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CH. 8. IDENTIFYING DNA AS THE GENETIC MATERIAL. 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. CH. 5 & 6 REVIEW. ANSWER THE FOLLOWING QUESTIONS:

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Ch 8

CH. 8

IDENTIFYING DNA AS THE GENETIC MATERIAL


Ch 5 6 review

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.


Ch 5 6 review1

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?


Ch 8

  • Ch. 8.1 – Identifying DNA as the Genetic Material

  • Griffith finds a “transforming principle.” - NOTES


Ch 8

  • 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.


Ch 8

  • Ch. 8.1 – Identifying DNA as the Genetic Material

  • Avery Identifies DNA as the transforming principle - NOTES


Ch 8

  • 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.


Ch 8

  • Ch. 8.1 – Identifying DNA as the Genetic Material

  • Hershey & Chase confirm that DNA is the genetic material – NOTES


Ch 8

  • 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.


Ch 8

  • Review

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


Ch 8

  • ANSWER:

  • That bacteriophages are made up of a protein coat surrounding DNA.


Ch 8

  • 8.2 – Structure of DNA

  • DNA is composed of 4 types of nucleotides (monomer):

    • Nucleotide composed of:

      • Phosphate group

      • 5 carbon sugar

      • Nitrogen base


Ch 8

  • 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:

    • Phosphate group

    • Ribose sugar

    • Nitrogen base

      • Cytosine = C

      • Uracel = U (replaces thymine)

      • Adenine = A

      • Guanine = G

  • Letter abbreviations refer both to the base & to the nucleotides that contain that base


Ch 8

  • 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.


Answer to questions

ANSWER TO QUESTIONS

  • 1. THE 4 NITROGEN BASES.

  • 2. THE NITROGEN BASES, BECAUSE THE REMAINING PARTS OF THE NUCLEOTIDE ARE IDENTICAL.


Ch 8

  • Watson & Crick Developed an accurate model of DNA - NOTES


Ch 8

  • 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.


Ch 8

  • 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.


Ch 8

  • 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


Ch 8

  • 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.


Ch 8

  • 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.


Ch 8

  • DNA Replication


Ch 8

  • 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


Ch 8

  • 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.


Ch 8

  • 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


Ch 8

  • 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)


Ch 8

  • 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.


Ch 8

  • 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. 8.11 visualizes transcription


Ch 8

  • 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.


Ch 8

  • 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


Ch 8

  • 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.


Ch 8

  • GENETIC CODE


Ch 8

  • Genetic Code


Ch 8

  • 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 CCC A A U G A

  • A) methionine(start), proline, glutamine, stop


Ch 8

  • 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


Ch 8

  • 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. 8.16 Translation

  • Read pg. 247


Ch 8

  • 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


Ch 8

  • TRANSLATION


Ch 8

  • 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


Ch 8

  • 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

  • READS:


Ch 8

  • 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.


Ch 8

  • 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


Ch 8

  • 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

  • http://staff.tuhsd.k12.az.us/gfoster/standard/bmut.htm


Ch 8

  • 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


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