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Biology 3.1 Biological molecules > proteins > Flashcards

proteins Flashcards

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1
Q

what are amino acids?

A

monomers that make up a polymer called a polypeptide which can combine to make proteins

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2
Q

what is the central carbon atom on an amino acid attached to?

A

-amino group (-NH2)
-carboxyl group (-COOH)
-hydrogen (-H)
-R group - a variety of different chemical groups which cause amino acids to differ

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3
Q

how many types of naturally occurring amino acids are there?

A

20

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4
Q

what element do amino acids have which differs them from carbohydrates and lipids?

A

nitrogen

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5
Q

which additional element do some amino acids have?

A

sulfur

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6
Q

what is a polypeptide?

A

many amino acids chemically joined by peptide bonds

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7
Q

what is a dipeptide?

A

two amino acids chemically joined together by a peptide bond

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8
Q

describe a condensation reaction to join two amino acids to form a dipeptide?

A

reaction is between the carboxyl group of one amino acid and the amine group of the second amino acid. Water is removed and a peptide bond is formed

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9
Q

what do polypeptide bonds have?

A

they always have an amine group on one side and a carboxyl group on the other

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10
Q

what is the primary structure of proteins?

A

the sequence of amino acids in the polypeptide chain, held together by peptide bonds

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11
Q

what is the secondary structure of proteins?

A

folding/ coiling of the polypeptide chain into an alpha helix or beta pleated sheet held by hydrogen bonds

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12
Q

which part of the amino acids do hydrogen bonds form in the secondary structure?

A

between the hydrogen on the amine group and the oxygen on the carboxyl group

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13
Q

what is the tertiary structure of proteins?

A

further folding of the secondary structure to form a 3D shape, held by disulphide bridges, ionic bonds and hydrogen bonds

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14
Q

where do disulphide bridges form on cysteine amino acids and what kind of bonds are they?

A

between two sulphurs from two different R groups
covalent

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15
Q

list the bonds that hold the tertiary structure in place in order of strength?

A
  1. disulphide bridges
  2. ionic bonds
  3. hydrogen bonds
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16
Q

what determines where bonds form on the tertiary structure?

A

DNA code determines sequence of amino acids

17
Q

what is a quaternary structure of proteins?

A

the 3D shape that forms when there’s more than one polypeptide chain

18
Q

what are the two types of proteins?

A

globular and fibrous

19
Q

what are some examples of globular proteins?

A

enzymes, plasma proteins, haemoglobin, antibodies

20
Q

why are globular proteins soluble?

A

they carry out metabolic reactions

the parts of the polypeptide chain with hydrophobic R groups are in the centre of the molecule and the hydrophilic R groups are on the outside

21
Q

why are globular proteins being soluble an advantage for enzymes and plasma proteins?

A

enzymes are in solution so they can catalyse chemical reactions

plasma proteins are dissolved in water of the blood plasma, and they lower water potential of the blood

22
Q

what are fibrous proteins?

A

structural molecules

23
Q

what are examples of fibrous proteins?

A

keratin
collagen

24
Q

describe the structure of collagen?

A

-primary structure is an unbranched polypeptide chain
-secondary structure the polypeptide chain is coiled and held together by hydrogen bonds
-lots of the amino acid glycine helps close packing
-in the tertiary structure, the helix is twisted into a second helix held together by disulphide brides, ionic bonds and hydrogen bonds
-its quaternary structure is made of three such polypeptide chains wound together like a rope (fibre)

25
Q

how is collagen insoluble?

A

-external R groups on the molecule are non polar
-it is large
-straight tertiary structure

26
Q

how are collagen molecules in the fibre arranged?

A

so that the end of one fibre is not in line with the end of another- means there isn’t a weak spot in the structure which would lead to a tendon breaking under force of muscle contraction

Biology 3.1 Biological molecules (9 decks)

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