AP Bio

AP BioAP Bio

10/04/0410/04/04

Itinerary 10/05/04Itinerary 10/05/04 Due Today: Writing an Essay for the AP ExamDue Today: Writing an Essay for the AP Exam Topics for todayTopics for today

ReviewReview DNA ReplicationDNA Replication

OverviewOverview Messelson-Stahl ExperimentsMesselson-Stahl Experiments In DetailIn Detail Worksheet- This worksheet is due next Tuesday, 10/12Worksheet- This worksheet is due next Tuesday, 10/12

Itinerary 10/06/04Itinerary 10/06/04 DNA TranscriptionDNA Transcription DNA TranslationDNA Translation Discussion of next week’s laboratoryDiscussion of next week’s laboratory

ReviewReview1. Name the four classes of biomolecules

ReviewReview1. Name the four classes of biomolecules2. Define ‘monomer’ and ‘polymer.’

ReviewReview1. Name the four classes of biomolecules2. Define ‘monomer’ and ‘polymer.’3. What is a nucleotide?

ReviewReview1. Name the four classes of biomolecules2. Define ‘monomer’ and ‘polymer.’3. What is a nucleotide?4. What are the three components of a nucleotide?

Structure of DNA/RNA (1)Structure of DNA/RNA (1)

Three Components

1)Phosphate Group

2)‘Pentose Sugar’

3)Nitrogenous base

ReviewReview1. Name the four classes of biomolecules2. Define ‘monomer’ and ‘polymer.’3. What is a nucleotide?4. What are the three components of a nucleotide?5. What is the difference between the purines and the

pyrimidines?


You need to remember these!


pyrimidines?6. What is the name of this sugar?


Deoxyribose and Ribose are both 5 carbon sugars


pyrimidines?6. What is the name of this sugar?7. Base Pairing

http://images.google.com/imgres?imgurl=http://www.sweatshopnews.com/Gary%2520Coleman.jpg&imgrefurl=http://www.sweatshopnews.com/interviews.htm&h=400&w=317&sz=20&tbnid=PZXgtcmrX6kJ:&tbnh=119&tbnw=94&start=1&prev=/images%3Fq%3DGary%2BColeman%26hl%3Den%26lr%3D%26ie%3DUTF-8%26sa%3DG


Gary Coleman



Gary Coleman

Guanine-Cytosine

Gary Coleman

Guanine-Cytosine


Gary Coleman Alex TrebekGuanine-Cytosine Adenine-Thymine

DNA Replication-DNA Replication- Overview (1) Overview (1)

In Text- Pp 287- 297In Text- Pp 287- 297


In Text- Pp 287- 297In Text- Pp 287- 297 Step 1: The Double Helix is unzippedStep 1: The Double Helix is unzipped


In Text- Pp 287- 297In Text- Pp 287- 297 Step 1: The Double Helix is unzippedStep 1: The Double Helix is unzipped Step 2: Each strand directs the synthesis of two Step 2: Each strand directs the synthesis of two

new strandsnew strands


In Text- Pp 287- 297In Text- Pp 287- 297 Step 1: The Double Helix is unzippedStep 1: The Double Helix is unzipped Step 2: Each strand directs the synthesis of two Step 2: Each strand directs the synthesis of two

new strandsnew strands Step 3: The individual nucleotides are Step 3: The individual nucleotides are

connected to form two new strandsconnected to form two new strands





Semiconservative Replication (1)Semiconservative Replication (1)Process of DNA replicationis called ‘semiconservativereplication


Make sure you know this term. You’ll see it again!


This means that in each new double helix of DNA, one strand was from the parent.

Semiconservative Replication (4)Semiconservative Replication (4)



Semiconservative Replication (7)Semiconservative Replication (7)How do we know that DNA replicates with a ‘Semiconservative’ nature?


Any ideas?


Any ideas?

Meselson-Stahl experiment tested the three hypotheses for DNA replication

Semiconservative Replication (8)Semiconservative Replication (8)Meselson-Stahl ExperimentMeselson-Stahl Experiment


Where is the 15N found?




Let’s use the flashlight on Let’s use the flashlight on DNA ReplicationDNA Replication

Remember, DNA replication is the process of Remember, DNA replication is the process of making copies of DNA.making copies of DNA.



When would the cell do this?When would the cell do this?



When would the cell do this?When would the cell do this? Now we need to look at the specifics of DNA Now we need to look at the specifics of DNA

replication, and the replication, and the enzymes enzymes involved in each involved in each stepstep

But First, What’s an Enzyme?But First, What’s an Enzyme?

But First, What’s an Enzyme?But First, What’s an Enzyme? A type of ProteinA type of Protein

But First, What’s an Enzyme?But First, What’s an Enzyme? A type of ProteinA type of Protein Text Definition:Text Definition:

A class of proteins serving as catalysts, chemical A class of proteins serving as catalysts, chemical agents that change the rate of a reaction without agents that change the rate of a reaction without being consumed within the reactionbeing consumed within the reaction

Step 1: Separation of the Double Step 1: Separation of the Double HelixHelix


DNA Helicase unwinds the double helix•The site where the enzyme begins replication is called the origin of replication.


DNA Helicase unwinds the double helix•The site where the enzyme begins replication is called the origin of replication.•In Prokaryotes (Bacteria), there is a single origin; in eukaryotes, there are thousands

16-10-DNAReplicatAnim_B.mov

Show clip 16.10B

Step 2: Synthesis of complementsStep 2: Synthesis of complements

Step 2: Synthesis of complementsStep 2: Synthesis of complementsEnzyme- DNA polymerase


•DNA polymerase allows the new nucelotides to be added to the growing end of the strand one by one


•DNA polymerase allows the new nucelotides to be added to the growing end of the strand one by one

•NOTE: This new synthesis always occurs in the same direction, 5’3’

DNA directionalityDNA directionality

DNA directionalityDNA directionality

A new nucleotide is always added to the 3’ endof the strand

Synthesis of Complementary strandsSynthesis of Complementary strands

Synthesis of Complementary strandsSynthesis of Complementary strands

Show 16.13leading strand

Then Show 16.13lagging strand

Enzymes InvolvedEnzymes Involved

1) Helicase1) Helicase


1)1) HelicaseHelicase2)2) Single Stranded Binding ProteinSingle Stranded Binding Protein


1)1) HelicaseHelicase2)2) Single Stranded Binding ProteinSingle Stranded Binding Protein3)3) PrimasePrimase


1)1) HelicaseHelicase2)2) Single Stranded Binding ProteinSingle Stranded Binding Protein3)3) PrimasePrimase4)4) DNA polymeraseDNA polymerase


1)1) HelicaseHelicase2)2) Single Stranded Binding ProteinSingle Stranded Binding Protein3)3) PrimasePrimase4)4) DNA polymeraseDNA polymerase5)5) LigaseLigase

DNA Replication-SummaryDNA Replication-Summary

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