Semester 2 Unit 3 Biology - DNA

Basics to DNA & DNA Replication

Functions of DNA

Stores and transmits genetic information to make proteins. made up of repeating units of nucleotides

Location of DNA in Prokaryotes

Flots in cytoplasm

Location of DNA in Eukaryotes

Wrapped around proteins in the nucleus

Structure of DNA

DNA is made up of repeating units of nucleotides

3 Parts of DNA

Deoxirybose Sugar, Phosphate Group, and Base

2 Types of DNA Bases

Purines (two ringed) & Pyrimidines (one ringed)

Purine Bases

Adenine & Guanine

Pyrimidine Bases

Thymine & Cytosine

Thymine (pyrimidine)

Pairs With Adenine (purine)

Adenine (purine)

Pairs With Thymine (pyrimidine)

Guanine (purine)

Pairs With Cytosine (pyrimidine)

Cytosine

Pairs With Guanine (purine)

Hydrogen Bonds

Holds Bases Together

Covalent Bonds

Holds Backbone Together

Double Helix

Phrase Used to Describe the Shape of DNA

Double Stranded

Coiled like a Spiral Stair

Central Dogma

Framework for understanding the flow of information. Information flows in DNA to RNA to Protein

DNA Replication

Makes copies of DNA. Located in the Nucleus. Enzymes Used: Helicase & DNA Polymerase

First Step of DNA Replication

Helicase Unzips & Unwinds the DNA Strands by Breaking the Hydrogen Bonds

Second Step of DNA Replication

DNA Polymerase add Complementary Nucleotides to Exposed Strands

Step 3 of DNA Replication

Process continues until entire strand is copied

Result of DNA Replication

Two Identical Molecules of DNA. They Have one New & One Old Strand

Mechanism of DNA Replication

DNA Replication is said to be semiconservative since each new DNA molecule made had one old and one new strand

Accuracy & Repair

Copies Must be 100% Accurate. Enzymes Proofread & Fix Errors. Mutation: Change in Nucleotide at one Location

Primase

Helps DNA Polymerase Identify Where to Start Building

DNA Ligase

Glues DNA Fragments Together

Single Stranded Binding Proteins

Binds DNA Strands to Keep Them Separate

5’ to 3’ & 3’ to 5’

Refers to the Direction of the Anti-Parallel Strands. DNA Polymerase can Only Build in the 5’ to 3’ Direction

Leading Strand

DNA Polymerase moves smoothly from 5’ to 3’

Lagging Strand

DNA Polymerase Goes Back Against the Order of the DNA’s Unwinding

Okasaki Fragments

Fragments the DNA Polymerase Fixes in Chunks in Order to Follow the 5’ to 3’ Rule