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Biology🧬 > Biological Molecules > Flashcards

Biological Molecules Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

A disaccharide is formed when two monosaccharides bond together, by what reaction and what is the bond?

A

A condensation reaction occurs (water molecule eliminated) to form a glycosidic bond.

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2
Q

What is a long chain of monosaccharides called and how?

A

A polysaccharide which is formed by lots of condensation reactions, held together by glycosidic bonds.

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3
Q

What is a glycosidic bond?

A

A sugar bond

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4
Q

What is a hydrolysis reaction?

A

Using a molecule of water to break a chemical bond (opposite of a condensation reaction)

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5
Q

Why are carbohydrates/monosaccharides a good energy source?

A
  • Contain carbon, hydrogen, and oxygen
  • Large number of carbon-hydrogen bonds
  • Monosaccharides are hydrates of carbon
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6
Q

What is the difference between alpha and beta glucose structure (hexose sugar)?

A

In alpha, the -OH on carbon 1 is below, but its above in beta.
ABBA

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7
Q

What makes maltose?

A

Two glucose monomers

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8
Q

What makes sucrose?

A

Glucose and fructose

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9
Q

What makes lactose?

A

Glucose and galactose

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10
Q

What is the molecular formula of glucose?

A

C6 H12 O6

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11
Q

Describe glycogen

A
  • A polysaccharide made from a-glucose monomers
  • Is branched with 1-4 and 1-6 glycosidic bonds
  • Compact, dense and insoluble
    in a spiral shape
  • An energy store and source in animal cells
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12
Q

What types of starch are there?

A

Amylopectin: 70-80%
Amylose: 20-30%

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13
Q

Describe amylopectin (starch)

A
  • Polysaccharide of a-glucose monomers
  • Is branched, therefore as it makes up around 80% of starch, starch is classed as branched
  • Has 1-4 and 1-6 glycosidic bonds
  • Compact with spiral shape
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14
Q

Describe amylose (starch)

A
  • Polysaccharide of a-glucose monomers
  • Unbranched
  • 1-4 glycosidic bonds
  • Compact with spiral shape
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15
Q

Describe cellulose

A
  • Polysaccharide of b-glucose monomers
  • Polymers joined by hydrogen bonds, creating bundles called fibrils.
  • 1-4 glycosidic bonds
  • Is linear and every other one is rotated 180º to prevent spiralling
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16
Q

What is the function of starch?

A

Energy store and source for plant cells

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17
Q

What is the function of cellulose?

A

Is a structural unit for plants within the cell wall.

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18
Q

What is ribose?

A

A pentose sugar that is involved in respiration as it makes up ATP

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19
Q

What is deoxyribose?

A

A pentose sugar that is a component of a DNA nucleotide monomer

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20
Q

Briefly explain how you would test for a reducing sugar

A
  • Add an excess of Benedict’s solution to the sample
  • Gently heat in a water bath at about 80℃ for 5 minutes
  • A positive result would show a colour change from blue→ green, yellow, or brick-red depending on the concentration
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21
Q

Briefly explain how you would test for a NON-reducing sugar

A
  • Add and equal volume of and acid (HCL) to the sample
  • Heat at 80℃ where the acid will hydrolyse the disaccharide
  • Leave to cool and slowly add an alkaline (sodium hydrogen carbonate) to neutralise the acid
  • Add in Benedict’s solution and heat again
  • Sugar is non-reducing if there is a blue to green, yellow, or red change.
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22
Q

What sugar is NOT a reducing sugar?

A

Sucrose

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23
Q

Why is it easier and faster to hydrolyse a carbohydrate that has branched glycosidic bond (1,4 and 1,6)?

A

There are more ends to cut off from.

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24
Q

Why is it useful for a molecule to be insoluble?

A

It won’t decrease the water concentration inside of the cell, so water activity does not occur through osmosis

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25
Q

What can we use to test for starch, and what is the colour change?

A

Iodine
Orange→ Black

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26
Q

What is a triglyceride?

A

-Macromolecule
-Lipid

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27
Q

What is the structure of a triglyceride?

A

One glycerol molecule bonded to 3 fatty acids

28
Q

Explain the structure of a fatty acid

A

A carboxyl group with a hydrocarbon tail known as the ‘R’ group or variable group.

29
Q

What is a saturated fatty acid?

A

There are no double bonds is the hydrocarbon tail/’R’ group -Cn H2n O2
e.g C5 H10 O2

30
Q

What is an unsaturated fatty acid?

A

There are double bonds in the hydrocarbon tail/’R’ group
e.g C5 H8 O2

31
Q

What is monounsaturated?

A

One double bond in fatty acid

32
Q

What is polyunsaturated?

A

More than one double bond in a fatty acid

33
Q

Why do polyunsaturated fatty acids have lower melting points?

A

Double bonds give a ‘kink’ in the hydrocarbon which pushes them slightly further apart making the fatty acid more fluid - ?

34
Q

What reaction occurs to join the glycerol and the fatty acids in a triglyceride?

A

A condensation reaction

35
Q

What bond holds the glycerol and the fatty acids together in a triglyceride?

A

Ester bonds

36
Q

What is the difference between a triglyceride and a phospholipid?

A

The glycerol is bonded to only 2 fatty acids and one phosphoric acid at the top called a phosphate head. (the phospholipid)

37
Q

Is the phosphate head of a phospholipid Hydrophilic or Hydrophobic?

A

Hydrophilic
-polar
-attracted to water

38
Q

Is the fatty acids in a phospholipid Hydrophilic or Hydrophobic?

A

Hydrophobic
-non polar
-repelled by water

39
Q

How are the phospholipids arranged in the cell membrane (phospholipid bi-layer)?

A

Drawn as a circle with two lines (fatty acid tails)

O O O O O
l l l l l l l l l l
O O O O O

So that the hydrophobic tails don’t meet the water in/surrounding the cell.

40
Q

What are triglycerides used for?

A

Energy storage molecules -as they have long hydrocarbon tails with lots of chemical energy that is released when broken down

41
Q

Why are triglycerides good energy stores?

A

-Long hydrocarbon chains that release lots of chemical energy
-They are insoluble so don’t affect water potential; they clump together in droplets so that they are arranged in a ring with the so the hydrophobic fatty acids are protected by the glycerol.

42
Q

What are proteins made up of?

A

Long chains of amino acids (monomer)
2 amino acids= dipeptide
more than 2=polypeptide
- Proteins are made up of one or more polypeptides

43
Q

Explain the general structure of an amino acid

A

Has an Amine group (NH2), a variable (R) group, and a carboxyl group (COOH)

The variable group determines what amino acid it is.

44
Q

How many amino acids are there?

A

20

45
Q

What bonds hold amino acids together?

A

Peptide bonds via condensation reactions

46
Q

Name the 4 structural levels of a protein

A

Primary
Secondary
Tertiary
Quaternary

47
Q

What is the primary structure of a protein?

A

The sequence of amino acids in a polypeptide chain.
-e.g each gene has a unique base sequence so the primary structure will be different that determines its function.

48
Q

Explain the secondary structure of a protein

A

Hydrogen bonds form between the amino acids in the polypeptide chain which makes it coil or fold.
-Coils form an alpha helix structure
-Folds form a beta pleated sheet that zig-zags

(bonds between the -NH group and -CO group)

49
Q

Describe the tertiary structure of a protein

A

The precise 3D shape the protein held by bonds between the ‘R’ groups that lie close to each other.
-Hydrogen bonds
-Ionic bonds (between charged R groups)
-Weak hydrophobic interactions (between non-polar R groups)
-Disulphide bonds/bridges (only occurs between cysteine amino acids)

50
Q

What is the quaternary structure of a protein?

A

Proteins that consist of more than one polypeptide chain bonded together.
-Each polypeptide chain is a subunit of the protein
-e.g haemoglobin

51
Q

How many bases does a codon have?

A

3
aka a DNA triplet

52
Q

What is activation energy?

A

The minimum amount of energy needed to get a reaction to start

53
Q

What is the name of the compound made when and active site meets a substrate?

A

Enzyme-substrate complex

54
Q

Describe the Lock and Key model

A

The substrate and the active site are complementary to each other and fit, which then creates an enzyme-substrate complex, that splits the substrate.

55
Q

Describe the Induced-fit Model

A

The active site moulds to fit the substrate, changed by the ‘R’ group

56
Q

Explain the optimum temperature for enzyme activity

A

Adding more temp increases kinetic energy and increases collisions, yet too far, the enzymes will denature as bonds will break

57
Q

Describe what a Competitive Inhibitor is

A

Fits the enzymes active site creating an enzyme-inhibitor complex, preventing any substrates.

-Decrease rate of reaction
-Effect can be overcome by increasing substrate conc

58
Q

Describe what a Non-competitive Inhibitor is

A

They don’t fit the active site, therefore will find an alternative binding site called the Allosteric Site.
This will disrupt the tertiary structure and change the active site.

-Irreversible
-Can’t increase the substrate conc to reach normal rate, as the enzyme won’t work

59
Q

What is the ‘Law of the Minimum’ by Justus Von Liebig?

A

States growth is dictated not by total resources available, but by the scarcest resource, known as the ‘limiting factor’

60
Q

What is a monomer?

A

Monomers are the smaller units from which larger molecules are made.

61
Q

What is a polymer?

A

Polymers are molecules made from a large number of monomers joined together.

Monosaccharides, amino acids and nucleotides are examples of monomers.

62
Q

Name 2 polysaccharides of a-glucose

A

Glycogen
Starch

63
Q

Name a b-glucose polysaccharide

A

Cellulose

64
Q

What are two groups of lipid?

A

Triglycerides and phospholipids

65
Q

What are the bonds in triglycerides between glycerol and fatty acids?

A

Ester bonds

Biology🧬 (11 decks)

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