Exam 3- Genetics Flashcards
What is an allele?
alternate forms of an allele
- homozygous
- heterozygous
What is a gene?
unit of inheritance; basics of every characteristic
What are the Mendelian patterns of inheritance?
Organisms attain diversity of form, function, and behavior through hereditary modifications
What is the importance of different sequences of nucleotides in DNA?
- genetic differences
- enzyme differences
- appearance differences
What was Hippocrates’ early idea of genetics?
- 1st known expansion of hereditary pangenesis
- seeds produced and passed on during conception
What was Aristotles early idea of genetics?
Male and female semen produced flesh and blood offspring
What was the idea of spontaneous generation?
the supposed production of living organisms from nonliving matter, as inferred from the apparent appearance of life in some supposedly sterile environments.
What was the blending concept of inheritance?
black mouse + white mouse DOES NOT EQUAL gray mouse
What is experience-dependent inheritance?
- changed back on generations by adapting to the environment
- behavioral changes modify traits inherited by offspring
Gregor Medel
- inheritance in common pea
- formulated fundamental laws or heredity in the 1860s
- no knowledge of cells or chromosomes or microscope
- right organism, right experiment, right analysis
What are traits?
characteristics
- ex. wrinkled v.s smooth
characteristic vs. trait example?
characteristic:
stem length
trait:
tall or short
What are the parental plants? what are their offspring called?
The first two plants crossed
- their offspring are called F1
What was interesting about Medel’s f2 results?
- in every case of F2 results Mendel saw a 3: 1 ratio
- 3 dominant
- 1 recessive
What is a monohybrid cross?
- true breeding
- choose variants that only vary in one trait
- performed reciprocal crosses
Parental gen = P0
First filial generation offspring = F1
Second filial generation offspring = F2
Formulated Law of Segregation
What is true breeding?
- exact same characteristic
- homozygous plants
What is the Formulated Law of Segregation?
1:2:1
TT: Tt: tt ( Genotype Ratio)
3: 1
tall: short ( Phenotype Ratio)
Law of Segregation
- each individual has a pair of factors ( alleles) for each trait
- the factors ( alleles) separate ( segregate) during gamete formation
- each egg or sperm has only one
- fertilization gives offspring two factors for each trait
Genotype? Phenotype?
- genes in cells
- physical manifestation of genes
Principle of Dominance?
- dominant allele ( A ) masks expressing of recessive allele (a)
Test Cross?
- Individuals with recessive phenotype always have the homozygous recessive genotype ( gg)
- individuals with dominant phenotype have intermediate genotype
Dihybrid Cross?
- true breeding plants differing in TWO traits
- F1 plants= both dominant characteristics
- observed phenotypes among F2 plants
- Formulated Law of Independent Assortment
What is the Formulated Law of Independant Assortment?
9:3:3:1
- 3:1 tall/short
- 3:1 green/yellow
- a pair of factors for one trait segregate independently of the factors for other traits ( on nonhomologous chromosomes)
- all possible combinations of factors can occur in gametes
Multiplicative law?
Mendel’s second law, the law of independent assortment, states that the alleles of one gene segregate into gametes independently of the alleles of another gene.
