Module 2 | GENETICS

What does the chromosome theory of inheritance state?

genes are located on chromosomes

What accounts for inheritance patterns?

the behavior of chromosomes during meiosis & fertilization

What is genetics?

-branch of biology that deals with heredity and variation

-explains relations between genes & traits

Who is the father of genetics?

Gregor Mendel

Both Knight & Goss were studying edible peas (Pisum Sativum). What were the reasons for choosing peas?

-short generation time
-easy to grow
-inexpensive
-varieties (easily observable traits)
-cross fertilize & self fertilize

Instead of guessing how traits were passed down from parent to offspring, what did Mendel do first?

analyze patterns of inheritance

Mendel deduced the fundamental principle of genetics, including that parents pass on what?

-discrete heritable factors (later known as genes)
-responsible for inherited traits

Mendel chose the garden pea for what two reasons?

1 - available in many varient shapes & colors that could easily be identified and analyzed

2 - peas can self pollinate & cross pollinate

What does it mean to self pollinate vs. cross pollinate?

Self Pollinate - pollen of plant pollinates its own ovule
Cross Pollinate- transfer of pollen from one plant to ovule of second plant

What is a monohybrid cross?

a cross between parent plans that differ in only one trait/characteristic

Alternative forms of a gene that influence the same trait and are found at the same location in homologous chromosomes are called____________?

Alleles ( be dominant or recessive )

What are 5 lessons we learned from Mendel?

1-the existence of genes
2-genes are in pairs
3-halving of gene pairs in gametes
4-equal segregation
5-random fertilization

The gene may have different forms called what?

Alleles

What is the principle of segregation?

two alleles segregate during gamete formation

What is random fertilization?

Union of one gamete from each plant from a zygote

What is homozygote?

an individual that carries two identical alleles of a particular gene

What letters represent a recessive homozygote?

tt

What is a heterozygote?

an individual that carries two different alleles of a particular gene

What letters represent a heterozygote?

Tt

What is the difference between genotype and phenotype?

Genotype = genetic makeup (allelic makeup)
Phenotype = physical appearance

What is the principle of independent assortment?

The alleles of different genes segregate (assort) independently

What is a carrier?

A person with one copy of the allele for a recessive disorder & does not exhibit symptoms

What is an example of dominant disorder?

anchondroplasia (a form) of dwarfism

Is a dominant allele always more common in a population that the corresponding recessive allele?

No, a dominant allele is not necessarily more common in a population than the corresponding recessive allele

What is incomplete dominance?

F1 hybrids have an appearance in-between the phenotypes of two pure breeding parents

What is hypercholesterolemia?

A human trait that is incompletely dominant

What do recessive alleles represent in hypercholesterolemia patients?

recessive alleles characterized by dangerously high levels of cholesterol

What is an example of co-dominance/multiple alleles in humans?

ABO blood groups in humans are examples of multiple alleles

What is pleiotropy?
What is an example of this?

(Single gene —> multiple traits)
Impact of single gene on more than one hereditary characteristic
Sickle Cell Disease is an example of pleiotropy

What is polygenic inheritance?
What is an example of this?

(2 or more genes -> one trait)
Additive affects of 2 or more genes on a single phenotype
Skin Pigmentation is an example of polygenic inheritance

Recessive sex-linked traits are expressed more frequently in who?

Men (also more common to be color blind)

What is hemophilia?

blood clotting disease