Nucleic Acids

Your Assignment

Your Nucleic Acid Assignment

1. Define, compare and give examples of the two types of nucleic acids (structure, location and function).

2. What are the main uses of nucleic acids in cells (plants and animals)??

Additional Resources (1)

• The Tree of Life, Proteins and nucleic acids module

Additional Resources (2)

Nucleic Acids Web linksDNA Timeline:http://www.dnai.org/timeline/

Nobel Organisation DNA information site:

http://www.nobelprize.org/educational/medicine/dna_double_helix/readmore.html

Nucleic acids

• Ribo-nucleic acid (RNA)• Deoxyribonucleic Acid

(DNA) • They are polymers

made up of repeating monomer units called nucleotides

• DNA is double stranded helix, RNA is single

• C-H-O-N-P atoms621

Nucleic acids store and transmit hereditary

information• Information flows from DNA RNA

Proteins

Nucleotides: the monomers of nucleic acids

Consist of 3 parts:• 5 Carbon Sugar (Pentose)

– Ribose or Deoxyribose• Phosphate group• Nitrogenous Base

– Purines (A and G) (6 membered ring of C and N fused to a 5 membered ring)

– Pyrimidines (C, T, and U) (6 membered ring)– Only certain bases are compatible for bonding

together, Adenine with Thymine (A-T) and Cytosine, Uracil with Guanine (C-G)

• Sequence of bases is unique to each gene

Nucleotide Structure3 components:– Pentose sugar (ribose in DNA)

– Phosphoric acid– Organic base (always contains

nitrogen)

Phosphate

sugarbaseStay the same

ChangesContains nitrogen & carbon

Pentose sugar (5 Carbon atoms)

5 nitrogenous bases

4 Bases• Purines –

– Double ringed structure

• Pyrimidines – – Single ringed structure

Nucleic acids are polymers of nucleotides (polynucleotides) joined by phosphodiester bonds (phosphate to sugar)

Bondings

• The base and sugar join with a: glycosidic

bond

• The phosphate and sugar join with an:

ester bond

Both require a condensation reaction to occur

H

H

OH

OH

Phosphate

Sugar Base

2 condensation reactions occur in the formation of a nucleotide:

Ester bond

Glycosidic bond

DNA

• Genetic material inherited from parents• Extremely long: hundreds-thousands of genes• Contains the information that programs cellular

activities• DNA is “read” by proteins and translated into

proteins.• Double stranded helix • Has the ability to copy itself

Complementary Base Pairing

*Purines always pair with pyrimidines*

A joins to T (2 hydrogen bonds)C joins to G (3 hydrogen bonds)

see

C

A

G

T

2 hydrogen bonds

3 hydrogen bonds5’

3’

3’

5’

0.34nm

2nm

Type of Base Purine Pyrimidine

Structure

Bonding relationships

Adenine

Guanine

Thymine

Cytosine

= hydrogen bond

Type Purine Pyrimidine

Structure

Name Adenine

Guanine

Thymine

Cytosine/ Uracil

RNA

• Messenger RNA (mRNA) conveys the DNA code out of the nucleus to the cytoplasm (ribosome)

• Single stranded• Multiple complex

structures• A,U,G,C

RNA can adopt complex 3-D structures and is not restricted to the double helix structure

RNA carries information from DNA (nucleus) to the ribosome via reverse transcription, followed by translation.

Nucleotide

3 components:

Pentose sugar; deoxyribose

Phosphate group

Nitrogenous base; 4 types:

phosphate

sugarbase

Join by condensation

Stay the same

Changes

Contains nitrogen & carbon

Ribose sugar in RNA

Deoxyribose sugar in DNA

Pentose sugar (5 Carbon atoms)

Molecular Clocks• Linear sequences of nucleotides in DNA

are passed from parent to offspring. DNA determines the amino acid sequence of proteins

• Siblings have DNA that is more alike than an unrelated person

• 2 species should have similar DNA if they are closely related based on fossil and anatomical evidence

• The more differences in the DNA codes, the longer the time the two species have evolved separately.