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Biology Module 2 > Biological Molecules Inorganic ions and Tests > Flashcards

Biological Molecules Inorganic ions and Tests Flashcards

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1
Q

Calcium (Cations)

A
  • Increases rigidity of bone, teeth, cartilage and a component of the exoskeleton of crustaceans
  • important of clotting blood and muscle contraction
  • Activator for several enzymes such as lipase, ATPase and Cholinesterase
  • stimulates muscle contraction and regulates transmission of nerve impulses
  • regulates permeability of cell membrane
  • important for cell wall development in plants and formation of middle lamella between cell walls
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2
Q

Sodium (Cations)

A
  • involved in the regulation of osmotic pressure, control of water levels in body fluid and maintenance of pH
  • affects absorption of carbohydrate in the intesting and water in the kidney
  • contributes to nervous transmission and muscle contraction
  • constituent of vacuole in plants which helps maintain turgidity
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3
Q

Potassium (Cations)

A
  • involved in control of water levels in body fluid and maintenance of pH
  • assits active transport of materials across a cell membrane
  • involved in synthesis of glycogen and protein and breakdown of glucose
  • generates healthy leaves and flowers in flowering plants
  • contributes to nervous transmissions and muscle contraction
  • component of vacuoles in plants, helping to maintain turgidity
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4
Q

Hydrogen (Cations)

A
  • involved in photosynthesis and respiration
  • involved in transport of oxygen and carbon dioxide in the blood
  • involved in regulation of blood pH
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5
Q

Ammonium (Cations)

A
  • A component of amino acids, proteins, vitamins, and chlorophyll
  • some hormones are made of proteins
  • an essential component of nucleic acid
  • involved in maintenance of pH in the human body
  • A component of the nitrogen cycle
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6
Q

Nitrate (Anions)

A
  • A component of amino acids, proteins, vitamins and chorophyll
  • an essential component of nucleic acids
  • some hormones are made of proteins which contain nitrogen
  • A component of the nitrogen cycle
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7
Q

Hydrogencarbonate (Anions)

A
  • Involved in regulation of blood pH

- involved in transport of carbon dioxide into and out of the blood

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8
Q

Chloride (Anions)

A
  • Helps in production of urine in kidney and maintain water balance
  • involved in transport of carbon dioxide in and out of the blood
  • regulates the affinity of haemoglobin to oxygen through allosteric effects on the haemoglobin molecule
  • involved in regulation of blood pH
  • used to produce hydrochloric acid in the stomach
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9
Q

Phosphate (Anions)

A
  • increases rigidity of bone, teeth, cartilage and is a component of the exoskeleton of crustaceans
  • component of phospholipids, ATP, nucleic acids and several important enzymes
  • Involved in regulation of blood pH
  • helps root growth in plants
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10
Q

Hydroxide (Anions)

A
  • involved in regulation of blood pH
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11
Q

How do you test for carbohydrates

A
  • add 2 drops of iodine solution (potassium iodide) to a sample
  • if starch is present you will see a colour change from yellow-brown to blue-black
  • when dissolved in potassium iodide the iodine froms a triiodide ion this slips into the middle of the helix of the amylose helix which cause the colour change
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12
Q

How do you test for reducing sugars

A
  • place a sample of food in a test tube by dissolving it
  • then add 2 cm3 of benedict’s solution to the sample
  • heat the sample in the water bath at 80 degrees for 10-15 minutes
  • the intensity of the red colour is proportionate to the concentration of the sugar
  • if it is green then only a little precipitate will form and it is less concentrated
  • if it is red and orange a lot of precipitate is formed and it has a high concentrated of sugar
    or
  • put it into a centrifuge to separate the precipitate from the supernatant
  • using a pipette take the supernatant into a cuvette which is the placed into a colorimeter
  • don’t touch the cuvette or it will leave a fingerprint which will affect the transmission of light
  • use a red filter to detect how much light passes through the solution
  • if there is a lot of unreacted copper sulfate and the supernatant is still quite blue, absorption of red light is high and percentage transmission is low
  • there is litter unreacted copper sulfate than the supernatant is less blue absorption of red light is low and percentage transmission is high
  • have to 0 the colorimeter
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13
Q

How does the reducing sugar react with the benedict’s solution

A

if you heat a reducing sugar with benedict’s solution (alkane copper (II) sulfate) there is a colour change from blue to green to yellow to orange-red,
Benedict’s solution contains copper 2+ ions which are reduced to copper + ions forming orange red copper (I) oxide this forms a precipitate

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14
Q

How do you test for non-reducing sugars

A
  • first have to hydrolyse the bond to free up the reducing sugar groups and then test for reducing sugars as normal
  • first test a sample for reducing sugars are not there in the first place
  • take a separate sample and boil it with hydrochloric acid to hydrolyse the sucrose into glucose and fructose
  • cool the solution and use sodium hydrogencarbonate solution to neutralise it
  • test for reducing sugars again
  • green-yellow-orange-red indicate that a non-reducing sugar is present in the original sample
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15
Q

How do you test for lipids

A
  • emulsion test
  • take a sample and mix it thoroughly with ethanol, any lipid will go into the solution in the ethanol
  • filter
  • pour the solution into a water in a clean test tube
  • A cloudy white emulsion indicates the presence of lipids, this is made up of tiny lipid droplets that come out of solution when mixed with water this indicates the presence of lipids
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16
Q

How do you test for proteins

A

Biuret test

  • if protein is present the colour changes from light blue to lilac
  • may also do the reagents - add sodium hydroxide first then copper sulfate
  • the colour change is formed by a complex between the nitrogen atoms in a peptide chain and copper 2+ ions which is why this test detects the presence of peptide bonds
17
Q

How do biosensors work

A

they take a biological or chemical variable which cannot easily be measured and convert it into an electrical signal
- they can be used to detect contaminants in water, pathogens and toxins in food

18
Q

What is the principles of chromatography

A
  • the aim is to separate a mixture into its constituents - in this case biological molecules
  • there are two key components these are the stationary phase and the mobile phase
19
Q

What is the stationary phase

A
  • this is either chromatography paper or a thin layer chromatography (TLC) plate
  • the paper is made of cellulose
  • the TLC is often sheet of plastic coated with a thin layer of silica gel or aluminium hydroxide,
  • there are free OH groups pointing outwards in contact with the mobile phase
20
Q

What is the mobile phase

A
  • this is the solvent for the biological molecules
  • we can use water for polar molecules or ethanol for non-polar molecules as a simple level
  • the mobile phase flows through and across the stationary phase carrying the biological molecules with it
21
Q

How does Chromatography happen

A
  • draw line in pencil at bottom of chromatography paper or TLC, this is so it does not run as the pigments in the ink will separate, and shows you where to place the solution
  • spot the mixture of the pencil dot several times by using capillary tubing, make the spot as thin as possible
  • put in solvent,
  • make sure the solvent is put below the pencil line
  • cover the beaker with a watch glass or glass plate
  • let apparatus run until the solvent has reaches a point just underneath the top of the paper/ TLC then remove it from the solvent and lay on a white tile to dry
22
Q

What happens in chromatography

A

the components of the solution mixture travel with it

  • they travel at different speeds
  • by the time the solvent has reached the top of the plate some are travelling slowly and some are travelling quickly so are at different positions
23
Q

How to calculate the speed in chromatography

A 
R= x/y 
X= the distance of the pencil line to the centre of a spot of pigment
Y= the distance from the pencil line to the solvent front
24
Q

How to solve not seeing the molecules as they are colourless - chromatography

A
  1. Ultraviolet light - thin layer of chromatography plates have a chemical which fluoresces under UV light - most of it will glow under the plate except the places where the spots have travelled to
  2. Ninhydrin - to see amino acids allows the plate to dry and then spray it with ninhydrin this binds to amino acids which are then visible as brown or purple spots
  3. Iodine - allows the plate to dry and placed in an enclosed container with a few iodine crystals, the iodine forms a gas which binds the molecules in each of the spots
25
Q

Why are some more speeded than others , chromatography

A
  • depends on their solubility in the solvent and their polarity, it may also depend on their size
  • Exposed OH groups make the surface of the paper or plate very polar and allow it to form hydrogen bonds with the molecules alongside other dipole interactions
  • a higher polar solute will tend to stick to the surface and moves more slowly
  • a non polar solute will travel very quickly up the plate
  • if they travel at the same speed - use a different solvent or changing pH
26
Q

Why use chromatography

A
  • relatively quick

- urine testing and illegal drugs

Biology Module 2 (17 decks)

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