DNA RNA and Protein Synthesis Chapter 10 history

DNA, RNA, and Protein Synthesis Chapter 10

history DNA

DNA • 1953 – James Watson and Francis Crick came up with the model of DNA

LE 16 -6 Rosalind Franklin’s X-ray diffraction photograph of DNA

function DNA

DNA aka Deoxyribonucleic Acid What does DNA do? • Stores and transmits genetic information that tells cells which proteins to make and when to make them. What do proteins do? • Proteins, in turn, form the structural units of cells and help control chemical processes within cells.

structure DNA

What is DNA? • DNA is a long molecule or “chain” of nucleotides. • A nucleotide is made up of 3 things: – Phosphate group – Deoxyribose (sugar) – Nitrogen base.

DNA Structure • Made of repeating subunits called nucleotides. • There are 4 kinds of nitrogen bases.

DNA Structure • Four nitrogen bases – Adenine – Thymine – Guanine – Cytosine

Double-stranded Double Helix

Charagaff’s Rule This is how nitrogen bases pair up. Adenine = Thymine Guanine = Cytosine

DNA Structure Pyrimidines Purines • 1 ring base • Thymine and Cytosine • 2 ring base • Adenine and Guanine

replication DNA

DNA Replication • DNA replication is the process by which DNA is copied in a cell before the cell divides by mitosis, meiosis, or binary fission.

DNA Replication • When DNA is copied: – the 2 strands or sides “unzip” – RNA brings new nucleotides into the nucleus to match the exposed nitrogen bases.

Steps of DNA Replication • Step 1 - Unzip the DNA – Helicase enzymes separate DNA’s two chains of nucleotides

Steps of DNA Replication • Step 2 - Fill in the missing bases – Enzymes called DNA polymerases bind to the separated chains. – One base (nucleotide) at a time, the enzyme constructs a new complementary chain of nucleotides

Steps of DNA Replication • Step 3 - Complete and Pop Off – DNA polymerases finish replicating the DNA and fall off. There are now two identical DNA molecules

DNA: Base Pairing • Each nucleotide in DNA preferentially pairs with its partner nucleotide on the opposite strand. So one side • A pairs with T “compliments” • C pairs with G the other. • This structure of DNA is the physical basis for inheritance.

DNA Replication Summary • During DNA replication, the DNA molecule separates into 2 strands, then produces 2 new complementary strands following the rules of base pairing. • Each strand of the double helix of DNA serves as a template, or model, for the Check it out on new strand. page 201.

DNA Replication Use the principle of base pairing to create this strand of DNA’s complimentary copy. ACC GCT TTA GCC GAT TAC GAA That’s easy!! TGG When you’re done with that example, create a new DNA strand for your partner to work on.

mechanism for inheritance DNA

DNA: Chromosomes Genes are arranged along the long chains of DNA sequence, called chromosomes.

Incorrect DNA

Mutation • A change in the nucleotide sequence of a DNA molecule that affects genetic information.