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Biology Module 2 () > 2.2 Carbohydrates > Flashcards

2.2 Carbohydrates Flashcards

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1
Q

What are Carbohydrates? And what are there functions?

A

-Molecules containing Carbon, hydrogen and Oxygen
-For each carbon there is two hydrogen and one oxygen
-They can be used as sources of energy (glucose) store of energy (starch) and structural units (cellulose in plant cell wall)

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2
Q

What are monosachaarides

A

-A single sugar molecule
-Soluble in polar solvents (e.g water)
-They have a backbone of single-bonded carbons and an oxygen

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3
Q

What is the difference between a hexose,Pentose and triose sugar

A

-Hexose(6 carbons),pentose (5 carbons), triose (3 carbons)
-Hexose monosaccharides are usually monomers of complex carbohydrates as they bond together to form.
-Triose and tetrose sugars exist as straight chains whereas pentose and Hexose are more likely to be in rings

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4
Q

What are the properties of Fructose and Galactose

A

Fructose: very soluble and sweet
Galactose: less soluble but has an important role in production of glycoproteins and glycolipids.

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5
Q

What molecules make up lactose and what bond is formed?

A

-Glucose and Galactose
-Beta 1-4 glycosidic bond, it is beta because it bends upwards in a diagram

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6
Q

What molecules make up Sucrose and what bond is formed?

A

-Glucose and Fructose
-Alpha 1 Beta 2 glycosidic bond

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7
Q

What is a reducing sugar and how do you test for it?

A

-Sugars that act as reducing agents and contain the groups (C=O and -CHO)

1.Add Bendicts solution (its blue because of Cu^2+)
2.Put in water bath set to high temp, Cu^2+ will reduce to Cu^+, Brick red precipitate will form
3.Colour of solution indicates concentration of reducing sugar, clear blue colour means one isn’t present.

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8
Q

What is a non-reducing sugar and what is the test for it?

A

-Sugars that can’t be oxidised for e.g. Sucrose
1. Hydrolise the non-reducing sugar (Sucrose) into glucose and fructose by adding dilute hydrochloric acid
2.Boil solution and add Sodium hydrogencarbonate to neutralise it
3.Add Benedicts Solution, if solution turns Brick-Red there was a high concentration of reducing sugars so a non reducing sugar was present.

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9
Q

How do you carry out the Semi-quantative Benedicts test?

A
  1. A different type of Benedicts solution is used that produces copper thiocyanate. Solution will get progressively less dark blue with more reducing sugar present as more Cu^2+ ions are used from benedicts
  2. Let sample settle so supernatant can split from precipitate (we only want supernatant)
    3.Put Supernatant in colorimeter and measure % light absorbance
    4.Low reducing sugar concentration=dark blue supernatant=high light absorbance
    5.High reducing sugar concentration=light blue supernatant=low light absorption
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10
Q

What is Starch and where is it found?

A

-Starch is made up of alpha glucose and its function is to store energy
-It is found in leaves and roots of plants

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11
Q

What is glycogens function and structure and where is it found?

A

-Storage molecule for animals and fungi
-There is a 1-6 glycosidic bond found every 10th glucose unit
-Small granules in liver and muscles

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12
Q

Why is Glycogen more highly branched than amylopectin?

A

-Animals have a higher respiration rate as they are moving so glycogen has more branches for easier and quicker access to glucose via hydrolysis.

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13
Q

Why is glucose stored rather than free in phloem and blood?

A

-Its soluble so will lower water potential causing water to move out of cells.

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14
Q

Why is glucose branched and compact?

A

-Branching means lots of ends are available for hydrolysis and condensation
-Compaction means as many glucose molecules can be stored

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15
Q

What is cellulose made of and how are they joined?

A

-Alternate beta glucose molecules that are inverted so the hydroxyl groups are close enough to form 1-4 glycosidic bonds, its is a straight molecule

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16
Q

What is the functions of Cellulose?

A

-High tensile strength: cell walls are made of cellulose so this provides support
-It also prevents cells from bursting as it can withstand pressure from water
-Allows cell wall to be fully permeable as it forms microfibrils which have space between them
-Soluble and Inert

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17
Q

Why is cellulose important to humans?

A

-Hard to break down so forms fibres which are good for the digestive system

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18
Q

What are the functions of Lipids?

A

-Energy Source: Can be used during respiration
-Water Source: Water is a product of respiration
-Energy Store: insoluble in water so can be stored without affecting water potential
-Thermal insulation: whale blubber
-Stores vitamins: adipose tissue stores A,D E and K
-Buoyancy: fats less dense than water
-Waterproofing
-Cushioning
-Electrical insulation
-Hormone production
-Membrane formation

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19
Q

What are Lipids?

A

-Made of C,H and O
-Macromolecules: complex and large molecule so don’t form polymers
-Polar
-Insoluble in water but dissolve in alcohol

20
Q

What is the difference between a saturated and unsaturated fat?

A

-Saturated fat has no double carbon bonds so carbon form maximum number of bonds with hydrogen
-Unsaturated fat has double carbon bonds (1=monounsaturated fat, 2 or more= polyunsaturated fat) the double bond causes a kink in the chain

21
Q

How does the prescence of a double bonded carbon affect fats?

A

-Without double bonded carbon chains can pack closely so will be solid at RT. Whereas with the double bonded carbon chains can’t pack closely so are liquid at RT

22
Q

Why are Triglycerides ideal as energy storage molecules?

A

-Insoluble so don’t affect the water potential
-Release twice as much energy as carbohydrates per gram
-Form insoluble droplets with hydrophobic tails inwards and hydrophilic heads outwards.(Micelle)

23
Q

What are phospholipids?

A

-Modified triglycerides
-Contain elements P,C,H and O
-Diglycerides as they only contain two fatty acids and glycerol
-Amphipathic: has both hydrophilic and hydrophobic

24
Q

How is a Phospholipid bilayer structured?

A

-They arange themselves with hydrophilic heads towards water and hydrophobic tails away and have a double layer so inside is protected from water.
-Centre is hydrophobic so soluble substances can’t pass.

25
Q

What are the properties of the phospholipid bilayer?

A

-Phospholipids are free to move so its flexible and fluid
-Selectively permeable as only small and non-polar molecules can pass through

26
Q

What are Sterols?

A

-Type of lipid found in cells
-Complex ring structure with hydroxyl group at the end
-Amphipatic-hydroxyl group is polar so hydrophilic and rest is hydrophobic

27
Q

What is the importance of cholesterol in cell membranes?

A

-Produced by liver and intestines and make phospholipid bilayer more fluid at low temp vice versa.
-Fit in between phospholipid bilayers making them more rigid and stable.

28
Q

What is an R group?

A

-The only difference between amino acids are the R groups (20 different amino acids in cells)
-The R groups help make up the properties of the amino acid
-Glycine is the smallest amino acid as its R group is a H
-The amino acid cysteine has a disulfide bond between the R groups which is the strongest covalent bond

29
Q

What is the test for lipids?

A

1.Dissolve lipid in ethanol and then add to water
2.Cloudy emulsion will form on top if present as the dissolved lipid is insoluble

30
Q

How is a dipeptide formed?

A

-Two amino acids join via a condensation reaction the carboxyl group will lose an OH group and the amine group will lose a H and a peptide bond will form
-Water will also be released

31
Q

What is a Polypeptide and the primary structure of a protein?

A

-When more amino acids are added to a dipeptide molecule
-Proteins consist of one or more polypeptide chains folded into a 3D structure
-The primary structure of a protein is the sequence of amino acids

32
Q

What is the secondary structure in proteins?

A

-Two types: alpha helices and beta pleated sheets
-its the hydrogen bonds between the -NH2 and -CO groups which cause it to coil into a shape called alpha helices or a zig zagged sheet (beta pleated sheets).
-Both shapes can exist in the same polypeptide

33
Q

What is the tertiary structure of a protein?

A

-Interaction between the R-groups (ionic bonds between negatively and positively charged r-groups, disulfide bond between two cysteine amino acids, hydrogen bonds and hydrophilic and hydrophobic interactions (proteins are assembled in aqueous environment so hydrophobic parts assemble to inside and hydrophilic to outside).

34
Q

What is the quaternary structure of a protein?

A

-Several different polypeptide chains come together to form a quaternary structure held together with bonds
-For some the tertiary structure is its final 3D arrangement.

35
Q

What is Haemoglobin?

A

-Globular protein
-Carries oxygen round body in red blood cells
-Every 4 subunits a haem prosthetic group holds an iron ion
-Conjugative protein:has a non-protein group attached

36
Q

What enzymes are required to break down dipeptides?

A

Proteases

37
Q

Describe fibrous proteins?

A

-Long insoluble molecules
-Made of Small R-group amino acids
-Long polypeptide chain which isn’t parallel and has hydrogen bonds and crosslinks
-Strong structural roles

38
Q

Properties of Keratin

A

-Fibrous protein
-can be flexible hard or tough
-Contains the amino acid cysteine

39
Q

Properties of elastin

A

-made from tropoelastin
-strong due to cross linking
-Present in blood vessels and alveoli etc
-Elastin allows blood vessel to withstand pressure of blood

40
Q

Properties of Collagen

A

-Found in skin, tendons and ligaments and nervous system
-Provides mechanical strength and flexibility
-Made of three polypeptides wound together
-Every third amino acid is glycine so helixes can pack close

41
Q

What is a globular protein?

A

-Spherical shape
-Soluble(hydrophilic outside and hydrophobic groups inwards)

42
Q

What is a Prosthetic group?

A

-Conjugated protein attaches to this and this is essential for the protein to function

43
Q

What is catalase?

A

-Enzyme that speeds up the breakdown of hydrogen peroxide into water and oxygen
-Contains for haem groups to interact with hydrogen peroxide

44
Q

How are fibrous and globular proteins denatured?

A

Fibrous: lose their shape
Globular: become insoluble and therefore inactive

45
Q

What is paper chromatography?

A

-Mobile phase(usually water) moves through paper causing substances to separate out depending on their solubility ( more soluble and lighter molecules move faster)

46
Q

What is thin layer chromatography

A

-A sheet of glass is coated in silicone dioxide with -OH groups pointed outwards
-Solvent containing solutes passes through and some will absorb to surface depending on solubillity and interaction with hydrogen bonds between silicone dioxide

Biology Module 2 () (6 decks)

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