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Biology > Biological Molecules > Flashcards

Biological Molecules Flashcards

1
Q

What is a monomer?

A

Small, single molecule, many of which can be joined to form polymers

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2
Q

What is a polymer?

A

Large molecule, made up of many similar molecules joined together

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3
Q

What is a condensation reaction?

A

It joins 2 molecules together and eliminates a water molecule which forms a chemical bond eg. Glycosidic bond

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4
Q

What is a hydrolysis reaction

A

It separates 2 molecules and requires addition of a water molecule which breaks a chemical bond

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5
Q

What is a monosaccharide?

A

The monomers from which larger carbohydrates are made

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6
Q

What is a disaccharide?

A

Formed by the condensation of 2 monosaccharides

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7
Q

What is a polysaccharides?

A

Formed by thecondensation of many monosaccharides

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8
Q

Structure of glucose

A

6 carbon atoms

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9
Q

Glucose + glucose =

A

Maltose

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10
Q

Glucose+ fructose =

A

Sucrose

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11
Q

Glucose+ galactose =

A

Lactose

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12
Q

What is an isomer?

A

Same molecular formula but differently arranged atoms

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13
Q

Difference in a-glucose and b-glucose

A

OH group is below c1 on a-glucose but above c1 in B- glucose

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14
Q

Example of polysaccharides

A

Starch, glycogen and cellulose

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15
Q

Function of glycogen

A

Energy store in animal cells

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16
Q

Structure of glycogen

A

Polysaccharide of a-glucose with c1-c4 and c1-c6 glycosidic bonds so branched branched I can be rapidly hydrolysed to release glucose for respiration to provide energy large polysaccharide molecule; can’t leave cell. Insoluble in water; water potential of cell not affected ie.no osmotic effect

17
Q

Function of starch

A

Energy store in plant cells

18
Q

Structure of starch

A

Polysaccharide of a-glucose. Mixture of amylose and amylopectin; amylose has c1-c4 glycosidic bonds so is unbranched, while amylopectin has cl-c4 and c1-c6 glycosidic bonds so is branched. Helical-compact for storage. Large polysaccharide- can’t leave cell. Insoluble in water - no osmotic effect

19
Q

Function of cellulose

A

Provides strength and structural support to plant cell walls

20
Q

Structure of cellulose

A

Every other beta glucose molecule is inverted in a long, straight, unbranched chain. Many hydrogen bonds link parallel strands (cross links) to form Micro fibrils (strong fibres). It bonds are strong in high numbers and provides strength and structural support to plant cell walls

21
Q

Benedict’s test for reducing sugars

A

Add Benedict’s reagent (blue) to sample, heat in boiling water bath, positive= green, yellow , orange, red precipitate

22
Q

Benedict’s test for non - reducing sugars

A
  1. Add a few drops of dilute hydrochloric acid (hydrolyse sugar into its constituent reducing sugars)
  2. Heat in a boiling water bath
  3. Neutralise with sodium carbonate
  4. Add Benedict’s reagent and heat again
  5. Non-reducing sugar present = green / yellow / orange / red precipitate
23
Q

Determining glucose concentration

A
  1. Produce a dilution series of glucose solutions of known concentrations
  2. Perform a Benedict’s test on each sample
    • Heat with Benedict’s solution
    • Use same amount of solution for each test
    • Use excess Benedict’s
    • Remove precipitate by filtering
  3. Using a colorimeter, measure the absorbance of each sample and plot a calibration curve
    • Calibrate colorimeter using unreacted Benedict’s
    • Use a red filter
    • Less absorbance of filtrate = more sugar present (as removed precipitate)
    • Plot absorbance against glucose concentration
  4. Repeat with unknown sample (find absorbance) and use graph to determine glucose concentration
24
Q

test for starch

A

Add iodine dissolved in potassium iodide to solution and shake stir. Blue-black colour = starch present

25
Q

What are 2 groups of lipids

A

Triglycerides and phospholipids

26
Q

What are triglycerides?

A

Triglycerides are formed by the condensation of 1 molecule of glycerol and 3 fatty acids

27
Q

What forms an ester bond?

A

A condensation reaction between glycerol and a fatty acid (RCOOH)

28
Q

Properties of triglycerides related to structure

A

• High ratio of C-H bonds to C atoms in hydrocarbon tail
so release more energy than the same mass of carbohydrates
• Insoluble in water (clump together as droplets)
so no effect on water potential of cell

29
Q

What does a phospholipid consist of?

A

One fatty acids of a triglyceride is substituted by a phosphate -containing group. 1 fatty acid, glycerol, phosphate group

30
Q

Phospholipid properties related to structure

Biology (8 decks)

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