Chapter #10 10.1 Discovery of DNA 10.2 DNA Structure 10.3 DNA Replication 10.4 Protein Synthesis

Griffith’s Experiments

Griffith’s Experiments (2) 1928 A mouse injected w/ both heat killed S (virulent) and R types can cause pneumonia A HEREDITARY FACTOR must be released and taken into the R type Is this factor protein? DNA? RNA?

Avery’s Experiments 1940’s Wanted to determine if the material that was transforming was protein, DNA or RNA Protease to destroy protein Injected w/heat killed S cells and R cells Able to transform R to S RNase to destroy RNA DNase to destroy DNA Not able to transform R to S

Hershey-Chase Experiment 1952 Protein or DNA? Little protein found in viruses; all the DNA was present DNA!!!!!

The Structure of DNA Sugar-Phosphate Backbone Nitrogen Bases Deoxyribose (sugar found in DNA) Nitrogen Bases Adenine Thymine Guanine Cytosine

The Structure of DNA (2) Purine Pyrimidine Double ringed base Guanine and Thymine Pyrimidine Single ringed base Cytosine and Adenine Purines must pair with pyrimidines so the helix can be made (it can twist)

DNA Deoxyribonucleic acid Contains genes that code for proteins Involved in heredity

Adenine Nitrogen base in both DNA and RNA Purine that pairs with thymine in DNA and uracil in RNA

Guanine Nitrogen base in both DNA and RNA Purine that pairs with cytosine in both DNA and RNA

Thymine Nitrogen base in DNA only Pyrimidine that pairs with adenine

Cytosine Nitrogen base found in both DNA and RNA

Deoxyribose 5 carbon sugar found in DNA Makes up the backbone of DNA (sides of the ladder)

Phosphate Group Backbone of DNA Alternates with deoxyribose

Hydrogen Bonds Bond that joins the nitrogen bases together

Building block of nucleic acids Contains… Nucleotide Building block of nucleic acids Contains… 5 carbon sugar Nitrogen base Phosphate group

DNA Carries the Genetic Code

Replication Process of duplicating DNA Results in 2 DNA molecules (old and new strands mixed) Replication is said to be semi-conservative

DNA Helicase Enzyme responsible for the untwisting of DNA Starts the replication process

DNA Polymerase Enzyme responsible for attaching the nucleotides in the correct order during replication.

DNA RNA Deoxyribose Double stranded Thymine One version Ribose Single stranded Uracil 3 versions Sugar-Phosphate backbone Nucleic Acids Adenine, Guanine, Cytosine

Steps in replication DNA helicase unwinds the DNA molecule at several spots Breaks the hydrogen bonds between the bases DNA polymerase adds new nucleotides 2 new strands Original strand + new strand = semiconservative model

Structure of RNA Uracil – nitrogen base found only in RNA (pyrimidine) Ribose – 5 carbon sugar found only in RNA

Types of RNA tRNA - transfer mRNA - messenger rRNA - ribosomal

tRNA Used to carry amino acids to codons on mRNA Contains the anticodons on one end and an amino acid on the other end

mRNA Contain codons Made through transcription in the nucleus Read by the tRNA during translation in the ctyoplasm

Transcription Vs. Translation Transcription – process of making RNA from DNA in the nucleus of the cell Translation – process of making proteins tRNA recognizes codons of the mRNA and attaches the amino acids in the correct sequence for the protein that DNA coded for.

Codon Set of 3 bases found on mRNA Complementary to the anticodon on the tRNA

Anticodon Set of 3 bases found on a tRNA molecule Recognizes the codon on mRNA during translation

Amino Acid Building block of a protein 20 different kinds (essential and nonessential)

Peptide Bond Bond that joins amino acids together in the growing polypeptide chain

Polypeptide Made through translation Growing chain of amino acids that transforms into a protein

RNA Polymerase Enzyme responsible for attaching RNA nucleotides in the correct order.

Steps of Transcription (in the nucleus) DNA is the template RNA polymerase adds the RNA nucleotides Uracil replaces Thymine Once transcribed, mRNA leaves the nucleus and enters the cytoplasm Hooks up with a ribosome to begin translation

Steps of Translation Ribosome, mRNA and tRNA needed to begin Anticodon on tRNA matches with the codon on mRNA Always begins w/ start codon (AUG) Adjacent amino acids form peptide bonds tRNA keeps adding amino acids until the stop codon is read

Steps of Translation tRNA releases the polypeptide chain (it will fold and become a functional protein) “naked” tRNA molecules find more amino acids and the process starts all over (as certain proteins are needed)