+ Structure and Function of Large Biological Molecules.
-
Upload
amos-fletcher -
Category
Documents
-
view
227 -
download
1
Transcript of + Structure and Function of Large Biological Molecules.
+
Structure and Function of Large Biological Molecules
+Macromolecules
4 main types: carbohydrates, lipids, proteins, nucleic acids
Large molecules typically made of smaller subunits
Carbs, Nucleic acids, proteins = Polymers – built from monomers
+Synthesizing and Decomposing Macromolecules:
Dehydration Synthesis: “adding” monomers together to form a polymer.
Removal of an H2O molecule covalently bonds the monomers.
Hydrolysis: Breaking down of polymers into smaller subunits using water.
The H bonding to one monomer and the OH bonding to the other.
Both processes use enzymes!
+
Sugars and sugar chains – the fuel and building materials of life
Carbohydrates
+
Monosaccharides: Simple SugarsSugar units have empirical formula: CH2O
C chains range from 3-7
Enantiomers – different sugars!
5-6 C typically are aromatic!
+Glucose is Life
C1 and C5 bond to form ring
Glucose is a primary cellular fuel source for respiration
Glucose is also used as a building block for many other macromolecules
Can be stored for later use as di- and polysaccharides
2 forms of the rings α and βhttp://pslc.ws/macrog/kidsmac/toon_glu.htm
+α-glucose and β-glucose
+Disaccharides Through Dehydration Synthesis
2 monosaccharides bonded
Glycosidic linkage formed by dehydration synthesis
Disaccharides: maltose, sucrose, lactose
Linkages are named by the carbons that bond
Maltose is a 1-4 glycosidic linkage
Sucrose is a 1-2 glycosidic linkage
+Types of Glycosidic Linkages
1–4glycosidic
linkage
1–2glycosidic
linkage
Maltose
Sucrose
+Polysaccharides – huge chains of monosaccharides
Each monomer is added through dehydration synthesis
Huge chains are good for storage and even structure
Function of the poly- determined by type of linkage and sugar monomers
+Storage Polysaccharides
Plants create starch for storage
Glucose monomers = stored energy
Stored in plastids
Formed by 1-4 glycosidic linkages
+Storage Polysaccharides
Animals synthesize glycogen
Glucose monomers – high branched
Stored in liver and muscle
+
Structural Polysaccharides Cellulose – major
component of cell walls
Most abundant organic molecule on earth
Glucose monomers – different linkages!
Different forms of glucose but same 1-4 linkage!
+Cellulose: Tough Cell Walls…
Why?
Cellulose is straight chains and never branched
Form parallel chains
Different enzymes to digest!
Fiber
Chitin = exoskeletons
+
Hydrophobic, diverse molecules
Lipids
+Lipid Basics: Hydrophobic energy chains
Lipids are diverse in function but similar in their hydrophobicity
Typically have large regions that are hydrocarbon chains
+Building Blocks of Fats
Fatty acid chains Glycerol
+Triacylglycerol (TAGs)
AKA Triglycerides
Ester linkage!
Dehydration Synthesis! x3
+Saturated and Unsaturated Fats
Naturally occurring fatty acids have cis double bonds
+Cis vs Trans Fats
+Figure 5.12
Choline
Phosphate
Glycerol
Fatty acids
Hydrophilichead
Hydrophobictails
(c) Phospholipid symbol(b) Space-filling model(a) Structural formula
Hyd
rop
hilic
head
Hyd
rop
hob
ic t
ails
+Figure 5.13
Hydrophilichead
Hydrophobictail
WATER
WATER
+Steroids
Steroids have 4 carbon ring structures
Can be hormones or cholesterol
+
Multiple units, multiple uses
Proteins
+Functions of Protein
Proteins account for ~50% of the dry mass of most cells
Proteins act as catalysts, play roles in defense, storage, transport, and cellular communication
Greatest diversity in structure and function
+Figure 5.15-a
Enzymatic proteins Defensive proteins
Storage proteins Transport proteins
Enzyme Virus
Antibodies
Bacterium
Ovalbumin Amino acidsfor embryo
Transportprotein
Cell membrane
Function: Selective acceleration of chemical reactionsExample: Digestive enzymes catalyze the hydrolysisof bonds in food molecules.
Function: Protection against disease
Example: Antibodies inactivate and help destroyviruses and bacteria.
Function: Storage of amino acids Function: Transport of substances
Examples: Casein, the protein of milk, is the majorsource of amino acids for baby mammals. Plants havestorage proteins in their seeds. Ovalbumin is theprotein of egg white, used as an amino acid sourcefor the developing embryo.
Examples: Hemoglobin, the iron-containing protein ofvertebrate blood, transports oxygen from the lungs toother parts of the body. Other proteins transportmolecules across cell membranes.
+Figure 5.15-b
Hormonal proteinsFunction: Coordination of an organism’s activitiesExample: Insulin, a hormone secreted by thepancreas, causes other tissues to take up glucose,thus regulating blood sugar concentration
Highblood sugar
Normalblood sugar
Insulinsecreted
Signalingmolecules
Receptorprotein
Muscle tissue
Actin Myosin
100 m 60 m
Collagen
Connectivetissue
Receptor proteinsFunction: Response of cell to chemical stimuliExample: Receptors built into the membrane of anerve cell detect signaling molecules released byother nerve cells.
Contractile and motor proteinsFunction: MovementExamples: Motor proteins are responsible for theundulations of cilia and flagella. Actin and myosinproteins are responsible for the contraction ofmuscles.
Structural proteinsFunction: SupportExamples: Keratin is the protein of hair, horns,feathers, and other skin appendages. Insects andspiders use silk fibers to make their cocoons and webs,respectively. Collagen and elastin proteins provide afibrous framework in animal connective tissues.
+Protein Building Blocks - Peptides
All proteins are made of 20 different amino acids
Amino end
Carboxyl end
R = functional group
α CARBON
+Proteins are Polypeptides
Polymers of peptides are made through the formation of peptide bond
Carboxyl end of one AA bonds to the amino end of adjacent AA
Dehydration reaction to form peptide bond
N terminus (+) and C terminus (-)
+Figure 5.16
Nonpolar side chains; hydrophobic
Side chain(R group)
Glycine(Gly or G)
Alanine(Ala or A)
Valine(Val or V)
Leucine(Leu or L)
Isoleucine (Ile or I)
Methionine(Met or M)
Phenylalanine(Phe or F)
Tryptophan(Trp or W)
Proline(Pro or P)
Polar side chains; hydrophilic
Serine(Ser or S)
Threonine(Thr or T)
Cysteine(Cys or C)
Tyrosine(Tyr or Y)
Asparagine(Asn or N)
Glutamine(Gln or Q)
Electrically charged side chains; hydrophilic
Acidic (negatively charged)
Basic (positively charged)
Aspartic acid(Asp or D)
Glutamic acid(Glu or E)
Lysine(Lys or K)
Arginine(Arg or R)
Histidine(His or H)
+Figure 5.16a
Nonpolar side chains; hydrophobic
Side chain
Glycine(Gly or G)
Alanine(Ala or A)
Valine(Val or V)
Leucine(Leu or L)
Isoleucine(Ile or I)
Methionine(Met or M)
Phenylalanine(Phe or F)
Tryptophan(Trp or W)
Proline(Pro or P)
+Figure 5.16b
Polar side chains; hydrophilic
Serine(Ser or S)
Threonine(Thr or T)
Cysteine(Cys or C)
Tyrosine(Tyr or Y)
Asparagine(Asn or N)
Glutamine(Gln or Q)
+Figure 5.16c
Electrically charged side chains; hydrophilic
Acidic (negatively charged)
Basic (positively charged)
Aspartic acid(Asp or D)
Glutamic acid(Glu or E)
Lysine(Lys or K)
Arginine(Arg or R)
Histidine(His or H)
+Figure 5.17
Peptide bond
New peptidebond forming
Sidechains
Back-bone
Amino end(N-terminus)
Peptidebond
Carboxyl end(C-terminus)
Dehydration synthesis
Side chains vary in their charge, polarity, length
+Protein – Structure Dictates Function
3D structure of each protein is unique
Structure dictates function
Structure is determined due to 4 levels of folding
Most fundamental level of folding is sequence of AA
+Figure 5.19
Antibody protein Protein from flu virus
Primary Structure AA
SequenceSequence of AA
Read in order from N to C
Dictates secondary, tertiary, quaternary levels
+Secondary Structure
Regions of a peptide chain that are coiled or folded into patterns
Regulated by H bonding of atoms in the peptide backbone
α-Helix
β-sheets
+Tertiary
Structure
Overall shape of a protein
Stabilized by R groups and how they interact
Hydrophobic Interactions
Disulfide Bridges
Quaternary Structure
The interaction of multiple polypeptide chains
Forms a functional protein
Separate peptide chains
+Chaperonins: Protein Folders
+Protein Structure in a Cell
Folding is spontaneous
Other proteins aid in this process
Denaturation – unraveling/misfolding of a protein
+
Blueprints of life
Nucleic Acids
+Nucleotides
Monomers of nucleotides
2 types: DNA and RNA Deoxyribonucleic
acid Ribonucleic acid
+DNA to RNA to Protein
Genetic material
Inherited
Codes for all genes
DNA RNA Protein
+Nucleotides
Types
2 Types of sugars Ribose Deoxyribose
2 Categories of N bases Purines (Pure As Gold)
A and G Pyrimidines
C, T, U
+Polynucleotides – Nucleic Acids
Nucleotides are linked by a phosphodiester bond
Adjacent sugars are linked from 5’ end to first sugar to 3’ of next sugar
N Bases point inwards and provide “sequence” of DNA
+
Structure of DNA
Double helix
Sugar-phosphates are antiparallel
Bases pair 1 purine to 1 pyrimidine