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| CHAPTER 8
AN INTRODUCTION TO METABOLISM
Bioenergetics: The Laws of Thermodynamics – 8.2.1
>>>>>The chemistry of life is organized into metabolic pathways
---Metabolism
-Uptake of matter and energy
-Conversion to usable form
-Synthesis of cellular materials
-Elimination of waste products
Two types of metabolic pathways:
Catabolic pathways and anabolic pathways
---Catabolism
-degradation, releases energy
---Anabolism
-synthesis, consumes energy
>>>>>Organisms transfer energy
---Energy
Review types of energy
---Potential energy
---Kinetic energy
>>>>>Energy transfers are subject to the laws of thermodynamics (see fig 8.3)
---First Law of Thermodynamics
---Second Law of Thermodynamics
---Entropy (S)
Thermodynamics can determine whether or not a chemical reaction will occur in the cell, and how much energy it will consume or release
>>>>>Free energy and spontaneous reactions (see fig 8.5)
---Free energy (G)
---Total energy (H)
G = H - TS
In a chemical reaction the energy change (ΔG) between the reactants and the products is the amount of useable energy that can be harvested to do work.
ΔG = ΔH - TΔS = Gfinal products - Gstarting material
>>>>>Free energy and chemical equilibrium
-As a chemical reaction approaches equilibrium the free energy (ΔG) of
the system decreases.
-When a reaction is pushed away from equilibrium, the free energy (ΔG) of
the system increases.
-At chemical equilibrium, ΔG=0. When ΔG=0 no work can be done.
Free energy and Metabolism (see fig 8.6)
---Exergonic reactions
---Endergonic reactions
EXERGONIC REACTIONS ENDERGONIC REACTIONS
Chemical products have less free energy than the reactant molecules Products store more free energy than reactants.
Reaction is energetically downhill Reaction is energetically uphill
Spontaneous reaction Non-spontaneous reaction (requires an energy source)
ΔG is negative ΔG is positive
-ΔG is the maximum amount of work the reaction can perform +ΔG is the minimum amount of work the reaction requires to occur.
-Metabolic disequilibrium (see fig 8.7)
-Many biological reactions are reversible; therefore they have the
possibilityof reaching equilibrium.
-However, in the cell chemical reactions are kept from reaching
equilibrium because the products of one reaction are
the reactants for the next reaction.
-The linking of chemical reactions makes up metabolic pathways and results in metabolic disequilibrium.
-In a cell when equilibrium is reached, the cell is dead.
Activation Energy – 8.2.2
>>>>>Enzymes speed up metabolic reactions by lowering energy barriers
---Catalyst
---Enzymes
---Activation energy
---Transition state
---Energy profile of a reaction
Enzyme Characteristics - 2.8.3
Enzyme Action: The Induced-Fit Model - 2.91
>>>>>Enzymes are substrate-specific
---Substrate
---Active site
---Induced fit
>>>>>Enzymes active site is a catalytic center
---Steps in the catalytic cycle of enzymes
>>>>>A cell’s chemical and physical environment affects enzyme activity
---Effect of temperature and pH
---Cofactors
---Coenzymes
Enzyme Regulation: Allosteric Regulation - 2.9.2
Feedback Inhibition and Cooperativity 2.9.3
>>>>>Enzyme inhibitors
---Competitive inhibitors
---Noncompetitive
>>>>>Metabolic order of the cell’s regulatory systems and structure
---Feedback inhibition
ATP Structure and Function - 4.1.1
>>>>>ATP powers cellular work by coupling exergonic reactions to endergonic reactions
The Structure and Hydrolysis of ATP
---ATP (Adenosine Triphosphate)
Types of work driven by ATP
1. Mechanical work
2. Transport work
3. Chemical work
Phosphorylated Intermediates - 4.1.2
>>>>>How does ATP drive work?
-Phosphorylated or activated intermediates
>>>>>ATP is continually regenerated
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| CHAPTER 7
MEMBRANE STRUCTURE AND FUNCTION
Membranes: Basic Structure – 6.2.4
>>>>>Membrane structural models have evolved as new data is acquired.
Earliest models were deduced from indirect evidence
1. Membranes are made of lipid
2. Phospholipids are amphipathic molecules that can form membranes
---amphipathic
3. Cell membranes are phospholipid bilayers (see fig 7.2)
4. Biological membranes contain proteins
5. Biological membranes are coated with proteins that generally absorb water.
Davson-Danieli model
-phospholipid (PL) bilayer
-globular protein coating
-Hydrophilic zones = polar head groups + globular proteins
-Hydrophobic zone = 2 x hydrophobic tails
-about 8 mm thick
Confirmed in 1950's
Problems with this model:
-all membranes are not the same
-How do the proteins stay attached?
Singer and Nicolson: FLUID-MOSAIC MODEL (see fig 7.3)
-proteins embedded in the lipid bilayer
-Hydrophilic zones = polar head groups + hydrophilic portion of proteins
-Hydrophobic zone = 2 x hydrophobic tails + hydrophobic portion of proteins
Confirmed by freeze-fracture and freeze-etch micrographs (see fig 7.4)
---Fluid
---Mosaic
The Plasma Membrane: The Fluid Mosaic Model – 7.1.2
>>>>>A membrane is a fluid mosaic of lipids, proteins, and carbohydrates.
Membranes as a fluid (see fig 7.5)
Fluidity is two-dimensional (not three)
Factors which influence fluidity of membranes
-lipid composition
-temperature
Proteins as the Mosaic of the Cell Membrane – 7.1.3
Membranes as a Mosaic (see fig 7.6)
A mosaic of different proteins are embedded in the lipid bilayer. These proteins have two types of spacial arrangements.
1. integral proteins
Some functions of integral membrane proteins (see fig 7.9)
-transport proteins
-enzymes
-receptors - signal transduction
-cell-to-cell junctions
-cell-to-cell recognition
-attachment of cytoskeleton to extracellular matrix (ECM)
2. peripheral proteins
Membranes have a bifacial orientation (i.e. sidedness) (see fig 7.10)
-different lipid composition
-different proteins or protein orientation
-carbohydrate (always outside)
What’s outside on the inside of the cell?
Simple and Facilitated Diffusion – 7.2.1
>>>>>Membranes are built to be selectively permeable.
---Selective permeability
Two factors which influence permeability
-solubility characteristics of the substance crossing the membrane
-presence of transport proteins
Permeability of the bilayer
Nonpolar (hydrophobic) molecules
Polar (hydrophilic) molecules
---Transport proteins
>>>>>Passive transport (i.e., diffusion across a membrane)
---Concentration gradient
---Net directional movement
---Diffusion (see fig 7.11)
-caused by thermal motion
-movement of molecules is random, but net movement is directional
-net movement continues until the system reaches a dynamic equilibrium
-spontaneous (-ΔG)
Much of the movement of substances across membranes occurs by diffusion and therefore is a form of passive transport.
---Passive transport
Passive Transport: Osmosis - 7.2.2
>>>>>>Osmosis is the diffusion of water (see fig 7.12)
---Hypertonic solutions
Hypertonic (a.k.a. Hyper-osmotic) solutions have greater solute concentration and therefore a lower water concentration.
---Hypotonic solutions
Hypotonic (a.k.a. Hypo-osmotic) solutions have lower solute concentration and therefore a higher water concentration.
---Isotonic solutions
Isotonic (a.k.a. Iso-osmotic) solutions have the same solute concentration and equal water concentrations.
---Osmosis
-Osmosis is direction determined by total solute concentration
-Influenced by factors which govern diffusion
>>>>>Cellular survival depends on balancing water movement
Three water balancing scenarios (see fig 7.13)
Cells without walls
Cells without cell walls are not tolerant to excessive water movements.
1. Hypertonic environment
Water moves out of the cell and the cell crenates or shrivels
2. Isotonic environment
No net movement of water, and the cell volume remains stable.
3. Hypotonic environment
Water moves into the cell. the cell swells and eventually lyses or bursts.
Cells with walls
Cells with cell walls are more tolerant to excessive water movements, but still exhibit cellular changes.
1. Hypertonic environment
Water moves out of the cell and the cell undergoes plasmolysis.
---Plasmolysis
2. Isotonic environment
No net movement of water, and the cell becomes flaccid or limp.
---flaccid
3. Hypotonic environment
Water moves into the cell. the cell swells until the internal pressure equals
the osmotic pressure and the cell becomes turgid.
---Turgid-the pressure of the water in the cell wall makes the cell wall stronger
---Osmoregulation- is an adaptation to control the water balance in organisms living in hypertonic, hypotonic or terrestrial environments.
>>>>>>Specific proteins facilitate diffusion of selected solutes
---Facilitated diffusion (see fig. 7.15) is diffusion across a membrane with the help of transport proteins.
Transport proteins are proteins that let things move into the cell thru the cell wall.
Still diffusion but with a twist.
-Involves transport proteins
Three types
-Bind-and-release
-Selective channel
-Gated channel
Active Transport: Ion Pumps and Cotransport – 7.2.3
Active Transport: The Sodium-Potassium Pump – 7.2.4
>>>>>>Active transport of solutes against a concentration gradient.
---Active transport-is an energy-requiring process where a transport protein pumps a molecule across a membrane against its concentration gradient.
-Energy requiring
-Used to maintain ion gradients (e.g., sodium-potassium pump)(see fig. 7.16)
>>>>>Ion pumps can generate voltage across membranes.
Cell that have an unequal distribution of ions across their plasma membrane have a membrane potential.
---Membrane potential is a charge difference across a membrane. (charge difference)
May act to drive diffusion of ions across membrane by creating an electrochemical gradient.
---Electrochemical gradient
The sodium-potassium pump (Na+/K+ ATPase pump) in animals is an electrogenic pump that translocates 3 Na+ ions out of the cell, for every 2 K+ ions into the cell.
---Electrogenic pump uses active transport to create a membrane protential
The proton pump (see fig 7.18) is another of the main electrogenic pumps in biological systems (bacteria, fungi, plants, chloroplasts, mitochondria).
>>>>>In cotransport, a membrane protein couples the transport of one solute to the transport of a different solute (see fig 7.19).
---Cotransport
May be a symporter (both solutes heading in the same direction) or an antiporter (solutes heading in opposite directions)
Energy-Requiring Transport: Endocytosis and Exocytosis – 7.2.5
>>>>>Exocytosis and endocytosis, the transport of large molecules
---Exocytosis
---Endocytosis
EXOCYTOSIS ENDOCYTOSIS
Export of macromolecules from a cell Import of macromolecules into a cell
Vesicles from the ER and/or Golgi fuse with the plasma membrane Vesicle form at the plasma membrane inward and pinch off into the cytoplasm
Used by secretory cells to export products (e.g., insulin, neurotransmitters) Used by cells to import extracellular substances
Three types of endocytosis: phagocytosis, pinocytosis, and receptor-mediated endocytosis (see fig 7.20)
---Phagocytosis
---Pinocytosis
---Receptor-mediated endocytosis
-Occurs in progressive stages
-Involves ligand-receptor interaction.
---Ligand
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| CHAPTER 6
A TOUR OF THE CELL
Prokaryotes vs. Eukaryotes 6.2.2
>>>>>An overview of “the cell”
---Prokaryotic versus Eukaryotic cells
PROKARYOTES EUKARYOTES
Single circular chromosome 2 or more linear chromosomes
No nucleus or nuclear envelope Nucleus with a nuclear envelope
Genetic material in a “nucleoid region” Genetic material within the nucleus
No organelles Contains membrane-bound organelles
---Nucleoid (see fig 6.6)
---Cytoplasm
---Cytosol
---Organelle
Plant and Animal Cell Overview: The Basics – 6.2.3
---Plasma membrane (see fig. 6.7)
-Compartmental organization
>>>>>The nucleus contains the cell’s genetic library (see fig. 6.10)
The Nuclear Envelope: The Initial Tour – 6.2.5
Nuclear Function: Who’s in Charge? – 6.2.6
---Nucleus
---Nuclear envelope
---Chromatin
---Chromosomes
---Nucleolus
>>>>>Many cell organelles are connected through the endomembrane system
Endomembrane system
-components include:
-Nuclear envelope
-Endoplasmic reticulum
-Golgi apparatus
-Lysosomes
-Vacuoles
All of the components are related either directly or indirectly
Cellular Function: Endoplasmic Reticulum – 6.3.1
>>>>>The endoplasmic reticulum manufactures membranes and performs other vital biosynthetic functions
---Endoplasmic reticulum (ER) (see fig 6.12)
-Smooth ER
Functions
1. Synthesis of lipids
2. Carbohydrate metabolism
3. Detoxification
4. Calcium storage
-Rough ER
Functions
1. Manufacture of membranes
2. Synthesis of secretory proteins
A. Makes glycoproteins by attaching sugars to the proteins
---Glycoproteins end up going to the surface of the cell, they stick out, to the outside of the cell. They can act as surface identifiers. Like a name tage.
sugar decorations.
Cell Function: Golgi Apparatus – 6.3.2
>>>>>The Golgi apparatus finishes, sorts and ships many cell products (see fig 6.13)
---Golgi apparatus
-Cis face and trans face
Food Vacuole Formation: The Role of the Lysosome – 6.3.3
>>>Lysosomes are digestive compartments (see fig 6.14)
---Lysosomes
Functions of lysosomes:
1. Intracellular digestion
---Phagocytosis
-Macrophages
2. Recycling of cellular material
3. Programmed cell destruction
Still More Vacuoles and Peroxisomes – 6.3.4
>>>>>Vacuoles have diverse functions in cell maintenance
---Vacuoles
Vacuoles (large) versus vesicles (smaller)
Vacuole Types:
---Food vacuole
---Contractile vacuole
---Central vacuole (see fig 6.15)
---Tonoplast
>>>>>Peroxisomes consume oxygen in metabolic functions (see fig 6.19)
---Peroxisomes
Functions:
1. Oxidation of molecules
A. Breakdown of fatty acids
2. Breakdown of peroxide (H2O2)
3. Detoxification
Alcohol
>>>>>Mitochondria and chloroplasts are the main energy transformers of cells
General features:
-Double membrane
-Membranes are not part of the endomembrane system
-Contain ribosomes and DNA
Make some but not all of their proteins (10-20%)
-Are semi-autonomous
Can grow, move, change shape and reproduce
-More permeable outer membrane
Mitochondria: Welcome Guests – 6.3.5
---Mitochondria (see fig 6.17)
Features:
-Size 1-10μm
-Number per cell varies with metabolic activity
-Outer membrane is highly permeable to small molecules but blocks passage of
proteins and other macromolecules
-Inner membrane is highly folded to increase surface area. The infolded
structures are called cristae
-Space between the outer and inner membranes is called the intermembrane
space
-Space inside the inner membrane is called the mitochondrial matrix
---Plastids
Three types of plastids: Amyloplasts, Chromoplasts, and Chloroplasts
The Structure of a Chloroplast - 10.2.2
---Chloroplasts (see fig 6.18)
Features:
-Size 2.0-5.0 μm
-Number per cell varies with metabolic activity
-Outer membrane is highly permeable to small molecules but blocks passage
of proteins and other macromolecules
-Inner membrane runs along the inside of the outer membrane creating a narrow
intermembrane space
-Space inside the inner membrane is called the stroma.
---Stroma
-A third membrane system, the thylakoids, is found in the chloroplast stroma.
---Thylakoids
---Grana
---Thylakoid space
>>>>>The cytoskeleton provides structural support and functions in cell motility (see fig 6.20).
---Cytoskeleton
General functions:
-Mechanical support for the cell
-Allows the cell to maintain shape and change shape
-Involved with organelle movement and cell movement by interacting with specialized proteins called motor molecules
General features:
-Constructed from at least three types of fibers: microtubules (thickest), microfilaments (thinnest), and intermediate filaments (in between size)
(see table 6.1)
>>>>>Plant cells are surrounded by cell walls (see fig 6.28)
Composed of cellulose fibers embedded in a matrix of other polysaccharides and proteins.
Development of the cell wall:
-Young plant cell secrete a thin flexible primary cell wall
-Between the primary cell walls of adjacent cells is the middle lamella that is
composed of sticky polysaccharides that cement the cells together
-As the plant cells mature and stop growing they may add a hardening substance to the primary cell wall and/or secrete a secondary cell wall between
the primary cell wall and the plasma membrane
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| CHAPTER 5
STRUCTURE AND FUNCTION OF MACROMOLECULES
Dehydration Synthesis and Hydrolysis: Disaccharides – 5.2.1
>>>>>Macromolecules and polymers.
---Macromolecules
---Polymer are large molecules consisting of many identical or similar subunits connected together.
---Monomer is a subunit (or building block) of a polymer.
>>>>>The reaction that forms a polymer from monomers is a polymerization reaction.
Most biological polymerization reactions are condensation reactions also called a dehydration synthesis reaction (see fig 5.2).
---Condensation reactions (a.k.a. dehydration synthesis reaction)
are polymerization reactions in which the covalent linkage of the monomeres is accompanied
---Hydrolysis is the breaking of the covalent bond between two monomers by the addition of water
(hydro lysis… splitting the connection)
absorbs the monomers.
>>>>>Diversity in polymers comes from the variation in the arrangement of the monomers.
FOUR CLASSES OF MACROMOLECULES
Macromolecule type Monomer type Linkage
CARBOHYDRATES SUGARS GLYCOSIDIC
LIPIDS
FATTY ACIDS ESTER
PROTEINS AMINO ACIDS PEPTIDE
NUCLEIC ACIDS NUCLEOTIDES PHOSPHODIESTER
Carbohydrates: Monosaccharides - 5.1.1
>>>>Carbohydrates are used as fuels and building material
---Carbohydratesare organic molecules made of sugars and
-Monomers of simple sugars are called monosaccharides.
---Monosaccharide monomers of simple sugars
1. macromolecules
a.
General structure of carbohydrates (see fig 5.3)
1) Each carbon has a hydroxyl group (-OH) and at least one hydrogen (-H) attached to it for except one carbon, which has a carbonyl group instead of the hydroxyl.
aldose or ketose.
Aldose: c double bond o is like… at the end and its diagonal
Ketose is within the chain.
Monosaccharides
PAY ATTENTION TO WHAT IS ATTACHED TO THE MONOSACCHARIDE. (hexose sugars)
2) The size of the carbon skeleton
Some examples of common sugars:
ALDOSES KETOSES
TRIOSE (C3H6O3) 3-carbon Glyceraldehyde Dihydroxyacetone
PENTOSE (C5H10O5) 5-carbon Ribose Ribulose
HEXOSE (C6H12O6) 6-carbon Glucose Fructose
3) Enantiomers exist for each asymmetric carbon
4) In aqueous solutions, monosaccharides with 5 or more carbons in the skeleton form ring structures (see fig 5.4).
>>>>Disaccharides (see fig 5.5)
---Disaccharides
---Glycosidic linkage
α (alpha)-linkage and β (beta)-linkage (see fig 5.7)
a the orientation is down. B the OH is down.
Examples of disaccharides:
DISACCHARIDE MONOMERS COMMON USE
Maltose Glucose + Glucose Important in beer brewing
Lactose Glucose + Galactose Sugar present in milk
Sucrose Glucose + Fructose Table sugar, most common
disaccharide
Polysaccharides: Energy Storage Molecules – 5.1.3
>>>>>Polysaccharide
stored sugars can be hydrolyzed as needed.
Storage polysaccharide (see fig 5.6)
---Starches is a glucose polymer that is used as a storage phlysaccharide in plants.
Amylose carbon #1 is linked to carbon #4. So, alpha 1-4 linkage. Really flexible. Kinda like spaghetti.
and Amylopectin (these are starches) difference between amylose & amylopectin.. is not only is there an alpha 1-4 linkage, but theres a 1-6 linkage. This one has brances, the other one doesn’t.
one dissolves really easily in water. The shorter one dissolves better… the shorter one is…
if the longer one has more interactions w. water
---Glycogen is a glucose polymer that is used as a storage polysaccharide in animals.
-similare structure to amylopectin, but with more branches
-the branches attach by means of 1-6 glycosidic linkages.
Polysaccharides: Structural Molecules – 5.1.4
Structural polysaccharides cellulose & chitin
---Cellulose (see fig 5.8) in a linear unbranched plymer of glucose in beta 1-4 linkages. If you have enough you can build a table. Gives you a rigid rod like structure
Found in plant cell walls
---Chitin (see fig 5.10) a structural plysaccharide that is a plolymer of an amino sugar.
Arthropods use chitin as an exoskeleton & the cell wall of fungi.
Lipids: An Introduction – 5.2.1
>>>>>Lipids are mostly hydrophobic molecules with diverse functions
---Lipids are a diverse group of organic molecules that are insoluble in water, but will dissolve in nonpolar solvents (ex: ether, chloroform, benzene).
-important lipid types are: fats, phospholipids, and steroids.
Important lipid types are: fats, phospholipids, and steroids.
>>>>Fats and Oils (see fig 5.12)
---Fats
---Oils
---Fatty acids (FA)(see fig 5.11)
---Glycerol
---Ester linkage a linkage that forms between an acid and an alcohol
---Triglycerol (a.k.a. triglyceride)
Saturated vs. Unsaturated Fats – 5.2.2
Features of saturated and unsaturated fats (see fig 5.12):
SATURATED UNSATURATED
No double bonds between carbons One or more double bonds
between carbons
Maximum number of hydrogen atoms bonded to the carbon of the skeleton (saturated) Chain kinks at each double bond, so individual chains cannot pack closely together enough to solidify easily.
Usually solid at room temperature Usually liquid at room temperature
Most animal fats Most plant fats
Phospholipids, Waxes, and Steroids – 5.2.3
>>>>>Phospholipids (see fig. 5.13)
---Phospholipids 2 parts of the E
basic component of cell membranes
hydrophilic (polar) head & hydrophobic (nonpolar) tail. Having polar and non polar ends, phospholipids can form a lipid bilayer,
amphipathic
Hydrophillic heads and hydrophobic tails
Micelles and Bilayers (see fig. 5.14)
Micelle is like a circle. Phospholipid bilayer um.. straight line
>>>>>Steroids (see fig. 5.15)
---Steroids
composed of 4 fused rings.
Nucleic Acids: An Introduction to Genetic Material – 5.2.4
>>>>>Nucleic Acids: Genetic material Information storage and transmission.
---gene
---nucleic acids
has Nitrogen.
deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)
---nucleotide (see fig. 5.27)
chain building effect.. a bunch of neucleotides… something about neucleic acid
Composed of sugar, phosphate group, and a nitrogenous base. condensation reaction that connects the phosphate to the sugar.
The sugar is a pentose (5 carbons) in a ring conformation.
In RNA the pentose is ribose, whereas in DNA the pentose is a derivative of ribose called, deoxyribose. (deoxy- without oxygen)
Rna is not stable & it deals w. the linkage..?
No variability in the sugar phosphate backbone.
The sugar and phosphate group make up the nucleic acid backbone.
---Phosphodiester linkage
There are two families of nitrogenous bases:
Pyrimidines and Purines
---Pyrimidines
Cytosine
Thymine (only in DNA)
Uracil (only in RNA)
---Purines
Guanine
Adenine
DNA: A=T G=C
RAN: A=U G=C
Always match with purine with pyrimidine
>>>>DNA consists of two chains in a double helix structure elucidated by Watson and Crick (see fig 5.28)
The strands are help together by hydrogen bonding between the paired bases.
A--T C--G
>>>>>Proteins are the molecular tools for most cellular functions.
Proteins: amino acids and the peptide bond.
A protein is a polymer of amino acids connected in a specific sequence. ← SPECIFIC SEQUENCEEEEEE
Protein functions (see table 5.1):
Proteins are the molecular tools for most cellular structures.
Structural support
Storage (of amino acids)
Transport (e.g. hemoglobin)
Signaling (chemical messengers)
Cellular response to chemical proteins (receptors)
Movement (contractile proteins)
Immuno-defense (antibodies)
Catalysts (enzymes)
A protein function is dependant on the protein conformation
>>>>A protein is a polymer of amino acids connected in a specific sequence
Proteins: Amino Acids and the Peptide Bond – 5.3.1
---Protein
are poly-amino acids
can also be called peptides or polypeptides because of their multiple peptide bonds.
Two standard functional groups
-amino and carboxyl
a variable side moiety designeated “R” which has other functional groups
---Amino acids (see fig 5.17)
α (alpha)-carbon
---Peptide bond (see fig 5.18)
---Polypeptide
Amino Acids: The R Groups – 5.3.2
Classes of amino acids:
Nonpolar
Polar
Charged
Acidic
Basic
Primary and Secondary Structure – 5.3.3
The protein structure leads to its final conformation and also its function
1) Primary structure (see fig 5.21)
---Primary structure the specific sequence of amino acids in a particular protein is the primary structures.
N-terminus versus C-terminus
Changes in the primary structure can result in changes in all the remaining levels of structure.
2) Secondary structure
---Secondary structure
Polypeptide backbone
α (alpha)-helix and β (beta)-pleated-sheet
---α (alpha)-helix
---β (beta)-pleated-sheet
Tertiary Structure – 5.3.4
3) Tertiary structure
---Tertiary structure
Amino acid side chains
Interactions of amino acid side chains:
-Covalent linkage
Disulfide bridges
-Weak interaction
Van der Waals interactions
Ionic bonds
Hydrophobic interactions
Hydrogen bonding
Quaternary Structure – 5.3.5
4) Quaternary structure (when a protein has more than one polypeptide chains)
---Quaternary structure
>>>>>What determines protein conformation?
A proteins native conformation is dictated by the primary structure and the subsequent secondary, tertiary and quaternary structures that result.
Protein Structure: A Summary – 5.3.6
>>>>>Four levels of protein structure
Conformation changes
---Denaturation (see fig 5.23)
>>>>>Protein folding
Chaperonin proteins aid the folding of many proteins (see fig 5.24)
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