Carbohydrates, Lipids and Cell Membranes

Question 1

Monosaccharide

Answer 1

Generally have molecular formulas that are some multiple of the unit CH2O. Sugars vary in the location of their carbonyl groups (C=O), the length of their carbon skeletons, and the spatial arrangement around asymmetric carbons.
Glucose (C6H12O6) is the most common monosaccharide.
The molecule has a carbonyl group (C=O) and multiple hydroxyl groups.

Question 2

Disaccharide

Answer 2

Consists of two monosaccharides joined by a glycosidic linkage, a covalent bond formed between tow monosaccharides by a dehydration reaction.

Question 3

Polysaccharide

Answer 3

Macromolecules, polymers with a few hundred to a few thousand monosaccharides joined by glycosidic linkages.
Serve as energy storage (starch, glycogen), or structural roles (cellulose, chitin)

Question 4

Starch

Answer 4

A plant polysaccharide. Plants store starch, a polymer of glucose monomers, as granules within cellular structures known as plastids, which include chloroplasts. Allows plant to stockpile surplus glucose as starch as stored energy.

Question 5

Glycogen

Answer 5

An animal polysaccharide.
Animal cells stockpile glycogen as dense clusters of granules within liver and muscle cells.
Hydrolysis of glycogen releases glucose when the demand for sugar increases.

Question 6

Cellulose

Answer 6

A structural polysaccharide of plant cell walls, consisting of glucose monomers joined by β glycosidic linkages

Question 7

Chitin

Answer 7

A structural polysaccharide, consisting of amino sugar monomers, found in many fungal cell walls and in the exoskeletons of all arthropods

Question 8

Lipids

Answer 8

Any group of large biological molecules, including fats, phospholipids, and steroids, that mix poorly, if at all with water.

Question 9

Fat

Answer 9

A lipid consisting of three fatty acids linked to one glycerol molecule; also called a triacylglycerol or triglyceride

Question 10

Fatty acid

Answer 10

A carboxylic acid with a long carbon chain. Fatty acids vary in length and in the number and location of double bonds; three fatty acids linked to a glycerol molecule form a fat molecule.

Question 11

Saturated fat

Answer 11

A fat in which all carbons in the hydrocarbon tail are connected by single bonds, thus maximising the number of hydrogen atoms that are attached to the carbon skeleton

Question 12

Unsaturated fat

Answer 12

A fat that has one or more double bonds between carbons in the hydrocarbon tail. This reduced the numbers of hydrogen atoms attached to the carbon skeleton

Question 13

Phospholipid

Answer 13

A lipid made up of glycerol joined to two fatty acids and a phosphate group. The hydrocarbon tails of the fatty acids, act as nonpolar, hydrophobic tails, while the rest of the molecule acts as a polar, hydrophilic head.
Phospholipids form bilayers that function as biological membranes

Question 14

Amphipathic

Answer 14

Having both a hydrophilic region and a hydrophobic region.

Question 15

Fluid mosaic model

Answer 15

The cell membrane as a mosaic of protein molecules drifting laterally in a fluid bilayer of phospholipids

Question 16

Integral proteins

Answer 16

A membrane protein which penetrates the hydrophobic interior of the lipid bilayer. The majority are transmembrane proteins, which span the membrane; other integral proteins extend only partway into the hydrophobic interior.

Question 17

Peripheral proteins

Answer 17

Membrane proteins that do not embedded in the lipid bilayer at all; they are appendages loosely bound to the surface of the membrane, often to exposed parts of integral proteins

Question 18

Diffusion

Answer 18

The spontaneous movement of a substance down its concentration or electrochemical gradient, from a region where it is more concentrated to a region where it is less concentrated

Question 19

Endocytosis

Answer 19

Cellular uptake of biological molecules and particulate matter vis formation of vesicles from the plasma membrane

Question 20

Exocytosis

Answer 20

The cellular secretion of biological molecules by the fusion of vesicles containing them with the plasma membrane

Question 21

Glycolipid

Answer 21

A lipid with one or more covalently attached carbohydrates

Question 22

Glycoprotein

Answer 22

A protein with one or more covalently attached carbohydrates