Chapter 10 DNA and RNA

10.1 DNADeoxyribonucleic Acid

• Experiments– Griffith –

• MICE!!• pneumonia• Determined that some how the harmful strain

infected the harmless• Discovered Transformation

Oswald Avery• What caused transformation?

• Different enzymes to try and stop transformation.

• Deoxyribonuclease , no transformation.

• Taking place in the DNA!!!

Alfred Hershey and Martha Chase• Studied viruses or bacteriophages. (made

of DNA or RNA and a protein shell)

• Used radioactive markers on the protein shell and the DNA to see what is passed…found that genetic material was in the DNA.

10.2 DNA STRUCTURE

James Watson, Francis Crick, and Rosalind Franklin

• Discovered the double helix structure.

Structure of DNA

• 3 Main parts of the nucleotide– Deoxyribose – 5 carbon sugar– Phosphate– Nitrogenous base (adenine, guanine, cytosine,

thymine)

• Double Helix • Chargaff’s rule (base pairing)

– Guanine – cytosine– Adenine - thymine

• Held together by hydrogen bonds

• Purines • Pyrimidine

         

        

                 

        

AdenineGuanine

ThymineCytosine

10.3 Chromosomes and DNA replication

• Prokaryotes – DNA in cytoplasm

• Eukaryotes – DNA in nucleus– DNA extremely long!!!

• Human DNA actual size is 3 meters long• Chromosome 13 has a DNA segment 3.2 cm long

DNA Replication

• Use rules of base pairing– Original = GTTACCATG creates new strand

CAATGGTAC.

• At any point DNA can begin replication (replication fork)

• Helicases separate the DNA strands.• Enzyme called DNA polymerase start the

replication• Semi-conservative – not all of it is new.• Replicates in both directions until done, read in

only one direction.

Errors in Replication

• Mutation

• Proofreading and repair can prevent this.

10.4 RNA and Protein Synthesis

• Flow of genetic info

• DNA RNA Protein

• Transcription translation protein synthesis

• Fig 10-12

• Differences between DNA and RNA

DNA RNA

Sugar Deoxyribose Ribose

Shape Double stranded Single Strand

Nitrogenous

Bases

Cytosine – Guanine

Adenine - Thymine

Cytosine-Guanine

Uracil - Adenine

Types of RNA

• Messenger RNA (mRNA) – carry copies of instruction from DNA

• Ribosomal RNA (rRNA) – part of ribosome’s where proteins are assembled.

• Transfer RNA (tRNA) – Transfers each amino acid to ribosome from codes.

• Transcription– Starts with RNA polymerase that finds a

promoter on the DNA.– Separates strand of DNA, makes a copy

(mRNA), then DNA returns to normal– RNA Editing (pre-mRNA)

• Not all RNA strands are perfect, some have introns and exons.

• Introns are useless parts, exons are good parts, introns are removed and exons are pushed together to form one whole sequence, then capped.

– mRNA is formed until reaches a terminal signal

• Genetic code– Codon - Sets of 3– UCGCACGGU = UCG CAC GGU =

serine – histidine – glycine

Pg 207

One represents start (methionine , AUG, 3 represents stop)

Translation• Decoding of mRNA

• Pg 208 (know process, find tRNA, mRNA, ribosome, nucleus, polypeptide chain, codon, anticodon.

In your Notes• Write

TACAATGCTCAAACT

• 1. mRNA Strand to match

• And Decode