Grand Finale

Published April 14, 2013 by shariestar

Finally completed this blog assignment! What a tedious but fun and informative ‘mission’!!! I guess it would not have been as tedious had i started when the task was given and followed the instructions that clearly stated to post stuff every week! *sigh*….procrastination is such a horrendous disease….:(…but luckily its over with! 
Now on to focusing on prepping for finals!!!!
Mr Mathews….couldn’t ask for a better teacher!!! An excellent coach with his ingenious, efficient teaching strategies! He successfully caught everyone’s interest in class and made us want to learn more about biochemistry! This man DEFINITELY deserves an award!

GOOD LUCK EVERYONE!
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Nucleic Acids & Nucleotides

Published April 14, 2013 by shariestar

Nucleic acids are un-branched polymers of nucleotides

Nucleotides have 3 components

  1. nitrogenous base
  2. a 5-carbon sugar (pentose)
  3. a phosphate 

Without the phosphate group, the molecule is a nucleoside

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The nitrogenous bases are derivatives of pyrimidines and purines

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Nucleotides are linked by phosphodiester bridges

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THE STRUCTURE OF DNA

  • It contains 2 polynucleotide strands wound around each other
  • The hydrophilic backbone of alternating deoxyribose and phosphate groups is on the outside
  • The purine and pyrimidine bases are stacked on the inside
  • The slightly offset pairing of the two strands creates a major and minor groove
  • The strands run anti-parallel to each other and are exactly complimentary 
  • Each row of bases is 3.4 Å from the next row and each complete turn of the link is 36 Å

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The common purines and pyrimidines in both DNA and RNA are planar and hydrophobic. These factors make it feasible to stack the bases.

Stacked bases are stabilized by

  • hydrophobic interactions
  • van der Waals forces
  • dipole-dipole interactions

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LIPIDS!!!!

Published April 14, 2013 by shariestar

LIPIDS

Lipids are often defined as water-insoluble (or sparingly soluble) organic compounds found in biological systems and are either hydrophobic or amphipathic.

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Roles of Lipids

  • Fuel storage (fats & oils)
  • Structural elements in membranes (phospholipids and sterols)
  • Emulsifying agents (bile salts)
  • Hormones (steroids- testosterone, progesterone, estradiol)
  • Intracellular messenger (DAG)
  • Enzyme cofactors (lipoic acid/PDH complex)

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FATTY ACIDS

Composed of a long hydrocarbon chain and terminal carboxyl group

Most naturally occurring FAs have an even number of Cs (14-24) and are either saturated or unsaturated.

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Greater the chain length, greater the melting point

Greater the degree of un-saturation (number of double bonds), lower the melting point

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 CHOLESTEROL

Maintains the fluidity in the membrane and is a precursor molecule for hormones

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TCA & ETC

Published April 14, 2013 by shariestar

TCA

The tricarboxylic acid cycle (TCA cycle) is a series of enzyme-catalyzed chemical reactions that form a key part of aerobic respiration in cells. This cycle is also called the Krebs cycle and the citric acid cycle. The greatly simplified cycle below starts with pyruvate, which is the end product of gylcolysis, the first step of all types of cell respiration.

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ETC

Electron transport chain (ETC) couples electron transfer between an electron donor (such as NADH) and an electron acceptor (such as O2) with the transfer of H+ ions (protons) across a membrane. The resulting electrochemical proton gradient is used to generate chemical energy in the form of adenosine triphosphate (ATP)

 

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Glycolysis

Published April 14, 2013 by shariestar

Glycolysis occurs in the cytosol and works for both aerobic and anaerobic organisms. It produces energy directly and indirectly (by supplying substrate for the citric acid cycle and oxidative phosphorylation. It also produces intermediates for biosynthetic pathways.

The main players:

  • Insulin
  • Glucagon
  • Muscle
  • Red Blood Cells
  • Liver
  • Adipose tissue

2 ATPs are used and 4 ATPs are synthesized for each molecule of glucose 
Under aerobic conditions, the 2 NADH molecules generateed in glycolysis also yeild energy via oxidative phosphorylation. 

The step catalysed by PFK is the main control step but HK and PK are also subject to metabolic control.

PFK is inhibited by metabolic signs of surplus of energy: ATP, citrate and H+

 

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ENZYMES!!!!

Published April 14, 2013 by shariestar

Enzymes are biological catalysts/molecules that speed up chemical reactions with itself being consumed in the process. It does so by lowering the activation energy of the reaction, which is the minimum amount of energy required for the reaction to occur.

These remarkably versatile biochemical catalyst have 3 common distinctive features

  • catalytic power
  • specificity
  • regulation

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FISCHER LOCK AND KEY MODEL

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KOSHLAND INDUCED FIT

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Several factors affect the functions of enzymes

  • temperature
  • pH
  • Substrate concentration

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Enzymes can also be further classified according to the type of reaction they catalyze

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There’s also different types of inhibition:

  • competitive inhibition
  • non-competitive inhibition
  • un-competetive inhibition

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Amino Acids and Proteins

Published April 14, 2013 by shariestar

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All amino acids found in proteins have this basic structure, differing only in the structure of the R-group or the side chain..

 

The simplest, and smallest, amino acid found in proteins is glycine for which the R-group is a hydrogen (H).

Essential Amino Acids

•Protein  in our diet provides the amino acids for the body to synthesize its own proteins

•Hydrolytic enzymes in the stomach and SI break down food proteins to component amino acids

•On absorption they join the body’s amino acid pool which includes amino acids from the constant turnover of cells
•Amino acids are also used to provide raw material for the synthesis of purines, pyrimidines, porphyrins, etc
 
Amino acids which must be supplied from the diet include:
•Histidine
•Isoleucine
•Leucine
•Lysine
•Methionine
•Phenylalanine
•Threonine
•Tryptophan
•Valine
 
PROTEINS
All proteins regardless of where found contains all the same essential 20 amino acids.
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