Download Macromolecules

Macromolecules
Nucleic Acids & Proteins
Objectives for Today
• Nucleic Acids (NA)
• DNA
• RNA
• Proteins
NA
code for
proteins
Proteins
‘read’
NA
The Genetic Code
• Every cell in your body, whether it’s a hair cell, a
white blood cell or bone cell, contains the EXACT
same genome
• Genome: the entire genetic sequence of a living
organism
• So why do cell’s look different? Because they are
READING different parts of the book (genome)
• The complexity of an organism is based in no way
on how long it’s genetic code is
Central Dogma of Biology
Central Dogma of Biology
Example
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You work out and your muscles are becoming oxygen deprived (forming lactic acid)
You need hemoglobin to help transport oxygen to these muscles via your red blood cells!
Specialized proteins hurry to your DNA and help ‘transcribe’ the hemoglobin gene to take it to
another location outside the nucleus
The result is a messenger RNA that provides instructions straight from the DNA on how to ‘make’
hemoglobin
Other proteins ‘translate’ the mRNA instructions into another form – an actual 3D protein
People who have a mutation in the hemoglobin gene have sickle cell anemia 
Sickle Cell Anemia
As recently as 1973, the average lifespan for people with sickle
cell disease was only 14 years. Currently, life expectancy for
these patients can reach 50 years and over.
Nucleic Acid Structure
• Deoxyribonucleic acid (DNA)
• Ribonucleic acid (RNA)
• All nucleic acids have ‘ends’ defined as 5’
and 3’ that are important in directionality
of forming DNA and RNA
DNA
• These 5’ and 3’ ends are
important during the
processes of DNA synthesis &
transcription
• DNA is always built & read 5’
to 3’ by transcriptional
machinery
• DNA is made up of a “sugarphosphate” backbone and the
nitrogenous bases that are
attached
RNA
• Unlike DNA, most RNA is
• single-stranded
• MUCH shorter
• Very unstable
• RNA can fold on itself creating loops
and hairpins, especially non-coding
RNA
CONCLUSION on Nucleic Acids
• NUCLEIC ACIDS ROCK!
• Nature vs. Nurture
• They are the nature part of who we are!
So what does the genetic code code for?
• PROTEINS!
• Lipids & carbohydrates come from the
food we eat or are synthesized in our
bodies from precursers
• Our DNA codes has roughly 26,000
genes
• Less than 3% of our genome actually
codes for something…WHAT!?
Importance of Proteins
• Proteins play many roles in our body
• All enzymes are proteins!
• Catalyze chemical reactions
• Involved in all steps of metabolic pathways
• Many hormones are proteins
• Oxytocin
• Human growth hormone
Monomer of Proteins
• Amino acids
• They all have an alpha carbon, an
amino group, a carboxylic acid group
and a differing ‘side chain’ (R)
• There are 20 amino acids
• The “R” group gives amino acids their
properties
• Interactions of R groups determines
final protein shape after folding
R-Groups
• The R group of an amino acid can
be categorized by chemical
properties
• Hydrophobic – hate water
• hydrophilic - love water
• Ionic
• The interactions of these R groups
determine structure and function
of that region of the protein.
Chains of Amino Acids
• Amino acids are held together
by peptide bonds
• Peptide bonds are formed via a
dehydration reaction between
the amino group of one AA and
the carboxyl group of the
adjacent one
• Chains of amino acids are called
polypeptides
• Poly = many
Structures of Polypeptides
• The structure of a polypeptide determines it’s function
• Primary structure: the sequence of the amino acids
• Secondary structure: structures within a short region of
the sequence
• Alpha helices
• Beta sheets
• Tertiary structure: folding of the protein
• Quaternary: multiple subunits assembled into final
structure
Green Fluorescent Protein
• First isolated from jellyfish and used as a transgenic gene
• Used as a reporter gene to study regulatory part’s of DNA
Denaturation of Proteins
• When a protein loses it’s shape, it cannot function anymore 
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Heat
Chemicals
pH change
Radiation
Folding of Proteins
• The folding of a protein (determined by Rgroup interactions) is absolutely vital for
function
• Special proteins called chaperone proteins
have the sole job of helping proteins fold
after they come off the assembly line (on
the ribosome)
• Mis-folded proteins from gene mutations
of environmental factors can cause disease
• Neurological diseases are especially
associated with mis-folded proteins
• variant Creutzfeldt-Jakob disease
• Alzheimer's
Variant Creutzfeldt-Jakob disease (vCJD)
• Human version of mad cow disease (humans cannot get MCD)
• You can get it if you eat the brain or spinal cord of cow with MCD
• Accumulation of prion proteins in the brain
• Hard for body to remove them because of the blood-brain barrier