8.1 dna structure & function. nucleic acids dna & rna are nucleic acids monomer?...
TRANSCRIPT
8.1 DNA Structure & Function
Nucleic Acids
•DNA & RNA are nucleic acids•Monomer?
▫Nucleotides
5-C Sugar
P N- Base
DNA History•Watson & Crick
developed “double-helix” model of DNA structure in 1953
•Used work of Rosalind Franklin
http://www.nature.com/scitable/topicpage/rosalind-franklin-a-crucial-contribution-6538012
DNA Structure
•Double helix▫Two chains (strands) of nucleotides twisted
around each other•Within each strand:
▫Sugar-Phosphate Backbone formed by sugar & phosphates of nucleotides
▫Nucleotides of the backbone are connected by phosphate bonds
DNA Structure
http://click4biology.info/c4b/3/images/3.3/dinucleotide.gif
Phosphate bond
Making DNA
DNA Structure
•How are the two strands of nucleotides connected?
•Two strands arrange themselves so that the N-bases are in the center
•N-bases complementary bond with each other using hydrogen bonds▫Cytosine – Guanine (C-G)▫Adenine – Thymine (A-T)
DNA Function
•DNA acts as a blueprint for all life•DNA is arranged in genes
▫Gene: sequence of nucleotides in DNA▫Each chromosome contains hundreds of
genes!•One gene gives instructions for making
one specific protein▫Remember: protein function
Enzymes, transport, movement, immunity, etc
DNA Function
•Each protein is responsible for a trait▫Trait: physical manifestation of gene
•Each human has the same genes, but we are not all the same. Why?▫Different order of nucleotides in our genes!
RNA Structure
•Single-helix▫Only one strand of nucleotides
•The 5-C sugar in RNA is ribose•Does not have the base thymine, but has
the base uracil instead
http://www.tildee.com/Xbwj6f
RNA Function
•Enzymes make a RNA copy of one DNA gene▫RNA is much smaller than DNA
•The cell uses this RNA copy to make a protein
Central Dogma
DNA
RNA Protein