Unit 4 Review: Molecular Genetics

Topics/ Concepts

 Historical work involving discovery of DNA:

Griffith Chargaff

 Avery and colleagues Rosalind Franklin, Maurice Wilkins

 Hershey and Chase James Watson, Francis Crick

 Complementary base pairing (purines, pyrimidines, hydrogen bonding)

 DNA structure (antiparallel, double helix, nucleotides, 5’ and 3’ ends, etc.)

 DNA replication

 Leading strand vs. lagging strand

 5’ and 3’ ends

Okazaki fragments

 Replication fork(s); origin of replication

 Primer(s)

 Enzymes/proteins involved with DNA replication (Helicase, Single-strand binding proteins, Primase, DNA polymerase, ligase)

 DNA Repair Mechanisms

 mismatch repair; excision repair

 nuclease

 Characteristics of DNA and RNA

 DNA vs. gene vs. chromosome

 Transcription (How is mRNA made? Enzymes involved?)

 Translation (Functions of tRNA and rRNA)

 Codon vs. anticodon

 Enzymes involved in protein synthesis

 Mutations

 Types & functions of RNA

Ch. 16-17 Review Questions (due: )

1) Fill in the following chart, which highlights the scientist who helped to establish DNA as the genetic material.

Investigator(s) / Experimental Organisms/Design and Conclusions
Griffith
Avery
Hershey and Chase
Chargaff
Franklin

2) Summarize the evidence and techniques Watson and Crick used to deduce the double helix structure of DNA.

3) Label the following structure of DNA using

the list below:

  • nucleotide
  • cytosine
  • guanine
  • adenine
  • thymine
  • purine base
  • pyrimidine base
  • 5’ end of chain
  • sugar-phosphate backbone
  • 3’ end of chain
  • hydrogen bonds
  • deoxyribose
  • phosphate group

4) In the following diagram showing the replication of DNA, label the following items: leading strand, lagging strand, Okazaki fragment, DNA polymerase, DNA ligase, Helicase, Primase, single-stranded binding proteins, RNA primer, replication fork, and 5’ and 3’ ends of parental DNA.

5) Determine the amino acid sequence for a polypeptide coded for by the coded for by the following DNA antisense strand (HINT: first determine the mRNA sequence that will be transcribed).

3’- T A C G G A C T G A A A T T C A C T- 5’

6) What determines if a ribosome remains free in the cytosol?

7) Using the chart in your textbook (p. 314), fill in the following table:

DNA triplet / mRNA codon / tRNA Anticodon / Amino Acid
GGG
GAA
Lysine
AGC
Leucine
ATA
AAA
CAA

8) Define the following and explain what type of point mutation could cause each of these mutations:

a)silent mutation

b)missense mutation

c)nonsense mutation

d)frameshift mutation

9) Eukaryotic cells modify mRNA after transcription. Describe how the pre-mRNA is modified with respect to:

a)the 5’ ends and 3’ ends

b)RNA splicing of interior sections (introns vs. exons)

10) Sketch and describe the anatomy of a ribosome. Include in your labeled sketch and/or your description the following: large ribosomal unit (80s), small ribosomal subunit (70s), E site, P site, A site, mRNA binding site, and growing polypeptide.

11) Sketch and label a 7 base-pair DNA segment starting from the skeleton provided. The first two base-pairs of the parent strand are still hydrogen-bonded, but the remaining five base-pairs of this replication fork are separated and undergoing replication. The lines extending from the 2 parent strands are there to guide you, not to take the place of the parent nucleotides that you need to draw.

Your sketch MUST include:

 3’ and 5’ carbons for EACH nucleotide

 leading strand

 lagging strand

 parent strands

 arrows indicating direction of DNA synthesis (these arrows should be on the inside)