Biology Unit 5 Exam Study Guide
DNA, RNA, and Protein Synthesis
1. Define the following:
codon: sequence of 3 nucleotides together – codes for specific amino acid (building blocks of protein)
anticodon: 3 nucleotides on the bottom of the tRNA; complementary base pair with the codons on mRNA.
(to make sure they are bringing the correct amino acid-If the anti-codon doesn’t base pair with the codon, then the wrong amino acid was brought)
purine: Adenine & Guanine – double ringed nitrogenous bases
pyrimidine: Thymine & Cytosine – single ringed nitrogenous bases
point mutation: substitution in a single base pair; result can change the entire structure of a protein or it might
not have any affect if the change codes for the same amino acid
frameshift mutation: single base is added or deleted from DNA; affects ALL the amino acids after the mutation
2. What are the differences between DNA and RNA:
DNA
RNA
Base pairs: Adenine, Thymine, Guanine, Cytosine
Base Pairs: Adenine, Uracil, Guanine, Cytosine
Sugar: Deoxyribose
Sugar: Ribose
Structural differences: Double Helix
Structural differences: Single Strand
3. What are the three parts of a nucleotide:
Simple sugar (deoxyribose or ribose)
Phosphate group
Nitrogenous bases (ATCG or AUCG)
4. Explain the purpose and where each process takes place:
Replication
Purpose:
Copy DNA (for enough DNA to enter cell cycle)
Where does this take place: Nucleus
Transcription
Translation
Purpose:
Transcribe DNA into mRNA – to take instructions from
DNA in nucleus to ribosome for protein synthesis
Purpose:
Code for specific amino acids – determines
proteins…traits
Where does this take place: Nucleus
Where does this take place: Ribosome
5. What are the roles of the following in protein synthesis?
-DNA: holds instructions for the entire organism
-mRNA: takes instructions from DNA in nucleus to ribosome
-tRNA: transfers amino acid to ribosome – 1 at a time
-rRNA: assembles amino acids in correct order because it is the ribosome structure
6. What type of BioMolecule are enzymes? How do enzymes assist in gene expression/DNA sequencing?
Enzymes – PROTEIN
Proofread DNA and repair incorrect bases
7. This is one side of a DNA strand: 5’ATG CGT TTT AGC CCG 3’
-Give the corresponding DNA strand: 3’ TAC GCA AAA TCG GGC 5’
-Give the mRNA strand that would be made from the original: 3’ AUG CGU UUU AGC CCG 5’
-Give the amino acid sequence that would be made from the above mRNA strand: Methionine – Arginine –
Phenylalinine – Serine – Glycine
8. Explain how a mutation can be:
-Helpful: helps adapt to better suit your environment
-Hurtful: makes life more difficult; life threatening, etc.
-Ineffective: more than 1 codon codes for specific amino acids – therefore would show no affect because the
correct amino acid could still be coded for even with certain point mutations
9. How can a mutation be passed from parent to offspring?
Gametes – Sex Cells – Sperm/Egg
10. Name three things that can affect gene expression.
External Environment – mutagens
Internal Environment – other cells, etc
Inherited traits – from parents
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