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.
  • The mice got pneumonia and died.
  • Transformation had occurred.

Transformation: one strain of bacteria changes into another.

Hersey –Chase Experiment: studied viruses

  • Virus- Non living
  • Bacteriophage: virus that infects bacteria
  • Has DNA or RNA and a protein coat.
  • Showed that bacteria has DNA

DNA

Long molecule made of nucleotides

  • Nucleotide: 3 parts
  • 5 carbon sugar “Deoxyribose”
  • Phosphate group
  • 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

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”)

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)
  • 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

  • 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
  • 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