Lecture 5 - Genetics And Mendel Flashcards
What describes the Hardy-Weinberg Equilibrium?
An equation which explains if there are evolutionary factors at play. Assumes there are none until proven wrong. Calculates gene frequencies at a given time.
List the assumptions of Hardy-Weinberg Equilibrium.
- Random mating (no sexual selection)
- No natural selection
- No gene flow
- No genetic drift, large population
What is the Hardy-Weinberg equation?
p² + 2pq + q² = 1
In the Hardy-Weinberg equation, what does ‘p’ represent?
Frequency of the DOMINANT allele in the population.
In the Hardy-Weinberg equation, what does ‘q’ represent?
Frequency of the RECESSIVE allele in the population.
What does p² represent in the Hardy-Weinberg equation?
Percentage of homozygous dominant individuals.
What does q² represent in the Hardy-Weinberg equation?
Percentage of homozygous recessive individuals.
What does 2pq represent in the Hardy-Weinberg equation?
Percentage of heterozygous individuals.
If the equation equals one, what does that entail?
If the numbers match the equation, then no evolutionary forces took siege. The equilibrium is basically a null hypothesis.
What is a Mendelian trait?
Discrete traits that work in a Mendelian fashion. Ie a 1:1 ratio and dominant and recessive style.
Define codominance.
A dominant trait that does not mask a recessive trait.
What are polygenic traits?
Traits controlled by multiple genes
Examples include adult height and skin color.
Which components are present in human blood?
- Red blood cells (erythrocytes)
- White blood cells (leukocytes)
- Plasma
What are the two blood groups? Are they considered Mendelian traits or not?
ABO - measures blood type, Mendelian
Rh - measures positive or negative, not Mendelian
What are antigens? What do they do?
They are present on the cell. They tell the immune system they belong to the body and to not attack them.
What are antibodies? What do they do?
They are found in our plasma an detect pathogens in the system.
What is the significance of Karl Landsteiner’s work?
Discovered that different blood types, when mixed, cause blood agglutination (antibodies react to wrong blood type and clump together).
Why is AB+ the universal recipient?
Because it doesn’t have the antibodies to react to the foreign blood.
Why is O- the universal donor?
Because it doesn’t have antigens.
What are clines in genetics?
Gradual frequency changes of traits
Suggests gene flow or natural selection; abrupt changes indicate genetic drift.
What is sickle cell anemia?
Inherited blood disorder affecting red blood cells. Causes blockages and clumping, and deoxygenated blood.
What is the relationship between sickle cell anemia and malaria?
Heterozygous individuals (Hb^A Hb^S) have some malarial resistance.
What is lactase persistence?
Continuation of lactose digestibility even throughout adulthood
- lactase persistence is a regulatory gene, therefore it switches off, but it can continue throughout adulthood for some populations
Where did lactase persistence first emerge?
In Northern Europe during the Neolithic period (12,000 BP).
Associated with dairying agricultural groups. It was a mutation that allowed these populations to consume dairy.
