Download DNA polymerase

Genetic Disorders Project
DUE FRIDAY, 2/26/10
Tri-fold brochure
Printed out BEFORE class on Friday
Powerpoint
Placed on O drive BEFORE class on Friday
Pedigree
Bibliography
MLA format
Activity: DNA to Disease
You will be given a DNA sequence to
transcribe and translate.
You will perform a BLAST search against a
database of known proteins to determine
which protein your sequence encodes.
What will happen if this protein mutates or
malfunctions?
DNA
DNA- What is it??
 Stores genetic
information and
provides a way for
that information to be
copied.
“Code”
 Deoxyribonucleic Acid
 Made up of repeating
units of nucleotides
3 parts
Discovering DNA Structure Paper Lab
 1) Color nucleotides using the provided key. Cut
them out.
 2) Determine the 3 parts of a nucleotide.
Answer part A questions.
 3) Fit the nucleotides together like a puzzle.
How do they fit together?
Link together all nucleotides to make a large class DNA
molecule.
Answer parts B and C questions.
What’s Next??
1) Course selection
2) Work on projects if time permits
DNA Discovery- Who Gets the Credit?
What is the genetic material inside cells?
1928, Frederick Griffith
Studied 2 strains of bacterial pneumonia
1 killed mice, 1 didn’t
Griffith’s Experiments
So what is this inheritable stuff??
By 1944, it was narrowed down to DNA or
protein. BUT WHICH ONE IS IT??
1952, Alfred Hershey & Martha Chase
Bacteriophages
 Bacteriophages are
viruses that infect and kill
bacteria cells.
 Bacteriophages are made
up of a DNA core and a
protein coat.
 Which part goes into the
cell- the protein coat or
the DNA??
Hershey and Chase’s Experiment.
 Hershey and Chase grew
bacteriophages in radioactive
isotopes of sulfur and
phosphorus.
 Proteins contain sulfur. DNA
contains phosphorus.
 Please Sir… (PS)
 Don’t Pee
(DP)
RESULTS
Rosalind Franklin
 Rosalind Franklin
made X-ray
photographs of the
DNA molecule. Her
photographs showed
that DNA was shaped
like a helix.
Watson and Crick
 Watson and Crick
constructed a model
of DNA in 1953.
 Their model showed
that DNA was a
double helix, with two
stands of nucleotides
wound around each
other.
Other Contributors
Erwin Chargaff
Maurice Wilkins
Linus Pauling
Sir Lawrence Bragg
SO WHO GETS THE CREDIT??
Review
1) How did Griffith’s experiment indicate
the presence of a “transforming factor” in
bacteria?
2) Describe the experimental design that
allowed Hershey and Chase to distinguish
between the 2 options for genetic material.
Structure of DNA
 Long, twisted, doublestrand.
 DNA is a made of
units called
nucleotides.
 Each nucleotide is
made up of
 sugar (deoxyribose)
 phosphate group
 nitrogen base.
Structure of DNA cont’d…
There are 4 nitrogenous bases in DNA:
Adenine (A)
Thymine (T)
Guanine (G)
Cytosine (C)
Chargaff’s Rules: A-T G-C
Weak hydrogen bonds hold these together
Base pairs are COMPLEMENTARY
Pyrimidines/ Purines
Pyrimidines- single-ring structures (T/C)
Purines- double-ring structures (A/G)
Structure of DNA cont’d…
Try this:
DNA Replication
 Before mitosis, a cell
replicates its DNA
(Interphase).
 Takes place in the
nucleus.
 Each strand of the
double helix has all the
information to make the
other half through base
pairing (they are
“complementary”).
Steps of DNA Replication
 1) Enzymes called
helicases break the
weak hydrogen bonds
between the base pairs
and “unzip” the molecule.
 2) Complementary bases
pair up (A-T G-C)
DNA Polymerase
 3) New complimentary
strands are “sealed” by
the enzyme DNA
polymerase.
 As a result, 2 identical
DNA molecules are
produced.
Animation
Accuracy of DNA Replication
Fast and accurate!
DNA Megamolecule Activity
 Blueprint for
hemoglobin
 Sickle Cell Anemia
(#50)
 Black/Red strands
 Nitrogen bases
represented by 4
different colors
DNA Extraction Lab
Where is DNA?
The project that underwrites this lab activity has been supported by The US Department of Education, Fund for the
Improvement of Postsecondary Education (FIPSE), grant # P116B060093.
DNA Review
A-T
G-C
Genome- specific order of DNA base
pairs.
DNA is found in our chromosomes.
Both plants and animals have DNA.
Why use
strawberries?
Strawberries are octoploid, meaning
that they have 8 copies of each
chromosome.
* So we will get LOTS of DNA!
Plant Cell
Protocol for
DNA Extraction
1. Place 1 strawberry in a
plastic, resealable bag and
smash. Why?
2. Add 10 mL DNA extraction
liquid (soap, water, and
salt). Why?
Protocol for DNA Extraction (Continued)
3. Filter the
strawberry
mess. Why?
Protocol for DNA Extraction (Continued)
4. Add 90% alcohol. Why?
Protocol for DNA
Extraction (Continued)
5. Spool… DNA now visible!
Now what?
6. Look at DNA under a microscope.
Barriers a plant cell must overcome to
have DNA extracted.
 Crush to break open cell wall, cell membrane,
and nuclear envelope to let DNA out.
 Add soap to break down lipids (fats) in cell wall
and nuclear envelope.
 + salt charge keeps – charge of DNA from
repelling each other.
 Adding alcohol allows DNA that is insoluble in
alcohol to rise from watery layer.
Dna is the
universal language
of life
Questions to think about…
 How do researchers proceed when they attempt
to translate a message in an unknown
language?
 How could you crack the previous slide’s code?
 Suppose you know the group of symbols in the
4th word stands for “universal”… how could you
use this information?
 Once the message is translated into English, is it
still the same message?
So just what is DNA?
DNA holds a “code” in the sequence of
letters for making specific proteins.
The language of genes is written as a
sequence of bases along the DNA chain.
How Does This Happen?
RNA
 Ribonucleic Acid
 RNA has ribose
instead of
deoxyribose sugar.
 RNA has uracil
instead of thymine.
 RNA is singlestranded instead of
double-stranded.
3 Types of RNA
 mRNA
 The “messenger”
 Copies DNA’s code
 rRNA
 Makes up the
ribosome
 tRNA
 Transfer RNA
 Makes a protein
Protein Synthesis
 From a DNA strand, a
protein is made.
 2 steps:
 1) TranscriptionDNA is copied onto
mRNA
 2) TranslationmRNA message is
used to “make” a
protein
Review
1) Which molecule completes the flow of
info from DNA to protein?
2) List 2 ways RNA is different from DNA.
3) What kind of nucleic acid is made
during transcription?
4) List and describe the role of the 3 RNA
types.
Transcription
 During transcription, the
DNA message is copied
into a mRNA molecule.
 Occurs in the nucleus.
 TRY THIS:
DNA: ATTGCCGAA
RNA:
Translation
 During translation,
the cell uses the
information from
mRNA to produce a
protein.
 Occurs in the
ribosome.
Codon
 The genetic code is
read three letters
(bases) at a time
 A codon or “word”
consists of three
consecutive bases on
mRNA that specify a
amino acid.
Genetic code
 Proteins are made by
joining amino acids
into long chains called
polypeptides.
 How do codons
become a protein?
 Video
Mutation
 Mutations are changes in
the DNA sequence that
affect genetic information.
 Today, we will discuss 3
types of mutations.
Mutations
 Mutations in which one nucleotide has been replaced by another are
point mutations.
 Frameshift mutations (insertions) shift the reading frame of the
genetic message by adding or deleting several nucleotides.
 Deletions are when 1 nucleotide has been removed from the
sequence.
What Causes Mutations?
Mutagens- physical or chemical agents
that cause mutations.
Radiation, uv light
Can be harmful or helpful: