L.8 Genetics

Question 1

What is a Chromosome?

Answer 1

a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.

Contain genes in a linear sequence

Question 2

What are alleles?

Answer 2

Alleles are alternative forms of a gene.

Dominant alleles require only one copy to be expressed

Recessive alleles require two copies to be expressed.

Question 3

What is a genotype and what are the three different genotypes possible?

Answer 3

A genotype is the combination of alleles one has at a given genetic locus.

1. Homozygous; same allele
2. Heterozygous; two different alleles
3. Hemizygous; only having one allele

Question 4

What is a phenotype?

Answer 4

The observable manifestation of a genotype

Question 5

What are the three different patterns of dominance?

Answer 5

1. Complete Dominance; one allele takes over
2. Codominance; both alleles are physically present (AB blood type)
3. Incomplete Dominance; No dominant alleles, an intermediate phenotype (purple flower color)

Question 6

What is the difference between Penetrance and Expressivity?

Answer 6

Penetrance: is the poportion of a population with a given genotype who express the phenotype

Expressivity: referes to the varying/different phenotypic manifestation of a given genotype.

Question 7

What are Mendel’s first and second laws?

Answer 7

1st; (of segregation) an organism has two alleles for each gene, which segregate during anaphase I in miosis, resulting in gametes carrying only one allele for a trait.

2nd; (of independent assortment) states that the inheritance of one allele does not influence the probability of inheriting an allele for a different gene, in prophase I

Both increasing diversity in the offspring

Question 8

Support for DNA as genetic material came from different experiments, explain these.

1. Griffith
2. Avery-MacLeod-Mccarty
3. Hershey-Chase

Answer 8

1. Converting of non-virulent bacteria to virulent bacteri by exposure to hear killed virulent bacterial
2. DNA degradation caused cessation of bacterial transformation.
3. Radiolabled DNA could be found in bacteriophage infected bacteria

Question 9

What is a gene pool?

Answer 9

All of the alleles found in a given population

Question 10

What are mutations?

Answer 10

DNA mutations are permanent changes in the DNAsequence of a gene. Mutations range in their severity. Some damage the way a cell or whole organism functions, or even cause lethality, while others have no effect. Mutations also range in the amount of DNAaltered.

Question 11

Nucleotide mutations include two major types, which are?

Answer 11

Point mutations; substitution of one cucleotide for another

Framshift mutations; moving the 3 letter transcriptionla reading frame.

Question 12

What are the 3 types of point mutations?

Answer 12

1. Silent; no effect on protein
2. Missence ; one amino acid for another
3. Monsense; sub a stop codon for an amino acid

Question 13

What are the two different FRameshift mutations?

Answer 13

Insertions and Deletions, bot result in a shift in the reading frame leading to changes doe all downstream amino acids.

Question 14

What are the 5 chromosomal mutations affecting whole segments of DNA?

Answer 14

1. Deletion: large segment of DNA is lost.
2. Duplication: Segment of DNAis copies multiple times.
3. Inversion: Segment of DNA is reversed.
4. Insertion: Segment of DNA is moved from one chromosome to another.
5. Translocation: Segment of DNA is swapped with a segment of DNA from another chromosome (Flip/flop)

Question 15

What is genetic leakage?

Answer 15

Genetic leakage is a flow od genes between species through hybrid offspring

Question 16

What is genetic drift?

Answer 16

Occurs when the composition of the gene pool changes as a result of chance.

Variation in the relative frequency of different genotypes in a small population, owing to the chance disappearance of particular genes as individuals die or do not reproduce.

Question 17

Use founder effect, bottlenecks and inbreeding in the same sentence.

Answer 17

The founder effect results from bottlenecks that suddenly isolate a small population leading to inbreeding and increased prevalence of certain homozygous genotypes.