What is DNA?

Where do we find DNA? In the nucleus

What the heck is it?

Why is it soooooooooo important?

Hint… It’s SUPER IMPORTANT and Mz. C. will be mentioning it over and over and over and… you get the picture!

NucleusChromosome

DNA

Nucleic Acid

Nucleotide

Cell

What do ALL of these organisms have in common?

WE all share a universal genetic code: DNA

How do we know what DNA looks like????

•Rosalind Franklin•Chemist…•Used X-Rays and was able to get two photos of crystallized DNA•Watson and Crick used the X-ray data Franklin obtained to figure out the 3-D structure of DNA •Died before she was 38... (due to Cancer caused by Radiation Poisoning)

Watson & Crick•1953•Watson & Crick used Rosalind's X-Rays to figure out the structure of DNA…•(Did they give her any credit??? NAH… not until later!)

What they “Announced”

•Using Rosalind X-Rays, Watson & Crick determined that phosphates and sugars were on the “outside” of the DNA molecule and nitrogen bases were on the “inside”

•They also figured out that DNA is a double helix…

•Rosalind figured out that DNA was in a helical shape… but… didn’t get any further details•What’s a helical shape? Let’s talk helicopters… and screws…!

Helix = Spiral

Helic-opter…

Helical screw…Helical spring…

Helical staircase…

Helical drill…

DNA

Purpose of DNADNA is one of “THE BIG FOUR” Organic Macro-molecules (a Nucleic Acid)Deoxyribonucleic Acid

Why do we have DNA?It is our genetic information

• The “code” for all of our traits/characteristics!

It gives each cell it’s “instructions”

Nucleic Acids…

2 Types:DNA & RNA

Nucleic Acid is a PolymerNucleotides are the

monomers

Stores genetic information (genes)

Gives instructions to make proteinsOne gene=One protein

sugar

phosphate

nitrogen base

What is a Nucleotide?

H

H2

H H

H3

HH H

H

H

O

O

O

C C

C

N

N

PO

O

O

C

C

C C

C

O

OO

C

C

1.

2.

3.

1.

2.

3.

1. Phosphate Group

2. 5-Carbon Ribose Sugar

3. Nitrogen Base

Three “Similar” Parts

One phosphate groupBonded to

One sugar (ribose)To make the “side” of the ladder

One nitrogen baseMakes the “rungs” (steps) of the

ladder•There are different Nitrogen bases

• DNA & Genes

Different Nitrogen BasesThere are four nitrogen bases in DNA (making up four different nucleotides)

Adenine

Guanine

Thymine

Cytosine

A

C

G

T

Nucleotide Bonding

Nucleotides are bonded together in alternating sugar and phosphate groups •The “Backbone”

This creates a long chain with nitrogen bases sticking off of the side

Making the DNA Ladder

• Two chains line up next to each other...

• The Nitrogen bases bond together in the center to hold the two chains together like a “zipper”• The bases are held by Hydrogen

bonds The Nitrogen bases only bond in

“Complementary Pairs”!

DNA: Double Stranded (Helix)

• The Nitrogen bases bond in the center of the “Ladder”

• The ladder then “twists” into a helix

• The tighter it “twists”, the more “condensed” it becomesWhich means it is more

dense and compact

DN

A D

OU

BL

E H

EL

IX

ladder shaped molecule

Erwin Chargaff

Chargaff discovered that DNA contains the same amount of adenosine as thymine (A-T) and the same amount of cytosine as guanine (C-G).

A AA AA A

AT

T

T

T TTT

CCC G G

G

ALL THUGS CARRY GUNS!

Chargaff’s Base Pair RulesAdenine always bonds with Thymine. A = T

A

CG

T

DNA: All Thugs Carry Guns

Cytosine always bonds with Guanine. C = G

Nucleotide

PS

N-b

Pairing DNA NucleotidesWhat is a nucleotide?

Rule:

A with T

C with G

What is the base pairing rule?What would be the complementary nucleotide pairing for these strands?

DNA•DNA is the “instruction manual” (the “recipe book”) which tells the cell what proteins to make•But, DNA is “stuck” in the nucleus

•It is too large to pass through the nuclear membrane

•Which organelle makes proteins?•__________________

•How do the instructions get from the nucleus to the Ribosome???????

RNA – Ribonucleic AcidSmall, Single Stranded COPY of the DNA message

Copy of ONE GENE

RNA is small enough to pass through the nuclear membrane and bring the message to the Ribosome in the cytoplasm3 differences from DNA

This allows the organism to recognize that the RNA is NOT the original!

DNA vs. RNA

RNA is Ribonucleic Acid – DNA is Deoxyribonucleic Acid

An Oxygen molecule is missing… making it “Deoxy”…

RNA is a short, single stranded copyDNA is large, double stranded orginal

RNA contains a different Nucleotide!Uracil (Not Thymine)Remember: ALL UNDER-

ACHIEVERS CAN'T GRADUATE

Rules for RNA Base Pairing

C = G

A = UC

A

T

G

G

U

C

A

DNA

RNA

RNA copies the DNA message by pairing with the DNA nucleotides… An “A” is paired with a “U”. “C” and “G” are always paired together…

ALL UNDERACHIEVERS CAN’T GRADUATE!

What is the function of RNA?

Carries the DNA coded message out of the nucleus

RNA copies the information for one geneOne gene = One protein

Brings message to the RibosomeRibosome reads the code and

makes the correct protein

Types of RNA

There is only ONE Type of DNA

There are THREE Types of RNAMessenger RNA (mRNA)Transfer RNA (tRNA)Ribosomal RNA (rRNA)

You only need to know two!

Nitrogen Base

Sugar

(Ribose)

Phosphate

Group

RNA

RNA Codes for Amino Acids

The nitrogen bases in RNA code for amino acids

Monomers of Protein

A triplet of nitrogen bases codes for one amino acid

The triplet is called a “codon”

(You NEED to know that!)

DNA vs RNA

Nucleic Acids

DNA RNA

RNA to Polypeptide

•The Scientific Name for Protein is:Polypeptide- Because peptide bonds hold Amino Acids together

•The Ribosome reads each “codon” (triplet code) and calls for different Amino Acids to be bonded in the chain

•Think “CAN of PEPSI”

Peptide Bond

C N

Overall process of protein synthesis

transcription translation

DNA RNAProtein

What does a chain of amino acids represent?

- a protein!

Threonine

Arginine

Glycine

Glycine

Proline

Asparagine

ProlineAlanine

Polypeptide Chain – A Protein

CodonsOne codon codes for one amino acid.

A sequence of amino acids is a protein... A different sequence makes a different protein!

EX: ACG = amino acid (threonine)

CGC = amino acid (arginine)

GGA = amino acid (glycine)

ACG

GGAGGC

CCA

AAC

CCG

GCCCGC

Threonine

Arginine

GlycineGlycine

Proline

Asparagine

Proline

Alanine

Amino Acid

protein

Let’s Try It…

• DNA “Complementary Pairs”

•Remember:•All Thugs•Carry Guns

Let’s Try It…

• RNA “Complementary Pairs”

•Remember:•All Underachievers•Can’t Graduate