biological molecules Flashcards

1
Q

What should be identified in strange enzyme diagrams?

A

Prosthetic groups/cofactors, competitive inhibitors, noncompetitive inhibitors, required materials (i.e: ATP), and conditions needed, justifying all of these.

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2
Q

What do fatty acids contain?

A

A carboxylic group, so they have oxygen atoms present.

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3
Q

How do you measure lactose concentration using a colorimeter?

A

Set the colorimeter to 0 using a blank and a red filter, then use known concentrations of lactose produced via serial dilution to construct a calibration curve. Test the unknown sample using the same method and read from the calibration curve to determine the lactose concentration of the unknown solution.

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4
Q

Why can galactose be used as a respiratory substrate?

A

Its bonds contain energy, which can be broken by respiratory enzymes. Galactose is also soluble, allowing it to move within the cell as the H/OH groups can form H bonds with water.

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5
Q

Why can’t lactose pass through cell membranes?

A

It is too big to pass between phospholipids and there is only a small concentration gradient. It needs a carrier protein/pump to pass through.

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6
Q

How do polysaccharides form?

A

They are formed by condensation reactions that create glycosidic bonds between monomers, releasing a molecule of water.

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7
Q

What is the advantage of glycogen as an energy storage molecule?

A

Glycogen is insoluble, metabolically inactive, compact, and highly branched, allowing for rapid breakdown and release of glucose when needed.

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8
Q

What affects the melting points of fats?

A

Fats with more double bonds have lower melting points , as they are more kinked , so molecules less uniformly packed together , so lower temp needed for melting

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9
Q

How are DNA nucleotides and ATP similar?

A

Both have a pentose sugar, adenine as a base, a phosphodiester bond between the sugar and the phosphate, an OH group on carbon 3 of the sugar, and a phosphate group.

ATP has two additional phosphates, deoxyribose replaced by ribose, and an OH group on carbon 2 of the sugar (ribose).

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10
Q

How do you estimate glucose concentration using a calibration curve?

A

Find the absorbance of the sample using a colorimeter, then from the graph, find the concentration that corresponds to this absorbance by following the absorbance value on the y-axis across to the line of best fit and down to the concentration on the x-axis.

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11
Q

What do glucose and cholesterol have in common?

A

Both contain carbon atoms, hydrogen atoms, oxygen atoms, and have hydroxyl groups.

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12
Q

Why is cellulose suitable for plant cell walls?

A

It is insoluble, unreactive/inert, has high tensile strength, and is flexible.

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13
Q

What are the similarities and differences between chitin and glycogen?

A

Both are polysaccharides composed of 6 carbon sugar monomers with 1-4 glycosidic bonds and CH2OH side groups.

Chitin has -glycosidic bonds, contains nitrogen, has no 1-6 glycosidic bonds, and is not branched.

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14
Q

What is mycoprotein’s fat content compared to animal protein?

A

Mycoprotein has less fat and less saturated fat than animal protein.

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15
Q

What does a color change from blue to purple indicate in the biuret test?

A

It suggests that the solution contains protein, as enzymes can be detected by this test since they are globular proteins and water soluble, so can be in solution since their hydrophilic r- groups are on the outside + vice versa

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16
Q

How should a hydrogen bond be represented?

A

As a horizontal/vertical dashed line between the O on one water molecule and the H on the adjacent water molecule, with the Hs labeled delta positive and the Os labeled delta negative.

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17
Q

What color change does glucose produce in Benedict’s test?

A

A positive color change is seen as it is a reducing sugar.

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18
Q

What can lead to an overestimation of reducing sugar concentration by Benedict’s reagent?

A

The presence of other reducing sugars in the sample.

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19
Q

How do you get a 0% transmission reading with a colorimeter for a solution w/ no glucose in?

A

Use a solution that the Benedict’s test has been done on that has no reducing sugar to calibrate the colorimeter to zero.

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20
Q

Why is using a colorimeter better than a color chart for estimating glucose concentration?

A

It is more objective/quantifiable, as the instrument has greater precision than a chart.

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21
Q

Why does ice float on water?

A

Ice is less dense than water as the molecules spread out to form a crystal lattice, providing insulation for the water below.

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22
Q

How do ions interact with water?

A

Ions are polar charged, and water is also polar, allowing ions to be attracted to and bind with water
tak up minerals+ nutrients from water

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23
Q

What is the significance of plants in yogurt production?

A

Dairy animals use plants for food, making plants the base of this food chain. Some yogurts also contain fruit and plant flavoring.

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24
Q

What contributes to water’s temperature stability?

A

Many hydrogen bonds between molecules require a lot of energy to break, resulting in high specific heat capacity (maintain temp) and high latent heat of vaporization.(evaportation)

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25
Q

How does water provide a stable environment for aquatic organisms?

A
  • Water is a thermally stable environment for aquatic organisms,
  • so aquatic organisms use less energy on temperature control and the internal temperature of organisms changes only slowly so their enzymes and thus their metabolism functions correctly
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26
Q

What roles does water play in living organisms?

A

It acts as a medium for reactions, a transport medium, and can dilute toxic substances, allowing for oxygen uptake and waste product removal.

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27
Q

What properties of water allow for the transpiration stream in plants?

A

Cohesive and adhesive properties enable water movement and surface tension, allowing insects to inhabit the water’s surface.

28
Q

Why is water’s transparency important?

A

It allows for underwater photosynthesis.

29
Q

What does water’s high density provide?

A

Flotation/support for organisms.

30
Q

Why is it hard to tell if milk gives a positive result for the lipid test?

A

Milk is already a cloudy white emulsion.

31
Q

Where else are hydrogen bonds found besides water?

A

In protein secondary structure (alpha helices and beta pleated sheets), tertiary structure, cellulose chains, and between DNA bases.

32
Q

Why is glucose well-suited for its function?

A

It is soluble, small for easy transport, can be quickly respired to produce ATP, and can form disaccharides and polysaccharides.

33
Q

Why can’t bacteria digest certain polysaccharides like agarose?

A

They lack the correct enzyme, and the polysaccharide does not fit the active site of the enzymes they possess.

34
Q

What does the presence of reducing sugar indicate in an experiment with bacteria and polysaccharides?

A

It suggests contamination by a substrate they can break down, another microorganism, or mutated microorganisms capable of digestion.

35
Q

What makes glycogen a good storage molecule?

A

It is insoluble, made of alpha glucose, can be quickly hydrolyzed due to its branched structure, and is compact and energy dense.

36
Q

What is the structure of cellulose?

A

It is made of beta glucose with 1,4 glycosidic bonds, is unbranched/linear, and forms fibrils and fibers.

37
Q

Why do animals use glycogen instead of amylose for energy storage?

A

Animals have a high metabolic rate requiring rapid ATP releases, so they need a more branched polysaccharide for faster hydrolysis.

38
Q

Why is nitrogen fertilizer applied to farmland?

A

To maintain yield over time by replacing lost nitrogen/nitrates, which are essential for amino acid and protein production.

39
Q

What happens to an iodine-amylose complex when heated to 60 degrees Celsius?

A

The hydrogen bonds holding the amylose in shape break, causing the helix to unravel and iodine to be released.

40
Q

What is amylose?

A

A coiled polysaccharide consisting of alpha glucose joined with 1-4 glycosidic bonds, forming granules and being unbranched.

41
Q

What are triglycerides composed of?

A

One glycerol and three fatty acids, with an ester bond between the glycerol and each fatty acid.

42
Q

What are the functions of lipids in living organisms?

A

Thermal insulation, energy storage, organ protection, cell membrane structure, steroid hormone production, buoyancy, waterproofing, and vitamin absorption.

43
Q

What are the differences between triglycerides and phospholipids?

A

Triglycerides have three fatty acids and no phosphate, while phospholipids have two fatty acids and a phosphate.

Both contain glycerol, fatty acids, ester bonds, and the elements C, H, and O.

44
Q

How do you test for lipids using the emulsion test?

A

Add ethanol to the sample, mix thoroughly, then add water. A positive result turns the mixture cloudy/milky/white.

45
Q

Why are lipids in animals solid at room temperature?

A

They have fewer double bonds than those in plants.

46
Q

How do amino acids bond together?

A

Via peptide bonds formed between the amine of one amino acid and the carboxyl group of another through a condensation reaction.

47
Q

What is the difference between starch and sucrose in terms of glucose release?

A

Starch contains only glucose, while sucrose contains 50% glucose and 50% fructose, so starch releases more glucose when hydrolyzed.

48
Q

What is the digestibility difference between starch and cellulose?

A

Starch is digestible, while cellulose is indigestible due to the lack of enzymes for cellulose digestion in humans.

49
Q

What defines a substance as an amino acid?

A

It must have both an amine and a carboxylic acid group.

50
Q

How does hydrolysis of polysaccharides occur?

A

By breaking glycosidic bonds through the addition of water/H2O.

51
Q

How do you test seed pods for protein?

A

Crush a small amount of seed pod, add biuret solution, and a positive result causes a color change from blue to mauve/purple.

52
Q

How do you test seed pods and leaves for reducing sugar?

A

Crush samples with water, filter to remove solids, add Benedict’s reagent, and heat. A color change from blue to green/yellow/orange/red indicates increasing concentration.

53
Q

How do you measure the change in concentration of reducing sugar during a reaction?

A

Take samples of the same volume at various times and use the previous steps to determine the reducing sugar present.

54
Q

Why is it better for humans to eat cows than seeds directly?

A

Cows can digest plant matter better than humans, and meat and milk provide essential amino acids that seeds may lack.

55
Q

How can the concentration of reducing sugar be measured with a colorimeter?

A
  • Concentration of reducing sugar can be measured with a colorimeter by using known concentrations of reducing sugar and heating each of these solutions with Benedict’s solution, using the same volumes of solution Benedict’s and reducing sugar solution each time.
  • Excess Benedict’s should be used to give a correct reading.
  • If reducing sugar is present then the colour of the solution should change from blue to (brick) red.
  • You would then filter out the precipitate to obtain the filtrate, and calibrate / zero the colorimeter using water or unreacted Benedicts.
  • You should use a red filter to calibrate the colorimeter, and should read the transmission or absorbance of each solution.
  • Less transmission /more absorbance of filtrate = more sugar present.
  • You would then obtain a calibration curve, plotting transmission or absorbance against reducing sugar concentration, and you would use a reading of unknown sugar solution and read off graph to find concentration
56
Q

How is a colorimeter used to measure reducing sugar concentration?

A

A colorimeter is used by heating known concentrations of reducing sugar with Benedict’s solution and measuring the color change from blue to green/yellow/orange/brown/red. Excess Benedict’s ensures accurate readings.

Filter out the precipitate to obtain the filtrate and calibrate the colorimeter using water or unreacted Benedict’s.

57
Q

What does less transmission or more absorbance indicate in a colorimeter reading?

A

Less transmission or more absorbance of the filtrate indicates a higher concentration of reducing sugar present.

A calibration curve is obtained by plotting transmission or absorbance against reducing sugar concentration.

58
Q

How can the concentration of reducing sugar be estimated using Benedict’s solution?

A

To estimate concentration, compare the degree of final color change with a standard solution, filter out and weigh the precipitate, or centrifuge the solution.

Greater mass or larger pellet size indicates more sugar present.

59
Q

What is the process to break down a non-reducing sugar into a reducing sugar?

A

Add hydrochloric acid to the sugar solution, boil it, then neutralize with sodium hydrogencarbonate before testing as normal.

60
Q

What interactions produce the tertiary structure of a protein?

A

R groups interact through attraction/repulsion, disulfide bridges, hydrogen bonds, and ionic bonds. Hydrophilic R groups are on the outside, while hydrophobic R groups are on the inside.

61
Q

What is collagen and its structural characteristics?

A

Collagen is a protein made of amino acids joined by peptide bonds, forming a left-handed helix with glycine every third amino acid. It is unbranched, helical, and consists of three chains with hydrogen bonds between them.

Collagen is insoluble due to few hydrophilic R groups and has staggered crosslinks for strength.

62
Q

What role does collagen play in the body?

A

Collagen plays a structural role and is part of tendons, cartilage, ligaments, bone, connective tissue, bronchi, bronchioles, the trachea, and skin.

63
Q

Why is collagen suitable for making ligaments?

A

Collagen has high tensile strength, does not stretch, is insoluble, and is flexible, making it ideal for holding bones together at joints.

64
Q

What is the function of hemoglobin?

A

Hemoglobin transports oxygen and is a globular protein that is soluble due to the folding of hydrophobic R groups on the inside and hydrophilic R groups on the outside.

65
Q

Describe the structure of hemoglobin.

A

Hemoglobin consists of a primary structure of amino acids, secondary structure with alpha helices and beta pleated sheets, tertiary structure with various bonds, and a quaternary structure of 4 polypeptides (2 alpha and 2 beta chains) with a haem group per polypeptide.

The prosthetic group, haem, contains Fe2+ for oxygen transport.

66
Q

How are collagen and hemoglobin similar?

A

Both have a primary structure of amino acids joined by peptide bonds, helical sections in their secondary structures, and disulfide/ionic/hydrogen bonds in their tertiary structures. Both also have a quaternary structure with multiple polypeptides.

67
Q

What is the primary structure of a protein?

A

The primary structure is the sequence of amino acids that make up a polypeptide.