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Flashcards in The structure of proteins Deck (27)
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1

What elements do proteins contain?

Carbon, hydrogen, oxygen and nitrogen

2

How many different amino acids are found in cells?

20

3

Why are 5 of these 20 amino acids found in cells classified as non-essential?

Because our bodies can make them from other amino acids

4

How many amino acids can we only obtain from food? (and therefore are essential)?

9

5

Why are 6 of these 20 amino acids found in cells classified as conditionally essential?

because they are only required by infants and growing children

6

What part of the amino acid determines its type?

The R group

7

Draw the structure of an amino acid and label its different parts

d

8

Describe how two amino acids undergo a condensation reaction

The amine (-NH2) group of one amino acid and the carboxyl group (-OOH) of the other react and join to a central carbon atom. It is able to do this because the hydroxyl (-OH) in the carboxylic acid group (-OOH) reacts with one hydrogen atom in the amine group (-NH2) of the other amino acid. A water molecule (H20) is produced and a peptide bond is formed between the two amino acids

9

What is the name of the bond formed between two amino acids?

A peptide bond

10

What is always produced in a condensation reaction?

Water

11

What is the name of two amino acids joined together?

A dipeptide

12

What is the name of two or more amino acids that have joined together?

A polypeptide

13

What is the name of the enzyme that helps speed up the reaction for the condensation of amino acids?

peptidyl transferase

14

Where is peptidyl transferase found?

In ribosomes

15

What are ribosomes known for in regards to proteins?

Ribosomes are the site of protein synthesis

16

How are polypetides able to fold into complex and unique structures?

The R groups on the amino acids are able to form bonds which fold the polypeptide chains. The different sequence of R groups make the chains fold in unique ways.

17

What is the definition of the primary structure of proteins?

It is the sequence in which the amino acids are joined

18

What is the definition of the secondary structure of proteins?

It is the formation of hydrogen bonds within the amino acid chain

19

What are the two ways in which the formation of hydrogen bonds can alter the shape of the amino acid chain?

The hydrogen bonds may create a alpha helix type structure Or the hydrogen bonds may form between parallel polypeptide chains which would create a beta pleated sheet structure.

20

What is the definition of the tertiary structure of proteins?

It is when the R groups interact with each other to enable further folding of the polypeptide chain.

21

What are the 4 interactions that could occur between the R groups?

Hydrophobic and hydrophilic interactions Hydrogen bonds Ionic bonds Disulfide bonds (also known as disulfide bridges)

22

What are Hydrophobic and hydrophilic interactions?

They are weak interaction between polar and non-polar R groups

23

What are Hydrogen bonds?

They ate the weakest of the bonds formed and they are between the delta charges

24

What are Ionic bonds?

These are stronger than hydrogen bonds and form between oppositely charged R-groups

25

What are Disulfide bonds (also known as disulfide bridges)?

These are covalent and so the strongest of all the bonds. However, they only occur between R-groups that contain sulfur atoms

26

What is the definition of the Quaternary structure of proteins?

It is the interaction between two or more identical or different protein chains (as opposed to within one protein chain). The interactions between the sub-units are the same in tertiary structure.

27

How are peptides broken back into their individual amino acids?

A water molecule is added to break the peptide bond in a hydrolysis reaction. A enzyme named protease catalyses the reaction.