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Chapter 12 Study Guide
1. Where is DNA found in a cell?
a. Prokaryotic? CYTOPLASM
b. Eukaryotic? NUCLEUS
2. Draw and label a DNA nucleotide/strand.
3. What are the base pairs in DNA? ADENINE AND THYMINE (A AND T), CYTOSINE AND
GUANINE (C AND G)
4. What did the following scientists conclude from their experiments?
a. Watson and Crick BUILT
c. Erwin Chargaff FOUND
THE FIRST MODEL OF
THAT THE AMOUNT OF
THE DNA DOUBLE HELIX
C=G AND A=T IN
b. Rosalind Franklin
SAMPLES OF DNA
COLLECTED DATA FROM
AN X-RAY REFRACTION
PHOTO OF DNA
5. What is the double helix?
A TWISTED LADDER SHAPE FORMED BY COMPELEMENTARY STRANDS OF
DNA
6. What type of bond holds the base pairs of a DNA molecule together? HYDROGEN
BONDS
7. What is DNA replication? Describe the outcome of replication. What does it mean that
DNA Replication is Semi-Conservative? THE COPYING OF THE DNA MOLECULES
IN A CELL, RESULTING IN TWO COMPLETE COPIES OF DNA. IT IS
SEMICONSERVATIVE BECAUSE TWO PARENT STRANDS SEPARATE AND
SERVE AS A BLUEPRINT TO REPLICATE TWO NEW STRANDS OF
COMPLEMENTARY DNA.
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8. Draw AND label the three parts of a RNA nucleotide.
9. What are the differences between DNA and RNA?
DNA is double stranded, pairs Thymine with Adenine and has Deoxyribose sugar in it’s
nucleotides; RNA is single-stranded, pairs Uracil with Adenine and has Ribose sugar in it’s
nucleotides.
10. What are the base pairs in RNA?
A and U, C and G
11. What is mRNA and what is it’s function?
mRNA is a copy of the DNA code to make one protein. It takes the DNA code from the nucleus,
in 3 base sequences called codons to the ribosome to make a protein.
12. What is tRNA and what does it do?
tRNA is the RNA that has anticodons that are complementary to mRNA codons and they pair up
at the ribosome, bringing one amino acid each to make a protein.
13. What is the Central Dogma of Biology? DNA codes for RNA, which is used to make
proteins (Protein Synthesis).
14. What is transcription and what does it produce? Where does it happen? Describe the
process. Be able to transcribe DNA into mRNA (review your Transcription worksheet).
Transcription is the process of using DNA to make a complementary mRNA stand in the
nucleus. The bases on the DNA nucleotides are used to pair up with complementary mRNA
nucleotides. It copies one gene from the DNA molecule.
15. What is a codon?
A 3 base sequence of bases in DNA or RNA that codes for 1 amino
acid.
a. On which RNA molecule are codons found? mRNA
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b. How many bases represent 1 codon? 2 codons? 3 codons? 3, 6, 9
16. Know how to use the genetic code to figure which amino acid a codon represents. (See
question 25)
17. What is translation? Where does it happen? Describe the process.
Translation is the process of reading the mRNA code at a ribosome in the cytoplasm to make a
protein. mRNA binds to a ribosome and tRNA anti codons pair up with the mRNA codons,
bringing in amino acids in the correct order to form one protein.
18. What is an anticodon? Where are anticodons found (which RNA molecule)?
An anticodon is a 3 base sequence that is on a tRNA molecule. It is complementary to a specific
mRNA molecule.
19. How is rRNA used in protein synthesis?
rRNA combines with proteins to make the ribosomes (protein-makers).
20. What is a point mutation? A change in one DNA nucleotide in a gene
a. Describe the three types of point mutations. Insertion-extra base added to a gene;
Deletion-base removed from a gene; Substitution- one base is exchanged for
another
b. What is a frame shift mutation? A mutation that moves all the nucleotides after it
wither forward or backward.
c. Which point mutations cause frame shifts? Insertion or Deletion
21. What is a chromosomal mutation?
A change in the genetic material that can be seen at the chromosomal level (like in a karyotype).
22. Describe the four types of chromosomal mutations. Review the Power point slide for this
topic.
 Duplication- part of a chromosome has been repeated
 Deletion- part of a chromosome has been lost
 Inversion- part of a chromosome has been flipped
 Translocation- part of a chromosome has broken off and attached to another chromosome
23. Replicate the following DNA strands. Make a slash between codons.
a. AGA/GCC/CGC/TCA/ATA/GAC/CCG/TAT/GCA/GT
TCT/CGG/GCG/AGT/TAT/CTG/GGC/ATA/CGT/CA
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b. TTG/ACC/GAG/GGA/CCA/TGA/TAG/GAG/ACC/CC
AAC/TGG/CTC/CCT/GGT/ACT/ATC/CTC/TGG/GG
24. Transcribe the following DNA strand into mRNA. Make a slash between codons.
a. TAG/CGG/CTC/GAC/ACA/TCG/ATA/TAG/CTA/GCA
AUC/GCC/GAG/CUG/UGU/AGC/UAU/AUC/GAU/CGU
25. Translate the above mRNA strand into an amino acid sequence. Use the Genetic Code
chart provided below.
Isoleucine/ Alanine/Glutamic
Acid/Leucine/Cysteine/Serine/Tyrosine/Isoleucine/Aspartic Acid/Arginine
26. Describe Protein Synthesis. (Short Answer. Write in complete sentences.)
The first step of protein synthesis is Transcription. Transcription happens in the nucleus
when mRNA is copied from a DNA segment called a gene. This mRNA strand is the
instrustions to make one protein. The mRNA leaves the nucleus and goes to the
cytoplasm, where the second part of protein synthesis, Translation happens. Translation
is when the mRNA binds to a ribosome and the tRNA molecules bring in once amino
acid at a time, matching their atnitcodons with the mRNA codons. This makes sure that
the amino acids are joined together to make a protein in the correct order.