Presentation on theme: "MOLECULAR GENETICS. DNA- deoxyribonucleic acid 1953- James Watson and Francis Crick discover the structure of the DNA molecule DNA is a double helix (twisted."— Presentation transcript:
There are four nitrogen bases: Adenine Guanine Cytosine Thymine
Nucleotide- the building block molecule of DNA 1 sugar 1 phosphate group 1 nitrogen base
Nitrogen base pairs Adenine always pairs with Thymine Guanine always pairs with Cytosine (Often called Complimentary base pairs) The bases are held together with Hydrogen bonds
Functions of DNA: 1.Replication- so that genetic material and information is passed from one generation to another and to succeeding cells 2.Control of cellular activities: DNA carries the code for assembling enzymes and other proteins that cells need
Quiz: answer these questions on a piece of paper 1.Describe the basic structure of DNA. 2.Describe the parts of a nucleotide. 3.What are the complimentary base pairs? 4.What type of bond holds nucleotides together?
DNA Replication DNA makes a copy of itself just before the cell divides
Steps of replication: 1.DNA double helix molecule unwinds and unzips. 2. New DNA nucleotides find their complimentary base pair. 3. Results in two identical molecules of DNA
RNA- ribonucleic acid 1.The sugar in RNA is ribose 2.RNA is single stranded 3.The nitrogen base uracil replaces thymine (what base is complimentary to Uracil)
RNA transcription- DNA is used as a template for producing an RNA molecule
How does RNA form? 1. DNA is used as a template (model) to make RNA 2. RNA has three forms: messenger RNA (mRNA) transfer RNA (tRNA) ribosomal RNA (rRNA)
3. The molecule of DNA unwinds and unzips 4. One side of DNA acts as a template for producing a complimentary RNA strand 5. RNA molecules strip away from DNA, leave the nucleus and enter the cytoplasm
RNA now has the instructions for how to make a specific protein.