Exam 2 Flashcards
What are macromolecules?
Large molecules composed of thousands of covalently bonded atoms
What are the four classes of macromolecules?
- carbohydrates
- lipids
- proteins
- nucleic acid
What is a polymer?
Long molecule consisting of many similair building blocks.
What is a monomer?
The building blocks of polymers.
Which 3 of the 4 types of macromolecules are polymers?
- carbohydrates
- proteins
- nucleic acids
What is a dehydration reaction?
Two monomers bonded together through the loss of a water molecule.
What is hydrolysis?
A reaction were a polymer is broken down by adding water molecules.
What are carbohydrates?
- serve as fuel and building material
- includes sugars and polymers of sugars
- simplest carbohydrates are monosaccharides, or single sugars
- polysaccharides are polymers composed of many sugar building blocks
What is the typical molecular formula of monosaccharides?
Multiples of CH20
- C2H402
- C6H12O6
What is the most common monosaccharide?
Glucose (C6H12O6)
How are monosaccharides classified?
- By the location of carbonyl group (C=O) as aldose (if carbonyl group is at the end of the skeleton) or ketose (if carbonyl group is within the carbon skeleton).
- By the number of carbons in the carbon skeleton
How are monosaccharides often presented, and how does this differ from their actual typical form?
- Often depicted as linear skeleton
- Typically form rings in aqueous solutions
What is a disaccharide?
Two monosaccharides joined by a dehydration reaction?
What is the covalent bond between the two monosaccharides in a disaccharide called?
Glycosidic linkage
What are the roles of polysaccharides?
storage and structural
What determines the structure and function of a polysaccharide?
Its sugar monomers and the positions of it’s glycosidic linkages.
What is starch?
- A storage polysaccharide of plants consisting entirely of glucose monomers
- plants store surplus starch as granules within chloroplasts and other plastids
- simplest form of starch is amylose
What is glycogen?
- storage polysaccharide in animals
- vertebrates store glycogen mainly in liver and muscle cells
What is cellulose?
- A polysaccharide that is a major component of cell walls
- like starch it is a polymer of glucose, but the glycosidic linkages differ
- difference is based on two ring forms for glucose : alpha (α) and beta (β)
What is the shape of polymer with α glucose?
Helical
What is the shape pf polymers with β glucose?
Straight. H atoms on one strand can bond with OH groups on other strands.
What are microfibrils?
- Parallel cellulose molecules held together by straight polymers of β glucose monomers bonding H atoms to OH groups.
- Form strong building materials for plants
Can humans digest cellulose?
No. The enzymes hat digest starch by hydrolysing α linkages cannot hydrolyse the β linkages in cellulose, and it passes through the digestive tract as insoluble fibre.
How do some animals digest starch?
Many herbivores have symbiotic relations with microbes the produce enzymes that can break down cellulose.
What is chitin?
A structural polysaccharide found in the exoskeleton of arthropods and cell walls of fungi.
What are lipids?
- hydrophobic
- consist mostly of hydrocarbons which form non polar covalent bonds
- the one class of macromolecules that do not form polymers
What are fats?
Constructed from glycerol and fatty acids
Wha is clycerol?
a three carbon alcohol with a hydroxyl (-OH) group attached to each carbon
What is a fatty acid?
a carboxyl group - C = O attached to a long carbon skeleton \
OH
What is a triacylglycerol?
- Three fatty acids joined by an ester linkage
- also called triglyceride
How do fatty acids vary?
- length (number of carbons)
- number and location of double bonds
What is a saturated fatty acid?
- A fatty acid that has the maximum number of hydrogen bonds possible and no double bonds
- saturated fatty acids make saturated fats
- solid at room temperature
- most animal fats are saturated
What is an unsaturated fatty acid?
- A fatty acid that has one or more double bonds
- unsaturated fatty acids called unsaturated fat or oils
- liquid at room temperature
- plant and fish fats are usually unsaturated
What is the danger of saturated fats?
They may contribute to heart disease through plaque deposits
What is hydrogenation?
Process of converting unsaturated fats to saturated fats by adding hydrogen.
What are trans fats?
Fats with trans double bonds created by hydrogenating vegetable oils. They may contribute more to heart disease than saturated fat.
What is an example of a fatty acid that is not synthesised in the human body?
- Omega-3 fatty acids
- required for normal growth and thought to protest against cardiovascular disease
- must be supplied through diet
What us the major function of fats?
Energy storage, in mammals stored in adipose cells. Also used to cushion vital organs an insulate body.
What is a phospholipid?
-two fatty acids and a phosphate group O are attached to a glycerol (-OH) I
O = P - O(δ-)
I
O
I
- two fatty acid tails are hydrophobic, but phosphate group and its attachments form a hydrophilic head
What are phospholipids a major component of?
The phospholipid bilayer is found in all cell membranes.
What are steroids?
Lipids characterised by a carbon skeleton consisting of four fused rings
What is cholesterol?
A steroid that is a component in animal cell membranes
Why can cholesterol be dangerous?
Although it is essential, high levels of cholesterol in blood can contribute to cardiovascular disease
What are proteins?
Large molecules composed of long chains of amino acids intricately folded into a specific 3-D shape, with a wide diversity and range of functions
What are 8 types of proteins?
- Enzymatic proteins: Selective acceleration of chemical reactions e.g. digestive enzymes catalyse the hydrolysis of bonds in food molecules
- Defensive proteins: Protect against disease e.g. antibodies destroy viruses and bacteria
- Storage proteins: storage of amino acids e.g. casein in milk, stores amino acids for baby mammals in milk
- Transport proteins: transport of substances e.g. haemoglobin transports oxygen
- Hormonal proteins: Coordination of an organisms function e.g. insulin regulating blood sugar levels
- Receptor proteins: Response of cell to chemical stimuli e.g. receptors in walls of nerve cells detecting signal molecules from other nerve cells
- Contractile and motor proteins: Movement e.g. responsible from movement of cilia and flagella, and actin and myosin responsible for con traction of muscles
- Structural proteins: Support e.g. keratin in hair, horns, feathers; collagen and elastin framework off animal connective tissues.
