DNA, RNA & PROTEINS Part 1
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Transcript of DNA, RNA & PROTEINS Part 1
DNA, RNA & PROTEINSDNA, RNA & PROTEINSPart 1Part 1
The molecules of life
• DNA provides the instructions for an organisms structure and characteristics
• DNA can be copied to make new cells that are identical to the original cell (Replication)
• Roles of DNA: Store, Copy and Transmit Information
• RNA (Nucleic Acid used for making protein)– Transcription– Translation
• Protein synthesis– Amino acids
DNADNA• Deoxyribonucleic Acid (DNA) is the
blueprint for life: contains ALL the necessary information to make a new organism
DNA structure• DNA is a polymer of
nucleotides– Each nucleotide composed of
• a phosphatephosphate, • a sugar (deoxyribose), • and organic nitrogenous base.
Four DNA bases• Four kinds of nitrogenous bases:
Purine basesA = AdenineG = Guanine
Pyrimidine basesT = ThymineC = Cytosine
DNA: Complimentary base pairing• Adenine pairs with Thymine
A T
• Cytosine pairs with Guanine
C G
Each DNA strand is a compliment of the other
Original strand Matching copy A TC GG CT AA TG CG CT AT A
DNA STRUCTURE
• DNA is a double helix • Discovered by
Watson and Crick, 1953
DNA structure
Antiparallel Strands
DNA REPLICATION (in the nucleus)
• Each DNA strand becomes a template, parent strand becomes apart
• Proper base-pairs areassembled on that template(with proper enzymes:polymerase and ligase).
• There’s always a pool of nucleotides (A,C,T,G) in the nucleus
Semi-Conservative Replication½ of the original is “conserved” and the other half is “new”
RNA structure and synthesis• RNA: Ribonucleic Acid• Is very similar to DNA
(repeating subunits, nucleotides).
• Difference between RNA and DNA:– Each nucleotide contains a different sugar
(ribose instead of deoxyribose)– Bases are A, G, C, and U (uracil, not thymine)
A pairs with U; G pairs with C
RNA
• RNA is single stranded and shorter
• RNA is less stable than DNA: RNA doesn’t persist in the cell for long (sometimes it exists for a few seconds), whereas DNA can persist for the life of the cell.
Protein Synthesis
DNARNA
Proteins
• 3 different RNA molecules involved in protein synthesis:– Messenger RNA (mRNA)– Ribosomal RNA (rRNA)– Transfer RNA (tRNA)
transcription
translation