genetic diversity)

Answer 5

1. Mutations
2. independent assortment within meiosis
3. recombination

Question 6

Detailed explanation of mutations and how it is a source of genetic variation

Answer 6

-stable change in DNA
-very rare
-some = neutral, bad, good
- something we cannot control
- environments can affect mutation rate
(high radioactivity, metals), temperature

Question 7

Types of Mutations

Answer 7

-Point mutation
- Insertion/deletions (changes length of the sequence)
-Repeating
-inversions (rearrangement)

Question 8

Examples of mutations

Answer 8

G6PD Deficiency in humans
- untreated = severe anemia
- also protects against malaria

Question 9

How does independent assortment of chromosomes create diversity

Answer 9

• meiosis
• parents make diploid –> haploid gametes
• a lot of different combinations in offspring

Question 10

How does recombination = genetic diversity

Answer 10

• 2 chromosomes that are homologous (code for the same alleles)
• line up during synapsis at the chiasmata = recombinant

Question 11

Before Mendel people did not understand how offspring resembled their parents, what were the 2 theories that tried to explain hereditary?

Answer 11

1. Preformationism = believed that only one parent contributed to the inheritance
2. theory of blending inheritance
   - believed that parents genes mix together and blend

Question 12

Why doesn’t the theory of blending inheritance work

Answer 12

blending genes = not reversible and it will not ever be selected out
- no more variation
- if a mutation arises and it = bad - offspring will have to keep blending
- NS cannot select against this mutation

Question 13

Mendel’s pea plant

Answer 13

when the parent pea plants were cross
-F1 generation were all the same genotype (heterozygous)
- F2 generation had variation

• offspring inherit one allele per gene at random from each parent

Question 14

Discrete vs Continuous Traits

Answer 14

DISCRETE: simple mendelian genetics
- dominant, recessive (can tell by the phenotype)
CONT: complex, quantitative, different variation, not fixed
(human height)

Question 15

T/F
Quantitative traits are often affected by many factors

Answer 15

TRUE
they are affected by complex polygenic inheritance
- environmental interactions