OChem Chapter 12,14 Test

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Fibrous Functions
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structure and contractive
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Fibrous Structure
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key: hiedrical structure

 

mostly non-polar amino acids are coiled together into super structures

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Globular Functions
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Metabolic Work:

-Catalysis

-Transport

-Regulation

-Protection

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Globular Structure
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Soluble (hydrophilic side chains)
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Fibrous Solubility
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insoluble in water
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Fibrous Structure (Primary…)
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  • No tertiary
  • Usually have quaternary

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α-Keratines (where?)
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hair, skin, nails, horns, hoofs, wool

(Fibrous Proteins)

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Strength of Fibrous Proteins
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h-bonding and disulfide bridges between peptide chains
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Hemoglobin Structure
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4 polypeptide chains (2-α and 2-β)

 

alpha-helices separated by beta-turns

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Hemoglobin (where?)
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blood
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Myoglobin Structure
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Only 1 polypeptide chain
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Protein function ulitmately depends on…
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primary structure (amino acid sequence)
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Genetic Mutation
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An alteration in the DNA structure of a gene that may in turn produce a change in the primary structure of a protein
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Sickle-cell Hemoglobin
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Region critical to binding oxygen are NOT changed

 

Sickling is the aggregation of the hemoglobins (hydrophobic attractions between the hydrophobic pocket and residue 6 (Val))

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Sickle-cell Anemia (where?)
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Western Africa

likely because of high incidence of malaria

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Denaturation
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Loss of native conformation brought about by a change in envirnmental conditions, resulting in a loss of physiological function
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Denaturation alters which structures
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Alters secondary, tertiary and quaternary structures
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Digestion
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Breaks peptide bonds and alters primary structure

 

Not denaturation

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Denaturation (Globular vs. Fibrous)
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Globular protein have weaker secondary forces and thus are denatured easier.
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7 Methods of Denaturation
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  1. Increase Temp
  2. UV and ionizing Radiations
  3. Mechanical Energy
  4. Changes in pH
  5. Organic Chemicals
  6. Salts of Heavy Metals
  7. Oxidizing and Reducing Agents

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Increased Temp
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Increased motion disrupts non-covalent attractions

 

Example: cooking and sterilization

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UV and Ionizing Raditions
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Causes chemical reactions

 

Example: X-ray

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Mechanical Energy
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Example: Whipping Eggs
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Changes in pH
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Affects salt bridges
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Organic Chemicals
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Affects hydrophoic interactions

 

Example: Rubbing Alcohol

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Salts of Heavy Metals
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"Pb2+, Hg2+ and Ag+ react with sulfdryl groups and forms metal disulfide bridges

 

Example: Mecury Poisioning"

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Oxidizing and Reducing Agents
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Oxidizing: forming disulfide bridges

Reducing: breaking disulfide bridges

 

Example: Perm

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Matabolism Functions
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  • Obtain energy in chemical form by degradation of nutrients
  • Convert a wide vareity of molecules into a few precursor molecules
  • Synthesize cell molecules
  • Produce or modify biomolecules necessary for specific functions in specialized cells

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Catabolism
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Biochemical degradation/break-down of energy-containing compounds (energy releasing)

 

Exampe: Combustion of C6H12O6, opposite of photosynthesis

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Catabolism Process
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Nutrient molecules

Precursor Molecules

Acetyl CoA

Water and Carbon Dioxide

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ATP
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adenine triphosphate

 

 Used for energy required processes

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NADH
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nicotinamide adenine…

 

Used to make ATP

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Stages 2 & 3
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use much of energy to create energy carrier molecules (ATP and NADH)
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Catabolism

(oxidation or reduation)

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Oxidation process

 

low energy → high energy

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Anabolism

(oxidation or reduation)

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Reduction process

 

high energy → low energy

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Enzymes
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  • Organic Catalyst
  • Can be denatured
  • Proteins

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Active Site
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  • Where the substrate binds
  • Has anchor points

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Anchor Points
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  • Hold the substrate in place
  • Use IMF to do so

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Substrate
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Reactant molecule
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Complementarity
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Enzymes highly specific to their substrates
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Induced Fit
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Protein/enzyme changes space as the substrate binds
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Lock and Key
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Enzyme doesn’t change shape, fits directly into active site
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True Substrate
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the reactant that in supposed to react
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Substrate Analog
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a molecule similar to the true substrate (size, shape, charge, polority)
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Competitive Inhibitor
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Substrate analog that binds in the active site (binds but doesn;t react)
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Non-competitive Inhibitor
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;alosteric;-a molecule that binds to a region other than the active site causing the conformation change which prevents the true substrate from binding
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Cofactors/Coenzymes
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ions/molecules that are needed to complete a protein’s structure so that in can function
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Apoenzyme
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(apoprotein) polypeptide portion
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Haloenzyme
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Entire functional protein/enzyme

 

Cofactors/coenzymes + apoenzyme = haloenzyme

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Riboflavin
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in FAD
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Niacin
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in MAD
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Covalent Modification
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enzyme activity is regulated by covalently attaching a group which either activates or deactivates that enzyme’s activity
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Feedback Inhibition
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when the product of one reaction serves as an inhibitor for a previous reaction
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Regulatory Enzymes
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enzymatic activity controlled by binding of activators/inhibitors

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