A. Griffith and his mice: In 1928, while trying to prepare a vaccine for pneumonia, 1. Griffith discovered that harmless bacteria, when combined with heat-killed harmful bacteria, would become virulent (able to cause disease). (page 339) 2. The bacteria had undergone transformation a. a change in phenotype caused when bacterial cells take up foreign genetic material

B. Avery’s Experiment 1. Avery continued this research, and in 1944 he demonstrated that DNA is the material responsible for this transformation. 2. He demonstrated this by using 2 enzymes a. enzymes destroy bacterial protein  mice died b. enzymes that destroyed bacterial DNA  mice did NOT die

C. The Hershey-Chase Experiment Alfred Hershey and Martha Chase performed a bacteriophage (virus that infects bacteria) experiment. 2. showed that viral DNA, when injected into bacterial cells, will produce more viruses. 3. They concluded that DNA, NOT PROTEINS, is the source of genetic material (page 341)

A. DNA: A double helix of nucleotides that controls the production of proteins. **Proteins form the structural units of cells & control all chemical processes in a cell**

1. Each nucleotide is made up of 3 parts: a. A phosphate group b. Sugar (deoxyribose) c. A nitrogen base (adenine, thymine, cytosine or guanine)

2. Purine class, double ringed C & N atoms a. Guanine & Adenine 3. Pyrimidine class, single ringed C & N atoms a. Thymine & Cytosine

B. Base-Pairing Rules: by Erwin Chargaff (1949). 1. In any DNA molecule, the amount of Adenine = the amount of Thymine 2. the amount of Cytosine = Guanine 3. These bases pair together (by Hydrogen bonds) and form complementary strands of DNA

C. Watson & Crick Used Chargaff’s rule & Franklin’s x-ray to develop a 3D model of DNA 2. Determined that a purine on one strand of DNA is always paired with a pyrimidine on the opposite strand 3. Adenine forms 2 hydrogen bonds with thymine 4. Cytosine forms 3 hydrogen bonds with guanine

5. The Double Helix: DNA looks like a twisted ladder (spiral) 6. The two strands are complementary and the same length The Double Helix: DNA looks like a twisted ladder (spiral) The sides of the ladder are formed by two strands of alternating sugar and phosphate groups The rungs of the ladder are formed by the base pairing of A=T (2 Hydrogen bonds) and C=G (3 Hydrogen Bonds). The two strands are complementary and the same length

7. The bases on 1 strand determine the bases of the other strand = complimentary base pairing  C A T G G A T T G C C A T C G  G T A C C T A A C G G T A G C

 DNA Replication: The process of making a copy of DNA (S-phase of the cell cycle ).  One strand of DNA acts as a template, or pattern, on which the other strand is built.

A. Steps of DNA Replication: 1. Enzymes, called DNA Helicases, unwind the double helix a. breaking the hydrogen bonds between the bases. b. As the strands are separated, they are held apart by proteins. c. This leaves replication forks on both sides of the DNA where the helix is separated.

2. At the replication fork, enzymes known as DNA polymerases add the correct bases to the exposed strand. a. As the DNA polymerase moves along, two new double helixes are starting to form. 3. Once all of the DNA has been copied, the DNA polymerase receives a signal to detach. b. The result is two new DNA molecules, each composed of a new and an original strand.

B. Checking For Errors 1. What happens if the wr0ng nucleotide gets attached by DNA polymerase? a. DNA polymerase “proof-read” the strand. They will only add nucleotides to the strand if the previous nucleotide is correct. b. If the previous one is incorrect, it will go back and fix the mistake.

C. DNA molecules have multiple replication forks that work at the same time. D. This can help to replicate a human chromosome in about 8 hours

 Central Dogma of Biology: DNA → RNA → Protein

A. RNA and DNA Compared: 1. RNA is single stranded and DNA is double stranded 2. RNA has a ribose sugar and DNA has deoxyribose 3. RNA has a base of Uracil (U) and DNA has the base Thymine 4. **There is no T in RNA, so A=U and C=G**

B. Transfer of Information from DNA to RNA 1. Transcription: The instructions for making a protein are transferred from a gene to RNA. a. occurs in the nucleus of the cells

C. Steps of Transcription 1. RNA Polymerase (an enzyme that adds and links complementary RNA nucleotides) binds to a gene’s promoter (a sequence of DNA that acts like a start signal) 2. RNA polymerase unwinds the double helix, exposing DNA nucleotides 3. RNA polymerase adds and links complementary RNA nucleotides together.

D. RNA Editing 1. Introns: Segment of mRNA transcribed from eukaryotic DNA but removed before translation of mRNA into a protein. a. non-coding portions of DNA. 2. Exons: Sequence of nucleotides on a gene that gets transcribed and translated into proteins

A. The Genetic Code 1. The RNA instructions are written in a series of three-nucleotide sequences called codons. 2. Each codon “codes” for a specific amino acid. (Fig. 13-6, pg 367 Shows the human genetic code) 3. The amino acids are linked together to form a protein. 4. Start codon: AUG  Methionine (Met) 5. Stop codons, UAA, UAG, UGA

B. RNA to Protein 1. Translation: The instructions on the RNA molecule are used to put together amino acids and make proteins. a. Occurs in the cytoplasm of the cell.

C. TYPES OF RNA 1. Messenger RNA (mRNA): RNA produced by transcription that transmits information for protein synthesis. a. It passes the “message” from DNA to ribosomes.

2. Transfer RNA (tRNA): A single strand of RNA that temporarily carries a specific amino acid on one end. a. Each tRNA has an anticodon - A three-nucleotide sequence on tRNA that is complementary to an mRNA codon 3. Ribosomal RNA (rRNA): RNA molecules that are part of the structure of ribosomes.

D. Steps of Translation: 1. mRNA leaves the nucleus and enters the cytoplasm. a. Then tRNA reads the start code of mRNA (AUG) and orients itself in a region of a ribosome called the P site. 2. The A site of the ribosome is ready to receive the next tRNA. The tRNA then binds to the codon.

3. The P and A sites are holding tRNA molecules (each with its own amino acid). a. The amino acids are linked together by a peptide bond. 4. The tRNA in the P site leaves, the tRNA in the A site moves over, and a new tRNA molecule binds to the codon in the A site. 5. The amino acids continue to join together until a stop codon is reached (UAG, UAA, or UGA). a. A protein is created.

A. Gene mutations 1. Point Mutation: Mutation in which one or just a few nucleotides in a gene are changed. a. Base deletion, insertion or substitution 2. Frameshift mutations are insertions and deletions B. 4 type of Chromosomal Mutations 1. Deletion, duplication, inversion, translocation 2. Descriptions on your Guided Reading or pg. 374

C. Mutagens: physical or chemical agents that cause mutations in organisms 1. Example: xray radiation, UV radiation, pesticides D. Not all mutations are bad. 1. Some help the organisms become better suited for their environment. 2. If the mutation is present in the gametes, the mutation can be passed to offspring

A. Prokaryotic Gene Regulation 1. Prokaryotes only transcribe genes when that specific protein is needed by the cell. 2. This allows prokaryotes to respond to their environment. 3. DNA binding proteins in prokaryotes regulate genes by controlling transcription.

4. Use a group of genes called an operon 5. Lac operon a. E.coli uses the lac operon to produce proteins that are able to digest the sugar lactose. b. The lac operon is regulated by a repressor protein that binds to lac operon site in the absence of lactose. c. In the presence of lactose, the repressor protein falls off the lac operon site, so the lac genes can be transcribed.

B. Eukaryotic Gene Regulation 1. Most genes are controlled by a TATA box. a. The TATA box binds a protein that helps position RNA polymerase so transcription can begin. 2. Also regulated by transcription factors that bind to regulatory regions of DNA 3. RNA interference also controls gene expression in eukaryotes.

C. Genetic Control of Development 1. Genes called homeobox genes control cell differentiation during development 2. Hox genes are a group of homeobox genes a. In flies, Hox genes determine the identity of each body part b. They are arranged in the exact order that they are expressed, from anterior (head end) to posterior (tail end) c. A mutation in one of these genes can completely change the body part

3. Metamorphosis a. This is how organisms can change their genes in response to the environment b. Metamorphosis is regulated by external environmental factors and internal hormonal factors c. The speed of metamorphosis is determined by environmental changes that stimulate hormonal changes that affect translation.

 How did Griffith set up his experiment?  Mice & S. pneumoniae  R bacteria did not kill the mice  S bacteria killed the mice  Heated killed S bacteria did not kill the mouse  Heated killed “S” & normal “R” killed the mice  What did Griffith’s experiment discover?  Transformation

 What is transformation?  A change in genotype caused when cells take up foreign genetic material.  What is a vaccine?  A substance that is prepared from weakened or killed disease causing agents (bacteria or virus) that is given to an organism to protect the body from future infections.

 What does virulent mean?  Able to cause disease  What is a bacteriophage?  A virus that infects bacteria  What sugar in found in nucleotides?  deoxyribose

 What is a nucleotide?  It is a subunit of DNA  Which scientists used bacteriophages in their experiment?  Hershey and Chase  What type of bacteria did Hershey & Chase infect with bacteriophages?  E.coli

 What did the Hershey-Chase experiment show?  That DNA, not protein, is the genetic material of viruses.  What are the 4 nitrogen bases in DNA?  Adenine, Thymine, Cytosine, Guanine  What are the 3 parts of a nucleotide?  A phosphate group, sugar and a nitrogen base

 What does “DNA” stand for?  Deoxyribonucleic acid  Which 2 bases are purines?  Adenine & Guanine  What did Franklin’s and Wilkins x-ray diffraction photographs tell them about the structure of DNA?  DNA resembled a tightly coiled helix

 Which 2 nitrogen bases are pyrimidines?  Thymine & Cytosine  What is Chargaff’s rule?  Adenine – Thymine  Cytosine – Guanine  What are the complimentary base pairs for this strand: C-T-A-A-G-C-T-A-G-G  G-A-T-T-C-G-A-T-C-C

 What 2 scientists developed the 3D model of DNA?  Watson & Crick  What 2 scientists looked at the structure of DNA on x-rays?  Wilkins & Franklin  True or False: Complimentary strands of DNA serve as a template for building new DNA.  True

 What enzyme “unzips” DNA during replication?  DNA helicase  What is a replication fork?  The areas where the double helix separates during DNA replication

 What is the name of the enzyme that adds nucleotides to exposed nitrogen bases during DNA replication?  DNA polymerase

 How are errors avoided when DNA replicates?  DNA polymerase will “proof-read” the strand as it adds nucleotides. It will only add a nucleotide if the previous pair is correct. If the previous nucleotide is wrong, it will go back and replace it with the correct nucleotide.

 Why do chromosomes need multiple replication forks during DNA replication?  If there were only 1 replication fork, replication would take too long.  What does prokaryotic DNA look like?  Circular

 What is transcription?  DNA  RNA  The instructions for making a protein are transferred from a gene (DNA) to RNA

 Where does transcription occur?  Nucleus  Describe RNA in 3 ways:  Single stranded  Has ribose sugar  Thymine is replaced with Uracil

 What is the name of the enzyme that adds RNA nucleotides to the gene’s promoter during transcription?  RNA polymerase  What is a codon?  A 3 nucleotide sequence that codes for an amino acid

 What are the 3 steps of transcription?  1. RNA polymerase binds to the promoter site on DNA 2. RNA polymerase unwinds & separate DNA  3. RNA polymerase adds RNA nucleotides to the open DNA strand

 What is translation?  RNA  Proteins  Instructions on RNA are used to put together amino acids to make proteins  What is the central dogma of biology?  DNA  RNA  protein  What types of RNA are a part of translation?  mRNA, tRNA, r RNA

 Where does translation occur?  Cytoplasm  What is the start codon?  AUG  How do stop codons stop translation?  They do not code for an amino acid  There are 64 codons but 20 amico acids, what does this tell us about the genetic code?  Several codons can code for the same amino acid

 What is the function of mRNA?  It holds the information for protein synthesis and passes the message from DNA to the ribosomes  What is the function of tRNA?  To bring the correct amino acid to the ribosomes to make the protein  What 3 nucleotide sequence is found on the tRNA?  anticodon

 What are the 2 mains types of mutations?  Gene mutations and chromosomal mutations  What 2 types of mutations are considered frameshift mutations?  Insertions and deletions  What are the 3 types of point mutations?  Base substitutions, base deletions and base insertions

 What a re the 4 types of chromosomal mutations?  Deletions, duplications, inversions, translocations  What is a mutagen?  A physical or chemical agent that can cause a mutation  What is an operon?  A group of genes in prokaryotes that are all regulated together

 What is the name of the prokaryotic operon that we studied?  Lac operon  What regulates the Lac operon?  Repressor proteins that bind to the operator to prevent transcription  When is the Lac operon turned “on”.  In the presence of lactose

 What 3 things control Eukaryotic transcription?  TATA Box, transcription factors and RNA interference  True or False: Most mutations have no effect on the organism  True

 What do Hox genes control with the organism?  Body plan  What segments of DNA must be removed before translation can occur?  Introns