CHAPTER 11.1 GENES ARE MADE OF DNA

What is in your GENES? No not that kind! These kind of genes!

GRIFFITH’S “TRANSFORMING FACTOR” IS THE GENETIC MATERIAL Frederick Griffith proved that a substance in one strain of bacteria causes a change in another strain

FIGURE 11.1

AVERY SHOWS DNA IS THE TRANSFORMING FACTOR Oswald Avery, Alfred Hershey, and Martha Chase took Griffith’s experiment one step further Did experiments with viruses Concluded that DNA is the genetic material of the cell

VIRUS EXPERIMENTS PROVIDE MORE EVIDENCE A virus consists of a package of nucleic acid in a protein coat Bacteriophage- a virus that infect bacteria

VIRUS

Figure 11-4

DNA’S STRUCTURE 1950 Rosalind Franklin and Maurice Wilkins produced photographs of DNA using x-ray crystallography

Erwin Chargaff- 1952 Observed that the number of adenine equals the number of thymine . Observed that the number of guanine equals the number of cytosine.

DOUBLE HELIX In 1953 James Watson and Francis Crick looked at the photographs and with Chargaff’s discovery gave DNA a shape of a double helix

DOUBLE HELIX Double Helix- twisting shape Hypothesized that the strands were connected by hydrogen bonds

CLASS WORK Make a list of at least four of the scientists we discussed today and discuss their contribution to the discovery of DNA.

NUCLEIC ACIDS STORE INFORMATION IN THEIR SEQUENCE OF CHEMICAL UNITS CHAPTER 11.2 NUCLEIC ACIDS STORE INFORMATION IN THEIR SEQUENCE OF CHEMICAL UNITS

THE BUILDING BLOCKS OF DNA DNA- deoxyribonucleic acid, heritable genetic information of an organism Polymer built from monomers Nucleotides- monomers of DNA, building blocks, contain three parts

NUCLEOTIDES 1) A ring shaped sugar called deoxyribose 2) A phosphate group 3) A nitrogenous base

NITROGENOUS BASE Divided into two groups Pyrimidines- single ring structures Purines- double ring structures

DNA STRANDS Nucleotides are joined together by covalent bonds between the sugar and phosphate

COMPLEMENTARY BASE PAIRS Adenine (A) bonds to Thymine (T) Guanine (G) bonds to Cytosine (C) EXAMPLE: AAT GCT ATG TTA CGA TAC

PRACTICE 1) AAT GGC TAT 2) CAT GAT TAC 3) CCG TTA CCA 4) GCG ATA GAC 5) CAG TCA GCA

THE TEMPLATE MECHANISM When a cell divides a complete new set of genetic instructions is made Stopped here

THE TEMPLATE MECHANISM DNA Replication- the process of copying the DNA molecule

Enzymes Involved in Replication DNA Helicase- unzips DNA, breaks the Hydrogen bonds between the base pairs in order to create origin of replication

REPLICATION OF THE DOUBLE HELIX DNA Polymerase- makes the covalent bonds between the nucleotides

Class Work 1. Describe how DNA replicates by using a template. 2. List the steps involved in DNA replication. 3. Under what circumstances is DNA replicated?

Class Work 1. What are the three parts of a nucleotide? Which parts make up the backbone of a DNA strand? 2. List the two base pairs found in DNA. 3. If six bases on one strand of a DNA double helix are AGTCGG, what are the six bases on the complementary section of the other strand of DNA?

THE TEMPLATE MECHANISM When a cell divides a complete new set of genetic instructions is made

THE TEMPLATE MECHANISM DNA Replication- the process of copying the DNA molecule

REPLICATION OF THE DOUBLE HELIX DNA Polymerase- makes the covalent bonds between the nucleotides

Class Work 1. Describe how DNA replicates by using a template. 2. List the steps involved in DNA replication. 3. Under what circumstances is DNA replicated?

A GENE PROVIDES THE INFORMATION FOR MAKING A SPECIFIC PROTEIN CHAPTER 11.4 and 11.5 A GENE PROVIDES THE INFORMATION FOR MAKING A SPECIFIC PROTEIN

ONE GENE, ONE POLYPEPTIDE- Don’t need to write George Beadle and Edward Tatum worked with the bread mold neurospora crassa

ONE GENE, ONE POLYPEPTIDE- Don’t need to write One Gene-One Enzyme Hypothesis- the function of an individual gene is to dictate the production of a specific enzyme Now…ONE GENE-ONE POLYPEPTIDE HYPOTHESIS

INFORMATION FLOW: DNA TO RNA TO PROTEIN RNA- ribonucleic acid, has a sugar or ribose, base uracil, single stranded

INFORMATION FLOW: DNA TO RNA TO PROTEIN Deoxyribose Thymine Double-Stranded RNA Ribose Uracil Single Stranded

INFORMATION FLOW: DNA TO RNA TO PROTEIN

INFORMATION FLOW: DNA TO RNA TO PROTEIN Transcription- when DNA is converted into single stranded mRNA, in nucleus mRNA moves to cytoplasm while DNA stays in the nucleus

INFORMATION FLOW: DNA TO RNA TO PROTEIN Translation- the nucleic acid information (RNA) is converted into amino acids, in cytoplasm Codon- a three-base “word” that codes for one amino acid Several codons form a polypeptide

TRANSLATION: RNA TO PROTEIN Transfer RNA- translates the 3 letter codon of mRNA into an amino acid

TRANSLATION: RNA TO PROTEIN Anticodon- a triplet of bases that is complementary to a specific mRNA sequence

THE TRIPLET CODE Marshall Nirenberg figured out that the codon UUU makes the amino acid phenylalanine

CHANGE THE DNA to mRNA 1. TAT CAT GAT 2. CCA GGG CTA 3. TAC TAG TTC 4. GCA ATA TTC 5. GCA ATG CCT PAGE 12 CLASSWORK/HW

CLASS WORK 1. How did Beadle and Tatum's research result in the "one gene–one polypeptide" hypothesis? 2. Which molecule completes the flow of information from DNA to protein? 3. Which amino acid is coded for by the RNA sequence CUA? 4. List two ways RNA is different from DNA.

THERE ARE TWO MAIN STEPS FROM GENE TO PROTEIN CHAPTER 11.5 THERE ARE TWO MAIN STEPS FROM GENE TO PROTEIN

TRANSCRIPTION: DNA TO RNA 3 types of RNA Messenger RNA (mRNA) Transfer RNA (tRNA) Ribosomal RNA (rRNA) Messenger RNA- an RNA molecule which is transcribed (COPIED) from a DNA template RNA Polymerase- links the RNA nucleotides together

EDITING THE RNA MESSAGE Intron- non-coding regions of DNA Exon- parts of a gene that will be translated or expressed RNA Splicing- when the introns are removed from the RNA before it moves to the cytoplasm

TRANSLATION: RNA TO PROTEIN Transfer RNA- translates the 3 letter codon of mRNA into an amino acid

TRANSLATION: RNA TO PROTEIN Anticodon- a triplet of bases that is complementary to a specific RNA sequence Ribosomal RNA- located in the ribosome

CLASS WORK 1. What kind of nucleic acid is made during transcription? 2. How do introns and exons relate to RNA splicing? 3. List the three RNA types involved in transcription and translation, and describe the role of each. 4. Briefly describe the steps of protein synthesis.

MUTATIONS CAN CHANGE THE MEANING OF GENES CHAPTER 11.6 MUTATIONS CAN CHANGE THE MEANING OF GENES

HOW MUTATIONS AFFECT GENES Mutation- any change in the nucleotide sequence of DNA Two types Base Substitution Base Insertion/Deletion

WHAT CAUSES MUTATIONS? Errors in DNA replication Mutagens- physical or chemical agents that cause mutations X-rays UV Light Smoking Mutations can be harmful or beneficial

Muscular hypertrophy- double muscles

CLASS WORK 1. Explain why a base substitution is often less harmful than a base deletion or insertion.
 2. Describe how a mutation could be helpful rather than harmful.
 3. Give an example of a mutagen. PAGE 13 in Packet