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Biology > Biological Molecules 12 > Flashcards

Biological Molecules 12 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is a covalent bond?

A

Atoms sharing a pair of electrons in their outer shells. A more stable compound called a molecule is formed.

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2
Q

What is an ionic bond?

A

Ions with opposite charges have an electrostatic bond called an ionic bond.

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3
Q

What is a hydrogen bond?

A

The electrons within a molecules are not evenly distributed but tend to spend more time at one position. This region is more negatively charged than the rest of the molecule. These are polarised and they can form weak electrostatic bonds.

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4
Q

What is a monomer?

A

Single repeating subunits what can be used to make a polymer.

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5
Q

What is a polymer?

A

Long chain of repeating monomers.

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6
Q

How are polymers formed?

A

Polymerisation.

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7
Q

What is a condensation reaction?

A

When monomer subunits are joined together and a water molecule is eliminated.

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8
Q

What is a hydrolysis reaction?

A

How polymers are broken down back into their monomers through the addition of water and a catalyst.

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9
Q

What is metabolism?

A

All chemical processes that take place in living organisms are collectively.

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10
Q

What is a monosaccharide?

A

The basic monomer unit of sugar.
Glucose
Fructose
Lactose

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11
Q

What is a disaccharide?

A

A pair of monosaccharides combined.
Maltose
Sucrose
Lactose

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12
Q

What is a polysaccharide?

A

Many monosaccharides.

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13
Q

Test for reducing sugar. (Monosaccharides)

A

Dissolve food sample in water.
Equal volume of Benedict’s reagent added.
Heat in water bath for 5 mins.
If reducing sugar present solution turns orange-brown.

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14
Q

How is maltose formed?

A

Glucose + Glucose

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15
Q

How is sucrose formed?

A

Glucose + Fructose

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16
Q

How is lactose formed?

A

Glucose + Galactose

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17
Q

How are monosaccharides joined together?

A

Water is removed through a condensation reaction forming glycosidic bond.

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18
Q

Test for non-reducing sugar. (Disaccharides)

A

Dissolve in water.
Add 2cm of food to 2cm of Benedict’s reagent in a test tube and filter.
If the solution remains blue then there are no reducing sugars.
Add 2cm of food sample to 2cm to hydrochloric acid and place in water bath for 5mins this will hydrolyse any disaccharide present into monosaccharides.
Slowly add sodium hydrogen carbonate to the test tube to neutralise as Benedict’s will not work in acidic conditions.
Retest using Benedict’s solution, adding 2cm and placing in water bath for 5mins.
If present the solution will turn orange-brown.

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19
Q

Test for starch.

A

Place 2cm of sample into test tube.
Add two drops of iodine solution and shake.
If present solution will change blue-black.

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20
Q

Features of starch

A

Found in plants.
Used for storage.
Made up by alpha glucose easily transported and readily used in respiration.
Chains may be branched or unbranched this means more enzyme activity can happen at one time.
Wound into tight coil making molecule very compact and easy to store.
Insoluble so doesn’t affect water potential.

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21
Q

Features of glycogen.

A

Found in animals.
Used for storage.
Made up of alpha glucose which is easily transported and result used in respiration.
Shorter chains and more branched than starch so compact and easy to store and easily attacked by enzymes.
Insoluble so doesn’t effect water potential.

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22
Q

Features of Cellulose

A

In plants for protection.
Made up of beta glucose.
Straight unbranched chains which parallel allowing hydrogen bonds to make cross links for strength.

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23
Q

Features of lipids.

A

Contain carbon, hydrogen and oxygen.
The proportion of oxygen to carbon and hydrogen is much smaller than in carbohydrates.
They are insoluble in water.
Soluble in organic solvents such as alcohols and acetone.

24
Q

Roles of lipids.

A

Sources of energy, when oxidised provide a lot of energy and release water.
Waterproofing, insoluble in water.
Insulation, slow conductors of heat so used beneath skin to retain body heat and around nerves.
Protection, around delicate organs such as kidney.

25
Q

What are triglycerides made up of?

A

Three fatty acids and a glycerol, each fatty acid forms an Ester bond with glycerol in a condensation reaction eliminating water.

26
Q

What is a saturated fat?

A

No double bond.

27
Q

What a unsaturated fat?

A

Double bond present.

28
Q

The structure of triglycerides related to their properties.

A

High ratio of energy storing carbon hydrogen bonds to carbon atoms making them good storage molecules.
Low mass to energy ratio for easier storage.
Insoluble and non polar so don’t affect water potential.
Release water when oxidised.

29
Q

What is a phospholipid made up of?

A

Glycerol, 2 fatty acids and a phosphate molecule.
Fatty acid molecules repel water making them the hydrophobic legs.
Phosphate attracts water making it the hydrophilic head.
This makes the molecule polar.

30
Q

The structure of phospholipids related to their properties.

A

Can form a hydrophobic barrier between inside of cell and outside.
Hydrophilic head provides structure.
Allows them to form glycolipids by combing with carbohydrates which are important for cell recognition.

31
Q

Test for lipids.

A

Take completely dry, grease free test tube.
Add 2cm of sample and 5cm of ethanol.
Shake to dissolve.
Add 5cm of water.
Cloudy white colour indicates the presence of lipids.

32
Q

What is an amino acid?

A

Basic monomer that forms a polymer called a polypeptide.

33
Q

What is the amino acid made up of?

A 
Amino group (NH2)
Carbonyl group (COOH)
Hydrogen atom (H)
R group
34
Q

How are dipeptide formed?

A

Removal of water and condensation reaction forming a peptide bond.

35
Q

What is meant by ‘the primary structure of proteins’?

A

The sequence of amino acids in a polypeptide.

36
Q

What is meant by ‘the secondary structure of proteins’?

A

Amino acids in a polypeptide form weak bonds called hydrogen bonds giving the polypeptide 3D structure.

37
Q

What is meant by ‘the tertiary structure of proteins’?

A

Polypeptide is folded further using disulphides bridges, ionic bonds and hydrogen bonds giving its shape for its function.

38
Q

What is meant by ‘the quaternary structure of proteins’?

A

Contain more than one polypeptide bond linked in various ways.

39
Q

Test for proteins.

A

Place a sample in test tube and add an equal volume of sodium hydroxide solution at room temperature.
Add a few drops of copper sulphate solution and mix gently.
Purple colour indicates the presence of peptide bonds hence a protein.

40
Q

What is the role of an enzyme in a reaction?

A

Lowering activation energy while itself remaining unchanged.

41
Q

Describe the structure of an enzyme.

A

Enzymes are globular proteins.
The functional area of the enzyme is called the active site which is a small depression made up of small amino acids.
The reactant is called the substrate.
Combined they are the enzyme-substrate complex.
The substrate molecule is held by temporary bonds made with the amino acids in the active site.

42
Q

Explain the induced fit model enzyme action.

A

It proves that the active site forms when the enzyme and substrate interact.

43
Q

Factors effecting enzyme activity.

A

Temperature, too low not enough kinetic energy, too high enzymes denatures.
pH, change can cause denature.
Concentration, happens more often

44
Q

What is a competitive inhibitor?

A

Have the same molecular shape as substrate this allows them to fit into the active site of the enzyme. It is not permanently bound to to the active site.

45
Q

What is a non competitive inhibitor?

A

Attach themselves to the binding site which is not the active site of the membrane. It changes the active site in a way where the substrate can no longer bind to it.

46
Q

What is a nucleotide made up of?

A 
Pentose sugar
Phosphate group
Nitrogenous organic base
-uracil 
-cytosine
-adenine
-guanine
47
Q

How are dinucleotides formed?

A

Two mononucleotides tides joined together by the elimination of water called a condensation reaction forming a phosphodiester bond.

48
Q

What is a polynucleotide?

A

Many mononucleotides joined by the elimination of water called condensation forming a phosphodiester bond.

49
Q

What is base pairing?

A

Bases can make hydrogen bonds when two strands come together.
Adenine and thymine 2 bonds
Guanine and cytosine 3 bonds
These are complimentary

50
Q

Why is DNA stable?

A

Phosphodiester backbone protects the more chemically reactive organic bases in the double helix.
Hydrogen bonds link bases giving them more stability.

51
Q

Function of DNA

A

Stable structure means it is easily passed from generation to generation.
The two strands are only joined by hydrogen bonds which separate during DNA replication.
Base pairing means DNA can be replicated and transferred as mRNA.

52
Q

What is ATP made up of?

A

Adenine
Ribose
3 phosphates

53
Q

How does ATP store energy?

A

Adenosine triphosphate is a nucleotide with 3 phosphates which have unstable bonds and a low activation energy which means they are easily broken releasing energy.
Water is used o convert ATP to ADP in hydrolysis aswell as an enzyme called ATP hydrolyse.
This is a reversible reaction and can be condensed.

54
Q

Role of ATP

A

Smaller requirements of energy because it’s a small amount of energy however immediate.

  • metabolic processes (making starch)
  • movement (filaments)
  • active transport
  • secretion (lysosomes)
  • activation of molecules (lower activation energy)
55
Q

Features of water

A

Polar therefore good solvent and can create hydrogen bonds.
Has a high specific heat capacity meaning chemical reactions can occur in them while not changing the conditions.
High latent heat of vaporisation meaning animals can use it to cool down.
Cohesion and surface tension meaning it can be pulled up through the xylem.

56
Q

What is water used for in metabolism?

A

Used in the break down of many complex molecules via hydrolysis.
Chemical reactions take place in aqueous mediums.
Water is the major raw material in photosynthesis.

57
Q

What can water dissolve?

A

Gases
Wastes
Inorganic ions
Enzymes

Biology (4 decks)

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