Lecture 2 Mechanisms of Mendelian genetics

Question 1

Albinism

Answer 1

a genetic defect; occurs when melanocytes cannot make enough melanin to color hair, skin and eyes. There is no cure for this disorder

Question 2

Tyrosinase

Answer 2

enzyme that TYR gene produces; required for synthesis of melanin pigment

Question 3

Role of Melanin

Answer 3

-protection of DNA in skin cells against UV radiation (sunlight)\
-In the eye, melanin is needed for proper eyesight

Question 4

Green Revolution (genes in agriculture)

Answer 4

increased agricultural production worldwide
-high yielding crops
-resistance to disease/pests
-facilitate harvest

ex of gmo (corn, soy, cotton, papaya, rice, rapseed, potatoes, tomatoes, dairy products, peas)

Question 5

The 3 divisions of genetics

Answer 5

● Transmission Genetics
● Molecular Genetics
● Population Genetics

Question 6

Transmission Genetics

Answer 6

● The oldest field of genetics
● Explores the inheritance patterns of traits
● How traits are passed from one generation to the next
● The conceptual framework was provided by Gregor Mendel in the
1860s

○ Genetic determinants pass from parent to offspring as discrete
units

■ These are now termed genes
● The basic experimental
approach is the genetic cross

○ Two selected individuals are mated
○ The traits in question are analyzed over several generations
○ Analysis is often quantitative in nature

Question 7

Molecular Genetics

Answer 7

Focuses on a Biochemical Understanding of the Hereditary Material

● Most modern field of genetics
● molecular features of DNA underlie gene expression
● Gene organization and function
● Detailed analysis of DNA, RNA and proteins

Question 8

Population Genetics

Answer 8

Concerned With Genetic Variation and Its Role in Evolution

● Genetic variation of populations and
● How variation is related to the environment
● Develop mathematical theories to explain the prevalence of certain alleles
within populations

Question 9

Model Organisms

Answer 9

● Model genetic organisms are organisms with characteristics that
make them useful for genetic analysis
● Six have been the most intensively studied genetically
● Some Characteristics

○ Short generation time
○ Production of numerous progeny
○ The ability to be reared in a laboratory environment

Question 10

Centromere

Answer 10

attachment point for spindle microtubules

Question 11

Telomeres

Answer 11

Tpis of a linear chromosome

Question 12

Origins of replication

Answer 12

Where the DNA synthesis begins

Question 13

Meiosis

Answer 13

The production of haploid gametes

• Four cells are produced from each original cell.
• Chromosome number in each new cell is reduced by
  half. The new cells are haploid.
• Newly formed cells from meiosis are genetically
  different from one another and from the parental cell.
• Meiosis in animals
  – Spermatogenesis: male gamete production
  – Oogenesis: female gamete production

Question 14

Fertilization

Answer 14

The fusion of haploid gametes

Question 15

Genetic variation

Answer 15

Consequences of meiosis

Question 16

Mendel’s Experiments; two types of crosses

Answer 16

● Monohybrid Crosses
● Dihybrid crosses

Question 17

Law of Segregation

Answer 17

● Principle of Segregation
● Concept of Dominance

Cross between two parents that differ in a single characteristic.
1. one character is encoded by two genetic factors.
2. two genetic factors (alleles) separate when gametes are formed.
3. The concept of dominant and recessive traits.
4. Two alleles separate with equal probability into the gametes.

Each individual diploid organism possesses two alleles for any
particular characteristic.
Two alleles segregate when gametes are formed, and one allele
goes into each gamete.

Question 18

Genetic Terminology

Answer 18

● An allele is a variant form of a gene
● Some genes have a variety of different forms, which are located at the
same position, or genetic locus, on a chromosome.
● Humans are called diploid organisms because they have two alleles

Question 19

How to predict genetic crosses (punnet square)

Answer 19

Independent events
P(A and B) = P(A) x P(B)

go to slide 33 and 34

Question 20

comparision between segragation and independent assortment

Answer 20

slide 37