Download Bio1A Unit 1-2 Biological Molecules Notes File

Biological Molecules
Proteins
Amino Acids
Components:
Amino
Carboxyl
R-Group
Structural
Functions
Fibrous, Golbular, Enzymes
Carbohydrates
Abbreviated chemical structure
Draw a sugar – monosaccharide
Dehyd synth & hydrolysis to make
Polysaccharides
Describe Function
Lipids
Draw - Parts of triglyceride
Function of triglycerides
Synthesis & degradation of
Phospholipids – function
Draw parts
Steroids – draw cholesterol
recognize
function
Nucleic Acids
1. Function - DNA
2. parts of nucleic acids
•Phosphate
•Pentose sugar - deoxyribose(DNA) ribose (RNA)
•Bases : G -A-T-C (DNA)
G-A-U-C (RNA)
3. Be able to write complementary strand
4. Function – RNA
5. Protein Synthesis
•
Transcription (be able to transcribe DNA to RNA)
•
Translation (be able to translate RNA to protein)
•
DNA code
Biological Molecues / Organic Compounds
•Molecules unique to living systems contain carbon and hence are organic compounds
•They include:
•Proteins
•Lipids
•Carbohydrates
•Nucleic Acids
Many are polymers -chains of similar units (monomers or building blocks)
–
–
Synthesized by dehydration synthesis / condensation
Broken down by hydrolysis reactions
X-O-H
+
H-Y
Dehydration
synthesis
X–Y +
Hydrolysis
Monomer
H2O
Bond Type
Proteins
Amino Acids
Peptide Bonds
Polysaccharides
Monosaccharides
Glycosidic Bonds
Nucleic Acids
Nucleotides
Phosphodiester
Bonds
Lipids
-
-
Amino Acids
•Building blocks of protein
•amino group = amine
•carboxyl group
•R group
•20 amino acids
•12 non-essential
•8 essential (must be in diet,
body cannot make)
Characterized by side chain
• Non-polar
• Polar
• Charged
Not a polymer
R group = side chain
Protein Synthesis
Terminology: peptide = chain of aa’s
Dipeptide: 2 aa’s
Tripeptide: 3 aa’s
Polypeptide: multiple aa’s
Macromolecules: huge proteins
N-ter
amino
terminus
Start
Variations in sided chains determine how the protein will
interact with other molecules or itself.
• Cysteine (R = -SH) can form a disulfide bond (covalent, rare)
• Other side chains will interact through hydrogen (primary)
ionic bonding
• Ultimate structure is typically most thermodynamically
stable (best fit)
• Driven by interaction with H2O envirnoment
C-ter
carboxy
terminus
Finish
Disulfide bond
Protein Structure “folding”
•Primary Structure (1°) = Denatured – Sequence (List in order) of amino acids in order
•Secondary Structure (2°) – Done by Hydrogen bonding between side chains – specific shapes
•α-helicies β-pleated sheets
•Tertiary Structure (3°) – Hydrogen & covalent bonds - Final shape of 1 peptide (may be final protein)
•Quaternary Structure – multiple proteins and/or other components combined – final protein
Protein Classes
I. Fibrous – Extended and strandlike – water insoluble – Structural function
•Collagen, Keratin, Elastin – connective tissue (ligaments, tendons, cartilage) bone, teeth, hair, elasticity
•Contractile fibers – myofilaments in muscle
II. Globular – compact blobs –water soluble
Compact, spherical proteins with tertiary and quaternary structures
Examples: antibodies, hormones, and enzymes
Molecular Chaperones
•Help other proteins to achieve their functional three-dimensional shape
•Maintain folding integrity
•Assist in translocation of proteins across membranes
•Promote the breakdown of damaged or denatured proteins
Enzymes
•Most are globular proteins that act as biological catalysts
•Holoenzymes (complete) consist of an apoenzyme (protein) and a cofactor (usually an ion; ieFe2+, Cu2+)
•Enzymes are chemically specific
•Frequently named for the type of reaction they catalyze
•Enzyme names often end in -ase
•Lowers activation energy
Reversible unfolding of proteins due to drops in pH and/or increased temperature
Irreversibly denatured proteins cannot refold and are formed by extreme pH or temperature changes
Lipids
Contain C, H, and O, but the proportion of oxygen in lipids is less than in carbohydrates
Hydrophobic / Insoluble in water
Soluble in other lipids and organic solvents
I. Triglycerides = Neutral (non-polar) fats
Function: Insulation & Food Storage
1
:
3
Saturated –
II . Phospholipids
Function: Membranes
Unsaturated
Mono Poly -
III. Steroids – flat molecules with four interlocking hydrocarbon rings
Cholesterol – structural basis – make other steroids from cholesterol
•Bile Salts – fat digestion
•Hormones – chemical messenger (signaling)
Lipid hormones – testosterone, estrogen
•Vitamin D – for normal bone growth and function
Cholesterol
Testosterone
Estradiol (Estrogen)
IV. Eicosanoids – 20-carbon fatty acids found in cell membranes
Function – Signaling
V. Lipoproteins – lipid + protein (LDL & HDL)
Function – Transport
chenodeoxycholic acid
(bile salt)
Carbohydrates
• Their major function is to supply a source of cellular food (degraded and used as energy)
Glucose → ATP
• Very soluble – many OH’s  trademark of carbs
• Contain carbon, hydrogen, and oxygen - general formula: [(CH20)n]
• Three classes
– Monosaccharides
– Disaccharides
– Polysaccharides
Alcohol groups &
Aldehyde or ketone
Aldose sugar
Ketose sugar
ketone
group
Aldehyde
group
Glucose C6H12O6
Fructose C6H12O6
Sugars in solution forms ring (>90%)
1
2
or
Structural DNA & RNA
Isomers
1–4
glycosidic
linkage
-Galactose
Glucose
Glucose
Maltose
1–2
glycosidic
linkage
Glucose
Lactose
Glucose
Fructose
Sucrose
Polysaccharides
Starch-plant storage – less branched
glycogen – animal storage (liver & muscles)
Cellulose – plant polysaccharide – undigestible
Chitin – modified glucose - acetylated
Energy
Starch
Type
Bonding
Glycogen (animal)
α-glucose
14 & 16
highly branched
Amylose (Plant)
α-glucose
14 non-branched
α-glucose
14 & 16
branched
β-glucose
14 non-branched
Amylopectin (Plant)
Structural
Unit
Cellulose (Plant)
DNA: The Bodies Blueprint
Central Dogma: DNA → RNA → Protein
nucleic acids
DNA is a code for the production of protein
1 Gene = 1 Protein
Function: stores genetic information
Transfer genetic information during replication
Controls protein synthesis
DNA is made up of Nucleic Acids
•Composed of carbon, oxygen, hydrogen, nitrogen, and phosphorus
• Nucleotide - Their structural unit
N-containing base
pentose sugar
a phosphate group
•Five nitrogen bases
adenine (A)
guanine (G)
cytosine (C)
thymine (T)
uracil (U)
•Two major classes – DNA and RNA
Sugar phosphate
backbone
C
G
T
A
DNA double stranded - antiparallel
C
G
Written
--GATC---CTAG--
T
A
(alongside but opposite direction)
(think of a street cars going opposite directions)
Function – “backup” copy in case of damage
Hydrogen bonding
RNA
Single stranded, uses uracil (U) instead of thymine (T)
mRNA - messenger RNA – “work order” determines what proteins are made
rRNA – component of ribosomes (haloenzyme that makes protein)
tRNA – transfer RNA – brings amino acids to ribosome to make proteins
ATP – source of usuable energy = “molecular currency”
Like A from RNA but has 2 additional phosphate groups
From DNA to Protein
Nucleus
•Gene-containing control center of the cell
•Contains the genetic library with blueprints
for nearly all cellular proteins = DNA
•Dictates the kinds and amounts of proteins
to be synthesized
RNA
DNA
Polymerase
Transcription
mRNA
Ribosome
Translation
1. Transcription
RNA polymerase binds DNA  copies small pieces into RNA
RNA polymerase
mRNA
RNA-DNA
hybrid region
RNA
nucleotides
Polypeptide
1. Transcription
Original DNA
ACAAG------------------------CATGGT
|||||||||||||||||||||||||||||||||||
TGTTC------------------------GTACCA
DNA splits
ACAAG------------------------CATGGT
TGTTC------------------------GTACCA
RNA polymerase
Transcribes (copies)
DNA  RNA
ACAAG------------------------CATGGT
ACAAG------------------------CAUGGU
|||||||||||||||||||||||||||||||||||
TGTTC------------------------GTACCA
DNA rejoins
RNA separates and floats away
ACAAG------------------------CATGGT
|||||||||||||||||||||||||||||||||||
TGTTC------------------------GTACCA
ACAAG------------------------CAUGGU
2. Translation
Occurs at the ribosome where ribosome decodes RNA
•Ribosome = Enzyme that make aa peptide bonds
Tri-nucleotide code - 3 nucleotides → 1 amino acid
DNA triplets (Codon) are transcribed into RNA
Translation starts at Methionine (AUG)
Translation ends at stop codons UAA, UAG, UGA