DNA Review Guide
A. Define the following terms:
1. Nucleotide- is the building block of DNA; it is made of phosphate, sugar, & nitrogen base
2. Base pair- A pairing of purine with pyramidine bases; Adenine bonds with Thymine using 2 hydrogen
bonds; Guanine bonds with cytosine using 3 hydrogen bonds
3. Deoxyribose- the kind of sugar found in DNA, it has one less oxygen than ribose sugar
4. Ribose- the kind of sugar found in RNA
5. Phosphate- made of phosphorous and oxygen; together with sugar, it forms the “backbone” of a DNA
molecule
6. Base- There are four nitrogen containing bases used to make DNA; these are guanine, adenine, thymine,
or cytosine.
7. Double helix- The shape of DNA, also known as a twisted ladder; it is two strands of DNA twisted
around each other
8. Replication- making two copies of DNA that are identical to the original, parental DNA molecule
9. Semi-conservative- When DNA is replicated (copied) one half (1 strand) of the new DNA molecule is a
parental strand that was saved and reused. The other half (strand) is all new DNA
10. Complementary- the 2 strands of DNA that make a DNA molecule fit together like puzzle pieces; the
strands pair up with a purine (Adenine or Guanine) always bonding with a pyrimidine base (A bonds to
Thymine, G to cytosine).
11. DNA- deoxyribonucleic acid; the substance that genes and chromosomes are made of; it is the blueprint
of life that carries the codes for all the traits living things have; holds instructions for making proteins
12. Amino Acid- the building blocks of protein; must be joined up in a specific sequence to make the right
protein
13. Protein- What you get when you follow the instructions found in DNA and all the Amino Acits to the
chain in the right order
14. Enzyme- a protein that helps chemical reactions; in the cell, three help with replication. They are:
DNA helicase which unwinds DNA; DNA polymerase which lays down new nucleotides & base pairs
then to a strand of DNA; and ligase which tied the nucleotides together to make DNA
15. Mutation- any change in the DNA
16. Substitution- The kind of mutation in the DNA where the original nucleotides have been replaced with a
different kind of nucleotide (adenine out in where thymine used to be, for example)
17. Deletion- All or part of a gene has been cut out of a chromosome
18. Insertion- extra DNA has been inserted into a chromosome
19. Inversion- when the base pair sequence of a gene has been reversed
B. Make the following:
1. A complementary strand of DNA to the one shown below:
DNA: ATG CTG CCA CCG ATG GGT ACT
DNA: TAG GAC GGT GGC TAC CCA TGA
2. A messenger RNA strand using the template DNA shown below:
DNA: ATG CTG CCA CCG ATG GGT ACT
RNA: UAG GAC GGU GGC UAC CCA UGA
3. An Amino Acid chain using the codons shown below;
RNA: AUG CCC UUU GGG CCA AUU UAG
Amino Acid: met- pro- phe- gly- pro- ile- (stop)
C. Identify the following people:
1. Watson & Crick- discovered the shape of DNA and how it went together; predicted how it would
replicate
2. Griffith- ran the first experiment that showed DNA could be the genetic material; Transformed living,
nonvirulent DNA into virulent DNA by exposing it dead, virulent DNA
3. Hershey & Chase- used a radioactively labeled bacteriophage type virus to prove that DNA is the
genetic mateiral
4. Chargoff- figured out how the bases form pairs by showing that the amount of T in DNA will equal the
amount of A, and the amount of G will equal C
5. Rosalind Franklin- used xrays of crystallized DNA to find that it was a double helix
D. Define
1. Parental DNA- the original DNA that is used as a template (pattern) for forming new DNA during
replication
2. Nitrogen bases- adenine, cytosine, thymine, guanine
3. Chagraff’s rule- the amount of T in DNA will equal the amount of A, and the amount of G will equal C
4. Purine- two ring nitrogen base used in DNA & RNA; Adenine & guanine
5. Pyrimidine- a one ring nitrogen base used in either DNA or RNA; cytosine, thymine, or uracil
6. 3’ to 5’- the direction in which DNA is made; phosphates are attached to the 3rd & 5th carbons in the
sugar
E. Drawing: Draw & label a replication fork in DNA. Be sure to label the parental strand, the replication
fork, and the new DNA strands
New
DNA
F. Essay: Be able to describe the experiment of either Griffith or of Hershey & Chase.
a) Fred Griffith worked with virulent “S” and nonvirulent “R” strains of Pneumoccocus bacteria
• He found
– R strain becomes virulent when it absorbs DNA from killed S strain bacteria
– Transformation- bacteria gets DNA from a dead bacteria and aquires new traits
• Study suggested that DNA was probably the genetic material
b) Hershey & Chase used radioactively tagged bacteriophage viruses to prove DNA is the genetic
material
• Viruses are made of DNA and protein
– They tagged DNA with 32P
– They tagged protein with 35S
– 32P showed up in the bacteria, 35S didn’t
G. Short Answer:
1. What is the Central Dogma and what does it say?
The central dogma is a summary of what DNA does and how it is copied for each new generation
It states:
DNA
DNA
Replication- DNA is used as a pattern to make more
DNA
RNA
Transcription- DNA is used as a pattern to make messenger RNA (so it can be used for
the instructions to make a protein)
RNA
Protein
Translation- the mRNA codons are used in sequence as instructions to build Amino
Acids into a protein chain
2. What is genetic wobble?
Genetic wobble is the idea that most amino acids are coded for by more than one codon. Usually the codons
are different only on the last base or two. So, if a point mutation does occur, as long as it happens to the last
base of a codon, it probably won’t cause a change in the amino acid that goes into the protein.