Quick Review 1.What is genetic information stored as? 2.What organelle is this information found in?

First Model of DNA 1953: James Watson, Francis Crick and Maurice Wilkins examined an amazing photograph made by Rosalind Franklin using a technique she developed called X-ray crystallography With what they had discovered about the composition of DNA and Franklin's photographs, Watson & Crick developed and proposed the first model for the structure of DNA

Watson and Crick Model consisted of two nucleotide chains that wrap around each other to form a double spiral. This shape is called a double helix.

DNA DeoxyriboNucleic Acid Genetic code of life Located inside the nucleus NEVER leaves the nucleus Double Stranded Shape of DNA is a double helix Made of nucleotides

Primary functions of DNA: 1.Store and Transmit genetic information 2.Direct its synthesis/replication 3.Code for protein synthesis

So, what is RNA? RiboNucleic Acid Copy of a gene in DNA Responsible for delivering genetic information from the DNA in the cell nucleus to the ribosome in the cytoplasm Located outside the nucleus Responsible for completion of the process of protein synthesis Single stranded 3 Types of RNA: Messenger, Transfer, Ribosomal Made of nucleotides

DNA and RNA

Nucleotides Monomers that make up DNA & RNA

Each nucleotide is composed of: A sugar, A nitrogen base A phosphate group:

Sugar Deoxyribose - a 5-carbon sugar in DNA Ribose - a 5-carbon sugar in RNA. This sugar has more oxygen than the sugar in DNA. Notice: Oxygen placement DEoxy (de means to remove. DNA has an Oxygen removed!!!

Nitrogen Base Purines –have a double ring of carbon and nitrogen atoms. –Adenine & Guanine Pyrimidines have a single ring of carbon and nitrogen atoms. Thymine & Cytosine (in DNA) Uracil & Cytosine ( in RNA)

Phosphate Group -PO 4

The phosphate group is attached to the sugar, and the sugar is attached to the nitrogen base

RNA – single stranded DNA – double stranded

Two nucleotides pair to form one of the "rungs" of the ladder in a DNA double helix.

The sugar and phosphate groups form the "backbone" or outer support of the DNA ladder-like double helix. Sugar phosphate backbone

Base Pairing Rules These rules describe the behavior of the bases. 1.Cytosine always bonds with guanine by forming three hydrogen bonds. (C - G) 2.Adenine always bonds with thymine by forming two hydrogen bonds. (A - T) In the RNA nucleotide, thymine is replaced by Uracil (A – U). 3.A pair of bases that always bond together is known as a complementary base pair.

3 Basic Types of RNA Messenger RNA – mRNA Transfer RNA – tRNA Ribosomal RNA - rRNA

Messenger RNA mRNA carries genetic information from nucleus to cytoplasm

Transfer RNA tRNA carries amino acids from cytoplasm to ribosomes

Ribosomal RNA rRNA consists of RNA nucleotides in globular form

Celebration of Learning Moment! You are to create a comparison between RNA and DNA. Be sure to include: 1.Type of Sugar 2.Type of nucleotides 3.Strand type

DNA & RNA Comparison DNARNA Sugar molecule is Ribose Sugar molecule is Deoxyribose Is single strandedIs double stranded Uses UracilUses Thymine Is smaller and leaves the nucleus Remains in the nucleus Has 3 basic typesOnly one kind of DNA COPY of genetic codeIs THE genetic code