Chapter 12: DNA and RNA

Elana Jacobs-Pontecorvo

Discoveries about DNA Avery (and other scientists):

experimented with destroying different parts of heat killed bacteria, and found out that:

DNA is a nucleic acidDNA store genetic information DNA transmits genetic information to the next

generation

Elana Jacobs-Pontecorvo

Hershey and Chase:Experimented with bacteriophages. Bacteriophages are viruses that inject their genetic material into the cell. They found that the genetic material was DNA

Elana Jacobs-Pontecorvo

Watson and Crick: made a model of DNA which was a double

helix, like this picture:

Elana Jacobs-Pontecorvo

DNA replication

The DNA molecule unzips into two strands

Each strand produces a new strand

The enzyme used is called DNA polymerase

Elana Jacobs-Pontecorvo

Types of RNA

Messenger RNA: sends messages from DNA to rest of the cell.

Ribosomal RNA: Makes up ribosomes

Transfer RNA: Help construct proteins.

Olenka Alvarado

Transcription

1. The enzyme, RNA polymerase, separates the DNA strands.

2. Nucleotides are made into a strand of RNA, by using a strand of DNA as a model.

Olenka Alavarado

Translation: process of cell making proteins

A) mRNA enters cytoplasm and attaches to ribosome, starts translation.

B) tRNA with an amino acid on top attaches to the mRNA strand with the anticodon that matches its codon.

C) ribosomes form peptide bond between the amino acids

D) tRNA leaves and the cell is left with a protein chain

Olenka Alvarado

Mutations

A) Gene Mutations: change in a single gene-Point Mutations: affect one nucleotide-Frameshift Mutations: affects all

amino acids after the change (insertion or deletion of nucleotide)

B)Chromosomal Mutations: changes in structure or number of chromosomes

Olenka Alvarado

Gene Regulation

Lac genes: turned off by repressors and on by lactose

Eukaryotic Genes: individually controlled.

Olenka Alvarado