Unit (11) Molecules of Life: Lipids and Proteins

Question 1

What are Lipids?

Answer 1

Biochemical compounds that contain carbon, hydrogen, and oxygen.

Question 2

What is the solubility of Lipids?

Answer 2

Insoluble in water but soluble in organic solvents.

Question 3

What are the two major categories for Lipid classification?

Answer 3

Fatty acid containing Lipids and Non fatty acid containing Lipids

Question 4

Which type of Lipids are considered fatty acid?

Answer 4

Fats and oils, waxes, phospholipids

Question 5

Which type of Lipids are considered non fatty acids?

Answer 5

Steroids

Question 6

What is the fundamental building block of many lipids?

Answer 6

Long chain carboxylic acids called fatty acids

Question 7

A saturated fatty acid contains?

Answer 7

Only carbon-carbon single bonds in the hydrocarbon

chain.

Question 8

A monounsaturated fatty acid contains?

Answer 8

One C = C double bond in the hydrocarbon chain.

Question 9

A polyunsaturated fatty acid contains?

Answer 9

Two or more C = C double bonds in the

hydrocarbon chain.

Question 10

Animal fats and vegetable oils are lipid esters known as?

Answer 10

triglycerides

Question 11

Glycerol (older name glycerin) is a small chain alcohol containing?

Answer 11

Three carbons with a

hydroxyl (-OH) group bound at each carbon.

Question 12

A monoglyceride contains?

Answer 12

one fatty acid attached to glycerol

Question 13

A diglyceride contains?

Answer 13

two fatty acids attached to glycerol

Question 14

A triglyceride contains?

Answer 14

three fatty acids attached to glycerol

Question 15

Fats are triglycerides containing?

Answer 15

saturated fatty acids and are solids at room temperature, i.e.: lard

Question 16

Oils are triglycerides containing?

Answer 16

unsaturated fatty acids and are liquids at room temperature

Question 17

Triglycerides (fats or oils) can be hydrolyzed (broken down) to produce?

Answer 17

glycerol and three fatty acids. When a strong base is used (i.e.: NaOH), glycerol and the sodium salts
of the fatty acids are produced.

Question 18

The sodium salts of fatty acids are called?

Answer 18

Soaps

Question 19

Fat or oil + strong base———> ?

Answer 19

glycerol + soap

Question 20

Waxes are?

Answer 20

simple lipids that, like oils and fats, are also esters of fatty acids. However, the alcohol portion of a wax is derived from long-chain alcohols (12-32 carbons) rather than glycerol.

Question 21

Phosphoglycerides are a family of lipids that are similar to glycerides except that?

Answer 21

one –OH group of glycerol is replaced by the ester of phosphoric acid and an amino-alcohol.

Question 22

Structurally, steroids are easily recognized because they all contain a?

Answer 22

characteristic four-fused ring system; three cyclohexane rings and one cyclopentane ring.

Question 23

The most abundant steroid found in the human body, and the most important, is?

Answer 23

Cholesterol

Question 24

In humans, most steroids function as?

Answer 24

hormones, powerful chemical messengers that transport signals from one cell to another.

Question 25

There are two main classes of steroid hormones:?

Answer 25

the sex hormones and the adrenocortical hormones

Question 26

Sex hormones control?

Answer 26

reproduction and secondary sex characteristics

Question 27

Adrenocortical hormones regulate?

Answer 27

numerous biochemical processes

Question 28

Amino acids are organic molecules that contain?

Answer 28

an amino group and a carboxyl group

Question 29

The amino acids in proteins are called?

Answer 29

alpha (a)-amino acids because the amino group is

attached to the (a)-carbon.

Question 30

All amino acids (except proline) contain?

Answer 30

–H, -NH2, and –COOH bound to the -carbon. They are differentiated by the side chains (called R-groups) also bound to the a-carbon.

Question 31

Amino acids are classified into four groups:?

Answer 31

nonpolar, polar acidic, polar basic, and polar-neutral

amino acids.

Question 32

All a-amino acids, except glycine, are?

Answer 32

chiral because the a-carbon is bound to four

different groups.

Question 33

When writing Fischer projections for amino acids, the -COOH group is always written?

Answer 33

at the top and the R group at the bottom

Question 34

Amino acids contain?

Answer 34

an acidic group (-COOH) and a basic group (NH2).

Question 35

Individual amino acids in a protein molecule are linked by?

Answer 35

Peptide bonds

Question 36

A peptide bond forms when?

Answer 36

a carboxylic acid from one amino acid reacts with the amino group of another amino acid.

Question 37

All peptide chains will have?

Answer 37

an amino group at one end (a free, unbound -NH3

+) and a carboxylate at the other (a free –COO-).

Question 38

By convention, we draw peptides and proteins

with?

Answer 38

the N-terminal (unreacted or free amino group) on the left end of the peptide chain and the C-terminal (the carboxylate group) on the right end of the polypeptide.

Question 39

Peptides are named by listing?

Answer 39

the amino acid residues in order from the N- to C-terminal.