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Biology SL > Topic 2: Molecular Biology > Flashcards

Topic 2: Molecular Biology Flashcards

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1
Q

What is polarity?

A

The slight difference in charge that occurs at different poles of a molecule, the covalent bonds between O atom and H atoms are polar covalent bonds (water), electrons are not shared equally therefore water is polar.

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2
Q

What pole in water is slightly positive?

A

Hydrogen, H atoms have a weaker attracts electrons more strongly, forming a slightly positive charge.

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3
Q

What pole in water is slightly negative?

A

Oxygen, attracts electrons more strongly, forming a slightly negative charge.

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4
Q

What is hydrogen bonding in water?

A

Polarity of water allows it to form weak associations with other polar molecules or charged ions through hydrogen bonds, these bonds form when hydrogen atom is attracted to a fluorine, oxygen or nitrogen atom of another molecule.

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5
Q

When does cohesion occur?

A

When molecules of the same type are attracted to each other.

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6
Q

What does the hydrogen bonding in water molecules allow?

A

Allows liquids to resist low levels of external force which creates surface tension. High surface tension is sufficiently dense allowing smaller organisms to move along its surface.

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7
Q

What is adhesion?

A

Attraction between polarity of water and polar substances. Water molecules form hydrogen bonds between each other and polar molecules.

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8
Q

What is a solvent?

A

Liquid that dissolves solute

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9
Q

What is a solute?

A

Dissolves in liquid

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10
Q

What is a solution

A

Solvent and solute

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11
Q

What kind of substances are attracted to water?

A

Substances with a positive or negative charge - they can easily dissolve because of their ionic composition.

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12
Q

What is a ‘hydration shell’?

A

Water forms hydrogen bonds with solute which forms a hydration shell around a solute.

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13
Q

Why do polar molecules dissolve in water?

A

Because they are hydrophilic and form hydrogen bonds with water

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14
Q

What region of a solute is the positive water hydrogen atoms attracted to?

A

The negatively charged region

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15
Q

What region of a solute is the negative water oxygen atom attracted to?

A

The positively charged region

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16
Q

Why do charged ions dissolve in water?

A

Because they are hydrophilic

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17
Q

What is water electrostatically attracted to?

A

Ions

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18
Q

Why do non-polar or uncharged atoms not dissolve in water?

A

Because they are hydrophobic - these substances are insoluble

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19
Q

What is a metabolic medium?

A

Water is a medium for metabolic and enzyme manipulated reactions

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20
Q

What is water’s role in cytosol?

A

Water makes up 80% of the cytosol and contains salts, fatty acids, amino acids and proteins - water dissolves the reactants and enzymes for metabolism

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21
Q

What is transported in xylem from roots to leaves in vascular plants?

A

Dissolved mineral ions

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22
Q

What is transported in the phloem from source to sink?

A

Dissolved sugars produced in photosynthesis.

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23
Q

What is carried in animal blood plasma?

A

Dissolved solutes transported in solution around the body; salt ions, amino acids, proteins, glucose, waste products of metabolism, small amount of dissolved sugars

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24
Q

What is buoyancy?

A

Upward force on an object placed in or on it - depends on density, object density lower than fluid the object will float.

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25
Q

Examples of buoyancy?

A

Bony fish have airfield swim bladders which are used to control overall density. Organisms that fly have to generate lift to stay airborne as buoyancy in air is much less than in water.

26
Q

What is viscosity?

A

Resistance of a fluid to flow due to internal friction. Water is more viscous than air as it forms hydrogen bonds which inc. the friction of flowing molecules. water can dissolve solutes with inc. viscosity of the solution

27
Q

What is thermal conductivity?

A

Measure of a material’s ability to move heat across a temp. grad. Water absorbs and transfers heat more rapidly than air because water particles are packed more tightly tgthr.

28
Q

What is specific heat capacity?

A

Quantity of heat needed to raise temp. of 1g of substance by 1C. Water has a higher SPC than air as its hydrogen bonds require additional energy to break - makes it an efficient coolant in sweat

29
Q

What are covalent bonds?

A

Sharing of electrons to form electron pairs btwn atoms

30
Q

Why does carbon form the basis of all organic compounds?

A

Due to its ability to form large and complex molecules via covalent bonding.

31
Q

How many covalent bonds does carbon make?

A

4

32
Q

What are monomers?

A

Organic compounds are typically composed of recurring subunits which are covalently joined to form polymers. Monomeric subunits of carbohydrates, nucleotides, proteins, lipids; monosaccharide, fatty acid, nucleotide, amino acid

33
Q

What is polymerisation?

A

Polymers can be formed from monomers via condensation reactions. A strong covalent bond is formed between monomers and a molecule of water is released. Anabolic reaction.

34
Q

What can polymers be broken down into?

A

Their monomeric subunits via hydrolysis reaction. A water molecule

35
Q

What are carbohydrates composed of?

A

Monomers called monosaccharide. These monomers link together by condensation reactions to form a disaccharide and polysaccharide polymers.

36
Q

What are glycoproteins?

A

Carbohydrate chain faces outwards and can be recognised by other receptors own other cells.

37
Q

Properties of lipids

A

substances that dissolve in non-polar solvents. E.g. fats, oils, waxes and steroids

38
Q

What are triglycerides?

A

Contain one glycerol molecule and three fatty acids molecules.

39
Q

What are saturated fatty acids?

A

Carbons are carrying as many hydrogen atoms as they can, no double bonds between the carbon atoms - straight molecule. Solid at room temp. because they can stack tightly.

40
Q

What are monounsaturated fatty acids?

A

One double bond within the hydrocarbon chain.

41
Q

What are polyunsaturated fatty acids?

A

At least two double bonds within the hydrocarbon chain.

42
Q

What are cis fatty acids?

A

Naturally curved. Hydrogen atoms are bonded to the carbon atoms on either side of the double bond are on the same side.

43
Q

What are trans fatty acids?

A

They are hydrogenated. H atoms one either side of the double bond are on opposite sides. Vast majority. of trans fats are the results of chemical processing in food processing factories.

44
Q

What are amino acids?

A

Proteins that are composed of long chains of recurring monomers. Each a.a. contains a central alpha carbon linked to an amino group, carboxyl group, H atom and a variable group.

45
Q

How many types of amino acids are there?

A

20

46
Q

What is an essential amino acid?

A

Cannot be produced by the body and must be present in diet.

47
Q

What is a non-essential amino acid?

A

Can be produced by the body.

48
Q

What is a conditional amino acid?

A

Can be produced by the body at lower rates.

49
Q

What is the function of haemoglobin?

A

Transporting oxygen from lungs to the tissues and facilitating the return transport of carbon dioxide. Composed of four polypeptides found in RBC/

50
Q

What is immunoglobulin?

A

Antibodies that bind to antigen.

51
Q

What is collagen?

A

Provides structural support to the extracellular space of connective tissues - proteins in dermis of the skin. Three polypeptides wound together.

52
Q

What is keratin?

A

Maintains elasticity in the skin - found in hair, nails, claws, hooves. Fibrous proteins composed of two polypeptide chains.

53
Q

What is a digestive enzyme?

A

Proteins that the body makes to break down food and aid digestion.

54
Q

What is insulin?

A

Peptide hormone responsible for uptake of glucose into cells reduces glucose conc. in blood secreted by the beta cells in pancreas

55
Q

What are enzymes?

A

Globular proteins which act as a biological catalysts by speeding up the rate of chemical reactions. Takes part in anabolic and catabolic reactions. are not changed or consumed by the reactions they catalyse.

56
Q

What is an anabolic reaction?

A

Build up complex molecules from simpler ones occurs via condensation reactions.

57
Q

What is a catabolic reaction?

A

Breaking down complex molecules molecules into simpler ones, occurs via hydrolysis reactions.

58
Q

What is an active sites?

A

The region on the surface of the enzyme which binds to the substrate molecule. The active site and the substrate compliment each other in terms of both shape and chemical properties. Composed of a few amino acids only but the interactions ensure the active site is complementary to the substrate.

59
Q

What is the induced fit model?

A

Enzymes active site is not a completely rigid fit for the substrate. The active site undergoes a conformational change when exposed to a substrate. explains how enzymes may exhibit broad specificity.

60
Q

What is an exergonic reaction?

A

If the reactants contain more energy than the products the free energy is released into the system. These reactions are usually catabolic as energy is released from broken bonds.

61
Q

What is an endergonic reaction?

A

Reactants contain less energy than the products, free energy is lost to the system. Reactions are usually anabolic as energy is required synthesise bonds between molecules.

Biology SL (4 decks)

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