Genetics/ Evolution Flashcards
Alleles
Alternative form of genes. Can be dominant ( only need one allele to show ,will show even with recessive trait) or recessive ( need 2 alleles to show ,will show only with other recessive trait not dominant).
Genotypes
Allelic configuration of a gene.
Homozygous- contains the same allele.
Heterozygous- contains different alleles.
Complete dominance
Person contains one dominant allele and one recessive
Phenotype
Physical manifestation of a gene.
Codominance
Contains two dominant alleles that are equally expressed.
Incomplete dominance
Has no dominant alleles, recessive traits are a mix of them.
Penetrance v. Expressivity
Penetrance is the proportion of the population who express a phenotype of a given gene.
Expressivity is the strength by which the phenotype is expressed.
What are Mendel’s two laws?
Law of segregation ( Mendel’s first law)- alleles of a gene segregate during meiosis with each gamete having one allele.
Law of independent assortment ( Mendel’s second law) - alleles segregate without being influenced by the other.
Griffith Experiment
Discovered the transforming principle by demonstrating that heat killed virulent bacteria converted nonvirulent live bacteria virulent.
Avery- MacLeod- McCarty
Lead to DNA being discovered as holding genetic information by degrading DNA, causing no transforming.
Hershey- Chase Experiment
Confirmed DNA housed genetic material because it was the only thing found in radiolabeled bacteriophage- infected bacteria.
Gene pool
All of the alleles of a gene in a population.
Point mutations v. Frameshift mutations
Point mutations in the DNA that involves removing one nucleotide for another.
Frameshift mutations are mutations that disrupt the reading frame of DNA.
Describe the following type of point mutations:
- Silent mutations
- Missense mutations
- Nonsense mutations
- Insertions and deletions
- Silent mutations are mutations where the nucelotide switched leads to no change in amino acid.
- Missense mutations are mutations that leads to different amino acid.
- Nonsense mutation- premature stop codon coded causing shortened protein.
- Insertions= adding nucleotide v. Deletions= removing nucleotide = causes frameshift mutation.
What are chromosomal mutations? Describe the following chromosomal mutations:
- Deletion
-Duplication
- Inversion
- Insertion
- Translocation
Chromosomal mutations are larger scales of chromosomes that doesn’t happen at the amino acid/ protein level.
- Deletion mutations- large portion of DNA.
- Duplication - Large portion of DNA are duplicated.
- Inversion- segment of DNA is reversed.
-Insertion - portion of chromosome is removed from one chromosome to another.
- Translocation - when a chromosome is swapped with another segment of chromosome.
Genetic leakage
Flow of genes between species resulting in hybrid offspring.
Genetic drift
When the gene pool of a population changes due to random things ( chance).
Founder effect
When something ( ie. natural disaster) decreases the population considerably causing a bottleneck. This causes inbreeding and more homozygous genotypes.
Why do we use punnett squares?
We can determine genotypic and phenotypic ratios formed from the mating of parents.
- Parent generation (P) - parents.
- Filial generation (F)- offspring.
- Monohybrid cross = cross involving one gene. Dihybrid cross= cross involving two genes.
Recombination frequency
- Represented by theta symbol.
It’s the likelihood of genes being seperated during meiosis during crossing over. - Genes closer together are less likely to be separated than genes further apart.