The Molecule of LifeThe Molecule of Life

What are the different DNA What are the different DNA Nitrogen BasesNitrogen Bases

1.Purines – double ring structure. 1.Purines – double ring structure.

AdenineAdenine GuanineGuanine

2.Pyrimidines – single ring structures2.Pyrimidines – single ring structures

CytosineCytosine ThymineThymine

DNA StructureDNA Structure The DNA

structure is shaped like a spiral stair case:

Double helixDouble helix

DNA REPLICATION

Replication is the process where DNA makes an exact copy of itself.

If you were to replicate DNA why would you do it, and how

would you do it?

JQ: Your pet dog stepped on

a sharp rock and got a cut. Be as detailed as you can in

explaining what happens next in the area of the

wound.

Need your textbooks!

DNA REPLICATIONDispersive Replication

DNA REPLICATIONConservative Replication

DNA REPLICATIONSemi-Conservative Replication

DNA REPLICATION

Meselson & Stahl Create the

Most Beautiful Experiment in Molecular Biology

What do the results tell us?

Hypothesis: Semi-Conservative

What do the results tell us?

General Ovewrview for DNA Replication

1. The two DNA strands separate (dark blue)

2. Each open strand serves as a template for the new strand (light blue)

3. Complimentary bases are added.

How is this all possible? What is doing the work?

What are the steps of DNA REPLICATION

What can you tell me/What do you notice aboutthis DNA?

Strands run in oppositeDirections - they areAntiparallel

5’ (five prime) end - hasPhosphate on end

3’ (three prime) end - hasHydroxyl group attached

Replication in Real Time

Replication Broken Down

DNA REPLICATION1. DNA Helicase (enzyme) splits open

double strand at origin and unwinds DNA. SSB’s keep the strand open.

2. RNA primase gets strand ready for DNA Polymerase (enzyme) to attaches free floating nucleotides in a 5’ to 3’ position on both strands. Stands are copied in one direction.

Leading Strand – is copied in one direction continuously.

DNA REPLICATION

Lagging Strand –is looped around and copied in fragments (okazaki fragments).

Okazaki fragments are linked together by an enzyme called ligase.

DNA Replication Stats• 1 strand of DNA ~ 150,000,000 base pairs

• 50 base pairs copied per second

• 834 molecules working at the same time!

• Humans have 46 pieces of DNA in their cells.

What’s the next questionbiologists asked?

Protein Synthesis Process of making proteins

Players Involved Players Involved

1. mRNA – messenger RNA, reads message from DNA

2. tRNA – transfer RNA, transfers amino acids

3. rRNA – ribosomal RNA, joined with proteins to make up the ribosome (protein factory of the cell)

Many, many, many enzymes are involved in this process as well.

Nucleic Acids - RNANucleic Acids - RNA

Monomer UnitMonomer Unit – Nucleotide – Nucleotide Ribose SugarRibose Sugar Phosphate GroupPhosphate Group Nitrogen BaseNitrogen Base

SugarN. Base

P

RNA Nitrogen BasesRNA Nitrogen Bases

1.Purines – double ring structure. 1.Purines – double ring structure.

AdenineAdenine GuanineGuanine

2.Pyrimidines – single ring structures2.Pyrimidines – single ring structures

RNA Nitrogen BasesRNA Nitrogen Bases

CytosineCytosine UracilUracil

RNA StructureRNA Structure The RNA is single

stranded

Protein Synthesis StagesProtein Synthesis Stages

Transcription – the process of obtaining info. from the DNA on how to make the protein. DNA mRNA

Translation – the process of using the Translation – the process of using the information (mRNA) to construct the information (mRNA) to construct the protein. protein.

Protein Synthesis Transcription

Why do fireflies glow?Why do fireflies glow?

Protein Synthesis Translation

Now that we know how Now that we know how protein synthesis works, protein synthesis works,

what is the next what is the next question?question?

How is it controlled?How is it controlled?

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