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biology > 2.1.2: biological molecules > Flashcards

2.1.2: biological molecules Flashcards

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1
Q

what 4 elements are most important in living organisms and how many bonds do they each form?

A
  • carbon (4 bonds)
  • hydrogen (1 bond)
  • oxygen (2 bonds)
  • nitrogen (3 bonds)
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2
Q

what is the difference between a covalent bond and an ionic bond?

A

covalent is a strong bond where 2 atoms share a pair of electrons while an ionic is when one atom donates an electron to another, leaving 2 ions, held together by opposite charges

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3
Q

what is an ion, and what is a positive and negative on called?

A

a charged atom. with a cation being a positively charged on and anion is a negatively charged one

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4
Q

what elements are present in water?

A

hydrogen and water

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5
Q

what elements are present in carbohydrates?

A

carbon, hydrogen and oxygen

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6
Q

what elements are present in lipids?

A

carbon, hydrogen and oxygen

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7
Q

what elements are present in proteins?

A

carbon, hydrogen, oxygen, nitrogen and sometimes sulfur

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8
Q

what elements are present in nucleic acids?

A

carbon, hydrogen, oxygen, nitrogen and phosphorus

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9
Q

what is a monomer and 2 examples?

A

a small single molecule, which can join to many other similar molecules (repeating units) to make a polymer
- amino acids
- nucleotides

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10
Q

what is a polymer and 2 examples?

A

a large molecule (macromolecule) made up of smaller monomers joined together
- proteins
- dna

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11
Q

what happens during a condensation reaction and what type of reaction is it?

A
  • when 2 molecules join together, involving the removal of water
  • anabolic reaction
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12
Q

what is a hydrolysis reaction and what type of reaction is it?

A
  • whenever a molecule is split apart, involving the addition of water
  • catabolic reaction
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13
Q

what does being polar mean?

A

with an uneven charge distribution across it meaning one part is slightly negative while the other part is slightly positive

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14
Q

how is water polar?

A
  • the oxygen atom has greater number of protons in its nucleus
  • it exerts a stronger attraction for the shared electrons
  • oxygen atom becomes slightly negative
  • 2 hydrogen atoms are slightly positive
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15
Q

why is water a liquid at room temperature and what are the advantages of this?

A
  • as molecules move, they continuously make and break hydrogen bonds therefore making it difficult to escape to form gas. therefore it has a highly boiling point and therefore is a liquid at room temperature
  • means aquatic habitats meaning fish can live underwater, it’s a major component of our cells, the cytoplasm stores water and it is an ideal transport medium
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16
Q

why is water a good solvent and why is it a good solvent for living organisms?

A
  • because it is polar, anything polar or is a charge ion can dissolve in it
  • it means that various molecules and ions can dissolve in the blood plasma and be transported around the body to cells that need them
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17
Q

how is water less dense when it is solid and how is it useful for living organisms?

A
  • due to the polar nature. the water molecules in ice are held further apart because each water molecule forms 4 hydrogen bonds to other water molecules, making a spaced- out lattice, which is less dense and floats
  • animals can stand and live on them
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18
Q

how is water cohesive and how is it useful in organisms?

A
  • stayed molecules are attracted to each other because of their polar nature (hydrogen bonds form)
  • helps water to flow as one mass making it useful to transport substances
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19
Q

how does surface tension of water occur and how is this useful for living organisms?

A
  • water molecules on surface are hydrogen bonded to the water molecules underneath and more attracted to the air molecules above, meaning the surface of the water contracts giving it the ability to resist force
  • allows little animals to walk on water and creates a habitat
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20
Q

how does water have a high specific heat capacity and why is it important for water?

A
  • the hydrogen bonds between water molecules can absorb a lot of energy, so it takes up a lot of energy to heat up
  • water donkey experience rapid temperature changes, making it very stable therefore a good habitat for organisms and a good temperature for enzyme- controlled reactions inside cells
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21
Q

how does water have a high latent heat of evaporation and how is this useful for organisms?

A
  • it takes a lot of energy to break all if the hydrogen bonds between water molecules in order for it to turn from a liquid to a gas
  • use evaporation as a cooling mechanism. for example for sweat, heat is lost form the body to make the sweat evaporate from the surface of the skin
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22
Q

what are monosaccharides, disaccharides, and polysaccharides?

A

1) single monomer unit of carbohydrate
2) when 2 monosaccharide join
3) multiple disaccharides join

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23
Q

what 2 monosaccharides make: a) sucrose b) maltose c) lactose?

A

a) fructose and glucose
b) glucose and glucose
c) glucose and galactose

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24
Q

monosaccharides:
1) molecule type? 2) taste? 3) soluble? 4) glycosidic bonds? 5) role? 6) structure? 7) examples?

A

1) single molecule
2) sweet
3) soluble
4) none
5) energy release, transported in blood, monomers for other carbohydrates
6) exist as a single ring shape or as a straight chain
7) glucose, fructose, galactose, ribose, deoxyribose

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25
Q

disaccharides:
1) type of molecule? 2) taste? 3) soluble? 4) glycosidic bonds? 5) role? 6) structure? 7) examples?

A

1) two molecules covalently bonded
2) sweet
3) soluble
4) one bond
5) energy release, storage and transport within plants
6) energy release, storage and transport within plants
7) sucrose, maltose and lactose

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26
Q

polysaccharides:
1) type of molecule? 2) taste? 3) soluble? 4) glycosidic bonds? 5) role? 6) structure? 7) examples?

A

1) many molecules covalently joined to each other
2) not sweet
3) insoluble
4) many bonds
5) energy store and a structural component in cell walls
6) kind chains with may be branched and coiled, making them compact
7) starch, glycogen and cellulose

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27
Q

what is the role of glucose?

A

used in aerobic respiration inside cells to release energy

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28
Q

what are some characteristics that glucose has that makes it useful?

A
  • small meaning it can pass through easily
  • soluble
  • reactive
  • easily broken down
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29
Q

how are alpha and beta glucose different?

A

alpha glucose has hydrogen on the top of carbon one and hydroxide on the bottom while beta has it opposite

30
Q

what sugars do dna and rna have?

A

deoxyribose sugar and ribose sugar (pentose sugars)

31
Q

what reaction occurs for disaccharides to form and how?

A

condensation reaction, forming a a 1-2 glycosidic bond

32
Q

why is the glycosidic bond called a 1-4 bond?

A

carbon number one on one of the glucose molecules and carbon number 4 on the other glucose molecule are bonded

33
Q

what reaction is used to break up a disaccharide and how?

A

a hydrolysis reaction by using heat or acid

34
Q

what type of glucose is starch made from and what are the 2 different types of starch ?

A

alpha glucose for example amylose and amylopectin

35
Q

what is the structure of amylose?

A

long chains of 1-4 linked alpha glucose, coiled into a spiral shape, stabilised by hydrogen bonds

36
Q

what is the structure of amylopectin?

A

long chains of 1-4 linked alpha glucose molecules with short side branches (1-6 linked)

37
Q

why is starch a great storage molecule in plants?

A
  • the chain coils in a spiral shape, making it very compact - it is not soluble in water meaning it doesn’t affect the water potential of the cell
38
Q

what is the structure of glycogen?

A

long chains of alpha glucose with 1-4 glycosidic bonds and highly branched (branches have 1-6 glycosidic bonds)

39
Q

why is glycogen a good storage molecule in animals?

A

it is highly branched with shorter chains making it extremely compact

40
Q

what type of glucose is cellulose made from and how can they join together?

A

beta glucose. if every other molecule is “flipped 180” (alternate glucose flip upside down) then the hydroxyl groups can reacts

41
Q

what is the structure of cellulose and how does it make ii ideal for the structure of plant cell walls?

A
  • a straight chain molecule rather than coiled. with many chains, linked by hydrogen bonds, forming microfibrils
  • microfibrils have high tensile strength due to the glycosidic bonds and the hydrogen bonds. the macrofibrils are embedded in gel-like pectin to give more strength
  • helps cell remain turgid to prevent wilting
42
Q

what is the structure of a triglyceride?

A

one glycerol molecule (a very simple alcohol) and 3 fatty acids (long hydrocarbon chains with an acid group/carboxyl group (cooh) at one end)

43
Q

how does a triglyceride form?

A

the oh on the fatty acids are lined up next to the oh groups on the glycerol. three condensation reactions occur, forming ester bonds

44
Q

what is the structure of a saturated fatty acid vs mono-unsaturated fatty acid vs polyunsaturated fatty acid?

A
  • saturated = no double bonds between carbon atoms
  • mono-unsaturated = one double bond between carbon atoms
  • polyunsaturated = more than one double bond between carbon atoms meaning multiple kinks and bends
45
Q

how are lipids good for a) insulation, b) waterproofing, c) being energy stores and d) being good energy sources in living organisms?

A

a) they are poor conductors therefore they prevent heat loss
b) hydrophobic
c) long hydrocarbon chains contain a lot of energy. they are unreactive, insoluble and compact
d) easily hydrolysed

46
Q

what are phospholipids?

A

modified triglycerides containing phosphorus, with a fatty acid tail (hydrophobic and non-polar) and a phosphate head (hydrophilic and polar)

47
Q

why is cholesterol bad for us?

A

too much ldl in the blood can cause deposits in the walls of the coronary arteries and other arteries, narrowing arteries and restricting blood flow causing possible heart attacks

48
Q

what is the role of cholesterol in the membrane?

A

maintaining the social integrity and regulating the fluidity of the cell surface membrane

49
Q

how many different amino acids are there and how do they differ from each other?

A

20 and they each have a different r-group

50
Q

what are the different levels of proteins?

A

primary, secondary, tertiary and quaternary

51
Q

what are the 2 shapes of the secondary structure of proteins?

A

alpha helix and beta pleated sheets

52
Q

how many polypeptides are the quaternary structure of proteins made from vs the other levels?

A

more than one vs one

53
Q

what are some examples of proteins in the quaternary structure?

A

enzymes, hormones, haemoglobin and collagen

54
Q

what are the characteristics of globular proteins?

A

compact, water soluble , roughly spherical shape, easily transported and usually have metabolic roles (tertiary and quaternary proteins)

55
Q

what are 3 globular proteins? (number of polypeptide chains, and the role)

A
  • haemoglobin with 4 chains to carry oxygen around the body, in red blood cells
  • insulin with 2 chains to help regulate blood glucose levels
  • amylase with 1 twisted and folded chain, which is an enzyme to catalyse the breakdown of starch
56
Q

why is haemoglobin known as a conjugated protein?

A

it’s a protein with a non-protein group attached called the prosthetic group (haem group made from iron)

57
Q

what are the characteristics of fibrous proteins?

A
  • long and thin strands
  • insoluble
  • small r-groups
  • not folded into 3d shapes
  • strong
  • metabolically inactive
58
Q

what are 3 examples of fibrous proteins? (role)

A
  • keratin =strong and fairly flexible, found in hair and nails
  • elastin = ability to stretch and coil, in the walls of blood vessels and surrounding the alveoli in the lungs
  • collagen = strong, used as a connective tissue in skin, tendons, ligaments and the nervous system
59
Q

what level of protein structure do keratin/elastin/collagen all show?

A

quaternary because they have more than one polypeptide chain

60
Q

what is the sequence of amino acids in fibrous proteins vs globular proteins?

A

repetitive sequence vs irregular sequence

61
Q

how stable are fibrous protein vs globular proteins?

A

less sensitive to changes in heat and ph vs more sensitive

62
Q

what is the test for starch?

A
  • iodine test
  • add 1cm of sample to each dimple of a spotting tile and add a few drops of iodine solution to each
  • orange > black/blue
63
Q

what is the test for lipids?

A
  • emulsion test
  • add 1cm of ethanol to a test tube and add 1cm of the sample. shake vigorously to dissolve and add 1cm of cold water
  • clear > cloudy emulsion
64
Q

what is the test for proteins?

A
  • biuret test
  • add 2cm sample solution to a test tube and add 2cm of biuret solution
  • blue > purple/lilac
65
Q

what is the test for reducing sugars?

A
  • benedicts test
  • add 2cm of sample solution to a test tube and add 2cm of benedicts solution. heat gently in a water bath at 85 degrees for 2 minutes
  • blue > green/yellow/ brick red
66
Q

how do you test for non-reducing sugars?

A
  • add 2cm of sample solution to a test tube and add 1cm of 1m hydrochloric acid then boil in a water bath for one minute. carefully neutralise with sodium bicarbonate. to make sure, check the ph with indicator paper and then carry out the benedict’s test
  • blue > green/yellow/brick red
67
Q

what is chromatography and what are the two types?

A
  • allows the separation of components from a mixture of molecules
  • paper and thin layer
68
Q

what is the mobile phase in paper and thin layer chromatography?

A
  • where the molecules can move
  • a liquid solvent
69
Q

what is the stationery phase of paper and thin layer chromatography?

A
  • where the molecules can’t move
  • paper = piece of paper
  • thin layer = layer of solid
70
Q

what is the method for paper chromatography?

A
  • draw a pencil line 1.5cm up from the bottom of the paper
  • place the first dot of the sample on this line and repeat until all the samples are there
  • put the paper into the solvent ensuring the solutes aren’t in the solvent
  • when the solvent reaches the top of the paper, mark with a pencil (solvent front) and let the paper dry
71
Q

how do you calculate rf values?

A

distance travelled by solute divided by distance travelled by solvent

biology (10 decks)

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