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biology OCR > 2.1.2 biological molecules > Flashcards

2.1.2 biological molecules Flashcards

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1
Q

outline the structure of a water molecule

A

a polar molecule with one oxygen and two hydrogrens. the hydrogens are slightly positive, and the oxygen is slightly positive. This enables hydrogen bonding between water molecules, and explains why it is such a good solvent.

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2
Q

why is water a good solvent?

A

due to it’s polarity, many solutes can be dissolved in water due to the negative and positive regions of the molecule

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3
Q

why is water a good transport medium?

A

helps cells transport and use substances like oxygen. It is cohesive as hydrogen bonds constantly break and form so water has fluid movement therefore it moves as one mass, water molecules are attracted to themselves. Water is also adhesive, meaning that water is attracted to other molecules or materials. Therefore it is a very fluid medium.

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4
Q

why is what a good coolant?

A

water has a high specific heat capacity, therefore helps to buffer temperature changes during chemical reactions- important in enzymic reactions. Water’s high specific latent heat of vaporization is important for cooling down.

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5
Q

what is a monomer?

A

a small repeating unit that joins together to form larger repeating molecules known as polymers

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6
Q

what chemical elements do carbohydrates have?

A

carbon, hydrogen, oxygen

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7
Q

what chemical elements do lipids consist of?

A

carbon, hydrogen, oxygen

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8
Q

what chemical elements do proteins consist of?

A

carbon, hydrogen, oxygen, nitrogen, sulfur

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9
Q

what chemical elements do nucleic acids consist of?

A

carbon, hydrogen, oxygen, nitrogen, phosphorous

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10
Q

what is the structure of a carbohydrate?

A

A ring structure, the number of carbons in each ring varies (triose, hexose etc.)

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11
Q

what is the structure of glucose?

A

a hexose monosaccharide. It is polar and water-soluble. glucose has two isomers- alpha glucose and beta glucose. The OH of alpha glucose is below, the OH of beta glucose is above.

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12
Q

draw alpha and beta glucose

A

…

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13
Q

what reaction bonds glucoses and what is the type of bond called

A

condensation reaction forming glycosidic bonds.

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14
Q

name the monosaccharides present in the disaccharides sucrose, lactose, and maltose

A

sucrose: glucose and fructose
lactose: glucose and galactose
maltose: glucose and glucose

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15
Q

what bond holds two alpha glucose molecules together

A

1-4 glycosidic bond

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16
Q

what is the structure of amylose?

A

very long chains of alpha glucose monomers joined via 1-4 glycosidic bonds. a component of starch.

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17
Q

what is the structure of amylopectin?

A

long chain of alpha glucose monomers joined via 1-4 glycosidic bonds. Additionally has branches due to 1-6 glycosidic bonds approximately every 25 monnomers. amylopectin is a component of starch

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18
Q

what is the structure of glycogen?

A

long chains of alpha glucose monomers joined by 1-4 glycosidic bonds, also has 1-6 bonds which branch often. a compact molecule

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19
Q

what is the structure of cellulose?

A

long chains of beta glucose monomers which form 1-4 glycosific bonds but alternate the beta glucose molecules so the -OH groups are close enough to react. Hydrogen bonds betewen the -OH groups hold cellulose in very compact structure.

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20
Q

what is the function of starch?

A

storage molecule in plant cells, very compact and insoluble in water. therefore can store more substance in less area. the chains can spiral increasing the compactness

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21
Q

what is the function of glycogen?

A

storage molecule for animal cells, a quick source of energy. many branches allow rapid hydrolysis so glucose can be obtained quickly.

22
Q

what is the function of cellulose?

A

strong structural function in cell wall. insoluble and resistant to hydrolysis.

23
Q

what are the functions of lipids?

A

Protects vital organs. Prevents evaporation and waterproofs plants (waxy cuticle). Insulates body. Forms myelin sheath around neurones. Awater source. A component of cell membranes. Hormone production, steroid hormones are lipid based. buoyancy of aquatic animals.

24
Q

describe the structure of a trigylcerirde

A

a glycerol molecule with three fatty acid chains attached.

25
Q

what is the difference between saturated and unsaturated fats?

A

saturated fats have no double carbon bonds, and are solid, unsaturated fats do not, and tend to be liquids.

26
Q

what is the condensation reaction for lipids in a triglyceride known as

A

esterification

27
Q

what is the structure of a phospholipid

A

a hydrophilic phosphate head, with two fatty acid hydrophobic tails. they form bilayers.

28
Q

function and structure of cholesterol

A

a sterol made in the liver and intestines. important in stability of membranes, it’s positioned between phospholipids.

29
Q

draw an amino acid

A

…

30
Q

what bond are amino acids joined by?

A

peptide bonds

31
Q

what is the primary structure of a protein?

A

the order and number of amino acids in a polypeptide chain, the chain always has one amino end and one carboxyl end.

32
Q

what is the secondary structure of a protein?

A

alpha helixes and beta pleated sheets. R groups are not involved, held by hydrogen bonds between amine and carboxyl groups.

33
Q

what is the tertiary structure of a protein?

A

the folding of the polypeptide chain, the R groups are held close enough to interact via: disulphide bonds, hydrophilic/phobic interactions, ionic bonds, hydrogen bonds.

34
Q

what is the structure of a globular protein?

A

compact, spherical, water soluble proteins, often due to hydrophobic R groups which avoid aqueous environments so the hydrophilic R groups stay outside forming a ball shape which is soluble

35
Q

what is the function of a globular protein?

A

often solubility related functions like regulating immunity, muscle contraction, chemical reactions. Act as hormones, enzymes, immunoglobulins, and transport molecules.

36
Q

outline a globular protein which is a hormone

A

insulin- held together by two disulphide bonds between cystine, this enables R groups to interact forming a spherical shape. Insulin is a hormone involves in the regulation of blood glucose concentration. They must be soluble, and fit into receptors.

37
Q

outline a globular protein which is an enzyme

A

amylase- responsible for the breakdown of starch into maltose. made up of a single polypeptide chain folded into alpha helixes and beta pleated sheets

38
Q

outline a globular protein which is a conjugated protein

A

haemoglobin- the oxygen-carrying red pigment of RBCs. It has a quaternary structure of 2 alpha and 2 beta subunits, each containing a prosthetic heam group. Haem contains iron which bonds to the oxygen in the protein, holding the conjugated protein together and enabling the transport of oxygen.

39
Q

what is a conjugated protein?

A

a globular protein that contains a non-protein group such as a lipid in lipoproteins, or haem in haemoglobin.

40
Q

what is the strucure of a fibrous protein?

A

long insoluble molecules containing a high proportion of amino acids with hydrophobic R groups. Variety of amino acids is limited so polypeptide chain is quite repetitive and organised. They normally produce long, unfolded, strong proteins

41
Q

name three examples of globular proteins

A

amylase, haemoglobin, insulin

42
Q

name three fibrous proteins

A

keratin, collagen, elastin

43
Q

what is keratin

A

fibrous protein found in hair

44
Q

what is collagen

A

a fibrous protein which is a connective tissue found in ligaments, tendons, the skin, and TNS.

45
Q

what is elastin?

A

a fibrous protein found in elastic fibres in the walls of blood vessels and alveoli

46
Q

how do you test for reducing sugars?

A

Benedict’s reagent: add reagent to the sample and heat. positive result will turn the blue solution to brick-red. Semi-quantitative so may be a range of colours depending on concentration of reducing sugar.

47
Q

How do you test for a non-reducing sugar?

A

Hydrolyse the glycosidic bonds with dilute HCl, then test with Benedict’s reagent and heat.

48
Q

how do you test for proteins?

A

Biuret test: add samle and biuret solution. a positive result would turn lilac from pale blue. the peptide bonds react with copper ions in the alkaline solution.

49
Q

How can you separate and identify amino acids#/

A

thin layer chromatography, calculate Rf values to identify

50
Q

how to calculate Rf values

A

distance travelled by solute/ distance travelled by solvent

51
Q

how do you test for lipids?

A

emulsion test: add sample, add ethanol and shake, add water, shake. positive reuslt is a cloudy emulsion

52
Q

what is used as a quantitative method to measure concentration of a substance in solution

A

colorimetry

biology OCR (6 decks)

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