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Lecture 05 Cell Metabolism
Anatomy Lecture notes 5
24
Anatomy
Undergraduate 1
09/06/2010

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Term
Anabolic metabolism
Definition
involves the *synthesis* of new molecules, uses energy.

Ex. the synthesis of proteins from amino acids
Term
Catabolic metabolism
Definition
involves the breakdown of molecules, a process that is usually designed to generate energy.

Ex. the breakdown of glucose to carbon dioxide and water
Term
Glycogen
Definition
is a polysaccharide, and is the storage form carbohydrates, specifically glucose.
Term
Glycogen synthesis
Definition
The creation of Glycogen. Glycogen consists of long chains of mocosaccharide gulucose.

Adjacent monosaccharide molecules are strung together by elimination of a hydroxyl group (-OH) from one of them and hydrogen (H) from the other. creating water (H20)
Term
Dehydration synthesis
Definition
a chemical reaction that involves the loss of water from the reacting molecule.

(-OH + H = H20)
Term
Fat synthesis
Definition
Fats are triglycerides and stored in adipose tissues. A molecule of fat consists of a *glycerol* molecule joined to three fatty acids

Fat synthesis occurs by elimination of the elements of water from one molecule of glycerol and three molecules of fatty acid. *dehydration synthesis*
Term
Protein synthesis
Definition
Proteins consist of chains of amino acids united by a covalent bond called a peptide bond.

The peptide bond is established by dehydration synthesis.
Term
Examples of Catabolic Metabolism
Definition
1)polysaccharides (eg. glycogen) into monosaccharides (eg. glucose)
2)Proteins into amino acids
3) fats into fatty acids and glycerol

uses process of hydrolysis (addition of a water)
Term
Enzymes (definition)
Definition
Proteins that act as catalysts for specific chemical reactions. They speed up reactions but are not consumed.

Enzymes function by lowering the activation energy of the reaction, so increasing the rate of the reaction.
Term
Activation Energy
Definition
The energy required to begin a chemical reaction
Term
Example of Enzymes
Definition
enzyme + A.B→enzyme.A.B.→enzyme+A+B

Lactace+Lactose→lactase.lactose→lactase+glucose+galactose
Term
Cofactors
Definition
Substances required for some enzymes to function
Term
Metal ions
Definition
Some enzymes are ineffective unless there is a specific metal ion is present.

Some of these metals are called trace elements because although they are essential components of our diet they are only needed in very small quantities.
Term
Coenzymes
Definition
Small organic molecules that work with enzymes. Many are derived from vitamin B complex

Examples of coenzymes are found oxidation-reduction reaction: nicotinamide adenine dinucleotid (NAD+) and flavin adenine dinucleotide (FAD)
Term
Poisons
Definition
Some poisons such as cyanide interfere with the respiratory enzymes in the mitochondria and kill cells by halting their ability to make ATP.
Term
Oxidation
Definition
romoval of two or more hydrogen atoms from a molecule.

Lactate+NAD+ --(lactate dehydrogenase)--> pyruvate+NADH + H

In this oxydation, therefore, NAD+ acquires two electrons and one proton (the other proton goes into solution). The resulting NADH molecules therefore store electrons generated in the body's oxidation reactions.
Term
NADH in oxydation
Definition
the electron in NADH together with hydrogen ions from the solution) will be used to interact with atmospheric oxygen to form water in the reaction:

4e- + 4H + O2 --> 2 H20
Term
Reduction
Definition
Opposite of oxidation. Refers to the addition of hydrogen atoms (electrons and hydrogen ions) to a molecule.

Oxidation and reduction reactions are always coupled: whenever a substances is oxidized, another is reduced.
Term
Why do we need energy
Definition
1) Synthesize molecules (anabolic metabolism)
2) Generate force and movement (in muscles)
3) Carry out active transport across membranes (e.g. pumping sodium ions out of cells).
Term
adenosine triphosphate (ATP)
Definition
a store of energy that can diffuse around the cell, and can be used to drive many different reactions
Term
What happens to polysaccharides and disaccarides during digestion?
Definition
They are hydrolyzed (split by enzymes and water) to monosaccharides --glucose, fructose and galactose. After absorption by the small intestine they are carried to the liver, where fructose and galactose are converted to glucose
Term
Glucose
Definition
a mono saccharide that is burned to produce energy in the body.

Any glucose that is not used for immediate energy production is stored in the liver and skeletal muscle cells in the form of granules of the polysaccharide glycogen.
If the glycogen storage areas are filled up, the liver transforms glucose to fat, which is stored in adipose tissue.

Glucose after burned produces: carbon dioxide, water and energy(heat and ATP)
Term
What are the 4 steps for the controlled burning of glucose.
Definition
1. glycolysis
2. formation of acetyl coenzyme A
3. addition of the acetyl two-carbon fragment to oxaloacetic acid to form citric to form citric acid in the Krebs cycle
4. oxidative phosphorylation, or the electron transport chain
Term
Glycolysis
Definition
converts one 6-carbon molecule of glucose to two 3-carbon molecules of pyruvate, in the process generating two molecules of ATP and two molecules of NADH
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