2.6. Proteins.

Question 1

More than _______of the dry mass of most cells is protein

Answer 1

50%

Question 2

Proteins have many important functions such as?

Answer 2

-All enzymes are proteins
-Proteins are essential components of cell membranes
-Some hormones are proteins, for example, insulin and glucagon
-The oxygen carrying pigments, hemoglobin and myoglobin are proteins
-Antibodies which attack and destroy invading microorganisms are protein
-collagen is a protein that adds strength to many animal tissues, for example, bone and the wall of arteries
-hair nails, and the surface layers of skin contain the protein keratin
-actin and myosin are the proteins responsible for muscle contraction
-proteins maybe storage products for example casein in milk and ovalbumin in eggs

Question 3

What is the general structure of amino acid

Answer 3

Center carbon atom
Amino group on the right
Carboxylic acid group on the left
The functional group on the top
The hydrogen element the bottom

Question 4

Have our peptide bonds formed?

Answer 4

One element loses a hydroxyl group from its carboxylic acid group while the other loses a hydrogen group from its amino group. This leaves the carbon atom of the first amino acid free to bond with the nitrogen atom of the second.. this link is called a peptide bond

Question 5

Have our peptide bonds formed?

Answer 5

One element loses a hydroxyl group from its carboxylic acid group while the other loses a hydrogen group from its amino group. This leaves the carbon atom of the first amino acid free to bond with the nitrogen atom of the second.. this link is called a peptide bond

Question 6

What is a peptide bond?

Answer 6

The covalent bond joining neighboring amino acids together in proteins, it is a C-N link between two amino acid molecules

Question 7

A protein molecule may have just one polypeptide chain or it may have

Answer 7

Two or more chains

Question 8

Hydrolysis of protein happen naturally in

Answer 8

Stomach and small intestine during digestion of proteins in food

Question 9

What is the primary structure?

Answer 9

The particular amino acids contained in the chains and the sequence in which they joined

Question 10

How is the secondary structure formed?

Answer 10

The amino acids in a polypeptide chain may have an effect on each other, even if they’re not next to each other in the primary sequence of amino acids. This is because the polypeptide chain can bend back on itself. Polypeptide chain, or part of it often calls into a cockscrew shape forming a secondary structure called alpha helix

Question 11

What causes the secondary structure?

Answer 11

The hydrogen bonding between the oxygen of C=O group of one amino acid and the hydrogen of -NH of the amino acid four places ahead of it

Question 12

Sometimes hydrogen bonding in proteins can lead to

Answer 12

Result in a much looser straighter shape than the alpha helix which is called a beta pleated sheet

Question 13

Sometimes hydrogen bonding in proteins can lead to

Answer 13

Result in a much looser straighter shape than the alpha helix which is called a beta pleated sheet

Question 14

What is the secondary structure?

Answer 14

The structure of a protein molecule, resulting from the regular coiling or folding of the chain of amino acids(m

Question 15

What is alpha helix?

Answer 15

A helical structure formed by a polypeptide chain held in place by hydrogen bond

Question 16

What is a beta pleated sheet?

Answer 16

A loose sheet like structure formed by hydrogen bonding between parallel polypeptide chains

Question 17

Although the hydrogen bonds are strong enough to hold the alpha helix and beta- plated sheet structures in shape, they are easily broken by

Answer 17

High temperatures and pH changes

Question 18

Why do some proteins have no regular arrangement in its secondary structure

Answer 18

Some proteins do not show regular arrangement because it depends on which R groups are present and what attraction occurs between amino acids in the chain

Question 19

What is tertiary structure?

Answer 19

The compact structure of a protein molecule, resulting from three dimensional coiling of the chain of amino acids
The secondary structure is itself coiled or folded to form the tertiary structure

Question 20

What are the four types of bond that helped to keep folded proteins in their precise ship?

Answer 20

-hydrogen bonds
-Disulfide bonds from between two cysteine(a sulphur containing amino acids) molecules contain sulfur atom.
-ionic bonds form between R groups containing amino and carboxyl groups
-hydrophobic interactions that occur between R groups that are non polar. Such R groups are hydrophobic so tend to avoid water if possible. If the protein is in a typical watery environment inside the cell, then the hydrophobic R groups tend to come together excluding water.

Question 21

How are the R groups that are hydrophobic and hydrophilic present in a tertiary structure?

Answer 21

The R groups are typically oriented towards the center of the proteins facing away from the watery environment, with the hydrophilic R groups surrounding them and pointing towards and in contact with the watery environment

Question 22

How are the R groups that are hydrophobic and hydrophilic present in a tertiary structure?

Answer 22

The R groups are typically oriented towards the center of the proteins facing away from the watery environment, with the hydrophilic R groups surrounding them and pointing towards and in contact with the watery environment

Question 23

What is the quarternary structure?

Answer 23

The three dimensional arrangement of two or more polypeptides or of polypeptide and non protein component such as haemoglobin

Question 24

How is hemoglobin an example of protein with quaternary structure?

Answer 24

It has four polypeptide chains

Question 25

What is a globular protein?

Answer 25

Protein whose molecules are folded into a relatively spherical shape.

Question 26

What is a globular protein?

Answer 26

Protein whose molecules are folded into a relatively spherical shape.

Question 27

Why do globular protein usually usually curl up?

Answer 27

So that there are nonpolar hydrophobic R groups point into the center of the molecule away from the watery surroundins. Water molecules are excluded from the center of the folded protein molecule. The polar hydrophilic R good remain on the outside of the molecule

Question 28

Why are globular proteins usually soluble?

Answer 28

Because water molecules cluster around their outward pointing hydrophilic R groups

Question 29

What are some examples of globular proteins?

Answer 29

Myoglobin, hemoglobin insulin and enzymes

Question 30

What are fibrous proteins?

Answer 30

The protein molecules, which form long strands. A protein whose molecule have a relatively thin, long structure that is generally insoluble and metabolically in active and whose function is usually structural

Question 31

What is an example of fibrous protein?

Answer 31

Keratin which forms hair nails and the outer layers of skin making the structures waterproof
Collagen

Question 32

What kind of chains is hemoglobin made up of?

Answer 32

Eat chain is a protein known as globin. Globin is related to myoglobin and so has a very similar tertiary structure.

Question 33

What kind of chains is hemoglobin made up of?

Answer 33

Eat chain is a protein known as globin. Globin is related to myoglobin and so has a very similar tertiary structure.

Question 34

What types of globin are used to make hemoglobin?

Answer 34

There are many types of globin- 2 types are used to make hemoglobin, and these are known as alpha globin and beta globin. Two of the hemoglobin chains known beta chains and alpha chains are made from them

Question 35

What is important in holding together the correct three dimensional shape of protein

Answer 35

The interaction between the hydrophobic R groups inside the molecule

Question 36

What is important in holding together the correct three dimensional shape of protein

Answer 36

The interaction between the hydrophobic R groups inside the molecule

Question 37

What causes sickle cell anemia

Answer 37

One amino acid(glutamic acid- which is polar) on the surface of beta chain is it replaced with a different amino acid(valine- non polar). Having a non-polar R group on the outside of the molecule makes the hemoglobin much less soluble.

Question 38

What is prosthetic group?

Answer 38

An important and permanent part of the protein molecule, which is not made of amino acids

Question 39

What is the prosthetic group in each of the polypeptide chains in haemoglobin?

Answer 39

Haem group

Question 40

How does hemoglobin carry oxygen?

Answer 40

Each haem group contains an iron atom. One oxygen molecule can bind with each iron atom.
A complete hemoglobin can carry eight oxygen atoms at a time

Question 41

How does hemoglobin carry oxygen?

Answer 41

Each haem group contains an iron atom. One oxygen molecule can bind with each iron atom.
A complete hemoglobin can carry eight oxygen atoms at a time

Question 42

How does the haem group change the color of haemoglobin?

Answer 42

The color changes, depending on whether or not the iron atoms are combined with oxygen. if they are the molecules known as oxyhemoglobin and is bright red. If not, the color is a darker more bluish red.

Question 43

Collagen makes up up to_____of total protein in mammals

Answer 43

25%