Celbiologie Hoofdstuk 5
Les 1
Leerdoelen:
1. Vorming (dehydratee en splitsing (hydrolysee an macromoleculen kunnen beschrij en
2. Van de biologische macromoleculen moet je kennen:
erschillende subgroepen
basis molecuulstructuren
functe
• Polymers: long molecules consistng of many similar smaller building blocks.
• These smaller building-blocks or molecules are called monomers.
• Three of the four classes of life’s organic molecules are polymers
Carbohydrates
Proteins
Nucleic acids
(lipidse
Polymers are disassembled to monomers by hydrolysis, a reacton that is essentally the
re erse of the dehydraton reacton.
Therefore the disassembly is not a random process. Think of: digeston of food.
Sugars
• Glucose (C6H12O6e is the most common monosaccharide
• Monosaccharides ha e molecular formulas that are usually multples of CH 2O (or (CH2Oene
• Monosaccharides are classifed by
• The locaton of the carbonyl group (-C=O; as aldose or ketosee
• The number of carbons in the carbon skeleton
• Monosaccharides ser e as a major fuel for cells and as raw material for building molecules
- A disaccharide is formed when a dehydraton reacton joins two monosaccharides .
- This co alent bond is called a glycosidic linkage.
- Polysaccharides, the polymers of sugars, ha e storage and structural roles
- The structure and functon of a polysaccharide are determined by its sugar monomers and the
positons of glycosidic linkages.
Concept 5.3: Lipids are a di erse group of hydrophobic molecules
• Lipids are the one class of large biological molecules that does not include true polymers
• The unifying feature of lipids is that they mix poorly, if at all, with water
• Lipids are hydrophobic because they consist mostly of hydrocarbons, which form nonpolar
co alent bonds
• The most biologically important lipids are fats, phospholipids, and steroids
,Fats
• Fats are constructed from two types of smaller molecules: glycerol and faty acids
• Glycerol is a three-carbon alcohol with a hydroxyl group atached to each carbon
• A fatty acid consists of a carboxyl group atached to a long carbon skeleton
• The major functon of fats is energy storage
• Humans and other mammals store their long-term food reser es in adipose cells
• Adipose tssue also cushions ital organs and insulates the body
Phospholipids
• In a phospholipid, two faty acids and a phosphate group are atached to glycerol.
• The two faty acid tails are hydrophobic, but the phosphate group and its atachments form a
hydrophilic head.
• When phospholipids are added to water, they self-assemble into double-layered structures
called bilayers.
• At the surface of a cell, phospholipids are also arranged in a bilayer, with the hydrophobic
tails pointng toward the interior
• The structure of phospholipids results in a bilayer arrangement found in cell membranes.
• The existence of cells depends on phospholipids.
Steroids
• Steroids are lipids characterized by a carbon skeleton consistng of four fused rings
• Cholesterol, a type of steroid, is a component in animal cell membranes and a precursor
from which other steroids are synthesized
• A high le el of cholesterol in the blood may contribute to cardio ascular disease
, Peptdes / proteins
• Proteins are all constructed from the same set of 20 amino acids
• Polypeptides are unbranched polymers built from these amino acids
• A protein is a biologically functonal molecule that consists of one or more polypeptdes
Amino Acid Monomers
• Amino acids are organic molecules with amino and carboxyl groups
• Amino acids difer in their propertes due to difering side chains, called R groups
Protein Structure and Functon
• The specifc act ites of proteins result from their intricate three-dimensional architecture
• A functonal protein consists of one or more polypeptdes precisely twisted, folded, and
coiled into a unique shape
• The sequence of amino acids determines a protein’s three-dimensional structure
• A protein’s structure determines how it works
• The functon of a protein usually depends on its ability to recognize and bind to some other
molecule.
Les 1
Leerdoelen:
1. Vorming (dehydratee en splitsing (hydrolysee an macromoleculen kunnen beschrij en
2. Van de biologische macromoleculen moet je kennen:
erschillende subgroepen
basis molecuulstructuren
functe
• Polymers: long molecules consistng of many similar smaller building blocks.
• These smaller building-blocks or molecules are called monomers.
• Three of the four classes of life’s organic molecules are polymers
Carbohydrates
Proteins
Nucleic acids
(lipidse
Polymers are disassembled to monomers by hydrolysis, a reacton that is essentally the
re erse of the dehydraton reacton.
Therefore the disassembly is not a random process. Think of: digeston of food.
Sugars
• Glucose (C6H12O6e is the most common monosaccharide
• Monosaccharides ha e molecular formulas that are usually multples of CH 2O (or (CH2Oene
• Monosaccharides are classifed by
• The locaton of the carbonyl group (-C=O; as aldose or ketosee
• The number of carbons in the carbon skeleton
• Monosaccharides ser e as a major fuel for cells and as raw material for building molecules
- A disaccharide is formed when a dehydraton reacton joins two monosaccharides .
- This co alent bond is called a glycosidic linkage.
- Polysaccharides, the polymers of sugars, ha e storage and structural roles
- The structure and functon of a polysaccharide are determined by its sugar monomers and the
positons of glycosidic linkages.
Concept 5.3: Lipids are a di erse group of hydrophobic molecules
• Lipids are the one class of large biological molecules that does not include true polymers
• The unifying feature of lipids is that they mix poorly, if at all, with water
• Lipids are hydrophobic because they consist mostly of hydrocarbons, which form nonpolar
co alent bonds
• The most biologically important lipids are fats, phospholipids, and steroids
,Fats
• Fats are constructed from two types of smaller molecules: glycerol and faty acids
• Glycerol is a three-carbon alcohol with a hydroxyl group atached to each carbon
• A fatty acid consists of a carboxyl group atached to a long carbon skeleton
• The major functon of fats is energy storage
• Humans and other mammals store their long-term food reser es in adipose cells
• Adipose tssue also cushions ital organs and insulates the body
Phospholipids
• In a phospholipid, two faty acids and a phosphate group are atached to glycerol.
• The two faty acid tails are hydrophobic, but the phosphate group and its atachments form a
hydrophilic head.
• When phospholipids are added to water, they self-assemble into double-layered structures
called bilayers.
• At the surface of a cell, phospholipids are also arranged in a bilayer, with the hydrophobic
tails pointng toward the interior
• The structure of phospholipids results in a bilayer arrangement found in cell membranes.
• The existence of cells depends on phospholipids.
Steroids
• Steroids are lipids characterized by a carbon skeleton consistng of four fused rings
• Cholesterol, a type of steroid, is a component in animal cell membranes and a precursor
from which other steroids are synthesized
• A high le el of cholesterol in the blood may contribute to cardio ascular disease
, Peptdes / proteins
• Proteins are all constructed from the same set of 20 amino acids
• Polypeptides are unbranched polymers built from these amino acids
• A protein is a biologically functonal molecule that consists of one or more polypeptdes
Amino Acid Monomers
• Amino acids are organic molecules with amino and carboxyl groups
• Amino acids difer in their propertes due to difering side chains, called R groups
Protein Structure and Functon
• The specifc act ites of proteins result from their intricate three-dimensional architecture
• A functonal protein consists of one or more polypeptdes precisely twisted, folded, and
coiled into a unique shape
• The sequence of amino acids determines a protein’s three-dimensional structure
• A protein’s structure determines how it works
• The functon of a protein usually depends on its ability to recognize and bind to some other
molecule.
