DNA and Protein Synthesis

Nucleic Acids

Nucleic Acids - Function

• Control the processes of heredity by which cells and organisms make proteins.

Nucleic Acids – Types

• DNA

–Deoxyribonucleic Acid

• RNA

–Ribonucleic Acid

As you know, DNA stands for….

DEOXYRIBONUCLEIC ACID

50% 50%

Is DNA a monomer or polymer 1. Monomer 2. Polymer

The monomer units of DNA are known as….

NUCLEOTIDES

All nucleotides have three “parts” in common. They all contain….

One of FOUR different NITROGEN BASES Phosphate Group Sugar= Deoxyribose

PLEASE UNDERSTAND, A NUCLEOTIDE IS A VERY COMPLEX STRUCTURE. IF WE REPRESENTED ALL OF THE ATOMS, IT WOULD LOOK LIKE THIS…

We will use our hands to represent a nucleotide.

PHOSPHATE NITROGEN BASE SUGAR

The four different Nitrogen Bases for DNA are abbreviated using the following letters….

A T G Adenine Thymine Guanine C Cytosine

Using your two hands, please show how you think two nucleotides will/should bond together.

Did you put your hands like this???

In DNA, Adenine always pairs with Thymine using two hydrogen bonds.

A T

A AND T AT THE ATOMIC LEVEL

In DNA GUANINE always pairs with CYTOSINE using three hydrogen bonds.

G C

G AND C AT THE ATOMIC LEVEL

THE ENTIRE MOLECULE AT THE ATOMIC LEVEL

Time to use your brain and hands in order to review nucleotide structure and type.

USING YOUR HAND, SHOW ME THYMINE USING YOUR HAND SHOW ME ADENINE SHOW ME CYTOSINE SHOW ME HOW CYTOSINE AND THYMINE BOND TO FORM A RUNG ON THE LADDER THEY DON’T

OK Now that you recognize nucleotide type and structure, it’s time to start building the polymer from these monomers.

In order to make a molecule of DNA, you would need to create many rungs to the DNA ladder.

Look. Many Rungs.

Etc…

What part of the nucleotide alternates to form the sides of the DNA ladder?

Sugar, Phosphate.

Sugar, Phosphate.

Sugar, Phosphate.

Etc… Etc…

What makes up the “RUNGS” of the ladder?

The Nitrogen Bases

Go Ahead!

Stack your hands on top of your partner’s hands building two rungs of the DNA ladder.

TRY IT!!!

If you link enough nucleotides together, the DNA molecule begins to take on the characteristic shape known as the

Double Helix

Let’s make a candy version of our DNA

Let’s Review First… • Nucleic Acid • Nucleotide • DNA • RNA • Nitrogen Base • Double Helix

Nucleic Acid – Structure • Made up of a chain of Nucleotides that contain – Phosphate backbone – Sugar – Nitrogen base • Guanine • Cytosine • Adenine • Thymine (Found only in DNA) • Uracil (Found only in RNA)

Nucleic Acids

DNA

SUGAR Phosphate

DNA

Let’s see how well you looked at the diagram…regarding the nitrogen bases, Adenine always bonds with which one?

1. Cytosine 2. Thymine 3. Guanine 4. Uracil

0% 0% 0% 0% 1 21 2 22 3 23 4 24 5 6 7 8 9 10 11 12 yt os in 13 e 14 T hy m in 15 e 16 G ua ni 17 ne 18 U ra ci l 19 20

SUGAR Phosphate

DNA

Let’s make a candy version of our DNA

Candy DNA • Pipe cleaner for the form • Red Twizzler = Deoxyribose • Black Twizzler = Phosphate • Colored Marshmallows = nitrogen bases

Candy DNA • Colored Marshmallows = Nitrogen Bases – Pink Marshmallow = Adenine – Green Marshmallow = Thymine – Yellow Marshmallow = Cytosine – Orange Marshmallow = Guanine • We’ll use toothpicks to join the nitrogen bases to the sugar

Let’s Build

What actual structures make up the sides of the ladder?

• Deoxyribose sugar • Phosphate

What structures make up the rungs?

• Nitrogen Bases

What do you notice about all the DNA molecules in the room?

• They are all different!

DNA Replication • 1.) DNA unzips • 2.) Free nucleotides bond with open complementary base pairs • 3.) 2 new strands formed

Let’s review DNA

Let’s Build A Protein

Protein Synthesis • It’s a process – DNA -> RNA -> Amino Acids (Protein)

RNA • Sugar is Ribose NOT what… • Has nitrogen base Uracil instead of Thymine – Also contains the other 3 bases…what are they?

• Only single stranded

RNA

Transcription • 1.) DNA strand unzips – The bonds between the nitrogen bases are broken • 2.) A single strand of mRNA (messenger RNA) is made – Pair up the bases • 3.) mRNA travels from nucleus to cytoplasm

Transcription

Why is mRNA called messenger RNA?

• Because it carries the directions to make a protein to the ribosome like a message

Translation • • • • mRNA meets up with a ribosome…why??

tRNA molecules bring amino acids to ribosomes – An mRNA codon will pair with a tRNA anticodon Codon: 3 Nitrogen base sequence in mRNA that specifies a specific amino acid – Anticodon: 3 Nitrogen base sequence in tRNA As tRNA’s are added, amino acids are bonded together and will be released as a fully functional protein.

Translation

That’s the process, Now how do you know what amino acids make up a particular protein • We use an mRNA codon chart