Show:
Extensions & Modifications of Basic Principles
Pedigree Analysis
Chemical Nature of the Gene
DNA Replication
Random
100

A heterozygote has a phenotype that is intermediate between both homozygotes.

  • What type of dominance is this?
  • What phenotypic ratio would you expect from a heterozygote cross?
  • Incomplete dominance
  • 1:2:1 phenotypic ratio
100

A trait appears equally in males and females and skips generations.

  • What is the most likely inheritance pattern?

Autosomal recessive

100

What did Griffith’s experiment demonstrate?

Existence of a “transforming principle”

100

What does “semiconservative replication” mean?

Each new DNA molecule has one old strand and one new strand


100

What is required for DNA synthesis to begin?

A primer.

200

A heterozygote expresses both alleles simultaneously (not blended).

  • What type of dominance is this?
  • Give one example from lecture.
  • Codominance
  • Example: MN blood type
200

A father passes a trait to all daughters but no sons.

  • What inheritance pattern does this indicate?

X-linked dominant

200

In Avery, MacLeod, and McCarty:

  • Which treatment stopped transformation?
  • What does this show?
  • DNase
  • DNA is genetic material
200

Each new DNA molecule has one old strand and one new strand

One intermediate (hybrid) band

200

What type of bond links nucleotides together in DNA?

Phosphodiester bond.

300

A cross between two heterozygotes produces a 2:1 ratio.

  • What genetic mechanism explains this?
  • Why is one genotype missing?
  • Recessive lethal allele
  • Homozygous lethal genotype dies before observation
300

Two unaffected parents have an affected child.

  • What inheritance pattern is most likely?
  • Why?
  • Autosomal recessive
  • Both parents are carriers
300

Why were radioactive phosphorus and sulfur used in Hershey–Chase?

  • DNA contains phosphorus
  • Protein contains sulfur
300

After two generations, what DNA pattern is observed?

One hybrid band and one light band

300

What isotope made DNA “heavy” in the Meselson–Stahl experiment?

N 15

400

Two genes are involved in producing a pigment. A mutation in one gene results in no pigment regardless of the second gene.

  • What type of interaction is this?
  • Which gene is epistatic?
  • Epistasis
  • The gene that blocks pigment is epistatic
400

Explain what “assume the trait is rare” means in pedigree analysis.

Individuals marrying into family are assumed homozygous normal

400

What is the significance of Chargaff’s rules?

A = T and G = C

400

Why is DNA synthesized in the 5’ → 3’ direction?


DNA polymerase can only add nucleotides to the 3’ end

400

Do bacteria have one or multiple origins of replication?

No only one

500

Draw a biochemical pathway with two genes controlling a trait.

  • Show how a mutation in the first gene masks the effect of the second
  • Label which gene is epistatic and which is hypostatic


  • Pathway: Gene A → Gene B → phenotype
  • Mutation in A blocks pathway → no phenotype
  • A = epistatic, B = hypostatic
500

Draw a pedigree that shows an X-linked recessive trait.

  • Include at least one affected male
  • Show how the trait is passed across generations


  • More males affected
  • No father-to-son transmission
  • Carrier females pass trait
500

Draw a nucleotide and label it 


check with me

500

Draw a replication fork and label:

  • leading strand
  • lagging strand
  • direction of synthesis
  • Leading = continuous
  • Lagging = discontinuous (Okazaki fragments)
500

Draw DNA after one round of semiconservative replication.

Each DNA molecule has one original strand and one new strand.