Chapter 12: Food proteins and enzymes

Question 1

What is a protein good for?

Answer 1

Amino acids, source of calories (energy)

Question 2

Calories:

Answer 2

amount of heat required to raise 1 g of water 1 degree

1 Calorie=1 kcal=1000 calories

Question 3

Where is energy stored?

Answer 3

Polysaccharides (glycogen) or fat (triglycerides

Question 4

Proteins

Answer 4

amino acids
20 amino acids
differ on R structure

Question 5

Fibrous Protein

Answer 5

insoluble in water

ex: muscle, connective tissue and hair

Question 6

Globular proteins

Answer 6

soluble in water

ex: eggs, dairy, enzymes, myoglobin

Question 7

Membrane proteins

Answer 7

not water soluble

transporters, receptors

Question 8

Primary 1ᵒ structure

Answer 8

the amino acid sequence

Question 9

Secondary 2ᵒ

Answer 9

local structure

• coils: alpha-helix, “random” coil
• extended: beta-strands (sheets)
• turns

Question 10

Tertiary 3ᵒ

Answer 10

overall 3-D structure

2 and 3ᵒ fold to produce 3D structure

Question 11

Quaternary 4ᵒ

Answer 11

multiple protein chains

-proteins can associate with other proteins

Question 12

Hydrolysis of protiens

Answer 12

• we reverse synthesis by chemically insert a water molecule, break apart the aa’s
  we are able to absorb and digest the individual amino acids

Question 13

Connective tissue

Answer 13

• triple helices of proline-rich peptides
• covalently cross-linked
• assembled into fibers

Question 14

How is gelatin formed?

Answer 14

collagen structure is “unwound” by heating in hot water

-the backbone forms a sol or gel of gelatin

Question 15

Red meat

Answer 15

red part is muscle protein + myoglobin

Question 16

In red meat fat between muscle is called?

Answer 16

seam fat

fat is held by connective tissue

Question 17

Within the muscle it is called

Answer 17

marbling (often prized)

Question 18

What is the contractile protein?

Answer 18

actomyosin: composed of several proteins, notably actin and myosin

Question 19

Myosin

Answer 19

is assembles in muscle fibers

Question 20

Seed Proteins

Answer 20

bran
germ
aleuron
starchy endosperm

Question 21

Starchy endosperm

Answer 21

85% of kernel
10-15% is protein
remains in white flour

Question 22

Prolamins

Answer 22

wheat proteins: storage proteins
gluten
-gliadin (mixture of proteins)

Question 23

Glutelins

Answer 23

wheat proteins
gluten
storage proteins
-glutenin (also a mixture)

Question 24

Albumins and globulins

Answer 24

wheat protein
`15% of seed protein
-cellular proteins
-enzymes

Question 25

Gluten proteins and flour types

Answer 25

high molecular weight glutenins form (S-S) crosslinks during kneading- “visco-elastic” dough

Question 26

Hard wheat

Answer 26

strong flour
bread flour (10-13% protein)
high gluten protein concentration

Question 27

Soft wheat

Answer 27

cake flour (8-10% protein)
lower gluten concentration
used for quick breads
minimally kneaded

Question 28

All-purpose flour

Answer 28

a blend of soft and hard wheat (9-12%)

Question 29

Enzymes

Answer 29

proteins
-ase
catalyze nearly all the reactions of life

Question 30

What do enzymes catalyze?

Answer 30

digestion
energy metabolism
biosynthesis
everything

Question 31

essential amino acids

Answer 31

body can not metabolize or make on its own in sufficient quantities
-must be in diets
9 of them

Question 32

Limiting amino acids

Answer 32

when a protein is low in one essential amino acid necessary for synthesis, that EAA is the limiting factor

Question 33

Protein quality

Answer 33

3. 9 hens egg
4. 1 Cows milk
5. 5 fish
6. 3 beef
7. 3 Soybeans
8. 5 Dry beans
9. 1 Corn