Genetics Final Review

Unit One

100

What is the expected phenotypic ratio for offspring of a heterozygous dihybrid cross?

9:3:3:1 

200

What characteristics make a good model organism?

Easy to breed, Large number of offspring, and Short life span

300

What is crossing over and when does it occur?

Crossing over is when homologous chromosomes exchange genetic material. Occurs during prophase I of meiosis

400

If two parents are both heterozygous for a recessive disorder, what is the probability that their child will be affected with that disorder?

25%

500

During which phase of the cell cycle is DNA replicated?

S phase

Unit Two

100

What are the Hardy-Weinberg assumptions?

no mutation, no migration, random mating, no natural selection, large population size

200

If the frequency of a recessive allele is 0.35, what is the frequency of the heterozygote?

2pq = 2(0.65)(0.35) = 0.455

300

What is the difference between expressivity and penetrance?

Expressivity is the degree to which a trait is expressed while penetrance is the percent of individuals with a specific genotype that display the associated phenotype.

400

A woman with blood type B marries a man with blood type A. They have a child with blood type O. What must be the genotypes of both parents and the child? 

Mom - I^Bi

Dad - I^Ai

Child - ii

500

AaBbcc is crossed with AaBbCc. What is the probability of obtaining offspring with genotype aabbcc?

¼ x ¼ x ½ = 1/32

Unit Three

100

What types of bonds are created between nucleotides during transcription?

Phosphodiester bonds

200

An organism has 30% uracil. How much of the other nitrogenous bases are present?

20% guanine, 20% cytosine, 30% adenine

300

The function of siRNA is..

It triggers degradation of other RNA molecules

400

How does Rat1 terminate transcription?

Recruited by the 5' end of pre-mRNA strand and then uses 5'--> 3' exonuclease activity to degrade the RNA transcript until it binds to RNA Polymerase II which stops both Rat1 activity and transcription.

500

What are the names of the two eukaryotic subunits in eukaryotic ribosome?

40S and 60S.

Unit 4

100

In humans, germ-line mutations are passed on to the offspring. True or False?

True

200

What type of base substitution (gene mutation) is a purine replacing a pyrimidine? 

Transversion

300

What are gain-of-function mutations?

Mutations that produce a new trait to appear in inappropriate locations or times in development

400

What is the difference between intragenic and intergenic suppressor mutations?

Intragenic suppressor mutations occur in the same gene while intergenic suppressor mutations occur at different genes.

500

What is a replicated error?

An incorrectly incorporated base serves as the template for replication which leads to a permanent mutation

Unit 4

100

During initiation of translation in bacteria, the
small ribosomal subunit binds to which
consensus sequence?

Shine-Dalgarno

200

What 3 ribosome sites are occupied by tRNA

Aminoacyl Site, Peptidyl Site, Exit Site

300

What 4 groups do all proteins have?

Amino group, hydrogen, radical group (side chain), carboxyl chain

400

What is the significance of codon-anticodon pairing during translation?

Ensures correct amino acids are added to polypeptide chain

500

How is the peptide bond formed between amino acids in P and A site?

Catalyzed by ribozyme activity of rRNA in large subunit