DNA double helix shape like a winding staircase

DNA -double helix shape -like a winding staircase

• Composed of 4 bases – – Guanine (G) Cytosine (C) Adenine (A) Thymine (T) • Always bond together A-T C-G • Each base connected to the _______-_______ • Nucleotide = 1 sugar + phosphate + base (like adenine)

• DNA is complementary – The sequence of bases on one strand determines the sequence of bases on the other. What is the complement to this single strand of DNA? Watson and Crick – 2 scientists that figured out the double helix shape of DNA. -(although they actually used the work of other scientists to figure it out)

DNA Replication • When cells ____, DNA makes an exact ____ of itself. • DNA serves as a template (the parent).

Enzymes involved • Remember enzymes are a type of ____ that help a reaction occur. • DNA Helicase – Enzyme that cuts open double stranded DNA. – Think scissors! – Makes a replication fork

Enzymes II • Primer (put on by the enzyme primase) – Short sequence laid down that is starting point for DNA Polymerase • DNA Polymerase – Enzyme that helps add bases 1 by 1. – Makes new 2 nd strand. – Can only add bases onto 3’ end • New strand made in 5’-3’ direction.

DNA Replication 5’---------3’ 3’---------5’ • 5’ to 3’ during DNA replication as well.

Okazaki Fragments make lagging strand

Replication – Daughter DNA Creates an exact copy! Each new strand has one of the original strands in it. Meselson Stahl experiment proved this.

Practice question • What is wrong with the DNA on the left? AATGGCGAGCT TTACCGGTCGT • Describe in your own words how the double strand of DNA on the left would make a copy of itself.

• http: //www. bioteach. ubc. ca/Teaching. Resou rces/Molecular. Biology/DNAReplication. sw f • http: //highered. mcgrawhill. com/sites/0072437316/student_view 0/c hapter 14/animations. html#

RNA Structure • Serves as a messenger between the ______ and the ____. • Carries information in order to make _______ in the _____.

RNA Structure • • • A= G= C= U= _______ replaces _______ • _______ stranded.

Transcription

Transcription Review Questions • 1. Describe 3 differences between RNA and DNA. • 2. Describe the process of transcription in your own words. • 3. What is the purpose of transcription? • 4. Transcribe the single strand of DNA below. ACCGTGTCGAATGC • 5. How might you compare the process of transcription and replication?