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biology - Moldule 2 Foundations In Biology > 2.1.2 Biological Molecules LMH > Flashcards

2.1.2 Biological Molecules LMH Flashcards

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1
Q

What is a polymer

A

A long chain of repeating monomers joined together

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2
Q

What is a monomer

A

A smaller unit from which larger molecules are made

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3
Q

What is a monosaccharide

A

A type of carbohydrate
Simple sugars made which contain 1 carbon ring
- beta glucose
- alpha glucose
- fructose

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4
Q

What is a disaccharide

A

A type of carbohydrate
Simple sugars made which contain 1 carbon ring
- maltose
- sucrose
- lactose

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5
Q

What is a polysaccharide

A

Type of carbohydrate
A chain or monosaccharides (simple sugars) with multiple repeating carbon rings
- cellulose
-Glycogen
- starch

Example: beta glucose monosaccharides joined together is the polysaccharide cellulose

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6
Q

What is a saccharide

A

Organic compounds which contain Carbon, hydrogen and oxygen

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7
Q

What are the three types of carbohydrates

A
  • Monosaccharides
  • disaccharides
  • polysaccharides
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8
Q

What types of bonds join together the carbon rings

A

Glycosidic bonds

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9
Q

What bonds join the elements and compounds in the carbon rings

A

Covalent

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10
Q

What is a hexose monosaccharide

A

a simple sugar made up of 6 carbon atoms

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11
Q

What is the difference between alpha and beta glucose

A

Alpha - hydroxyl group on Carbon 1 is below carbon ring
Beta - hydroxyl group on Carbon 1 is above carbon ring

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12
Q

Properties of glucose

A
  • small because it’s a monosaccharide so it can cross semipermeable cell surface membranes (phospholipids)
  • polar (has a positive and negative end) and soluble in water due to hydrogen bonds that form between the hydroxyl groups and water molecules
  • this solubility is important because it means glucose can dissolve in the cytosol (fluid within the cytoplasm) of the cell and move within the cell
  • bonds within the glucose molecule contain chemical energy which can be broken down by respiratory enzymes to release the energy
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13
Q

Ribose

A
  • a Pentose (5 membered ring) monosaccharide (simple sugar)
  • 5 carbons and a 5 membered ring
  • the sugar in nucleotides

Many nucleotides joined together makes a polynucleotide chain eg. RNA

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14
Q

Condensation reactions

A
  • Joining of two monomers to form polymers by removing a water molecule
  • produces water
  • glycosidic bond is formed
  • disaccharide is formed
  • must happen between two hydroxyl groups so there is a left over oxygen which can be used to form part of the glycosidic bond
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15
Q

Hydrolysis reaction

A
  • Water added
  • to glycosidic bond
  • which breaks it to form two monosaccharides
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16
Q

How does a condensation reaction form a glycosidic bond

A
  • One hydrogen atom from the hydroxyl group of one monomer
  • and the hydrogen and oxygen atoms from the hydroxyl group from another monomer
  • are removed to form a water molecule
  • a glycosidic bond then forms between the Carbon 1 of one monomer and carbon 4 of another monomer
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17
Q

Which monomers make up the disaccharide maltose

A

Alpha glucose and alpha glucose

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18
Q

Which monosaccharides make up the disaccharide sucrose

A

Alpha glucose and fructose

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19
Q

Which monosaccharides make up the disaccharide lactose

A

Glucose and galactose

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20
Q

Which monosaccharides is the polysaccharide cellulose made from

A

Beta glucose

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21
Q

Which monosaccharides is the polysaccharide startch made from

A

Alpha glucose

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22
Q

Which monosaccharides is the polysaccharide glycogen made from

A

Alpha glucose

23
Q

what do the numbers mean in the bonds eg. 1,4 alpha glycosidic bond

A

The numbers correspond to which carbons the bond is between

24
Q

What do you use to test for starch

A

Iodine

25
Q

How do you test for starch

A
  • Place a sample of the food into a dipping tile
  • use a pipette to place a few drops of iodine onto the sample
  • if the sample contains starch it will turn black
26
Q

What colour does a positive starch test turn

A

Blue - black

27
Q

Why does a positive starch and iodine test turn black

A

Due to the iodine reacting with the starch

28
Q

What is the difference between reducing and non-reducing sugars?

A

All monosaccharides and some disaccharides are reducing sugars. This means that they have the ability to donate electrons to another substance to reduce it (reduction is gain of electrons)
Non - reducing sugars can’t donate electrons

29
Q

Examples of reducing sugars

A

Glucose, fructose, galactose, maltose, lactose

30
Q

Name one non-reducing sugar

A

Sucrose

31
Q

How do you test for reducing sugars.

A
  • Add 2cm of the food sample (in liquid form) into a test tube
  • heat with 2cm of Benedict’s reagent in a water bath at 95°C - 100°C for 5 minutes
  • if reducing sugars are present there will be a colour change from blue to green, yellow, brown/orange to brick red depending on the concentration of reducing sugars
32
Q

Why does Benedict’s reagent change colour

A

Benedict’s reagent is an alkaline solution of copper (ii) sultate. When a reducing sugar is heated with Benedict’s solution, the reducing sugar reduces the blue Cu 2+ ions in the copper sultate, to produce a brick red precipitate called copper oxide
→ when cu 2+ accepts electrons from a reducing sugar it forms copper oxide which is red
The more reducing sugar is present, the more copper oxide precipitate is formed and the less blue Cu 2+ ions are left in the solution

33
Q

If the colour is - the concentration of reducing sugars is -

A

Stays blue → none
Green → very low
Yellow → low
Brown/ orange → medium
Brick red → high

34
Q

How to test for non-reducing sugars

A
  • Heat the sample with Benedict’s reagent in a water bath at 95°C - 100°C for 5 minutes
  • if no colour change add 2cm of the food sample to a different, clean test tube
  • next add 2cm of dilute HCL to the test tube in order to hydrolyse the disaccharide into its monosaccharide components
  • place in a water both at 95°C - 100 °C for 5 minutes
  • slowly add some sodium hydrogen carbonate (enough until it stops fizzing) to neutralise the HCL because Benedict’s reagent won’t work in acidic conditions
  • use a pipette to take some of the sample into a dipping tile and add some universal indicator to check that its neutral (it should go green)
  • again, heat with Benedict’s reagent in a water bath at 95°C to 100°C for 5 minutes
  • if a non reducing sugar is present it will go from blue to orange-brown
35
Q

How to do a serial dilution

A
  • Label six test tubes with the permanent marker pen as 0.32 M, 0.16 M, 0.08 M,
    0.04 M, 0.02 M, and 0.01 M, and place into a test tube rack.
  • Using the 10 cm’ measuring cylinder, measure out 10 cm’ of the 0.32 M glucose solution. It is important to be as accurate as possible, so use one of the dropping pipettes to make sure the meniscus of the solution is exactly on the 10 cm’ line of the measuring cylinder
  • Add the 10 cm of 0.32 M glucose solution to the test tube labelled 0.32 M.
  • Using the other 10 cm measuring cylinder and a dropping pipette, add 5 cm’ of distilled water to each of the other five test tubes.
  • Using a 5 cm syringe, take out 5 cm’ of the solution in the 0.32 M test tube and add it to the test tube labelled 0.16 M.
  • Invert the test tube three times. You do this by putting a test tube bung into the test tube and turning the test tube upside down.
  • Using a new 5 cm’ syringe, take out 5 cm’ of the solution in the 0.16 M test tube and add it to the test tube labelled 0.08 M. Invert the test tube three times.
  • Repeat step 7 for the 0.04 M, 0.02 M, and 0.01 M test tubes
36
Q

Reducing sugar test on serial dilution

A
  • Take 2 cm from the solution in the 0.32 M test tube using a 2 cm’ syringe, and add it to a new test tube. Label this as 0.32 M B. Using a 1 cm’ syringe, add 1 cm of Benedict’s quantitative solution.
  • Do the same with the solutions in the 0.16 M, 0.08 M, 0.04 M, 0.02 M, and 0.01 M test tubes, labelling them as 0.16 M B, 0.08 M B, 0.04 M B, 0.02 M B, and 0.01 M B.
  • Add these six test tubes to a water bath set to 95 °C for 5 minutes.
  • Remove the test tubes and place back into a test tube rack. Allow the precipitate to settle to the bottom of the test tube OR filter the solution to remove the precipitate and only be left with the colour of the Benedict’s solution.
37
Q

Measuring absorbance with colorimeter

A

-Fill a cuvette almost to the top with the solution from the 0.32 M B test tube. Do the same with the solutions from the 0.16 M B, 0.08 M B, 0.04 M B, 0.02 M B, and 0.01 M B test tubes.
- Fill another cuvette almost to the top with distilled water. This will be your blank.
- Zero the colorimeter by setting it to 0.0 and the filter is set to 680 nm (red filter).
- Place the blank cuvette into the colorimeter and press the reading button. This should give an absorbance of 0.0.
- Place the 0.32 M cuvette into the colorimeter and press the reading button.
Record the absorbance. Do the same with the other cuvettes.

38
Q

Finding concentration of glucose in a urine sample

A
  • Take 2 cm of the urine sample and add to a test tube. Label this as U.
  • Add 1 cm’ of Benedict’s quantitative solution to the test tube.
  • Place the test tube in a water bath set to 95 °C for 5 minutes.
  • Remove the test tube and place it into the test tube rack. Allow the precipitate to settle to the bottom of the test tube.
  • Fill a cuvette almost to the top with the solution from the test tube.
  • Use the blank cuvette and repeat steps 3 and 4 from ‘Measuring the absorbance with a colorimeter’.
  • Place the U cuvette into the colorimeter and press the reading button. Record the absorbance.
  • On the calibration curve graph, draw a line from this absorbance on the y-axis to the line of the graph, and down to the x-axis. The point on the x-axis where this line touches will be the concentration of glucose in the urine sample.
39
Q

What is starch

A

A granular storage molecule found in plants- a polysaccharide of alpha
glucose monomers bonded together with glycosidic bonds
When a plant photosynthesises and produces excess glucose, glucose is
converted to starch, which is a long term storage molecule.
It can be hydrolysed into maltose by the enzyme amylase, and then maltose
can be hydrolysed into alpha glucose by the enzyme maltase. The glucose can then be used as a respiratory substrate

40
Q

What is starch made from

A

It is made up of 2 different types of polysaccharides:
Amylose
Amylopectin

41
Q

What is the structure of amylopectin

A

A polysaccharide made up of many alpha-glucose monomers which are joined together by 1, 4 AND 1, 6 glycosidic bonds formed during condensation reactions (STRUCTURE)
The glycosidic bonds can form between C1 of one alpha glucose, and C4 of the adjacent glucose to form a chain (STRUCTURE)
And they can also form between C1 of one alpha glucose, and C6 of another glucose to form branched side chains (STRUCTURE)

42
Q

How is the structure of amylopectin linked to its function

A

A polymer of glucose, which can be hydrolysed by enzymes to provides the respiratory substrate
Branched chains due to 1-6 glycosidic bonds- so there are many sites for enzyme activity, so the molecule can be broken down and glucose removed more quickly for respiration.
Therefore, amylopectin provides a rapid supply of energy
Large molecule so it is insoluble, so it doesn’t affect the water potential of cells and causes osmosis to happen

43
Q

What is the structure of amylose

A

A polysaccharide made up of many alpha-glucose monomers which are joined together by only 1, 4 glycosidic bonds formed during condensation reactions (STRUCTURE)
The glycosidic bonds all form between C1 of one alpha glucose, and C4 of the adjacent glucose (STRUCTURE)
This forms a helical shape (STRUCTURE)
Which is stabilised by hydrogen bonding within the molecule (STRUCTURE)

44
Q

How is the structure of amylose linked to its function

A

The helical shape so it’s more compact so more energy can be stored in a small space
The large helical molecule so it’s less soluble than glucose, so it doesn’t affect the water potential
of the cell and therefore doesn’t causes osmosis to happen
A polymer of glucose, which can be hydrolysed by enzymes to provides the respiratory substrate

45
Q

What is glycogen

A

A granular storage molecule found in animals, fungi and bacteria, but NOT plants (although the main storage molecule in animals are fats)
A polysaccharide of alpha glucose monomers bonded together with glycosidic bonds
It is stored as small granules in the muscle and liver cells of animals
When the rate of respiration increases, glycogen is hydrolysed to form alpha- glucose molecules which is the respiratory substrate for respiration
Animals have a higher rate of metabolism than plants as they do things such as muscle contraction, therefore they need a long-term storage molecule that can be quickly hydrolysed to provide the respiratory substrate.

46
Q

What is the structure of glycogen

A

A polysaccharide made up of many alpha-glucose monomers which are joined together by 1, 4 AND 1, 6 glycosidic bonds formed during condensation reactions (STRUCTURE)
The glycosidic bonds can form between C1 of one alpha glucose, and C4 of the adjacent glucose to form a chain (STRUCTURE)
And they can also form between C1 of one alpha glucose, and C6 of another glucose to form branched side chains (STRUCTURE

47
Q

How is the structure of glycogen linked to its function

A

Polymer of alpha glucose, which can be hydrolysed by enzymes to provides respiratory substrate
Structure is the same as amylopectin but is more coiled, therefore it is more compact and so it can store a lot of energy in a very small space
Structure is the same as amylopectin but is more branched chains due to more glycosidic 1-6 bonds- so there are many sites for enzyme activity, so the molecule can be broken down and glucose removed more quickly for respiration.
Therefore, glycogen provides a rapid supply of energy
Large, insoluble molecule- so it doesn’t affect the water potential of the cell and therefore doesn’t’ causes osmosis to happen

48
Q

What is cellulose

A

It is a fibrous molecule found in cell - walls- it provides tensile strength to the cell walls to help the cell keep its shape and to withstand turgor pressure when water enters the cell by osmosis.

49
Q

What is the structure of cellulose

A

Polysaccharide made up of many beta-glucose monomers which are joined together by glycosidic bonds formed during condensation reactions
When 2 beta glucose molecules are next to each other, the OH on C1 of one of the beta glucose molecules is too far away from the OH on C4 of the adjacent molecule, so a condensation reaction cannot take place (see fig 5 and 6)
To overcome this, alternate beta-glucose monomers are flipped 180o so the position of every other OH group faces in the opposite direction
Long beta-glucose chains are straight/unbranched
Many chains lie parallel to each other and are held together with many weak hydrogen bonds that form
crosslinks between the alternate OH groups
This forms thicker chains called microfibrils, and many microfibrils combine to form macrofibrils, which
then also combine to form fibres

50
Q

How is the structure of cellulose linked to its function

A

A polysaccharide made up of beta-glucose monomers – forms long, straight, unbranched chains for high tensile strength
Alternate beta-glucose molecules are inverted so position of OH groups are inverted- this allows weak hydrogen bonds to form between chains to make thicker microfibrils to help give high tensile strength to keep the cell’s shape and to withstand turgor pressure
Many weak hydrogen bonds provides collective tensile strength to keep the cell’s shape and to withstand turgor pressure
The fibres made of many macrofibrils, which are made of many microfibrils, are very strong

51
Q

Amylose summary

A

Monomer - alpha glucose
Branched - no
Helix shape - yes
Glycosidic bonds present - 1,4
Source - plant

52
Q

Amylopectin summary

A

Monomer - alpha glucose
Branched - yes every 20 monomers
Helix shape - no
Glycosidic bonds - 1,4 and 1,6
Source - plant

53
Q

Glycogen summary

A

Monomer - alpha glucose
Branched - yes every 10 monomers
Helix shape - no
Glycosidic bonds - 1,4 and 1,6
Source - animal

biology - Moldule 2 Foundations In Biology (3 decks)

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