Chapter 2 (part B)

Question 1

What are the different types on polysaccharides and what are their purpose? (4)

Answer 1

• Starch (plant) and glycogen (animal) - energy storage:
  They are not as soluble in water, so they cannot easily move in or out of cells
• Cellulose (cell walls of plants) and chitin (exoskeleton) - structural

Question 2

proteins

Answer 2

• are polymers composed of amino acid monomers.
• Amino acids: Central carbon atom bonded to three functional groups.
  > Amino group (—NH2).
  > Acidic group (—COOH).
  > R group varies; determines uniqueness of amino acid.

Question 3

A protein is _______ when it loses structure and function.

Answer 3

denatured

> Occurs when proteins are exposed to extreme heat or pH.

Question 4

triglyceride

Answer 4

• A fat molecule
• Consists of:
  > one glycerol backbone.
  > three fatty acids.

Question 5

lipids

Answer 5

• Lipids are diverse in structure and function.
• Lipids have one common characteristic: They do not dissolve in water (hydrophobic), due to their hydrocarbon chains.
• Lipids contain more energy per gram than other biological molecules.
• Types:
  > Fats and oils are used for energy storage.
  > Phospholipids form membranes.
  > Steroids include sex hormones.

Question 6

Levels of Protein Organization (4 levels)

Answer 6

• Primary structure: linear sequence of amino acids
• Secondary structure: when polypeptide takes on a certain orientation in space
• Tertiary structure: final 3-dimensional shape
• Quaternary structure: when 2 or more polypeptides interact

Question 7

Functions of proteins (7)

Answer 7

• Structural proteins give support (keratin, collagen).
• Enzymes speed up chemical reactions.
• Hormones are chemical messengers.
• Actin and myosin move cells and muscles.
• Some proteins transport molecules in blood.
• Antibodies protect cells.
• Channels allow substances to cross membranes.

Question 8

monosaccharides

Answer 8

• are sugars with three-to-seven carbon atoms
• Pentose refers to a five-carbon sugar.
• Hexose refers to a six-carbon sugar, such as glucose.

Question 9

polysaccharides

Answer 9

• are long polymers that contain many subunits.

Question 10

What are the differences between saturated, unsaturated, and trans-fats?

Answer 10

• Saturated fatty acids have no double bonds between carbon atoms.
  >Saturated with hydrogen atoms. >Solid fats
  >Flat molecules that easily stick together in the blood
• Unsaturated fatty acids have one or more double bonds between carbon atoms.
  >Liquid fats. >Healthier for you, but have a shorter shelf life
• Trans-fats are oils hydrogenated to make them solid; processed food.
  >Chemically produced by adding hydrogen to vegetable oils. >Added to processed food for a longer shelf-life

Question 11

Polymer

Answer 11

Large organic molecules formed by combining monomers.

Question 12

peptide

Answer 12

• A polypeptide is a single chain of amino acids.

* A peptide bond joins two amino acids.

Question 13

phospholipids

Answer 13

• are comprised of two fatty acids and a phosphate group.
• The phosphate group is polar and forms the hydrophilic head of the molecule.
• The fatty acids are nonpolar and form the two hydrophobic tails of the molecule.
• Spontaneously form a bilayer in which the hydrophilic heads face outward toward watery solutions, and the tails form the hydrophobic interior.
• Phospholipids make up animal cell walls.

Question 14

Monomer

Answer 14

Repeated subunit of many large organic molecules.

Question 15

hydrolysis

Answer 15

components of water are added when polymers are broken down

Question 16

Distinguish a monomer from a polymer

Answer 16

• Polymer means many monomers. Sometimes polymers are also known as macromolecules or large-sized molecules. Usually, polymers are organic (but not necessarily).
• A monomer is a molecule that is able to bond in long chains.

Question 17

dehydration

Answer 17

an −OH and −H are removed as a water molecule when monomers are joined to build polymers.