Biology Unit 5 Exam Study Guide
DNA, RNA, and Protein Synthesis
1. Define the following:
codon: a codon is three nitrogenous bases located on the mRNA that code for one of the twenty specific amino
acids.
anticodon: an anticodon is three nitrogenous bases located on the tRNA that attach to the mRNA.
purine: a purine is a nucleotide that contains adenine or guanine. These two nitrogenous bases have single
ringed structure
pyrimidine: a pyrimidine is a nucleotide that contains the bases thymine or cytosine. These two nitrogenous
bases contain a double ringed structure.
point mutation: a point mutation occurs when a nitrogenous base is switched for a different nitrogenous base.
For every codon that is changed, the resultant amino acid could change. Only one amino acid could possibly
change as a result of a single point mutation.
frameshift mutation: a frameshift mutation is caused by the insertion or deletion of a nitrogenous base in a
DNA sequence. This type of mutation results in a shift in the reading pattern of the DNA and in multiple new
amino acids. This type of mutation is more dangerous than a point mutation.
2. What are the differences between DNA and RNA:
DNA
RNA
Base pairs: ATCG
Base Pairs: AUCG
Sugar: deoxyribose
Sugar: ribose
Structural differences: double strand, deoxyribose
sugar, contains thymine instead of uracil
Structural differences: single strand, ribose sugar,
contains uracil instead of thymine
3. What are the three parts of a nucleotide:
Phosphate group, nitrogenous base, ribose or deoxyribose sugar
4. Explain the purpose and where each process takes place:
Transcription
Translation
Purpose: to copy the DNA in the form or mRNA.
Purpose: to read the message sent from the nucleus
Transcription results in a copy (message) of the DNA
and construct proteins that the cell requires.
that will eventually be the blueprint for the cell’s
proteins that are constructed.
Where does this take place: nucleus
Where does this take place: ribosomes
5. What are the roles of the following in protein synthesis?
-DNA: DNA provides the instructions for making the cell’s proteins
-mRNA: acts as the messenger and delivers the copy of the protein instructions to the ribosomes.
-tRNA: carries amino acids in the ribosomes to the mRNA in the correct order
-rRNA: speeds up the formation of peptide bonds between amino acids
6. What type of BioMolecule are enzymes? AND How are enzymes created?
Proteins, enzymes are created during protein synthesis (transcription & translation)
7. This is one side of a DNA strand: ATG CGT TTT AGC CCG
-Give the corresponding DNA strand: TACGCAAAATCGGGC
-Give the mRNA strand that would be made from the original: UAC GCA AAA UCG GGC
-Give the amino acid sequence that would be made from the above mRNA strand: tyrosine, alanine, lysine,
serine, glycine
8. Explain how a mutation can be:
-Helpful: if the mutation changes the proteins the cell produces in a good way (camouflage, faster) than the
organism will benefit from the mutation
-Hurtful: sickle cell anemia is the result of a point mutation which manipulates the structure of hemoglobin
(blood) causing a sickle-shaped red blood cell.
-Ineffective: if the mutation results in the exact same protein being produced as the original than the mutation
results in an ineffective mutation.
9. How can a mutation be passed from parent to offspring? If the sex cells of an organism are mutated, those
mutations will be passed along to the organism’s offspring. Mutations in the body cells of the organism will not be
passed to the offspring.
10. Name three things that can affect gene expression.
Any mutation that changes the resultant proteins will cause a change in gene expression. Certain genes are
affected by environmental factors like light availability, temperature, or nutrition.
Other Vocab: Also be familiar with the following words/definitions.
Translocation, substitution, nonfunctional, genome, nucleotide, repressor gene, operon gene, Ecoli, lactose,
regulating gene, promoter gene
TEKS tested:
6: The student knows the mechanisms of genetics, including the role of nucleic acids and the principles of Mendelian Genetics.
The student is expected to:
A: identify components of DNA, and describe how information for specifying the traits of an organism is carried in the DNA
B:
C:
D:
E:
recognize that components that make up the genetic code are common to all organisms
explain the purpose and process of transcription and translation using models of DNA and RNA
recognize gene expression as a regulated process.
identify and illustrate changes in DNA and evaluate the significance of these changes