Biological Molecules Flashcards

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1
Q

What are the three types of carbohydrates?

A

Monosaccharides
Disaccharides
Polysaccharides

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2
Q

Define monosaccharides

A

Single sugar monomer, all are reducing sugars

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3
Q

Define disaccharide

A

A sugar formed from two monosaccharides joined by a glycosidic bond in a condensation reaction

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4
Q

Define polysaccharide

A

A polymer formed by many monosaccharides joined by glycosidic bonds in a condensation reaction

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5
Q

Define monomer

A

A small molecules that bond with many repeating subunits to form large molecules. e.g. glucose

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6
Q

Define macromolecules

A

They are long chains of molecular subunits

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7
Q

What are the two structurally different forms of glucose?

A

alpha-glucose and beta-glucose (isomers)

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8
Q

Molecular formula of glucose

A

C6H12O6

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9
Q

When does a condensation reaction occur?

A

When monomers combine by covalent bonds to form polymers or macromolecules and water is removed

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10
Q

What occurs during hydrolysis?

A

Covalent binds are broken when water is added

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11
Q

Functions of glucose (3)

A

1) Oxidised to release energy in the process of respiration
2) Glucose is the form in which carbohydrates are transported in the body
3) Building blocks for making larger molecules such as starch, glycogen and cellulose

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12
Q

What is the bond that links two glucose molecules?

A

Glycosidic bond

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13
Q

What type of sugars are glucose, fructose and maltose?

A

Reducing sugars

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14
Q

What type of sugar is sucrose?

A

Non-reducing sugar

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15
Q

Describe the breakage of glycosidic bonds with reference to the test for non-reducing tests

A

Non reducing sugars can also be tested for using Benedict’s reagent but first require addition of and heating to hydrolyse the sugar (breaks the glycosidic bond). The acid must be neutralised before doing the test

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16
Q

Function of starch

A

Main storage polysaccharide in plants

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17
Q

Describe the structure of starch

A

It consists of of two different polysaccharides, amylose and amylopectin. Amylose is unbranched helix shaped chain with 1,4 glycosidic bonds between alpha-glucose molecules. Amylopectin has 1,4 glycosidic bonds between alpha-glucose but also 1,6 glycosidic bonds form between glucose molecules creating branched molecule

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18
Q

Relate structure to function for starch

A

Amylose- the helix shape enables it to be more compact and resistant to digestion
Amylopectin- the branches may be easily hydrolysed for either respiration or storage

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19
Q

Function of glycogen

A

Main storage polysaccharide in animals and fungi

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20
Q

Describe structure of glycogen

A

Similar to amylopectin but with many more branches which are also shorter

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21
Q

Relate structure to function for glycogen

A

Is branched so it is more compact which helps animals store more, very fast hydrolysis

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22
Q

Function of cellulose

A

Main structural constituent of plant cell walls

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23
Q

Structure of cellulose

A

Long, unbranched polymers of glucose joined by beta- 1,4 glycosidic bonds. Many hydrogen bonds form between the long chains

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24
Q

Relate structure to function for cellulose

A

Hydrogen bonds are very strong and give cellulose its strength, provides strength to plant

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25
Q

What is the difference of elements in carbohydrates and lipids?

A

They consist of exactly the same elements (C, H and O) but lipids have a lower proportion of oxygen

26
Q

3 main groups of lipids

A

Triglycerides
Phospholipids
Steroids and waxes

27
Q

What type of molecules are triglycerides?

A

Non-polar, hydrophobic molecules

28
Q

How are triglyceride fats formed?

A

3 fatty acids react with glycerol to give a triglyceride fat and water. An ester bond is formed in the triglyceride fat

29
Q

Saturated fats

A

No double bonds in hydrocarbon chain

30
Q

Unsaturated fats

A

Contains one or more double bonds

31
Q

Functions of fats (3)

A

1) Energy supply, release more energy than carbohydrate. Due to their insolubility in water and compact structure, lipids have long-term storage qualities
2) Adipose cells beneath our skin which contains large quantities of fat hep insulate and maintain body temperature
3) Mechanical support around soft organs and electrical insulation around our nerve axons

32
Q

How is a phospholipid formed?

A

When a triglyceride fat reacts with phosphoric acid a phospholipid is formed

33
Q

Describe structure of phospholipid

A

Consists of a polar, hydrophilic head
And hydrophobic fatty acid tails (non-polar)

34
Q

Function of phospholipids

A

They are the main building block of cell membranes

35
Q

What are proteins made up of?

A

Carbon, hydrogen, oxygen and nitrogen and sulfur

36
Q

What are amino acids?

A

They are the building blocks required to make proteins

37
Q

Why do the 20 different amino acids all behave differently?

A

They have different R groups

38
Q

What is the smallest glycine and what is its side group?

A

Glycine. Side group- H

39
Q

How is a dipeptide formed?

A

Two amino acids react together to form a dipeptide and water. It is a condensation reaction between the COOH and the NH2 of the 2 amino acids

40
Q

Define and describe the primary structure of proteins

A

A polypeptide chain made of a sequence of amino acids. Not all have the same structure. The lengths, order, and the amino acids may be different

41
Q

Define the secondary structure of proteins

A

A polypeptide chain that forms coils or folds within itself

42
Q

What are the two types of secondary structure of proteins?

A

a-helix and B-pleated sheet

43
Q

Describe the a-helix

A

Hydrogen bonds form between NH and C-O(double bond) bonds of amino acids

44
Q

Describe the B-pleated sheet

A

This is composed by side by side chains connected by hydrogen bonds. All the peptide bonds are involved in interchain hydrogen bonding so the structure is stable

45
Q

Define the tertiary structure of proteins

A

Further folding of polypeptide chain to form specific 3-D structures

46
Q

What causes a chain to further fold into 3D structures?

A

Interaction between the R groups of amino acids. May be caused by: Hydrogen bonds, ionic bonds, disulfide bonds and weak hydrophobic interactions

47
Q

Describe the weak hydrophobic interactions

A

R groups do not want to interact with water so they interact with each other instead

48
Q

Define quaternary structure of proteins

A

A protein made up of 2 or more polypeptide chains

49
Q

What are the two types of protein?

A

Globular and fibrous protein

50
Q

State the characteristics of globular proteins

A

They are water soluble so they can easily move in watery substances to carry out chemical reactions. They are spherical in shape. (e.g. enzymes and hormones)

51
Q

State the characteristics of fibrous proteins

A

They are insoluble in water and not involved in chemical reactions. They have structural functionns. (e.g. keratin and elstin)

52
Q

Describe the structure of haemoglobin

A

Quaternary structure. Made of 4 polypeptide chains, two a-globin chains and two B-globin chains plus a haem group. It is spherical

53
Q

Relate structure to function of haemoglobin

A

Each chain has a haem group that binds to oxygen and contains iron

54
Q

Describe the structure of collagen

A

Quaternary structure made of 3 polypeptide chains that forms a triple helix. Every third amino acids in the chains are glycine which allows the polypeptide chains to tightly coil around each other

55
Q

Describe collagen fibril

A

Cross links of covalent bonds fold each collagen in a staggered manner

56
Q

Collagen fibre

A

Many collagen fibrils joining together

57
Q

Relate structure to function of collagen

A

The staggered manner provides high tensile strength. It is quite flexible

58
Q

What are the three functions of water

A

1) Water is a solvent
2) High specific heat capacity
3) High latent heat of vaporisation

59
Q

Define and describe high specific heat capacity

A

A large amount of energy is required to raise the temperature of water. Extra energy is required to break the H bonds. This helps in temperature regulation

60
Q

Define and describe high latent heat of vaporisation

A

Water liquid can absorb a lot of energy before becoming a vapour. Extra heat is required to break the H bonds between water molecules. Sweat is able to absorb lots of heat and reduce body temperature