protein (undone)

Question 1

what is the elemental composition of protein

Answer 1

carbon (C), hydrogen (H), oxygen (O), and nitrogen (N) and contain small amounts of sulfur (S) , iron (Fe) and phosphorus (P)

Question 2

what is the chemical structure of protein

Answer 2

proteins are large molecules composed of amino acids. amino acids are joined together by peptide links to form long polypeptide chains that make up proteins

Question 3

what is the basic structure of an amino acid

Answer 3

-an amino group (NH2) (basic)
-a carboxyl group (COOH) (acidic)
-a central carbon (C)
-a single hydrogen (H)
-a variable group (R): changes with each amino acid

Question 4

what are essential amino acids

Answer 4

cannot be manufactured by the body, therefore must be obtained from food

Question 5

give examples of essential amino acids

Answer 5

-valine
-lysine
-leucine
-isoleucine

Question 6

what are non-essential amino acids

Answer 6

can be manufactured by the body, therefore don’t need to be obtained from food

Question 7

give examples of non-essential amino acids

Answer 7

-serine
-glycine
-glutamic acid
-alanine

Question 8

how are peptide links formed

Answer 8

are formed when two amino acids join together. this results in the loss of a water molecule and is called a condensation reaction

Question 9

what are the stages in formation of peptide links

Answer 9

1. the COOH (acidic) group of one amino acids reacts with the NH2 (basic) group of another
2. the COOH (acidic) group loses an OH group. the NH2 (basic) group loses a hydrogen (H) atom 3. the result is a CO-NH bond. this new molecule is called dipeptide . when more than 20 amino acids join together, a polypeptide is formed. when more than 50 amino acids join together, a protein is formed. each protein consists of one or more polypeptide

Question 10

what is the reverse of the condensation reaction called

Answer 10

hydrolysis

Question 11

what is a primary structure

Answer 11

is the order or sequence of amino acids in protein chains, e.g. insulin contains 51 amino acids

Question 12

what is a secondary structure

Answer 12

involves the folding of the primary structure into definite shapes

Question 13

what are the main two types of cross-links

Answer 13

disulfide bonds and hydrogen bonds

Question 14

how do disulfide bonds occur

Answer 14

occur when two sulphurs from two amino acids from either a single polypeptide chain link together

Question 15

how do hydrogen bonds form

Answer 15

occurs when a hydrogen (N-H) from one amino acid group and an oxygen (C=0) from another amino acid group are joined together from either one or two Polypeptide Chains.

Question 16

what is a tertiary structure

Answer 16

involves the folding of the secondary structure of proteins into three dimensional shapes. form definite shapes such as fibrous and globular

Question 17

how are fibrous shapes arranged

Answer 17

polypeptide chains are arranged in straight, spiral or zigzag shapes

Question 18

what are the properties of fibrous shapes

Answer 18

-insoluble in water
-not easily denatured

Question 19

give examples of fibrous shapes

Answer 19

-gluten (wheat)
-elastin and collagen

Question 20

how are globular shapes arranged

Answer 20

polypeptide chains are arranged in a globular shape

Question 21

what are the properties of globular shapes

Answer 21

-soluble in water
-easily denatured

Question 22

give examples of globular shapes

Answer 22

-ovalbumin (egg whites)
-lactalbumin (milk)

Question 23

what is high biological value proteins

Answer 23

contain all the essential amino acids

Question 24

give sources of HBV proteins

Answer 24

egg, fish, milk, meat, cheese

Question 25

what is low biological value proteins

Answer 25

lack one or more of the essential amino acids

Question 26

give sources of LBV proteins

Answer 26

rice, wheat, maize, meat bones

Question 27

what are the properties of protein

Answer 27

denaturation, elasticity, maillard reactionm solubility, gel