Genetics Flashcards
Horizontal and vertical gene transfer
Horizontal: With a generation(HPV)
Vertical: parent to offspring
Law of independent assortment
Each pair of alleles segregates independently of any other pair of alleles during gamete formation. This law applies only to genes location on different chromosomes(not homologous).
What does each letter in the punnet square represent?
A haploid cell
Why did Mendel choose to experiment with garden peas?
They can cross pollinate, theyre big enough to manipulate, and theyre true breeding
What is the ultimate source of genetic variation? proximate sources?
Ultimate source: Mutation
Proximate:
- Horizontal Gene transfer
- Independent assortment
- Crossover
- Random fertilization
- Mate choice
What types of reproduction are the different sources of genetic variation limited to?
All: Mutation, horizontal gene transfer
Sexual reproduction only: Independent assortment, crossover, random fertilization, mate choice
What were the important conclusions of Mendel’s experiment?
- Inheritance is not due to blending of traits, traits are distinct(genes)
- Traits can be dominant or recessive(alleles)
- Traits segregate independently. Each parent carries 2 copies of the gene that separate from each other during meiosis
Which law and phase of meiosis do monohybrid crosses correspond with?
Law of segregation, metaphase/anaphase 1
Which law and phase of meiosis do dihybrid crosses correspond to?
Law of independent assort, metaphases 1 and 2
Law of Segregation
Alleles for a heritable trait segregate from each other during gamete formation. Therefore, an egg or sperm only gets one of the two alleles present in the somatic cell making the gamete. This corresponds to separation of homologous pairs in meiosis
Autosomes
non-sex chromosomes
X-0 system
sex-determining system where the dosage of x chromosome determines the sex. Male=X0,Female=XX
haplo-diploid system
Diploid=female, haploid=male. Common among colonial insects, often results in big size difference between genders
ZW system
Female=ZW(hemizygous), Male=ZZ
Incomplete dominance
Heterozygote presents an intermediate phenotype. no recessive alleles are present
Codominance
More than 2 alleles are present, including one or more recessive alleles
Pleiotropy
Multiple phenotypic effects result from one gene
Norm of reaction
Individuals with same genotype exhibit different phenotypes depending on conditions
Epistasis
Alleles of one gene impact phenotypic expression of another gene
Polygenic
Trait is due to contributions of multiple genes, resulting in a spectrum of phenotypes
Testcross
A testcross is performed to see if an individual with a dominant trait is homozygous or heterozygous. This is done by mating it with an individual expressing a recessive trait. If half the offspring express the recessive trait, the individual is heterozygous
Which forms of inheritance are of a molecular basis
- Incomplete dominance
- Codominance
- Pleitropy
- Norm of reaction
Which shape represents male and female in pedigrees?
Circle= Female Square= Male
PKU
(example of pleiotropy) A condition where there is a shortage of an enzyme that breaks down chemicals. The buildup of chemicals results in multiple phenotypic effects
Which forms of inheritance are complex
- Epistasis
2. Polygenic
Linked Genes
Genes on the same chromosome, sometimes inherited as a set
How are new combination of linked genes made?
crossing over
