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
Q

culinary application of solubility

A

mosit heat tenderisises meat by converting collagen to gelantine

26
Q

Gel formation

A

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
Q

gel formation culinary application

A

cheesecakaes, jelly sweets

28
Q

foam formation

A

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