DNA, RNA, and Protein Synthesis Chapter 10

history DNA

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

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

function dna

DNA aka Deoxyribonucleic Acid What does DNA do? What do proteins do? Stores and transmits genetic information that tells cells which proteins to make and when to make them. 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 Adenine = Thymine Guanine = Cytosine This is how nitrogen bases pair up. Adenine = Thymine Guanine = Cytosine

DNA Structure Pyrimidines Purines 1 ring base Thymine and Cytosine 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

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

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 new strand. Check it out on page 201.

ACC GCT TTA GCC GAT TAC GAA 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.