Chapter 9 Questions
1. What are the chemical names of DNA and RNA?
a. Deoxyribonucleic Acid and Ribonucleic Acid are the chemical names of DNA
and RNA.
2. What are the four nucleotides of DNA? Which ones form hydrogen bonds (base-pair)
with one another?
a. Adenine, Thymine, Guanine, Cytosine. A-T, G-C.
3. Describe the structure of the DNA molecule.
a. A DNA molecule is a double helix strand, which is like a ladder that was twisted
around. On each side there are nucleotides going down that are bonded with their
counterpart on the other side. There nucleotides on each side are connected by
phosphates and sugars to build the length.
4. How many different nucleotides form the structure of DNA?
a. There are four different nucleotides.
5. True of False? Adenine and thymine are purines.
a. False, Adenine and Guanine are purines.
6. True or False? Purines normally always base-pair with pyrimidines in DNA.
a. True.
7. What is the genetic code? What does it “do?”
a. Genetic Code is the instructions in your DNA.
b. It tells your cells what to do and shapes what you look like.
8. What is the complementary DNA sequence to ATGCTTAACCGA?
a. TACGAATTGGCT.
9. Describe the structure of a chromosome.
a. A highly compressed package of supercoiled molecule of DNA and it’s
supporting proteins.
10. How are chromatin and chromosomes similar? How are they different?
a. Both of them contain DNA. However, chromatin is wound up tightly unlike
chromosomes.
11. True or False? Histones hold sister chromatids together.
a. False.
12. What is the relationship between DNA, chromosomes and genes?
a. DNA is the largest unit, chromosomes and genes are consecutively smaller units.
13. How can you distinguish RNA from DNA? (There are three answers to this question.)
a. RNA is a single strand of code, while DNA is double-helix strand.
b. RNA does not have thymine, but rather Uracil.
c. RNA contains the sugar ribose.
14. What is the series of events which results in synthesis of a protein? Yes, this is a long
answer and it covers almost everything we discussed!
a. The sequence of gene nucleotides is read by enzymes. The sequence of gene
nucleotides is made into a complementary sequence of mRNA nucleotides in the
nucleus. mRNA is then processed in the nucleus, and then it moves from the
nucleus into the cytoplasm. Then one or more ribosomes bind to the mRNA. The
coded sequence of nucleotides in the mRNA is read by the ribosomes. tRNA
brings amino acids to the ribosomes for protein synthesis. Then the protein is
synthesized by ribosomes in the cytoplasm.
15. Why does tRNA take on its characteristic “t” shape?
a. tRNA shape occurs because of hydrogen bonding between nucleotides.
16. How does a ribosome know that a given tRNA molecule is carrying the amino acid called
for by the mRNA?
a. An end of tRNA carries a sequence of three nucleotides called the anticodon
which tells the ribosome its carrying amino acids.
17. If an mRNA molecule contains the codons UUU-ACA-AGC-GCA-UGG, what is the
sequence of amino acids in the polypeptide?
a. Phenylalanine, Threonine, Serine, Ala, Tryptophan.
18. At first, you may think you cannot do this problem, but you really can. What is the
sequence of amino acids that the DNA codons of CTA-CCC-TTG-ATA-ACT codes for?
a. GAU-GGG-AAC-UAU-UGA.
b. Which codes to: Aspartic Acid, Glycine, Asparagine, Tyramine, STOP.