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Just a thought…
Make a stack of books totalingabout 10,000 pages. That the stack of books representsonly about one-fiftieth of the informationcontained in the DNA ofevery human cell. Correlate thiswith the amount of informationrequired to code for a human being.
• Answers1. A chromosome consists of two replicated
strands of DNA tightly coiled around proteins.The two strands, called chromatids, are attached
at a point called a centromere.2. A gene is a segment of DNA that codes for a
protein or RNA molecule.3. A cell’s DNA is copied during the synthesis (S)
phase.4. When chromosomes break, the broken pieces
can detach completely or can reattach in various ways. Therefore, the chromosome is changed, or mutated.
5. (a) For each inherited trait, an individual has two copies of the gene, one from each parent.
(b) There may be alternative versions of genes.
(c) When two different alleles occur together, one of them may be completely expressed, while the other may have no observable effect on the organism’s appearance.
(d) When gametes are formed, the alleles for each gene in an individual separate independently of one another, and when gametes unite during fertilization, each gamete contributes one allele.
Vocabulary chapter 9 • Section 11. vaccine (190)2. virulent (190)3. transformation (191)4. bacteriophage (192)• Section 21. double helix (194)2. nucleotide (194)3. deoxyribose (194)4. base-pairing rules (197)5. complementary base pair (197)• Section 31. DNA replication (198)2. DNA helicase (198)3. replication fork (199)4. DNA polymerase (199)
Chapter: DNA: The Genetic Material
1. Identifying the Genetic Material
• A. Transformation
• B. Viral Genes and DNA
Identifying the Genetic Material
The experiments of Griffith and of Avery yielded results that suggested DNA was the genetic material.
Transformation
• Something in the heat-killed bacteria that once were able to produce a capsule that caused them to kill the mice was able to “transform” the once non-virulent bacteria into capsule producing, virulent ones!
• But what was that something????
Avery’s experiment
• DNA destroying enzymes helped prove it was the DNA not proteins that were the transforming factors!
Hershey and Chase used the bacteriophage T2 and radioactive labels to show that viral genes are made of DNA, not protein.
• The radioactive sulfur remained outside with the protein coat of the virus.
• The radioactive Phosphorus went inside the bacteria and showed that the DNA was the component that went inside and produced more viral proteins.
1. In 1928, the experiments of Griffith demonstrated transformation of
a. R bacteria into S bacteria.b. S bacteria into R bacteria.c. heat-killed S bacteria into R bacteria.d. S bacteria into heat-killed R bacteria.2. In 1952, Hershey and Chase used the bacteriophage
T2 to determine that genetic material is made of which of the following?
a. protein c. DNAb. RNA d. 35S
3. A microorganism that is virulent isa. able to cause disease. c. a bacteriophage.b. transformed. d. harmless.
4. Avery’s experiments showed thata. DNA is responsible for transformation.b. proteins are responsible for transformation.c. bacteriophages are responsible for transformation.d. virulent bacteria are responsible for transformation.
5. Hershey and Chase injected phages witha. S bacteria. c. radioactive isotopes.
b. R bacteria. d. vaccines. 6. Hershey and Chase found that T2
bacteriophagesa. inject their DNA into host cells.
b. cause host cells to produce viral DNA and proteins.c. keep most of their viral proteins outside the host cell.d. All of the above
______ 7. radioactive sulfur and phosphorous
______ 8. transformation
______ 9. bacteriophage
______10. vaccine
a. discovered by Griffith
b. infects bacteria
c. used in the Hershey and Chase experiments
d. helps protect the body against future infections by specific disease-causing agents
The Structure of DNA
DNA is made of two strands of nucleotides twisted into the form of a double helix.
Each nucleotide in DNA is made of the sugar deoxyribose, a
phosphate group, and one of four nitrogen bases. The four nitrogen bases found in DNA
nucleotides are adenine (A),thymine (T), guanine (G), and cytosine (C).
The two strands of DNA are complementary—each A on one strand pairs with a T on the opposite strand, and each G on one strand pairs with a C on the opposite strand.
Watson and Crick announced their discovery of the structure of DNA in 1953 with the help of data gathered by Wilkins, Franklin, and Chargaff.
3. The Replication of DNA
A. The Roles of Enzymes in DNA Replication
p 198
Summarize the steps of DNA replication
The Replication of DNA
Before a cell divides, it copies its DNA by a process called DNA replication.
In DNA replication, enzymes work to unwind and separate the double helix and add complementary nucleotides to the exposed strands.
The result of DNA replication is two exact copies of the cell’s original DNA.
Each new double helix is composed of one original DNA strand and one new DNA strand.
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