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DNA Structure and Function Review Sheet Answered
Avery showed that ___DNA______ is the genetic material.
Sketch the structure of DNA. (look in your notebook or textbook!)
Name the three parts to a nucleotide. List two differences in the nucleotide of RNA versus DNA.
Phosphate, sugar and a base. RNA has ribose as a sugar, DNA has deoxyribose. RNA is single
stranded, DNA is double stranded. In RNA adenine pairs with uracil, in DNA adenine pairs with
4. What is Chargaff known for? What are purines and pyrimidines? Chargaff’s work lead to understanding
the base-pairing rules, A with T and C with G. Purines are nitrogenous bases with two rings (A and
G), pyrimidines have one ring (C, T and U)
5. Describe DNA in eukaryotes versus prokaryotes. Prokaryotes have one circular chromosome and when
they replicate it starts at one point, moving out in both directions. Eukaryotes have many
chromosomes that look like strings. They replicate by having many replication forks work their way
long the chromosome from different places.
6. Name the process of copying DNA (DNA DNA). DNA replication
7. Describe the end result of DNA replication. Two separate double stranded DNA molecules, each having
one old strand and one new.
8. During DNA replication, a DNA strand that has the bases TACTAGGCC produces a strand with what
bases? ATGATCCGG (remember base-pairing rules and that there are no U’s because this is DNA)
9. What sugar is contained in DNA? What sugar is contained in RNA? DNA has deoxyribose, RNA has
10. List three differences between DNA and RNA. RNA has ribose as a sugar, DNA has deoxyribose. RNA is
single stranded, DNA is double stranded. In RNA adenine pairs with uracil, in DNA adenine pairs
with thymine.
11. Name the three types of RNA and give the function of each. Messenger RNA (mRNA) is a copy of the
DNA gene that travels to the ribosome, bringing the code for a protein. Ribosomal RNA (rRNA)
makes up a large part of the ribosome. Transfer RNA (tRNA) carries the amino acids to the ribosome
and helps line them up in the proper order.
12. What is produced during transcription? Where does transcription occur? mRNA is made from the DNA
template and it happens in the nucleus.
13. How many codons are needed to specify one amino acid? Two amino acids? Three amino acids? One
codon per amino acid (3 bases per codon). Then there is a stop codon which doesn’t specify an amino
acid. So an mRNA with 4 codons would result in 3 amino acids in the chain.
14. What happens during the process of translation? Where does it occur? tRNA anticodons pair with mRNA
codons, bringing amino acids with them. The ribosome links the amino acids together into the
polypeptide (protein).
15. Genes contain instructions for assembling ____Protein_____.
16. Define: point mutation, chromosomal mutation, inversion, translocation, frameshift mutation, insertion,
substitution, deletion All definitions are in the book (either in the back or in the actual chapter)
17. Explain how a deletion or insertion of a base pair results in a frameshift mutation. Since the mRNA is read
three bases at a time, if you add or remove one, every base after will be in the wrong spot. You can see
this best by viewing this sentence as each word being a codon. THE CAR HAS OIL becomes TEC
ARH ASO IL if you slide down every letter.
18. What did Watson and Crick determine the structure of DNA resembled? DNA is a double helix, looking
like a spiral staircase or twisted ladder.
19. How did Rosalind Franklin produce an image of DNA? Using X-ray crystallography she found an ‘X’
pattern, showing DNA was a helix with two strands.
20. What was Erwin Chargaff’s contribution to the early study of DNA? Chargaff found that there were the
same amount of A as T in DNA, and the amount of C and G were equal as well.
21. A 3-base “word” is known as a_________ Codon
22. If DNA has the 3- base sequence TAC, what will the codon on mRNA be? Use the chart in your book to
determine what amino acid it codes for. AUG which codes for Methionine (start)
23. In what part of the cell is mRNA made? Nucleus
24. Summarize the steps of DNA replication. Enzymes unzip the DNA, free-floating nucleotides are attached
where they belong (following base-pairing) by other enzymes. This continues until the chromosome is
completely copied.
25. A normal chromosome has genes in the order ABCDEFG. A mutation occurs, and the new chromosome
looks like: ABCDEFEFEFEFG. What kind of mutation is it? Duplication
26. The amount of adenine in an organism always equals the amount of which base? Thymine
27. What amino acids are coded for by the mRNA sequence AUGAAAGGCCCU? Use the chart below.
Methionine, Lysine, Glycine, Proline