Review Questions Chapter 12
Review Sheet
1. Below is a molecule of DNA. Label the following: sugar, phosphate, adenine,
cytosine, guanine, thymine, nucleotide, hydrogen bond.
Nucleotide
Phosphate
T
G
Sugar
C
A
Hydrogen
Bonds
2. What is the name given to the shape of the DNA molecule?
Double Helix
3. Name the scientists who helped discover the shape of the DNA molecule using a
technique known as X-ray diffraction.
Rosie Franklin
4. Name the scientists who figured out the correct arrangement of molecules to build the
first correct model of DNA.
James Watson and Francis Crick
5. Through the process of _Replication__ ___, DNA makes a copy of itself.
6. The parent strand of a molecule of DNA looks like this: AATCGGTATCGC
What would the bases for the daughter strand look like?
TTAGCCATAGCG
7. Explain why the process of DNA replication would be important to a cell getting
ready to divide.
Cells must copy DNA prior to cell division so each new cell has a complete copy of the
genetic code.
8. What are some situations in which your body would make new cells?
For example: repair of cellular damage
(heal puncture wound or cut, blood loss, cellular growth, immune response – produce
white blood cells, skin cells constantly replaced, etc.)
9. The process named in #7 takes place in the nucleus of the cell.
10. Identify how DNA is different from mRNA in each of the following:
a. Sugar – Deoxyribose (DNA), ribose (RNA)
b. Bases – RNA has a Uracil (U) instead of Thymine (T)
c. # of strands – 2 strands in DNA, 1 strand in RNA
11. DNA can’t leave the nucleus. How does the DNA code get to the ribosome? (In
other words, what molecule is produced from DNA to get that code to the ribosome?)
The genetic message (code) is copied to a molecule called mRNA. RNA polymerase
catalyzes (completes) this reaction.
12. If the DNA code is TTA GGG CTC CTA, what would the mRNA made from it look
like? AAU CCC GAG GAU
13. Divide mRNA code written in #12 into codons. Then, use the chart at the end of your
notes to translate it into amino acids.
ASN PRO GLU ASP
14. Label the parts in the diagram below, then answer the questions that follow.
Nucleus
A.
Ribosome
C.
B.
Two parts of the
ribosome
a. What is the molecule labeled “A” in the diagram above?
DNA
b. Label the nucleus in the diagram above.
c. Name the process occurring in the nucleus of the cell.
Transcription – DNA to mRNA
d. Where in the cell will the mRNA go once it has been constructed?
To the cytoplasm and join with the large and small subunit of the ribosome.
e. Once there, the mRNA will be read in groups of 3 bases called __________.
codons________.
f. Label the parts that make up the ribosome in the diagram above.
g. Name the process occurring at the ribosome.
Translation - RNA to Protein
h. At the ribosome, the mRNA will meet with what (labeled “B” in the diagram
above)?
tRNA – Transfer RNA
i. The group of 3 bases attached to “B” in the diagram is called a(n) ______
anticodon _________
j. If the codon is “AAC”, the anticodon would be __ UUG _________.
k. The molecules labeled “C” in the diagram are called __ amino acids ________
___________.
l. Joining amino acids together builds a ___ polypeptide (protein)__.
m. Amino acids are held together by ___ peptide ___ bonds.
n. How are proteins important to living organisms?
Protein and protein interactions are responsible for expressing our phenotype (
or the traits that we can see - eye color, hair color, skin color, shape of our
noses, mouths, eyes, etc.) In addition, proteins are enzymes and therefore
regulate many of the chemical reactions in our bodies
18. Explain what a gene is:
A gene is a segment of DNA that holds the genetic code for making a single specific
protein that will express a trait (attached earlobes, widow’s peak, tongue rolling, etc).
19. Explain the primary function of DNA in the cell: DNA holds the genetic code for
manufacturing proteins, thereby supporting (providing the instruction for) life. DNA is
the director (holds the genetic code) for making proteins.
20. Explain how the genetic code contained in DNA is turned into a protein (you should
use the terms: mRNA, rRNA, tRNA, transcription, translation, DNA, amino acids,
codons, anticodons, nucleus and cytoplasm
Remember flow of genetic information is DNA to RNA to Protein
1. During transcription in the nucleus, the DNA code for a gene is converted into
mRNA. mRNA takes the code to the cytoplasm and joins with a ribosome
(rRNA).
2. The ribosome and mRNA are joined by a tRNA (transfer RNA) molecule that
brings an amino acid.
3. The anticodons on the tRNA match the codons on mRNA.
4. As the mRNA is pulled through the ribosome, more tRNA’s come brining more
amino acids.
5. All the amino acids bond together in the right sequence forming a protein.
Steps 2 through 5 above all happen in the cytoplasm and are part of translation.