Samenvatting
CELBIOLOGIE
Nathalie Ridderhof
,Chapter 5: Biological macromolecules and lipids
Large molecules can be sorted in 4 main classes:
- Carbohydrates
- Lipids
- Proteins
- Nucleic acids
Macromolecules:
A giant molecule formed by the joining of smaller molecules, usually by a dehydration
reaction. Polysaccharides, proteins and nucleic acids are macromolecules.
5.1
Macromolecules are polymers, built from monomers.
- Polymer; A long molecule consisting of many similar or identical monomers linked
together by covalent bonds.
- Monomers; The subunit that serves as the building block of a polymer.
Enzymes:
A macromolecule serving as a catalyst. They speed up the chemical reaction. Most enzymes
are proteins.
• Dehydration reaction: A reaction in which two molecules are covalently bonded to
each other with the loss of a water molecule.
- One monomer provides a hydroxyl group (-oh)
- The other provides a hydrogen (-H)
• Hydrolysis: The bond between monomers is broken by the addition of a water
molecule. Hydrogen from water is being attached to one monomer and de hydroxyl
group is attached to the other monomer.
5.2 - Carbohydrates serve as fuel and building material.
Carbohydrates:
A sugar (mono-saccharide) or one of its dimers (disaccharides) or polymers
(polysaccharides).
Sugars:
- Aldose (aldehyde sugar)
- Ketose (ketone sugar)
Cellular respiration, cells extract energy from glucose molecules by breaking them down in a
series of reactions.
• Disaccharide consist of two monosaccharides joined by a glycosidic linkage, a
covalent bond formed between two monosaccharides by a dehydration reaction.
, - Disaccharides must be broken down to monosaccharides to be used for energy by
organisms.
- Lactose-intolerance is a condition in humans who lack lactase, The enzyme that
breaks down lactose.
Polysaccharides;
- Hydrolyzed as needed to provide sugar for cells.
- Serve as building material for structures that protect the cell or the whole organism.
Storage polysaccharides:
- Plants store Starch; a polymer of glucose monomers, granules within plastids. (stored
energy)
- The simplest form of starch, amylose, is unbranched.
- Animals store a polysaccharide called glycogen, a polymer of glucose that is more
extensively branched. Mainly in liver and muscle cells.
- Hydrolysis of glycogen in these cells releases glucose when the demand for sugar
increases.
Structural polysaccharides:
- The polysaccharide called cellulose is a major component of the tough walls that
enclose plant cells.
- Cellulose; polymer of glucose with 1-4 glycosidic linkages.
, • Enzymes that digest starch by hydrolyzing it’s a-linkages are unable to hydrolyze the
b-linkages of cellulose because of the different shapes.
Chitin:
Structural polysaccharide, consisting of amino sugar monomers found in many fungal cell
walls and in the exoskeletons of all arthropods ( insects, spiders, etc.)
5.3 – Lipids are a diverse group of hydrophobic molecules
Lipids;
Any of a group of large biological molecules, including fats, phospholipids, and steroids, that
mix poorly, if at all, with water.
Fats;
- Are not polymers
- Fat; three fatty acid molecules are each joined to glycerol by an ester linkage, a bond
formed by a dehydration reaction between a hydroxyl-group and a carboxyl-group.
Also called a triacyl-glycerol.
- Glycerol is a alcohol; bears a hydroxyl-group
- Fatty acid; A carboxylic acid with a long carbon chain. C-H bonds in this fatty acid are
the reason that they are hydrophobic.
• Saturated fatty acid; connected by single bonds.
• Unsaturated fatty acid; connected by one or more double bonds.
A diet rich in saturated fats → atherosclerosis
Deposits called plaques develop within the walls of blood vessels, causing inward bulges
(uitstulpingen) that disturb the blood flow and reduce the resilience (veerkracht) of the
blood vessels.
CELBIOLOGIE
Nathalie Ridderhof
,Chapter 5: Biological macromolecules and lipids
Large molecules can be sorted in 4 main classes:
- Carbohydrates
- Lipids
- Proteins
- Nucleic acids
Macromolecules:
A giant molecule formed by the joining of smaller molecules, usually by a dehydration
reaction. Polysaccharides, proteins and nucleic acids are macromolecules.
5.1
Macromolecules are polymers, built from monomers.
- Polymer; A long molecule consisting of many similar or identical monomers linked
together by covalent bonds.
- Monomers; The subunit that serves as the building block of a polymer.
Enzymes:
A macromolecule serving as a catalyst. They speed up the chemical reaction. Most enzymes
are proteins.
• Dehydration reaction: A reaction in which two molecules are covalently bonded to
each other with the loss of a water molecule.
- One monomer provides a hydroxyl group (-oh)
- The other provides a hydrogen (-H)
• Hydrolysis: The bond between monomers is broken by the addition of a water
molecule. Hydrogen from water is being attached to one monomer and de hydroxyl
group is attached to the other monomer.
5.2 - Carbohydrates serve as fuel and building material.
Carbohydrates:
A sugar (mono-saccharide) or one of its dimers (disaccharides) or polymers
(polysaccharides).
Sugars:
- Aldose (aldehyde sugar)
- Ketose (ketone sugar)
Cellular respiration, cells extract energy from glucose molecules by breaking them down in a
series of reactions.
• Disaccharide consist of two monosaccharides joined by a glycosidic linkage, a
covalent bond formed between two monosaccharides by a dehydration reaction.
, - Disaccharides must be broken down to monosaccharides to be used for energy by
organisms.
- Lactose-intolerance is a condition in humans who lack lactase, The enzyme that
breaks down lactose.
Polysaccharides;
- Hydrolyzed as needed to provide sugar for cells.
- Serve as building material for structures that protect the cell or the whole organism.
Storage polysaccharides:
- Plants store Starch; a polymer of glucose monomers, granules within plastids. (stored
energy)
- The simplest form of starch, amylose, is unbranched.
- Animals store a polysaccharide called glycogen, a polymer of glucose that is more
extensively branched. Mainly in liver and muscle cells.
- Hydrolysis of glycogen in these cells releases glucose when the demand for sugar
increases.
Structural polysaccharides:
- The polysaccharide called cellulose is a major component of the tough walls that
enclose plant cells.
- Cellulose; polymer of glucose with 1-4 glycosidic linkages.
, • Enzymes that digest starch by hydrolyzing it’s a-linkages are unable to hydrolyze the
b-linkages of cellulose because of the different shapes.
Chitin:
Structural polysaccharide, consisting of amino sugar monomers found in many fungal cell
walls and in the exoskeletons of all arthropods ( insects, spiders, etc.)
5.3 – Lipids are a diverse group of hydrophobic molecules
Lipids;
Any of a group of large biological molecules, including fats, phospholipids, and steroids, that
mix poorly, if at all, with water.
Fats;
- Are not polymers
- Fat; three fatty acid molecules are each joined to glycerol by an ester linkage, a bond
formed by a dehydration reaction between a hydroxyl-group and a carboxyl-group.
Also called a triacyl-glycerol.
- Glycerol is a alcohol; bears a hydroxyl-group
- Fatty acid; A carboxylic acid with a long carbon chain. C-H bonds in this fatty acid are
the reason that they are hydrophobic.
• Saturated fatty acid; connected by single bonds.
• Unsaturated fatty acid; connected by one or more double bonds.
A diet rich in saturated fats → atherosclerosis
Deposits called plaques develop within the walls of blood vessels, causing inward bulges
(uitstulpingen) that disturb the blood flow and reduce the resilience (veerkracht) of the
blood vessels.
