proteins⭐️ Flashcards

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1
Q

explain how amino acids are linked together to form proteins

A

amino acids form dipeptides and then polypeptides via a condensation reaction, forming peptide bonds. the water is formed from the OH group of the carboxylic acid on one amino acid and the H in the amine group of anther amino acid. this sequence of amino acids is called a primary structure

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2
Q

explain how polypeptides are arranged to form a secondary structure of a protein

A

hydrogen bonds form between the OH group of a carboxylic acid and the H group on the amine group causing the polypeptide chain to twist into an alpha helix or fold into beta pleated sheets

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3
Q

explain how the secondary structure of a protein forms the tertiary structure of the protein

A

the specific 3D structure of a protein, formed by either hydrogen bonds, disulfide bridges and ionic bonds

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4
Q

explain how to quaternary structure of a protein is formed

A

the large protein molecule is formed from two or more polypeptide chains and additional prosthetic group (non protein)

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5
Q

describe a test for proteins

A

add sample to dilute sodium hydroxide. add very dilute copper sulphate and mix. a positive test is purple colour change

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6
Q

why might two proteins have different tertiary structures if they have the same number and type of amino acid

A

different primary structure/different sequence of amino acids. different disulfide bridges, ionic or hydrogen bonds formed

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7
Q

What bond forms between amino acids?

A

Peptide bonds

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8
Q

How are polypeptides formed?

A

Amino acids linked together via a condensation reaction, forming peptide bonds and releasing a molecule of water

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9
Q

How are disulfide bridges formed?

A

Two molecules of cysteine come close together so the sulfur atom on one cysteine bonds to the sulfur atom of the other.

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10
Q

What are the four functions of proteins?

A

Enzymes, antibodies, transport proteins, structural proteins

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11
Q

What is a structural protein?

A

They consist of long polypeptide chains lying parallel to each other with cross links between them. An example is keratin and collagen. They’re physically strong

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12
Q

Discuss transport proteins as a function of proteins?

A

Present in the cell membranes such as channel proteins containing hydrophobic and hydrophilic amino acids which cause the protein to fold up and form a channel. Allows ions across the membrane

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13
Q

Discuss antibodies as a function of proteins

A

Involved in the immune response. Made up of two short polypeptide chains and two long polypeptide chains bonded together. They have variable regions

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