LB145Sec 001-004

Today’s Outline/Announcements

• Study Notes 6a Due.• Take up exam: Thursday

– View exam on Friday between 2-4pm in C-4.• Field Trip Sign-up.• Course Recap

– Membranes transport and proteins– How do proteins make energy?

• How are proteins made?• Introduction to DNA• Worksheet to follow along with today’s material.

Recap – Membranes and Proteins(Unit 1)

• What are proteins?• Where are proteins made?• What happens to them after they are made?• What do membrane proteins do?

Recap – Proteins and Energy(Unit 2)

• What is energy?• How is energy made in plants?• How is energy made in animals?• What role to proteins play in the production of

energy?

Fig. 17-4

DNAmolecule

Gene 1

Gene 2

Gene 3

DNAtemplatestrand

TRANSCRIPTION

TRANSLATION

mRNA

Protein

Codon

Amino acid

The Central Dogma of Molecular

Biology

Unit 3 – What Will You Learn?

• Structure of DNA/RNA.• How is DNA replicated?• How is RNA made?• How is RNA processed?• How does RNA make protein?• What happens to proteins after they are

made?

Structure of DNA and RNA

DNA Factoids

• Humans have 46 chromosomes.• Our 46 chromosomes have 3.2 billion base

pairs.• 99.9% of your base pair sequence is identical

to mine.• All living organisms on the planet have DNA.• We have ~24,000 genes.

DNA Factoids

• If stretched end-to-end, the DNA in 1 chromosome would stretch to ~ 2 inches.

• If tied together and stretched out, all the DNA in 1 cell would stretch to 6 feet!

• All the DNA in our body, if stretched out, could wrap around the earth 5 million times; it would reach the sun and back 70 times.

(50 trillionths of an inch wide)

What is DNA…

Campbell 8e, Fig. 16.21

© 2011 Pearson Education, Inc.

Stra

nd

2. RNA: RiboNucleicAcid

Stra

nd

2. RNA: RiboNucleicAcid

Stra

nd

Stra

nd

3’ carbon 3’ carbon

5’ carbon 5’ carbon

RNA nucleotide

1 of 4

1 of 4

RNA Bases

purines(2 rings)

pyrimidines(1 ring)

What is a nucleotide?

A molecule with a nitrogenous base, a ribose molecule and one or more phosphate groups.

ATP – Adenosine Triphosphate

Campbell 8e Fig. 8.8

High energy bonds!

ATP is a type of nucleotide… more specifically:a nucleoside triphosphate (or NTP)

5’

3’direction

of elongation

Nucleotides in DNA are nucleoside

monophosphate molecules.

Deoxyribonucleoside triphosphates (dNTPs) are bonded to DNA phosphodiester bonds.

Two types of bonds hold DNA together:1. Phosphodiester2. Hydrogen bonds

Base Pairing

Adenine pairs with Uracil in RNA

Purines Pyrimidines

Base Pairing

hydrogen bonds phosphodiester bonds

http://www.umass.edu/molvis/tutorials/dna/dnapairs.htm

Conceptual design and contents: Eric Martz Original Chime version: Eric Martz

Jmol implementation and current design: Angel Herráez Version 4.3, using Jmol 11.4

Offered under Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License

DNA Structure Tutorial

Where is DNA found in Eukaryotes?

Campbell 8e, Fig. 6.9b

How is DNA arranged in Eukaryotes?

http://ghr.nlm.nih.gov/handbook/illustrations/normalkaryotype

centromere

Short arm

Long arm

Origins of replication

Eukaryotes: DNA, Chromatin and Chromosomes

Campbell 8e, Fig. 16.21

Fig. 17-3b-3

(b) Eukaryotic cell

TRANSCRIPTION

Nuclearenvelope

DNA

Pre-mRNARNA PROCESSING

mRNA

TRANSLATION Ribosome

Polypeptide

Where is DNA found in Prokaryotes?

Campbell 8e, Fig. 6.6

Fig. 17-3a-2

(a) Bacterial cell

TRANSCRIPTIONDNA

mRNA

TRANSLATIONRibosome

Polypeptide

Application Question: Red Blood Cells

If you were to study red blood cells you might come across the claim that they have no DNA (or organelles!) – they are essentially membranous sacs filled with a protein called hemoglobin.- Given what you know about the composition

of DNA, how could you test this claim.Hint: Hershey and Chase

How could you test whether or not RBCs have DNA?

© 2011 Pearson Education, Inc.

© 2011 Pearson Education, Inc.

Amino Acids vs DNA

© 2011 Pearson Education, Inc.

© 2011 Pearson Education, Inc.

DNA’s structure naturally lends itself to being replicated!!

DNA Strands Are Templates for DNA Synthesis

Watson and Crick suggested that the existing strands of DNA served as a template (pattern) for the production of new strands.

Biologists then proposed three alternative hypotheses:

– Semiconservative replication.– Conservative replication.– Dispersive replication.

The Meselson-Stahl Experiment

• Meselson and Stahl designedan experiment to provide more information about whether one of these hypotheses was correct.

© 2011 Pearson Education, Inc.

© 2011 Pearson Education, Inc.

Fig. 16-9-3

A T

GC

T A

TA

G C

(a) Parent molecule

A T

GC

T A

TA

G C

(c) “Daughter” DNA molecules, each consisting of one parental strand and one new strand

(b) Separation of strands

A T

GC

T A

TA

G C

A T

GC

T A

TA

G C

DNA Synthesis Requires a Template DNA Strand

For THURSDAY:1. StudyNotes 6b is due.2. Take up the exam.3. Exam viewing: Friday 2-4pm in C-4.4. Field Trip Sign-up