PROTEIN Flashcards

1
Q

What elements are protein made up of

A

carbon hydrogen oxygen nitrogen

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2
Q

what is the chemical structure of proteins

A

proteins are large molecules composed of amino acids

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3
Q

basic structure of amino acids

A

NH2 to the left carbon in the middle H to the top R down below and cooh to the right

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4
Q

what is essential amino acids

A

cannot be manufactored by the therefore need to be obtained by food
example is lysine and leucine

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5
Q

what is non essential amino acid

A

can be manufactored by the body therefore dont need to be obtained by food
examples glycine proline

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6
Q

how is a peptide bond formed

A

a peptide bond is formed when two amino acids join together. the cooh loses a oh and the nh2 loses a h the oh and h join togther and make up a H20 molecule which is water that is then loss. this is called a codensation reaction

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7
Q

what is the strcuture of proteins

A

primary structure, secondary structure, tertiary structure

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8
Q

what is primary structure

A

involves the order or sequence of amino acids in protein chains

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9
Q

what is secondary structure

A

secondary structure involves the folding of primary structure of proteins into defiinite shapes.

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10
Q

what are the two types of crosslinks

A

disulfide bonds and hydrogen bonds

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11
Q

what is a disulfide bond

A

occurs when 2 sulfur of two amino acids join together to form either a single polypeptide chain or two different polypeptide chains

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12
Q

what is a disulfide bond

A

occurs when 2 sulfur of two amino acids join together to form either a single polypeptide chain or two different polypeptide chains

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13
Q

what is a disulfide bond

A

occurs when a hydrogen from the nh group of one amino acid and an oxygen from the c=o group of another amin acid join together to form either a single polypeptide chain or two different polypeptide chains

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14
Q

what is a tertiary structure

A

involes the folding of the secondary structure of proteins into three dimensional shapes.

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15
Q

what is denaturation

A

change in nature of a protein shape. unfolding of a
protein chain. resuting in an irreversible change in shape.
can be caused by heat enzymes, mechanical action. whipping and beating

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16
Q

what are the causes of denaturation

A

heat, enzymes,mechanical action

17
Q

heat

A

causes protein chain to unfold and bond together. causing food to coagulate and set.

18
Q

enzymes

A

cause a change to the nature of proteins structure

19
Q

elasticity

A

some fibrous proteins, eg gluten in wheat, are quite elastic

20
Q

culinary application of elasticity

A

gluten makaes yeast dough elastic enough to trap the CO2 gas produced bby yeast, helping it rise

21
Q

heat culinary application

A

eggs white coagulate and change from translucent to opaque at 60 degress celcius and egg yolks coagulate at 68 degrees celcius

22
Q

maillard reaction

A

the non enzymic browning of foods due to certain amino acids and sugars under dry heat. it produces an attractive brown colour and a crust with an appetising flavour

23
Q

maillard reaction culinary appliacation

A

roast potatoes and roast meat

24
Q

solubility

A

most proteins are insoluble in water. apart from collagn in meat.
and egg albumin

25
culinary application of solubility
mosit heat tenderisises meat by converting collagen to gelantine
26
Gel formation
gelatine can absorb large amounts of water when heated as protein chains uncoil and water becomes trapped. this froms a solution on cooling a solution forms a gel, a semi solid viscous solution that has a 3 dimensional protein matrix
27
gel formation culinary application
cheesecakaes, jelly sweets
28
foam formation
when an egg white is whisked, protein chains unfold and air bubbles form. protein chain entrap air creating a foam whisking also creates heat that begins to set the egg albumin (known as temporary foam) foam will collapse after a while unless subjected with heat