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Biological Molecules Flashcards

1
Q

What are monosaccharides?

A

They are molecules that contain elements of carbon, hydrogen and oxygen. They have a general formula of (CH2O)n where n is the number of carbon atoms. Examples include glucose, fructose and galactose.

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2
Q

What are isomers?

A

It is two or more compounds with the same formula but different arrangements. Therefore, they have different properties.

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3
Q

What are the glucose isomers?

A

They are alpha glucose and beta glucose.

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4
Q

What is the difference between alpha and beta glucose?

A

The order of the OH and H groups are reversed in alpha and beta glucose. In alpha, H is at the top but in beta, OH is.

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5
Q

What are disaccharides?

A

They are two monosaccharides joined together by a condensation reaction. This means a glycosidic bond is formed between them and an H2O molecule is released.

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6
Q

What is a condensation reaction?

A

This is when two molecules are combined to form one molecule and a water molecule is released.

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7
Q

What is hydrolysis?

A

This is when the bonds between molecules are broken down due to the addition of a water molecule. Amylase is an example of a hydrolytic enzyme which is in saliva to break down starch.

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8
Q

Name three common disaccharides.

A

Common disaccharides include maltose (made of two glucose molecules), sucrose (made of one glucose molecule and one fructose molecule) and lactose (made of one galactose molecule and one glucose molecule). Maltose is found in malt sugar, sucrose is table sugar and lactose is milk sugar.

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9
Q

What are polysaccharides?

A

They are made of more than two monosaccharides, which are joined by condensation reactions and have a glycosidic bond between.

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10
Q

Name three common polysaccharides.

A

Starch and glycogen are polyaccharides made with alpha glucose and cellulose is made with beta glucose.

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11
Q

What two alpha glucose polysaccharides make starch and how is it good for plants?

A

They are amylose and amlyopectin make starch. It’s helical structure means lots of glucose can be stored and side branches release it quickly. Starch is also insoluble in water so its water potential (pressure of water molecules on a membrane) is not affected and the cell doesn’t swell.

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12
Q

Describe amylose.

A

It is a long chain of alpha glucose, in a helical structure because of the glycosidic bond angles. This makes it compact, so lots of glucose can be stored in a small space. It has no branches, which means enzymes are slower to break it down as they only have two entrances.

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13
Q

Describe amylopectin.

A

It is a very long, branched chain of alpha glucose and enzymes can break it down easily due to its many side branches. As a result, glucose is released quickly which is helpful for when plants need energy rapidly.

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14
Q

Describe glycogen.

A

Animals store excess glucose as glycogen because of its compact helical structure and side branches, which mean glucose can be released quickly.

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15
Q

Describe cellulose.

A

It provides structural support in plant cell walls as each cellulose chain is linked by hydrogen bonds, which make strong fibres called microfibrils for structure. It is a long, unbranched chain of beta glucose which means it is straight as the angles don’t curve it. Therefore, many can be linked together for microfibrils.

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16
Q

What are lipids?

A

They are not polymers and they all contain hydrocarbons e.g. triglycerides and phospholipids.

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17
Q

What are triglycerides?

A

They are made of one glycerol molecule (an alcohol made of 3 carbons and 3 OH groups) and three fatty acids. The fatty acids are the hydrocarbon tails.

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18
Q

What are the differences between saturated and unsaturated fatty acids?

A

Saturated fatty acids don’t have any carbon double bonds and tend to be solid at room temperature. Unsaturated fatty acids have carbon double bonds and tend to be liquid at room temperature.

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19
Q

How are triglycerides formed?

A

They are formed by condensation reactions and an ester bond is formed between the fatty acids and glycerol, releasing a water molecule.

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20
Q

What are some properties of triglycerides?

A
  • They are used as long term storage molecules due to their insolubility.
  • Their hydrocarbon tails contain lots of chemical energy which is released when broken down (double that of carbohydrates).
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21
Q

What are miscelles?

A

They are made of triglycerides bundled together. The fatty acids tails face inwards to shield themselves from water because they are hydrophobic.

22
Q

What are phospholipids?

A

They are a type of lipid found in cell membranes. They are made from one glycerol molecule, two fatty acids (hydrophobic) and a phosphate group (hydrophilic) attached by ester bonds.

23
Q

What are some properties of phospholipids?

A
  • They made phospholipid bi-layers, used in cell membranes, in order to control what enters and leaves the cell.
  • The phospholipid heads (glycerol) are hydrophilic (loves water) and tails are hydrophobic so form a double layer where the heads face outwards and tails are internal.
  • The bi-layer centre is made of hydrophobic tails so water-soluble substances can’t pass through it and the membrane acts as a barrier.
24
Q

What do amino acids make?

A
  • Two amino acids make a dipeptide.
  • More than two amino acids make a polypeptide.
  • One or more polypeptides make proteins. They must have over 100 million amino acids.
25
What is the structure of an amino acid molecule?
- amino group (H2N) - carboxyl group (COOH) - variable group (changes depending on the amino acid) - carbon atom - hydrogen atom
26
How are dipeptides and polypeptides produced?
Amino acids are linked together by condensation reactions, which release a water molecule. The bonds formed between amino acids are called peptide bonds. Each amino acid is linked by carbon atom (from COOH) to nitrogen (from amino group).
27
What are the structures of proteins?
They have 4 levels of structure. There are primary, secondary, tertiary and quaternary structures.
28
What is the primary structure of a protein?
This is the sequence of amino acids in a polypeptide chain.
29
What is the secondary structure of a protein?
This is the coiling of a polypeptide chain into an alpha helix or the folding of it into a beta pleated sheet. This happens because the polypeptide chain doesn't remain flat and straight and hydrogen bonds form between amino acids to cause the coiling/folding.
30
What is the tertiary structure of a protein?
- This is when the coiled/folded chain coil/fold further as bonds (hydrogen, ionic, disulphide) form between different parts of the polypeptide chain. - Disulphide bonds/bridges form between sulphur atoms of the amino acid called cysteine. They are strong, covalent bonds.
31
What is the quaternary structure of a protein?
While the tertiary structure is usually the last level, those proteins with multiple polypeptide chains (e.g. haemoglobin & collagen) use the quaternary structure to assemble each chain together.
32
What is the shape and function of haemoglobin?
Shape - compact and soluble for ease of transport Function - Makes it great for carrying oxygen around the body
33
What is the shape and function of enzymes?
Shape - roughly spherical, due to tight folding of polypeptide chains and soluble Function - Often have roles in the metabolism
34
What is the shape and function of antibodies?
Shape - made of light polypeptide chains and two heavy polypeptide chains bonded together. They also have variable regions and variable amino acid sequences Function - involved in immune response in blood
35
What is the shape and function of transport proteins?
Shape - contain hydrophobic and hydrophilic amino acids, causing the protein to fold up and form a channel Function - move molecules across the plasma membrane (e.g. during active transport)
36
What is the shape and function of structural proteins?
Shape - consist of long polypeptide chains parallel to each other, with cross links between Function - physically strong to act as a great supportive tissue (e.g. keratin & collagen)
37
What are prosthetic groups?
They are extra groups added to proteins. For example, haemoglobin has a prosthetic group that contains iron. Conjugated proteins are proteins that have a prosthetic group (e.g. chlorophyll & mucus).
38
What is the induced fit model?
This is when the substrate doesn't exactly fit into the active site so they react and the active site changes shape. Therefore, they are able to bind together and form an enzyme-substrate complex.
39
What do enzymes do?
They lower the activation energy (amount of energy that needs to be supplied to chemicals before a reaction starts) so reactions happen at a lower temperature and speed up the rate of reaction.
40
What is an enzyme-substrate complex?
This occurs when a substrate fits into an enzyme's active site. It lowers the activation energy by holding two molecules so close together that the repulsion between them is reduced and they bond together. Or, the active site puts a strain on bonds so the molecule breaks more easily.
41
What are the models of enzyme action?
1. Lock and key model - substrate fits into the enzyme active site perfectly as they have a complementary shape. This has been contradicted by new evidence. 2. Induced fit model - The substrate slightly changes shape to fit the active site, which is why enzymes are so specific.
42
What is denaturation?
- tertiary structure of protein is altered and shape changed (by conditions e.g. pH or temperature, or a mutation) - substrate can't fit into active site
43
What factors effect enzymes?
- temperature - pH - enzyme concentration - substrate concentration
44
What is the formula for Q10?
(rate at x degrees celcius + 10 degrees celcius) / rate at x degrees celcius
45
How does temperature effect enzymes?
- increasing temps from 0 - molecules gain kinetic energy so there are more collisions between enzymes and substrates (= more enzyme-substrate complexes) - optimum temperature at 40 - maximum rate of reaction - increasing temps after 40 - too much kinetic energy means active site changes shape and denatures enzyme
46
How does pH effect enzymes?
- increasing pH (acidic) - H+ ions break bonds and enzymes denature - optimum pH (7) - maximum rate of reaction - increasing pH (alkaline) - OH- ions break bonds and enzymes denature
47
How does substrate concentration effect enzymes?
- at first, more substrate molecules = more enzyme-substrate complexes form - then, when all active sites are occupied by substrates, enzyme concentration is a limiting factor (saturation point)
48
How does enzyme concentration effect enzymes?
- at first, more enzyme molecules = more enzyme-substrate complexes form - then, all substrate molecules are acted upon so substrate concentration is a limiting factor
49
What is an inhibitor?
It stops enzymes in reactions.
50
What are competitive inhibitors?
- non-allosteric - similar shape to substrates - compete with substrates to bind to active site - block the active site so no substrates can fit it - more inhibitor = fewer substrates get in = fewer reactions - more substrates = higher chance of getting in
51
What are non-competitive inhibitors?
- allosteric - bind to substrate away from active site - the active site changes shape so substrates cannot fit in anymore - increasing concentration of substrate won't make a difference as enzyme activity is permanently inhibited
52
What does allosteric and non-allosteric mean?
Allosteric is when the substrate changes shape, and non-allosteric is when the active site changes shape.

Biology (8 decks)

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