Download Chapter 12 Study Guide

Name: __________ANS KEY______________________
Period: ______
Date: ___________
Chapter 12 Study Guide
1.) Describe Griffith’s experiment and the conclusions he drew from it.
- took heat killed disease causing bacteria and mixed it with harmless bacteria, transforming it then injecting it
in a mouse which died of pneumonia.
- Conclusion was the disease causing bacteria transferred their ability to cause disease
2.) What did Avery do to extend Griffith’s experiment and what did Avery conclude?
- treated it with 2 different enzymes; one that breaks down everything but DNA & the other that breaks down
DNA.
- The transformation only occurred with the first enzyme
- Which lead to his conclusion DNA stores and transmits the genetic info
3.) Describe the Hershey Chase experiment and the significance of using radioactive isotopes.
- labeled a bacteriophage with P-32 in DNA and the radioactivity was found inside the bacteria then they
labeled a 2nd bacteriophage with S-35 in the protein coat and there was no radioactivity in the bacterium
4.) What was the conclusion of the Hershey Chase experiment?
- genetic material of the bacteriophage is DNA
5.) Draw and label the components found in a DNA and a RNA molecule.
- DNA should be double stranded with A’s pairing with T’s and C’s pairing with G’s being the rungs, bases
should be bonded to the sugar deoxyribose, and the deoxyribose and phosphate should be bonded together
making the backbone
- RNA should be single stranded with the bases A,U,C, & G bonded to the sugar ribose. The sugar should be
bonded to the phosphate making the backbone
6.) What are the differences between the DNA and the RNA molecules (three)?
- DNA double stranded, deoxyribose for sugar, and contains thyamine
-RNA single stranded, ribose for sugar, and contains uracil
7.) Why is the percentage of cytosine always the same as the percentage of guanine?
- they always pair with each other
8.) Describe the role of histones and nucleosomes in chromosome structure.
- nucleosomes are composed of DNA wound around histones
9.) What are the steps in the process in which DNA is copied?
- DNA is unzipped breaking H-bonds
- DNA polymerase adds the complimentary base pairs in the 3’ to 5’ direction
- covalent bonds are formed between sugar phosphate backbone
10.) DNA replication results in __two__ identical molecules of DNA, in which each contains 1 _new_ strand
and 1 _original_ strand.
11.) What does semi-conservative mean and what is it referring to?
- when DNA is replicated one strand in new and the other is the original or conserved
12.) What is the difference between transcription and translation?
- transcription: taking the DNA sequence and making the complimentary mRNA sequence (happens in nucleus)
-translation: taking the mRNA sequence and matching in up with the tRNA anticodon which carries the
corresponding amino acid (happens on the ribosome)
13.) What are the three types of RNA and explain their role?
- mRNA: amino acids are made from these instructions
-rRNA: ribosomal RNA
-tRNA: transfers the matching amino acid based on mRNA message
14.) What is a promoter and what is its role in protein synthesis?
- region in the DNA sequence that the polymerase enzyme will bind to initiating replication (DNA polymerase)
or transcription (RNA polymerase)
15.) The genetic code is base on which type of RNA?
-mRNA
16.) What is a mutation?
- any abrupt change in the DNA sequence
17.) Describe the impact of the following mutation types on protein functioning.
a) Substitution- one nucleotide replaces another
b) Deletion- one nucleotide is removed
c) Duplication- one nucleotide is copied
d) Inversion – part of the chromosome switches with another
e) Translocation- part of one chromosome switches with a part of a nearby chromosome
18.) What is the difference between a point mutation and a frame shift mutation?
- point mutations: happen in one location only affecting one or two amino acids
- frameshift: shifts the reading frame affecting every amino acid following the mutation
19.) Are all mutations bad news for an organism? Explain your answer.
- no some lead to the same amino acid (silent) or some could give the organism an advantage over the rest of
the population
20.) During DNA replication, what two processes must occur before the two strands of a DNA molecule can
separate?
- H-bond must break & molecule must unwind
21.) What must happen to a DNA molecule before RNA polymerase can make RNA?
- the DNA molecule must separate into two strands
22.) What might be the effect of a mutation in the promoter sequence of a gene?
- the protein might not be transcribed
23.) Describe tRNA’s role in translation.
- tRNA brings the amino acid and matches it’s anticodon with mRNA complimentary codon
Going down the right hand side in order : DNA, Transcription, mRNA, translation, protein, amino acid
The sequence at the top: ATGAAGGCT
The mRNA sequence: AUGAAGGCU
The amino acid sequence: met, lys, ala