DNA and RNAStructure and

Function Mrs. Einstein

Research in Molecular Biology

WSSP

DNA and RNA

DNA (deoxy-ribonucleic acid) is the genetic material

It is a type of super polymer.

1. Some act primarily to carry instructions. They are

said to be "informational" or "instructional"

2. Some are best at performing operations. They are

said to be "operational". They are molecular

machines.

Nucleic Acids (P.C.F.NA.) DNA (Deoxyribonucleic Acid)

Double helix RNA (Ribonucleic Acid)

Single stranded Monomers: Nucleotides

nitrogen base (C-N ring) pentose sugar (5C)

ribose in RNAdeoxyribose in DNA

phosphate (PO4) group

Mono Nucleotide:

VIDEO

Deoxyribose vs. Ribose

The OH groups on the 5’ and 3’ carbons are thereactive groups through which nucleotides become joined

a nucleotide includes one phosphate group joined at the 5’ position…..

PO4

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PO4What to know about the phosphate:

1) linked at 5’ carbon

2) can have 1, 2, or 3 phosphate residues(nucleotide mono-phosphate, nucleotide di-phosphate ,nucleotide tri-phosphate)

3) ***the oxygens of the phosphate group are negatively charged at physiological pH.

Therefore DNA carries a large net negative charge!

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Classification of Nitrogen Bases

purinesdouble ring N base adenine (A)guanine (G)

pyrimidinessingle ring N base cytosine (C)thymine (T)uracil (U)

Nucleic PolymersSugar – Phosphate Backbone

phosphodiester bond in backbonenew base added to sugar of previous base

polymer grows in one directionWHY?

The polynucleotide chain

To form the polynucleotide chain, the oxygen of the 3' hydroxyl group on the chain “attacks” the phosphate of a nucleotide triphosphate eliminating H2O and releasing the two outermost phosphate residues.

The phosphodiesterbond

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**Notice that the DNA chain is synthesized in a 5’ to 3’ direction.

Antiparallel Structure

Two strands of DNA run opposite

each otherA-T contains 2 hydrogen bondsC-G contains 3 hydrogen bonds

DNA is double-stranded--two polynucleotide chains

Hydrogen bonds between bases hold these together

G and C have 3 H-bonds A and T make 2 H-bonds

Guanine

Cytosine

Adenine

Thymine

Base Complementary

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DNA strands are arranged in an anti-parallel manner

5' 3'

5' 3'

5'-TCGTCA-3'3'- -5'

5'-TGACGA-3'3'- -5'

"Flipped"

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Board Question: What is the complementary sequence of the sequence 5'-GGAATCG-3'?

A) 5’-GCTAAGG-3’

B) 5’-CCTTAGC-3’

C) 5’-CGATTCC-3’

D) 5’-GGAATCG-3’

3’-CCTTAGC-5’

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Board Question: Which DNA would be harder to denature (separate the two strands)?

A) ATTA D) GCGCGC TAAT CGCGCG

B) GCGC E) AGCGCT CGCG TCGCGA

C) AATATA TTATAT

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Critical Properties of DNA

1) Negative charge (will move toward a + electrode!)

2) DNA can be denatured and renatured (nucleic acidHybridization).

3) DNA is soluble in water.

4) DNA absorbs UV light.

5) DNA can be stained and amounts of DNA can be Measured using ethidium bromide.

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Critical Properties of RNA

1. RNA is single stranded

2. RNA functions as both informational (ex. mRNA) and as operational (rRNA) polymers

3. RNA contains uracil instead of thymine

4. RNA contains ribose instead of deoxyribose

4. RNA is more unstable than DNA

5. RNA is typically shorter than DNA

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Conclusion Board Questions: With a partner, use the molecule below to

answer the questions.

1. Name the molecule.2. Which letter would the Phosphate be added?3. Which letter would the base be attached to?4. Which letter is important for DNA replication and transcription?

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