DNA Replication and Protein Synthesis Questions
1. What is DNA and where is it stored?
The genetic material found in all living things. It is stored within a cell’s nucleus in condensed
structures known as chromosomes.
2. What does a nucleotide consists of?
One of four nitrogenous bases and a backbone, consisting of a phosphate group and 5 carbon
sugar (deoxyribose).
3. List the 4 types of nitrogenous bases found in DNA (give name in full).
Adenine
Thymine (only in DNA)
Guanine
Cytosine
4. Which 2 bases are purines?
Adenine and Guanine
5. What is the purpose of replication?
To enable the organism to grow and repair, through cell division (DNA replication is the first
step in mitotic cell division).
6. Which direction does DNA polymerase add nucleotides to the parental strand?
DNA strands are ALWAYS built from the five prime end to the three prime end (5’  3’)
7. What are the short strands of nucleotides which follow DNA polymerase on the lagging
side termed?
Okazaki fragments
8. Which enzyme breaks apart DNA initially?
Helicase
9. What specifically does the enzyme in question 8 break apart?
Breaks the relatively weak Hydrogen bonds between Nitrogenous bases
10. Who discovered the DNA molecules structure?
James Watson and Francis Crick are widely credited, although much of their work is based off of
Rosalind Franklin’s.
11. What is the full name of DNA?
DeoxyriboNucleic Acid
12. In what ways is the structure of mRNA similar to DNA? How does mRNA differ from
DNA?
Similar: Both contain the bases A, C, & G. Both have Phosphate groups. Helix sctructure.
Different: mRNA contains U, DNA contains T. DNA has deoxyribose as a 5 carbon sugar, mRNA
contains ribose. mRNA is single stranded while DNA is double stranded. DNA is stored
permanently while mRNA is only used temporarily.
13. What’s the function of tRNA?
Transfer RNA has an anticodon that is complementary to the codon on mRNA (IE. The codon
pairs with the anticodon). tRNA can also carry one amino acid, which is specified by the tRNA’s
anticodon. When the mRNA codon is read on a ribosome, a tRNA with the complementary
anticodon is called for and the amino acid it carries is added to the growing polypeptide chain.
The tRNA then moves back into the cytoplasm, searching for its specific amino acid to bond with
once again.
EX) The mRNA codon AUG pairs with the tRNA anticodon UAC. This specific tRNA can only carry
the amino acid Methionine (Met). Amino acids can be identified by their mRNA codon on your
Amino Acid wheel.
14. What’s a codon? …an anticodon?
Found in mRNA, a codon is a series of three nitrogenous bases that codes for a particular amino
acid. Found in tRNA, an anticodon is a series of three nitrogenous bases that pairs with (“is
complementary to”) the codons of mRNA.
15. Differentiate between transcription and translation.
Transcription is the process where the genetic code is copied from the nitrogenous bases in DNA
into codons on mRNA. Translation is the process of reading the codons on the mRNA and
synthesizing a protein using this information. You’re translating from the language of
nitrogenous bases and codons to the language of proteins.
16. What anticodon on the tRNA molecule would gain access to the codon UUG? AUC?
DNA
mRNA
tRNA
AAC
UUG
AAC
TAG
AUC
UAG
17. Why is protein synthesis essential for life?
Proteins are one of the basic structural units of the cell and its organelles. Proteins are also used
as enzyme, hormones, and antibodies. Without proteins, life as we know it would not exist.
**It is up to you to know the basic function of enzymes, hormones, and antibodies.**