How did we get to know about DNA? What is DNA? What does DNA stand for? What does DNA look like? How is it created? What makes DNA? Where does it happen? How do we look at DNA?

Griffith and Transformation 1928- British Scientist:

Problem: how bacteria makes people sick? Studied pneumonia on mice Looked at 2 strains of bacteria: harmless and

diseased

Results:Mice injected with diseased= deathMice injected with harmless = life

Heated up diseased injected into mice and life

Lead him to his theory of transformation

Transformation He mixed heated killed disease bacteria, with

harmless ones--- into mice= mice death.

How did it happen? Somehow the disease causing bacteria passed

their ability into the healthy bacteria resulting in diseased bacteria.

=Transformation: one strain changed permanently into another. Information was transferred: What information was transferred?

Genes==========

Avery and DNA 1944: Canadian biologist

Repeated Griffith’s work Problem: Which molecule was important

in the transformation?

Did same experiment except before injected mice added chemical to kill, carbs, proteins, lipids, nucleic acid RNA, and other molecules

=death

Continued….. Next added enzyme to kill DNA

Result===== life Concluded:

Discovered that the nucleic acid DNA stores and transmits the genetic info form 1 generation of an organism to the next.

Hershey/Chase Challengers:

1952 Studied viruses that infect living organisms.

Looked at bacteriophages: Composed of DNA or RNA core and a protein

coat

Video

Concluded: that the genetic materia of the bacteriophage was DNA, not

protein.

Every living thing has DNA. That means that you have something in common with

a zebra, a tree, a mushroom and a beetle!!!!

DNA stands for:D: DeoxyriboseN: NucleicA: Acid

DNA is too small to see, but under a microscope it looks like a twisted up ladder!

Is a nucleic acid

Usually in the form of a double helix

established by James Watson and Francis Crick

Nucleic Acid: macromolecule composed of nucleotide chains that convey genetic material

Nucleotide: long chains of chemical units

The DNA nucleotide is made up of three parts Phosphate group Nitrogenous base Sugar (Deoxyribose)

Phosphorous: consists of 1 phosphate and 4 oxygen

A five carbon sugar that connects the phosphate group and the nitrogenous base

Nucleotides are joined by covalent bonds between the sugar of one nucleotide and the phosphate of the next

Sugar-Phosphate Backbone: a repeating pattern of S-P-S-P

Deoxyribose: a monosaccharide containing five carbon atoms

The four nucleotides found in DNA are only different because of their nitrogenous bases

Thymine (T) Cytosine (C) Adenine (A) Guanine (G)

Pyrimidines: single ring structuresThymine (T)Cytosine (C)

Purines: larger, double ring structuresAdenine (A)Guanine (G)

Remember the three parts of DNA

This is a rail

This is a step

Green can only go with Red

Purple can only go with Yellow

The rails of the ladder consist of:DeoxyribosePhosphate group

The Steps of the ladder consist of:Nitrogenous bases (A, T, C, G)

The steps of the ladder are connected by the nitrogenous bases:They are connected by hydrogen bonds

T bonds with A C bonds with G

Draw the three components of the DNA nucleotideLabel the 5 carbons

Animation http://www.teachertube.com/

view_video.php?viewkey=a9fe76d6b3f30f02150b&page=1&viewtype=&category=

Replication begins with the untwisting of the double helix

This untwisting is the two strands of parental DNA

The two strands become the template for replication

The nucleotides line up along the template strand In accordance with the base-pairing rules

Enzymes then link the nucleotides to form the new DNA stands

The new DNA strands are called daughter DNA strands Identical molecules of the parent DNA

The enzymes that link the nucleotides to the daughter strands are called DNA polymerases

Daughter strands

The helical DNA molecule must untwist as it replicatesAnd must copy its two strands almost simultaneously

The speed of the process is a challengeNucleotides are added at a rate of 50/second in

mammalsAdded at a rate of 500/second in bacteria

Adds nucleotides only to the 3’ end of the strandNever to the 5’ end

So, a daughter strand can only grow in the 5’ to 3’ direction

One of the daughter strands can be synthesized in one continuous piece Working toward the forking point of the

parental DNA

The other daughter strand is synthesized in pieces DNA ligase ties (ligates) those pieces

together

Ensures multicellular organisms carry the same genetic information

This also means our genetic instructions are copied for the next generation of the organism

http://www.ncc.gmu.edu/dna/repanim.htm

http://www.wiley.com/legacy/college/boyer/0470003790/animations/replication/replication.htm

It requires the cooperation of more than a dozen enzymes and other proteins

It is extremely accurateAbout 1 in 1,000,000,000 nucleotides in DNA are

incorrectly paired

DNA polymerases carry out a proofreading step to remove nucleotides that have base-pairs incorrectly matched

Draw the process of replicationLabel all the steps and structures of DNA

replication

Because everyone’s fingerprints are different!

How does the police look at DNA to figure out who committed a crime?

The DNA gets cut up by special scissors!!!

The scissors can only cut the same color!

All of the cut up pieces of DNA are different

sizes.

BIG

LITTLE

A special machine sorts the DNA by size.

(Little pieces are fast, so they move faster to the bottom.) TOP

BOTTOM

We are ALL a little bit different!

Jack Bobbles DNA

Karen Jensen’s DNA

BIG

LITTLE

Jack Bobbles DNA Karen Jensen’s DNA

Our DNA has different sizes of pieces so it makes a different pattern when

it’s all cut up.

                         

                         

                       

                       

Jack Bobbles Karen

Jensen

This is what it really looks like!!!

Can you guess which one is Karen Jensen and which one is Mike Creighton?

Jack Bobbles Karen Jensen

Is the red box around Jack Bobbles DNA or around Karen Jensen’s DNA?

?

DNA controls the manufacture of all cellular proteins, not only enzymes

A gene is a region of DNA that contains the instructions for manufacture of one particular chain“one gene-one polypeptide”

DNA is like a set of blue prints because: It determines the sequence of amino acids

in every protein molecule in a cell

DNA’s four different bases- Guanine, Cytosine, Adenine, and Thymine

The various combinations of these four DNA bases make up a gene

That gene determines the composition and manufacture of proteins

The manufacture of proteins

The actual assembly of a protein takes place on ribosomes in the cytoplasm, not in the nucleus

The instructions for protein synthesis are transferred from genes on DNA to the ribosome by a second type of nucleic acid

Ribonucleic acid (RNA)

How is RNA different from DNA?

Hint: different in 3 ways

DNA’s structure is a double strand RNA’s structure is a single strand

DNA’s bases: A, T, C, G RNA’s bases: A, U, C, G (U=Uracil)

DNA’s sugar: deoxyribose RNA’s sugar: ribose

Three types of RNA carry out instructions for protein synthesis

Messenger RNA (mRNA) Transfer RNA (tRNA) Ribosomal RNA (rRNA)

1st mRNA carries the coded instructions for protein

synthesis from the DNA in the nucleus to the ribosome

2nd

tRNA brings the A.A. to the ribosome in the correct order so they can be built into the new protein

3rd

rRNA makes up the structure of a ribosome

The manufacture of a protein actually begins with the manufacture of mRNA

The manufacture of mRNA is called:

Transcription

Transcription is the process of transferring info. from a strand of DNA to RNA

Transcription begins with: a region of the two strands of DNA unwinding and separating (just like replication)

The DNA strand with the gene acts as a template strand (just like replication) It directs the sequence of nucleotides in the new

mRNA

The strand of mRNA will carry instructions for protein synthesis

Unattached RNA nucleotides are present in the nucleus, ready to be assembled into mRNARNA polymerase matches RNA bases with their

complementary bases on the DNA template strand

After transcription, the mRNA leaves the nucleus and moves to a ribosome, where protein synthesis will occur

Recall: The four bases of RNA

Adenine Guanine Cytosine Uracil

The sequence of the bases determines the sequence of amino acidsThese amino acids are to be assembled into

a new protein

There are 20 amino acids in proteins and only 4 base pairsSo…there has to be a way for the bases to

code for the amino acids

The code for each amino acids was found to be “three bases long”

Codon: a three-base code in DNA or mRNA

Example: GCC translate as the amino acid called Alanine

Since the codons are three bases long, there could be 64 different codonsBut there are only 20 amino acids

Some codons start or stop protein synthesis

Sometimes two or more different codons are used for the same amino acid

The codes for a.a.’s are universalHumans, bacteria, and viruses translate the

codes the same.

Since every living thing has DNA (and sometimes RNA) bacterium and trees may not be all that different from humans.

http://www.johnkyrk.com/DNAtranscription.html

http://www-class.unl.edu/biochem/gp2/m_biology/animation/gene/gene_a2.html

http://library.thinkquest.org/20465/g_DNATranscription.html

http://nature.ca/04/04_ecfm

Translation

Translation This is the transfer of

the information in the RNA into a protein.

This is what puts the bases together and READS the information for your genes.

More Websites…. http://www.ncc.gmu.edu/dna/

ANIMPROT.htm http://learn.genetics.utah.edu/units/

basics/transcribe/ugcode.cfm http://www.pbs.org/wgbh/aso/tryit/dna/

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