Chapter 12 lesson 1
Griffith’s Experiments: Scientist who injected mice with 2 types of bacteria.
1st type- pneumonia (mice died)
2nd type- harmless bacteria (mice lived)
 To find out why mice with pneumonia died Griffith heated pneumonia
bacteria and then injected it back into the mice. The mice lived.
 Transformation: Griffith then mixed the heat-killed pneumonia bacteria with
living harmless bacteria. He injected the mice with this mixture.
o The mice got pneumonia and died.
o Transformation had occurred.
Transformation: one strain of bacteria changes into another.
Hersey –Chase Experiment: studied viruses
http://highered.mcgrawhill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437
316/120076/bio21.swf::Hershey%20and%20Chase%20Experiment
 Virus- Non living
 Bacteriophage: virus that infects bacteria
o Has DNA or RNA and a protein coat.
o Showed that bacteria has DNA
DNA
http://www2.edc.org/weblabs/HowDoesDNAWork/DNA.html
Long molecule made of nucleotides
 Nucleotide: 3 parts
1. 5 carbon sugar “Deoxyribose”
2. Phosphate group
3. Nitrogenous base (4 bases)
 Adenine
 Guanine
 Cytosine
 Thymine
Base pairing- Adenine (A)= Thymine (T)
Cytosine(C)= Guanine (G)
Watson and Crick: created the double helix model.
Chapter 12 Lesson 2
 Prokaryotic cells – DNA is in cytoplasm
 DNA is very long
Histone: protein that chromatin is wrapped around.
Duplicating DNA- it “unzips”
DNA Polymerase: enzyme that starts DNA Replication
Histone
Chapter 12 lesson 3
RNA: similar to DNA
3 main differences
 5 carbon sugar (Ribose NOT Deoxyribose)
 Single stranded (NOT a Double Helix)
 Uracil NOT Thymine
3 TYPES of RNA
1. Messenger RNA (mRNA) - carries copies of amino acid
assembly instructions from DNA to the rest of the cell.
2. Ribosomal RNA(rRNA)- made of protein
3. Transfer RNA (tRNA) – transfers amino acids to Ribosome.Follows mRNA instructions
What is RNA? – It is a working copy of DNA and makes Protein
(“Protein Synthesis”)
http://www.pbs.org/wgbh/aso/tryit/dna/shockwave-nojs.html
Transcription
RNA Polymerase-uses DNA strand to make RNA copies.- Similar
to DNA Polymerase
 Promoter: signals in DNA that tell the enzyme (RNA
Polymerase) where to start making DNA copies. (Also where
to stop)
 Intron: pieces of RNA that have been removed
 Exon: Introns put back into RNA= forms mRNA
 Codon: a 3 letter word in mRNA (AUG)
o Examples: AGU-UCC-AAG
Translation- takes place on Ribosomes
 Cell uses information from mRNA to make proteins
Anticodon- the 3 bases (AUGC) on mRNA are paired with ones on
tRNA
o Examples: AGU-UCC-AAG (codon)
UCA-AGG-CGA (Anticodon)
RNA and DNA
 DNA= “Master plan” -Stays in the nucleus
 RNA= “Blueprint” – Leaves the nucleus to go to protein
building sites (Ribosomes) in cytoplasm
Chapter 12 Lesson 4
Mutations: Changes in DNA sequence that affect genetic
information
2 Types
1. Gene mutations- changes in single genes
2. Chromosomal mutations- Whole chromosome changes
Gene Mutations:
 Point mutations: affect one nucleotide
 Frameshift Mutation: insertion or deletion
o Changes the way the genetic information is read
Chapter 12 Lesson 5
Operon: a group of genes that work together
In bacteria:
 Lac Operon: genes that are turned on and off
 Repressors-Turn it off
 Lactose- Turn it on
*Most Eukaryotic Genes do not use Operons*
Hox Genes: Genes that control developing organs in Embryos