Chapter 3: Principles of Genetics

Who formed the foundational work on genetics?

• Gregor Mendel

What did Mendel’s experiment show?

• How traits are passed down from one gen to the next

What did Mendel’s P1 generation show?

• Parent generation

• Pure, true-breeding, homozygous dominant/recessive seeds

What happened when Mendel crossed yellow and green peas?

• All were yellow

What is Mendel’s Law of Segregation?

• Traits separate during reproduction

• Recessive traits can reappear

What is a punnet square?

• Obvious

How are punnett squares used in biotechnology?

• Predicting inheritance of traits/disorders

What is the Law of Independent Assortment?

• The inheritance of one trait does not impact the inheritance of another

Why is the Law of Independent Assortment important in biotechnology?

• Understand how traits and genetic disorders are inherited independently

What is a testcross?

• Demonstrates whether an individual with a dominant phenotype is homozygous or heterozygous

What is homozygous?

• Obvious

What is heterozygous?

• Obvious

Why are testcrosses important in biotechnology?

• Predicting inheritance of a disease

What is incomplete dominance?

• No allele is dominant

What does incomplete dominance show in biotechnology?

• How genetic variation creates intermediate phenotypes

What is codominance?

• Both traits show

What is an example of a trait determined by codominance?

• Human blood types

Why is codominance important in biotechnology?

• Medicine

• Transfusions

• Paternity testing

What is polygenic inheritance?

• Controlled by many genes working together

What is a classic example of polygenic inheritance?

• Skin color

• Height

• Weight

What type of results does polygenic inheritance produce?

• Range/gradient of phenotypes

How is sex determined?

• X and Y chromosomes

Why is sex determination important in biotechnology?

• Paternal testing

How are sex linked traits determined?

• Genes on x chromosomes

Why are males more likely to express X-linked disorders?

• Only one x chromosome

How do females express sex linked disorders?

• Carriers or homozygous dom/rec

Why is it important to understand sex linked inheritance in biotechnology?

• Understanding genetic disorders

What are chromosomal alterations?

• Large scale changes in chromosomal structure

What is deletion?

• One segment of chromosome deleted

What is inversion?

• One segment of chromosome flipped

What is translocation?

• One segment on each chromosome swap places

What is duplication?

• One segment is duplicated

What is crossing over?

• Exchange of DNA between homologous chromosomes

Why is crossing over important in science and biotech?

• Variability

• Evolution

When does crossing over occur?

• Prophase I of meiosis

What is nondisjunction?

• Failure of chromosomes to separate properly

What is the result of nondisjunction?

• Too many/few chromosomes

What disease does nondisjunction help explain?

• Downs

• Turner

• Klinefelter

What is Down’s Syndrome?

• Trisomy 21

What is Turner syndrome?

• Partial absence of x chromosome (females)

What is Klinefelter syndrome?

• Extra x chromosome (males)