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Biological Molecules Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What are polymers?

A

Large, complex molecules composed of a long chain of repeating units of monomers.

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2
Q

What are monomers?

A

Small, basic molecular units that can form a polymer.

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3
Q

Examples of monomers.

A

Amino acids, nucleotides, monosaccharides

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4
Q

How are polymers formed?

A

Condensation reactions
Chemical bonds form between long chain of monomers
A molecule of water is released

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5
Q

How are polymers broken down?

A

Hydrolysis reactions
Water molecule breaks down the chemical bond between monomers

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6
Q

What are the common monosaccharides?

A

Glucose, galactose, fructose

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7
Q

What are isomers?

A

Molecules with the same molecular formula but different arrangement (alpha glucose and beta glucose)

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8
Q

How are disaccharides formed?

A

Condensation reactions
(1,4 or 1,6) Glycosidic bonds hold the monosaccharides together
A molecule of water is also released

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9
Q

What are the common disaccharides?

A

glucose + glucose = maltose
glucose + fructose = sucrose
glucose + galactose = lactose

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10
Q

Alpha glucose arrangement

A

DDUD

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11
Q

Beta glucose arrangement

A

UDUD

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12
Q

What is Benedict’s test for reducing sugars?

A

Add Benedict’s reagent to sample and place in water bath that has been brought to boil.
+ result = coloured precipitate (green > yellow > orange > brick red)

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13
Q

How could you measure the quantity of reducing sugar in a solution? (2 ways)

A

Filter + dry + weigh precipitate
Use a colourimeter to measure absorbance of the remaining Benedict’s reagent

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14
Q

What is Benedict’s test for non-reducing sugar?

A

Add dilute HCl to sample
Place it in water bath that has been brought to a boil
Neutralise it with sodium hydrogen carbonate
Carry out Benedict’s test

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15
Q

Why is dilute HCl added to the sample?

A

To break the molecule down into monosaccharides.

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16
Q

What is starch?

A

A polysaccharide made up of alpha glucose monomers and is used as the main store of energy in plants. It is a mixture of the two polysaccharides: amylopectin (1,4 and 1,6) and amylose (1,4).

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17
Q

What are the properties of starch?

A

Amylose= coiled = compact = good for storage
Amylopectin = branched = quickly hydrolysed = glucose can be released quickly
Insoluble = prevents osmotic lysis = doesn’t affect water potential = water doesn’t enter or leave by osmosis

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18
Q

What is glycogen?

A

A highly branched polysaccharide made up of alpha glucose monomers and is the main storage of energy in plants and animals.

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19
Q

What are the properties of glycogen?

A

Coiled = compact = good for storage
Branched = quickly hydrolysed = glucose can be released quickly
Insoluble = prevents osmotic lysis = doesn’t affect water potential = water doesn’t enter or leave by osmosis
1,4 & 1,6 glycosidic bonds

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20
Q

What is cellulose?

A

A polysaccharide made up of beta glucose monomers that provide structural support to cell walls.

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21
Q

What are the properties of cellulose?

A

Long and unbranched chains of beta glucose
Insoluble = prevents osmotic lysis
Cellulose chains are linked together by hydrogen bonds to form microfibrils = provide high tensile strength
Hydrogen bonds strong in large numbers
1,4 glycosidic bonds

22
Q

What is the structure of an amino acid?

A

A carboxyl group (-COOH)
An amine group (-NH2)
R group attached to a carbon atom

23
Q

How are dipeptides and polypeptides formed?

A

Dipeptides are formed by the condensation of two amino acids
Polypeptides are formed by the condensation of many amino acids.
A molecule of water is also released
Peptide bonds

24
Q

What is the primary structure of a protein?

A

Sequence of amino acids in a polypeptide chain held by peptide bonds.

25
Q

What is the secondary structure of a protein?

A

Hydrogen bonds form between the amino acids in the polypeptide chains
This automatically coils into an alpha helix or folds to form beta pleated sheets

26
Q

What is the tertiary structure?

A

Further folding of the amino acid chain to form a 3D structure
Held in place by hydrogen, ionic, and disulphide bonds.

27
Q

What is the quaternary structure?

A

Made up of more than one polypeptide chain.

28
Q

What is the test for proteins?

A

Biuret test
Add Biuret reagent to sample
Positive result: colour change from blue to lilac

29
Q

What type of protein are enzymes?

A

3D tertiary structure globular proteins

30
Q

What are enzymes?

A

A biological catalyst that increases the rate of reaction by providing a lower activation energy of the reaction they catalyse.

31
Q

What is the active site?

A

The active site of an enzyme is where the substrate binds to and therefore has a specific shape.

32
Q

Why is the active site specific?

A

Due to the bonding in the tertiary structure.

33
Q

Why do enzymes enable reactions to take place at lower temperatures?

A

Heat is provided as the activation energy
Enzymes lower the activation energy
So less heat is needed to for a lower activation energy

34
Q

What is an enzyme-substrate complex?

A

When a substrate fits into an enzyme’s active site.

35
Q

Why does an enzyme-substrate complex lower the activation energy?

A

1) Two substrate molecules bonding together = closer in active site = reduces repulsion = bonds are easily made between molecules
2) Enzyme catalysing breakdown reaction = puts strain on bonds = bonds break more easily

36
Q

What does the lock and key model consist of?

A

The substrate having a complementary shape to the enzymes active site.

37
Q

What is the induced fit model?

A

The substrate isn’t complementary to the active site
Bonds in enzymes slightly distort which changes the shape of the active site
Active site moulds around the substrate and is now complementary

38
Q

What are the properties of an enzyme related to?

A

The enzymes tertiary structure
Different enzyme = different tertiary structure = different active site

39
Q

What are the six factors affecting enzyme activity?

A

Temperature
pH
Substrate concentration
Enzyme concentration
Competitive inhibitors
Non-competitive inhibitors

40
Q

How does temperature affect enzyme activity?

A

Too low = low kinetic energy = number of successful collisions between substrate and active site decrease = less enzyme-substrate complexes form
Too high = bonds holding enzyme break = changes shape of active site = no enzyme-substrate complex = enzyme is denatured

41
Q

How does pH affect enzyme activity?

A

Too high = H+ ions in acids and OH- ions in alkalis break the hydrogen and ionic bonds = changes shape of active site

42
Q

How does substrate concentration affect enzyme activity?

A

Rate of reaction increases
More substrate = more likely for collisions to happen between active site and substrate = more enzyme-substrate complexes form

43
Q

What is the saturated point due to substrate concentration?

A

A point where substrate concentration has no effect on rate of reaction because too many active sites have been filled

44
Q

How does enzyme concentration affect enzyme activity?

A

Rate of reaction increases
More enzymes = more likely for collisions to happen between active site and substrate = more enzyme-substrate complexes form
Until substrate concentration is the limiting factor

45
Q

How do competitive inhibitors affect enzyme activity?

A

Competitive inhibitors have similar shapes to the enzymes active site = join and occupy the active site = prevents substrate joining to active site = prevents reaction

46
Q

How do non-competitive inhibitors affect enzyme activity?

A

Attach onto the enzyme away from the active site = alters shape of active site = substrate can no longer bind to active site

47
Q

What are the 5 properties of water?

A

1) Metabolite in important reactions in condensation and hydrolysis reaction
2) Important solvent in which metabolic reactions can occur
3) High SHC acts as a buffer against sudden temperature changes
4) Large Latent Heat of Vapourisation provides a cooling effect with little water loss
5) Strong cohesion between water molecules to support the transport of water and provides surface tension

48
Q

What is the function of hydrogen ions?

A

Affects pH levels

49
Q

What is the function of sodium ions?

A

Involved in the absorption of glucose and amino acids via co-transport

50
Q

What is the function of phosphate ions?

A

Component of DNA, ATP and phospholipids

51
Q

What is the function of iron ions?

A

Component of haemoglobin in red blood cells

Biology (16 decks)

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