1. IDENTIFYING DNA AS THE GENETIC MATERIAL
CH. 8
IDENTIFYING DNA AS THE GENETIC MATERIAL

2. CH. 5 & 6 REVIEW ANSWER THE FOLLOWING QUESTIONS:
1. What macromolecule group does DNA & RNA belong in?
2. What monomer do we use to assemble the macromolecule group from question #1.

3. CH. 5 & 6 REVIEW ANSWER THE FOLLOWING QUESTIONS:
3. What is a nucleotide?
4. What would a nucleotide for DNA contain?
5. What would a nucleotide for RNA contain?

4. Ch. 8.1 – Identifying DNA as the Genetic Material
Griffith finds a “transforming principle.” - NOTES

5. Ch. 8.1 – Identifying DNA as the Genetic Material
Griffith finds a “transforming principle.”- QUESTION & ANSWER:
1. What was “transformed” in Griffith’s experiment?
That the R bacteria in the presence of the dead S bacteria became pathogenic.
2. Explain how the results support the experimenters conclusion.
The mice dying when they shouldn’t have means that the S bacteria must have contained some information that was able to change the harmless bacteria t deadly bacteria.

6. Ch. 8.1 – Identifying DNA as the Genetic Material
Avery Identifies DNA as the transforming principle - NOTES

7. Ch. 8.1 – Identifying DNA as the Genetic Material
Avery Identifies DNA as the transforming principle – QUESTION & ANSWERS:
1. How did Avery and his group identify the transforming principle?
1st identifying the 2 components: proteins & DNA
Used enzymes to break down the protein & the R-bacteria were still transformed to S bacteria killing the mice.
Only when an enzyme to break down DNA did the transformation failed to occur.
2. Explain how the results support their conclusions for the transforming principle.
By using the enzyme to break down DNA and not having the transformation occur.

8. Ch. 8.1 – Identifying DNA as the Genetic Material
Hershey & Chase confirm that DNA is the genetic material – NOTES

9. Ch. 8.1 – Identifying DNA as the Genetic Material
Hershey & Chase confirm that DNA is the genetic material – QUESTIONS & ANSWERS:
1. Summarize how Hershey & Chase confirmed that DNA is the genetic material.
A: They labeled the protein of bacteriophages with radioactive sulfur and their DNA with radioactive phosphorus. The bacteriophages were allowed to infect bacteria.
2. Summarize why the bacteriophage was an excellent choice for research to determine whether genes are made of DNA or proteins?
A: A bacteriophage consists of little more than a protein coat surrounding DNA. The protein coat is left behind when the viral DNA enters a bacterium.
3. Explain how the results support their conclusions.
A: That the phage’s DNA had entered the bacteria, but the protein had not, convincing scientists that the genetic material is DNA & not protein.

10. Review
1. What did Hersey & Chase know about bacteriophages that led them to use these viruses in their DNA experiments?

11. ANSWER:
That bacteriophages are made up of a protein coat surrounding DNA.

12. DNA is composed of 4 types of nucleotides (monomer):
8.2 – Structure of DNA
DNA is composed of 4 types of nucleotides (monomer):
Nucleotide composed of:
Phosphate group
5 carbon sugar
Nitrogen base

13. DNA is composed of 4 types of nucleotides con’t.
Nucleotide in DNA is composed of:
Phosphate group
Deoxyribose sugar
Nitrogen base
Cytosine = C
Thymine = T
Adenine = A
Guanine = G
Nucleotide in RNA is composed of:
Ribose sugar
Uracel = U (replaces thymine)
Letter abbreviations refer both to the base & to the nucleotides that contain that base

14. DNA is composed of 4 types of nucleotides con’t.
CHARGAFF’S RULE:
A = T
G = C
QUESTION:
What is the only difference among the 4 DNA nucleotides?
Which part of a DNA molecule carries the genetic instructions that are unique for each individual; the sugar-phosphate backbone or the nitrogen-containing bases? Explain.

15. ANSWER TO QUESTIONS 1. THE 4 NITROGEN BASES.
2. THE NITROGEN BASES, BECAUSE THE REMAINING PARTS OF THE NUCLEOTIDE ARE IDENTICAL.

16. Watson & Crick Developed an accurate model of DNA - NOTES

17. Watson & Crick Developed an accurate model of DNA – QUESTION & ANSWER:
What bases are considered pyrimidines & purines?
Pyrimidines = T & C
Purines = A & G
How did the Watson & Crick Model explain Chargaff’s rules?
The pyrimidine – thymine a single ringed base pairs with a purine – adenine a double ringed base so that the double helix will be able to maintain the correct shape.

18. Nucleotides always pair in the same way.
DNA nucleotides of a single strand are joined together by covalent bonds connecting the sugar of one nucleotide to the phosphate of the next nucleotide.
Alternating sugars & phosphates form the sides of a double helix sort of like a twisted ladder.
DNA double helix is held together by hydrogen bonds between the bases in the middle.

19. Nucleotides always pair in the same way – QUESTIONS & ANSWERS:
What sequence of bases would pair with the following sequence: T T A C G C G A C
A A T G C G C T G

20. 8.3 – DNA Replication
Replication copies the genetic information
Watson & Crick’s experiments showed that one strand of DNA is used as a template to build the other strand
Guarantees that each strand of DNA is identical.

21. Proteins carry out the process of replication
How :
DNA is unzipped at numerous places (H bonds broken)
Free floating nucleotides pair with the exposed bases (template strands)
DNA polymerase bonds the nucleotides together to form the new strands that are complementary to the template strand (original strand).
Creates 2 identical molecules of DNA.
Each DNA molecule has an original & a new strand.
Why DNA replication is called semiconservative replication.

22. DNA Replication

23. Replication is fast & accurate
Replication is fast because the DNA strand is opened at hundreds of different points & allowing nucleotides to be added at many spots at the same time.
Proofreading is carried out at the same time that nucleotides are added.
DNA polymerase can detect errors & make corrections.
Pg. 238, fig. 8.9 shows this process

24. 8.4 TRANSCRIPTION
RNA carries DNA’s instructions
Central Dogma
Information flows from DNA to RNA to proteins
Transcription converts a DNA message into an intermediate molecule, called RNA.
Translation interprets an RNA message into a string of amino acids, called a polypeptide.
Either a single polypeptide or many polypeptides working together make up a protein.

25. RNA carries DNA’S instructions con’t.
Prokaryotic cells:
Replication, transcription, and translation all occur in the cytoplasm at approximately the same time.
Eukaryotic cells:
Replication, transcription, and translation occur in different locations.
Replication & transcription – nucleus
Translation – occurs in the cytoplasm

26. RNA carries DNA’s instructions con’t.
RNA acts as an intermediate link between DNA in the nucleus & protein synthesis in the cytoplasm.
Gets used then destroyed.
RNA is single stranded, contains ribose sugar & has uracil instead of thymine
A (DNA) = U (RNA)
T (DNA) = A (RNA)
G (DNA) = C (RNA)
C (DNA) = G (RNA)

27. Transcription makes 3 types of RNA
Transcription is the process of copying a sequence of DNA to produce a complementary strand of RNA.
Part of the chromosome, called a gene, is transferred into an RNA message.
Transcription is catalyzed by RNA polymerase.

28. Transcription produces 3 major types of RNA molecules
mRNA (messenger RNA) – an intermediate message that is translated to form a protein
rRNA (ribosomal RNA) – forms part of ribosomes, a cell’s protein factories
tRNA (transfer RNA) – brings amino acids from the cytoplasm to a ribosome to help make the growing protein.
Pg. 241, Fig visualizes transcription

29. Transcription vs. replication
Similarities
Happen in nucleus of eukaryotic cells
Need enzymes to begin the process
Unwind the DNA double helix
Complementary base pairing to the DNA strand
Regulated by the cell
Differences
Replication makes sure each new cell will have one complete set of genetic instructions & occurs only once during each round of the cell cycle.
Transcription could make hundreds or thousands of copies of certain proteins or the rRNA or tRNA molecules needed to make proteins based on the demands of the cell, using a single stranded complementary mRNA strand.

30. 8.5 TRANSLATION
Amino acids are coded by mRNA base sequences
Translation is the process that converts, or translates, an mRNA message into a polypeptide.
Could be 1 or more polypeptides to make up a protein
Language of nucleic acids:
DNA – uses 4 nucleotides = A, G, C, & T
RNA – uses r nucleotides = A, G, C, & U
Language of proteins uses 20 amino acids

31. Triplet Code
Genetic code uses codons, which is read in groups of 3 nucleotide bases
Codon is a 3 nucleotide sequence that codes for a particular amino acid, referred to as the reading frame.
First 2 nucleotides are usually the most important in coding for an amino acid
Start codon – signals the start of translation and the amino acid is methionine
3 stop codons – signal the end of the amino acid chain.
If reading frame is changed, changes protein or even can prevent a protein from being made.
Almost all organisms, including viruses, follows the genetic code.
This allows scientists to insert a gene from 1 organism into another organism to make a functional protein.

32. GENETIC CODE

33. Genetic Code

34. A) methionine(start), threonine, asparagine, serine
DETERMINE WHAT AMINO ACID SEQUENCES ARE CREATED FROM THE FOLLOWING STRINGS OF NUCLEOTIDES
1) A U G A C C A A C A G C
A) methionine(start), threonine, asparagine, serine
2) A U G C C C C A A U G A
A) methionine(start), proline, glutamine, stop

35. Amino acids are linked to become a protein
Review:
mRNA is a short lived molecule that carries instructions from DNA in the nucleus to the cytoplasm
mRNA message is read in groups of 3 nucleotides called codons
How it translates the codon into an amino acid requires the use of rRNA & tRNA molecules

36. PG. 246, Fig. 8.16 Translation Read pg. 247
Amino acids are linked to become a protein
Ribosomes are made of a combination of rRNA & proteins & they catalyze the reaction that forms the bonds between amino acids.
Ribosomes have a large & small subunit that fit together & pull the mRNA strand through.
Small unit holds the mRNA strand & the large subunit holds onto the growing protein
tRNA carries amino acids from the cytoplasm to the ribosome
Has an L shape to the tRNA molecule, one end of the L is attached to the specific amino acid & the other end of the L, is called the anticodon, which recognizes a specific codon.
Anticodon is a set of 3 nucleotides that is complementary to an mRNA codon.
PG. 246, Fig Translation
Read pg. 247

37. 8.6 – GENE EXPRESSION & REGULATION
mRNA processing
Important part of gene regulation in eukaryotic cells is RNA processing.
mRNA that is produced by transcription needs to be edited
Exons are nucleotide segments that code for parts of the protein.
Introns are nucleotide segments that are located between the exons
Introns are removed from mRNA before it leaves the nucleus.
Exons are joined back together

38. TRANSLATION

39. 8.7 MUTATIONS
Some mutations affect a single gene & others affect the entire chromosome
Mutation is a change in an organism’s DNA
Types of gene mutations:
Point mutation – a mutation in which one nucleotide is substituted for another.
DNA polymerase could find & correct mistake, if not may permanently change an organism’s DNA
Frameshift mutation – involves the insertion or deletion of a nucleotide in the DNA sequence
Affects the polypeptide more than a point mutation (substitution)
Causes the reading frame from point of insertion or deletion to change the remaining amino acids

40. MUTATIONS
ORIGINAL NUCLEOTIDE SEQUENCE:
A U G C C G U U A A C G C G A U C C G G
READS:
MUTATED NUCLEOTIDE SEQUENCE:
A U G C A C G U U A A C G C G A U C C G G

41. Types of chromosomal mutations:
Gene duplication:
During crossing over chromosomes do not align & the chromosomal segments are different sizes. The chromosome receiving the larger segment would have part of the chromosome that is duplicated.
Gene deletion:
During crossing over chromosomes do not align & the chromosomal segments are different sizes. The chromosome receiving the smaller segment would have part of the chromosome that is deleted.
Translocation:
A piece of one chromosome moves to a non-homologous chromosome.

42. Mutations may or may not affect phenotype.
Phenotype – Collection of all of an organism’s physical characteristics.
Ex: black hair, blue eyes, attached ear lobes.
Chromosomal mutations
Usually have big affect on organisms
Ex: may break a gene causing it not to function
Ex: may create a new hybrid gene with a new function
Ex: may cause a gene to be more or less active
Gene mutations – could have a bad affect, no affect, or create a beneficial mutation
Could change the active site for an enzyme & now it cannot accept the substrate
Could affect how protein folds & possibly destroying the protein’s function
Could create a premature stop, making protein nonfunctional

43. Mutations can happen in body cells & in germ cells.
Impact on offspring
Mutations can happen in body cells & in germ cells.
Body cell mutations only affect that individual
Germ cell mutations may be passed to offspring
Can be source of genetic variations, which is the basis of natural selection.
Will affect the phenotype of offspring
Could be harmful & the offspring do not develop properly or could die before reproducing
Could be mutations not well suited to environment & the alleles will be removed from the population
Could be a mutation that is well suited to environment & the alleles will be increased in the population

44. Mutations can be caused by several factors
Mutagens – agents in the environment that can change DNA.
Speed up the rate of replication errors
Break DNA strands
Cause cancer
Types of mutagens:
UV light
Industrial chemicals