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biological molecules Flashcards

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Biology 101 flashcards
1
Q

how much water does our bodies lose, and through what?

A

our bodies lose up to 3l of water daily, mostly through sweat and urine production

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2
Q

how does dehydration occur in humans?

A

it happens when the volume of water lost is not balanced by the water intake through eating and drinking.

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3
Q

what are the symptoms of dehydration?

A

feeling faint, losing focus, dry and irritated eyes, cracked lips and sore throat, constipation, pungent and dark-coloured urine

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4
Q

why is water important in humans in terms of regulating body temperature?

A

-water has a high heat capacity and is used to transport heat around the body
-when water in sweat evaporates,the latent heat of vapourisation removed from the skin helps keep the body cool

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5
Q

why is water important in humans in terms of maintaining blood pressure?

A

water makes up half the volume of blood
-too little water and blood becomes too viscous
-too much water and blood vessels may burst

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6
Q

why is water important humans in terms of medium of transport?

A

water being a universal solvent allows for efficient transport of many soluble substances throughout the body

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7
Q

why is water important in humans in terms of solvent for chemical reactions?

A

water makes up more than half the volume of the cell cytoplasm and is where most chemical reactions occur in the cell

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8
Q

why is water important in humans in terms of lubrication?

A

fluid at the joints and tears on the eye reduce the wear and tear these surfaces experience

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9
Q

why is water important in humans in terms of preventing constipation?

A

undigested food should be passed out in a semi-solid form with some water present

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10
Q

why is water important in humans in terms of excretion?

A

the kidneys remove toxic metabolic waste from the body by diluting it in water and excreting it in urine

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11
Q

why is water important in plants in terms of regulating temperature?

A

when plants lose water vapour via transpiration, the latent heat of vapourisation removed helps keep the plant cool

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12
Q

why is water important in plants in terms of medium if transport?

A

water being a universal solvent allows for the efficient transport of many soluble substances via the xylem and phloem

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13
Q

why is water important in plants in terms of solvent for chemical reactions?

A

water makes up more than half the volume of the cell cytoplasm and is where most chemical reactions occur in the cell

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14
Q

what are carbohydrates, proteins, and fats called, and what do they all contain in common?

A

they are biological molecules
they all similarly contain carbon, hydrogen, and oxygen atoms in varying ratios

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14
Q

in carbs, what are the polysaccharides?

A

starch, cellulose, glycogen

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14
Q

in carbs, what are the monosaccharides?

A

glucose, galactose, fructose

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14
Q

in carbs, what are the disaccharides?

A

maltose, lactose, sucrose

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14
Q

what is the element composition of carbs?

A

carbon, hydrogen, oxygen only
hydrogen and oxygen always 2:1

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14
Q

what is the basic unit in carbs?

A

monosaccharide (C6H12O6)
simplest carbohydrate molecule

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14
Q

what is the role in organism of carbs?

A

all carbohydrates consumed are ultimately broken down into glucose
substrate for cellular respiration
substrate for lipid and amino acid synthesis

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14
Q

what are some examples of glucose?

A

honey, raisins, dates

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14
Q

what are some examples of galactose?

A

honey, celery, plums

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14
Q

what makes maltose and what are some examples of it?

A

glucose+glucose
malt sugar
apples, sweet potatoes, edamame

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15
Q

what are some examples of fructose?

A

honey, pear, mango

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15
Q

what makes lactose and what are some examples of it?

A

galactose+glucose
milk sugar
milk, yoghurt, cheese

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15
Q

what are reducing sugars?

A

glucose, galactose, fructose, maltose, lactose

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15
Q

what makes sucrose and what are some examples of it?

A

fructose+glucose
table sugar
sugar cane, maple syrup, gula melaka

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15
Q

what sugar isnt a reducing sugar?

A

sucrose

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15
Q

how to carry out the benedicts test?

A

if presented with solid sample grind with a mortar and pestle then add distilled water
-add 2cm3 of benedicts solution to 2cm3 of the liquid/aqueous sample
-heat the mixture for 5 minutes in a boiling bath

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16
Q

what do the results of the benedicts test mean?

A

remains clear blue=reducing sugars absent
turns brick-red=reducing sugars present

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17
Q

what are polysaccharides made out of?

A

polysaccharides are made out of many repeating subunits of glucose chemically bound together

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18
Q

where is starch commonly found?

A

starch is the storage in plants

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19
Q

where is glycogen commonly found?

A

glycogen is the storage in animals

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20
Q

where is cellulose commonly found?

A

cellulose is the structural support for the plant cell wall

21
Q

how to carry out the iodine test for starch?

A

add 3 to 5 drops of iodine solution to the sample

22
Q

what do the results of the iodine test mean?

A

remains yellowish-brown=starch absent
turns blue-black=starch present

23
Q

which class of biological molecules do fats belong to?

A

lipids (which also include many other important molecules such as phospholipids;cell membrane, and hormones;oestrogen and testosterone)

24
Q

what is the element composition of fats?

A

carbon, hydrogen, and oxygen
no fixed ratio of hydrogen and oxygen

25
Q

what is the basic unit of fats?

A

one glycerol backbone with three fatty acid tails

26
Q

what is the role in organism in fats?

A

long-term energy storage, insulation beneath the skin surface, cushion and protect internal organs from impact, major component of cell membrane, solvent for fat-soluble vitamins

27
Q

what are saturated fats?

A

solid at room temperature, increases risk of heart diseases

28
Q

what are unsaturated fats?

A

liquid at room temperature, lowers risk of heart diseases

29
Q

how does the ethanol-emulsion test for fats occur?

A

add the food sample to a beaker of ethanol and shake thoroughly to allow any fats present to dissolve
-filter the mixture and pour 2cm3 of the residue to 2cm3 of water

30
Q

what do the results of the ethanol-emulsion test for fats mean?

A

remains clear and colourless=fats absent
cloudy white emulsion formed=fats present

31
Q

what are proteins?

A

proteins account for more than 50% of the dry mass of most cells and are crucial for the basic functioning of a cell. proteins help to speed up chemical reactions, transport substances, and allow cells to move

32
Q

how are proteins formed?

A

there are 20 amino acids that can be chemically bound together in various lengths and sequences to form thousands of different proteins

33
Q

for proper functioning, how many proteins does a normal human have?

A

10000 different proteins for an estimated total of 400000 proteins for proper functioning

34
Q

what do amino acids contain?

A

they all consist of an amino group, a carboxyl group, and a hydrogen atom.

35
Q

what differs in amino acids?

A

the variable group that gives rise to the 20 different amino acids

36
Q

what do those 20 different amino acids do?

A

these 20 different amino acids come together in various lengths and sequences to form polypeptides which subsequently fold to become the proteins essential for life

37
Q

what are some products rich in proteins?

A

meat and dairy products, as well as leafy vegetables. eggs, nuts and beans

38
Q

what is the element composition of proteins?

A

carbon, hydrogen, oxygen and nitrogen
some amino acids have sulfur and phosphorus

39
Q

what is the basic unit of amino acids?

A

amino acid

40
Q

what is the role in organism in proteins?

A

enzymes speed up chemical reactions, antibodies and antigens protect cell from pathogens, hormones regulate various processes, contractile and motor proteins allow for movement

41
Q

how does the biuret test for proteins occur?

A

-add 2cm3 of sodium hydroxide solution to 2cm3 of the liquid/aqueous sample and shake thoroughly to mix
-add a 3 to 5 drops of copper(II) sulfate solution, shaking the mixture between drops

42
Q

what do the results of the biuret test for proteins mean?

A

remains blue=proteins absent
turns violet=proteins present

43
Q

what are enzymes?

A

enzymes are biological catalysts that speed up the rate of chemical reactions and remain chemically unchanged at the end of each reaction

44
Q

how do enzymes work?

A

-all enzymes are proteins and function best at their optimal temperatures and pH
-enzymes provide an alternative reaction pathway with a lower activation energy
-only a small amount of enzymes are needed as they remain chemically unchanged at the end of each reaction and can therefore be reused

45
Q

what is activation energy?

A

the minimum amount of energy reacting molecules need to have to undergo a reaction. the lower the activation energy, the more easily the reaction proceeds

46
Q

what is the ‘lock and key’ hypothesis?

A

substrate molecules have a complementary shape to fit into the active site of an enzyme. enzymes ensure specificity by having a unique active site that can only bind to a complementary substrate molecule. upon forming the enzyme-substrate complex, the substrate now requires a lower activation energy to undergo a reaction and can proceed to form new products by breaking or forming bonds

47
Q

what is the complementary substrate molecules for amylase?

A

starch

48
Q

what is the complementary substrate molecules for sucrase?

A

sucrose

49
Q

what is the complementary substrate molecules for protease?

A

proteins

50
Q

what is the complementary substrate molecules for lipase?

A

lipids

51
Q

how does temperature affect enzyme-cataylsed reactions?

A

being proteins, enzymes are sensitive to changes in temperature, and their ability to catalyse reactions will diminish when the conditions are too far from the optimal

52
Q

what is the optimum temperature of enzymes found in the human body?

A

around 37 degrees celsius

53
Q

what does the point below optimum temperature in the graph mean?

A

enzymes (and substrates) have insufficient kinetic energy
enzymes are inactive and enzyme activity is low

54
Q

what does the point at optimum temperature in the graph mean?

A

enzymes have the perfect of kinetic energy to bind to substrates and catalyse the reaction

55
Q

what does the point above optimum temperature in the graph mean?

A

enzymes denature and are no longer complementary to their substrates

56
Q

what does the trend below optimum temperature in the graph mean?

A

as temperature increases, reacting molecules have more kinetic energy and move faster
the frequency of effective collisions increase, causing more enzyme-substrate complexes to form more quickly for a greater rate of reaction

57
Q

what does the trend at optimum temperature in the graph mean?

A

enzymes are most active and have the greatest rate of reaction

58
Q

what does the trend above optimum temperature in the graph mean?

A

-too much kinetic energy disrupts the bonds holding the three-dimensional structure of the enzyme
-the specific shape of the active site is damaged, and the enzyme is no longer complementary to its substrate
-enzymes are denatured and cannot catalyse the reaction

59
Q

what is the effect pH has on enzyme-catalysed reactions?

A

enzymes are also sensitive to changes in pH, and their ability to catalyse reactions will diminish when the conditions are too far from the optimal

60
Q

what is the pH of stomach enzymes?

A

2 (very acidic)

61
Q

what is the pH of pancreatic enzymes?

A

8 ( a little basic/alkali)

62
Q

what does the point below optimum pH in the graph mean? (pH)

A

enzymes are denatured and no longer complementary to their substrates

63
Q

what does the point at optimum pH in the graph mean? (pH)

A

enzymes are most active

64
Q

what does the point below optimum pH in the graph mean? (pH)

A

enzymes are denatured and no longer complementary to their substrates

65
Q

what does the trend below optimum pH in the graph mean?

A

-deviations from the optimal pH disrupts the bonds holding the three-dimensional structure of the enzyme
-the specific shape of the active site is damaged, and the enzyme is no longer complementary to its substrate
-enzymes are denatured and cannot catalyse the reaction

66
Q

what does the trend at optimum pH in the graph mean?

A

enzymes are most active and have the greatest rate of reaction

67
Q

what does the trend above optimum pH in the graph mean?

A

-deviations from the optimum pH disrupts the bonds holding the three-dimensional structure of the enzyme
-the specific shape of the active site is damaged, and the enzyme is no longer complementary

68
Q

how does substrate concentration affect the rate of enzyme-catalysed reactions?

A

-at low substrate concentrations, enzyme activity increases rapidly when substrate concentration increases
-at high substrate concentrations, enzyme activity plateaus as all enzyme active sites are occupied and substrate molecules must wait for a free active site

69
Q

how does enzyme concentration affect the rate of enzyme-catalysed reactions?

A

-at low enzyme concentrations, enzyme activity increases rapidly when enzyme concentration increases
-at high enzyme concentrations, enzyme activity plateaus as all substrates have already formed enzyme-substrate complexes and there are no available substrates

70
Q

how does the size of the sample affect the rate of enzyme-catalysed reactions?

A

-large chunks of food have small surface to volume ratios, decreasing the effectiveness of enzyme reactions
-small pieces of food have large surface area to volume to ratios, increasing the effectiveness of enzyme reactions

bio (12 decks)

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