17.1 Flashcards
Choosing and breeding specific plants and animals for specific features and behavior’s?
Selective Breeding
Who proposed the first widely accepted theory of inheritance?
Aristotle
What did Aristotle say caused inheritance?
- Egg and Sperm consisted of particles (pangenesis) that was derived from all parts of the body
- Upon fertilization - pangenesis develop into parts of the body of which they were derived
What did Antony Van Leuwenhoek say?
- Complete person (homunculus) - in the head of sperm
- Came from father but developed in the mother
Who countered Antony Van Leuwenhoek’s proposal?
Regnier de Graaf - proposed that the egg that contains the entire person, but sperm stimulates the egg to develop
Who laid the foundation of the field of genetics?
Gregory Mendel (Monk and teacher)
How did Mendel lay the foundation of the field of genetics?
He analyzed over 28 000 pea plants in the monastery garden
What did he make sure to search for in the peas he researched?
He chose seven traits that were expressed in two easily distinguished forms
What types of plants exhibit the same characteristics generation after generation?
True breeding plants
What is the F1 generation?
The first set of offspring that is crated by the parent plants
What is the F2 generation
The offspring that is produced from the F1 generation.
What is it called when only one trait is crossed?
Monohybrid cross
The characteristic that is expressed?
Dominant
The characteristic that is not expressed?
Recessive
Do traits that did not appear in the F1 generation reappear in the F2 generation?
Yes
What is Mendel’s first law of segregation?
- All individual’s have two copies of one factor
- Each copy segregates randomly during gamete formation - each gamete receives one copy of every copy
What are alleles?
Different forms of each gene
What is an individual’s genotype?
Combination of alleles for any given trait
What is an individual’s phenotype?
Outward expression of trait that you can observe
What do you call an individual with two identical alleles for a trait such as RR or rr
They are homozygous dominant (RR) or homozygous recessive (rr)
What do you call an individual with two different alleles for a trait?
Heterozygous
How can you know if a phenotypically dominant individual is homozygous or heterozygous?
You can do a test cross with a homozygous recessive plant
What is Waltzer?
A recessive trait in mice that affects inner ear - they run in circles
What is it called when there are two genes involved in a cross?
A dihybrid cross
What is the Law of independent assortment?
- When two alleles for one gene segregate independently - of the other alleles for other genes during gamete formation
What is incomplete dominance?
- Condition in which neither of the two alleles are expressed - they conceal each others presence
What is an example of incomplete dominance?
When red flowers cross with white flowers to produce pink flowers
What are two genetic conditions in humans that show incomplete dominance?
- Sickle cell anemia
- Familial hypercholesterolemia
What happens in sickle cell anemia?
The hemoglobin in the red blood cells form needle like crystals that distort the shape of the cells
What does the allele look like for normal hemoglobin and for sickle cell?
Normal: Hb ^A
Sickle cell: Hb^s
What does the genotype look like for sickle cell trait and why is this an advantage?
- Hb^S Hb^A
- This is a heterozygous advantage because they are resistant to malaria
What happens in familial hypercholestolemia?
Tissues are unable to remove bad cholesterol from blood
What is co - dominance?
When both alleles are fully expressed a black and white horse crossing to create offsrpign with black and white speckled hair
Did sutton say that genes were carried on chromosomes?
yes
