1 Nucleotides: the subunits of DNA. 2 The four DNA bases GC A T

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Nucleotides: the subunits of DNA

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The four DNA bases

G C

A T

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DNA strand: polymer of nucleotides

DNA Double Helix

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Examples of proteinsProtein Role

alpha-keratin component of hair

beta-keratin component of scales

insulin regulates blood glucose level

actin & myosin muscle contraction

DNA polymerase synthesis of DNA

ATP synthase makes ATP

hemoglobin transport of oxygen

endonuclease cuts DNA (restriction enzyme)

EcoRI – restriction enzyme

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Hemoglobin: carrier of oxygen

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Mutant -globin Sickle blood cells

Fiber of sickle hemoglobin Sickle and normal blood cells

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Normal blood flow

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Sickle cell complications

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The alphabet of protein: 20 amino acids

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Protein: polymer of amino acids

Nucleotides vs. Amino Acids

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Nucleotide Amino Acid

Both made up of “backbone” and “residue” parts

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The inaccessible code

DNA is in the nucleus

Proteins are (mostly) made in the cytoplasm

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Decoding a codon: UGG

Only one way to code for tryptophan

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Decoding codons: AGC & AGU

Both code for serine!

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Stop codons Don’t code for an amino acid

They terminate translation

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RNA vs. DNA structureDNA RNA

linear polymer linear polymer

double-stranded single-stranded

deoxyribonucleotide

monomer

ribonucleotide

monomer

A,C,G,T bases A,C,G,U bases

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Transcription: DNARNA

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The Central Dogma

DNA

RNA

Protein

replication

transcription

translation