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Biology final > Biological molecules Module 2 > Flashcards

Biological molecules Module 2 Flashcards

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1
Q

Note that water CAN pass through phospholipid membrane but water soluble molecules CAN’T

A
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2
Q

Functions of water inside and outside of cells?

A

Water is a reactant in many important chemical reactions It’s a solvent, so allows biological reactions to take place in solution Water transports substances, liquid and a solvent so very useful can transport substances such as glucose and oxygen Helps temperature control as has a high specific heat capacity and high latent heat of evaporation It’s a habitat`

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3
Q

Why is water a polar molecule and what does this allow it to do?

A

Oxygen has a higher electronegativity than hydrogen, so attracts the electrons more making the oxygen delta negative, and the hydrogen’s delta positive Hydrogen bonding, as the delta positve hydrogen’s are attracted to the delta negative electrons of other water molecules

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4
Q

How can hydrogen bonding give water a high specific heat capacity?

A

Specific heat capacity is the energy required to raise the temperature of 1 gram of substance by 1 degree Hydrogen bonds between water molecules can absorb a lot of energy, meaning water requires a lot of energy to heat up Meaning it has a very stable temperature

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5
Q

How do hydrogen bonds give water a high latent heat of evaportation?

A

Hydrogen bonds mean that it takes a lot of energy to break the intermolecular forces between water molecules, so a lot of energy used up when water evaporates Good for cooling organisms, as when sweat evaporates it cools the surface of the skin

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6
Q

What’s cohesion and why are water molecules very cohesive and what does this help them do?

A

Is the attraction water molecules of the same type Occurs in water molecules as they are polar Helps them flow so they are good for transporting substances

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7
Q

How does water’s polarity make it a good solvent?

A

It can dissolve salts as the delta positively charged hydrogen’s will surround the negatively charged ions, and the delta negative oxygens will surround the positively charged ions, seperating out the salt causing it to dissolve

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8
Q

Why is water less dense when it is a solid?

A

Water molecules are held further apart in ice than they are in liquid, because each water molecule forms 4 hydrogen bonds to other water molecules making a lattice shape This is why ice floats

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9
Q

Why is ice floating useful to living organisms?

A

Ice acts as an insulating layer on top of the water, so the water bellow doesn’t freeze killing the living organisms

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10
Q

Most carbohydrates are polymers, what’s a polymer?

A

A molecule made up of many similar, smaller monomers bonded together

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11
Q

Structure of glucose?

A

It’s a hexose ( 6 carbon) monosaccharide Alpha glucose: starting at top right then going clockwise C1 bonded to CH2OH O C2 bonded to H above and OH bellow C3 bonded to H above and OH bellow C4 bonded to OH above and H bellow C6 OH bellow and H above Beta: the same as alpha, except on C2 OH is above, and H is bellow

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12
Q

How is glucose’s structure related to it’s function?

A

It’s the main energy source in animals as it’s structure makes it soluble, so can be transported easily, and it’s chemical bonds contain a lot of energy

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13
Q

What’s ribose?

A

Monosaccharide with five carbon atoms so it’s a pentose sugar Structure starting from Top of pentagon: O C1 OH above and H bellow C2 H above and OH bellow C3 H above and OH bellow C4 H bellow and CH2OH above

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14
Q

What elements do carbohydrates consist of?

A

Carbon Oxygen Hydroged

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15
Q

How do 2 monosaccharides bond together?

A

Via a condensation reaction, a molecule of H2O is lost from both OH groups reacting, and they become binded together by an oxygen (glycosidic bond) forming a disaccarhide

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16
Q

What’s the reverse of a condensation reaction?

A

A hydrolysis reaction, water is removed to split a molecule

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17
Q

What does the disaccharide maltose consist of?

A

2 molecules of alpha glucose binded to each other via a glycosidic bond

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18
Q

What does the disaccharide sucrose consist of?

A

When alpha glucose and fructose join together via a glycosidic bond

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19
Q

What does the disaccharide Lactose consist of?

A

When Beta glucose is bonded to galactose

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20
Q

What’s a polysaccharide?

A

When more than 2 monosaccharides join together

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21
Q

What do plants store excess glucose as?

A

Starch, when a plant needs energy breaks it down into glucose

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22
Q

What does starch consist of?

A

A mixture of the 2 polysaccharides of alpha glucose amylose and amylopectin

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23
Q

Describe the structure of amylose?

A

A long unbranched chain of alpha glucose. The angles of glycosidic bonds give it a coiled structure Condense structure makes it good for storage as can fit more into a smaller space

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24
Q

Describe the structure of amylopectin?

A

A long branched chain of alpha glucose, it’s side chains allow the enzymes that break down the molecule to get at the molecule to break the glycosidic bonds. So glucose can be released quickly

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25
How do animal cells store glucose?
Store it as glycogen, another polysaccharide of glucose
26
Structure of glycogen?
Polysaccharide of alpha glucose (used as storage if there's excess) , similar to amylopectin, except that it has far more side branches coming off it, so energy can be released more readily, which is good for animals Also soluble, so won't affect water potential of cells
27
Why is it useful that starch is insoluble in water?
Means it doesn't cause water to enter cells via osmosis, which would make them swell
28
Describe the structure and function of cellulose?
Long unbranched chains of beta glucose, the cellulose chains are linked by hydrogen bonds to form strong fibres called microfibrils The strong fibres provide strucutral support for the cell, eg. in plant walls
29
Explain the general structure of a triglyceride?
Glycerol bonded to 3 fatty acid chains Fatty acid chains are made of hydrocarbons (compounds that only contain hydrogen and carbon) The tails are hydrophobic, meaning the tails are insoluble in water
30
What elements do lipids contain?
Carbon, Oxygen and Hydrogen
31
How are triglycerides synthesised?
By the formation of an ester bond between each fatty acid and the glycerol molecule A condensation reaction occurs, between the OH group on the glycerol (prop-tri-ol) and the OH of the carboxylic group at the end of the hydrocarbon chain.
32
What's the process of synthesising a triglyceride called?
Esterfication
33
What's the type of reaction called which breaks down a triglyceride?
Hydrolysis
34
What's a saturated fatty acid?
Hydrocarbon chain containing no double carbon carbon double bonds (saturated with hydrogen)
35
What's an unsaturated fatty acid?
Hydrocarbon chain which has at least one carbon carbon double bond, causing it to kink
36
Structure of phospholipids?
The same as a triglyceride, except missing a fatty acid chain, in replace for a phosphate group in the other direction. The phosphate group is hydrophillic (attracted to water) and the and the fatty acid chains are hydrophobic
37
Why are triglycerides good energy storage molecules in animals and plants?
The hydrocarbon tails contain a lot of chemical energy when they are broken down They are insoluble, so don't affect water potential of cell, causing water to move in via osmosis, they are insoluble as Triglycerides bundle together as insoluble droplets, as glycerol shields hydrophobic fatty acid chains as they all face inwards to form a sphere
38
Describe the structure and function of a phospholipid bilayer?
Formed from a double layer of phospholipids, tails facing inwards as hydrophobic and phosphate heads facing outwards as hydrophillic Centre of the bilayer is hydrophobic, preventing water soluble substances passing through
39
What are the monomers of proteins?
Amino acids
40
What is a dipeptide?
When 2 amino acids join together
41
What is a a polypeptide?
When more than 2 amino acids join together
42
What are proteins made up of?
One or more polypeptides
43
General structure of an amino acid?
Carbon in centre Amine group to the left (NH2) Carboxylic group to the right (COOH) Hydrogen bellow R group above
44
What separates all amino acids?
They have different R groups
45
How are amino acids joined together?
A condensation reaction occurs between the OH of the Carboxylic group and the H of the amine group, removing water and forming a peptide bond
46
How do you split 2 amino acids?
Via a hydrolysis reaction
47
What's the primary structure of a protein?
The sequence of amino acids in the polypeptide chain
48
What's the secondary structure of a protein?
When hydrogen bonds form between nearby amino acids This makes it coil into an alpha helix, or fold into a beta pleated sheet, this is the secondary structure
49
What's the tertiary structure of a protein?
The coiled or folded chain of amino acids is often coiled and folded further. More bonds form between different parts of the polypeptide chain, forming their final 3D structure Such as Ionic, disulphide, hydrophillic/hydrophobic interactions
50
What's the Quaternary structure of a protein?
When a protein is made of several different polypeptide bonds held together by bonds, the quartenary structure is the way these polypeptide chains are assembled together Eg. haemoglobin is made up of 4 polypeptide chains
51
What bonds are present in the primary structure of a protein?
Peptide bonds
52
What bonds are present in secondary structure?
Hydrogen bonds
53
What bonds are present in tertiary structure?
Ionic bonds between negatively charged R groups, and positively charged charged R groups Disulfide bonds, forms between 2 amino acids of csyteine, as it's sulphur containing Hydrophobic and hydrophillic interactions Hydrogen bonds
54
What elements do proteins contain?
All contain Oxygen, Carbon Hydrogen, and Nitrogen Some contain sulphur
55
Structure of a globular protein?
Hydrophillic R groups on the outside, making them soluble, so they're easily transported in fluids
56
Structure and function of the globular protein haemoglobin?
Carries oxygen around the body in red blood cells It's a conjugated protein meaning it's a protein with a non protein group attached (prosthetic group) So each of the 4 polypeptide chains has a prosthetic group called haem, which contains iron, which oxygen binds to
57
Structure and function of the lipid cholesterol?
Has a hydrocarbon ring structure, attached to a hydrocarbon tail. The ring structure has a polar hydroxyl OH group attached to it Helps strengthen the cell membrane, by interacting with the phopholipid bilayer Has a small size and flattened shape, so can fit in between the phospholipid molecules in the membrane They bind to hyrophobic tails of the phospholipids, causing them to pack together more closely, this helps the membrane be less fluid and more rigid
58
Structure and function of the globular protein insulin?
Hormone secreted by the pancreas, helps regulate blood glucose level. Solubility important, as it can be transported in the blood to the tissues where it acts Consists of 2 polypeptide chains which are held together by disulphide bonds
59
Structure and function of the globular protein amylase?
Enzyme, that catalyses the breakdown of starch in the digestive system Made of a single chain of amino acids, it's secondary structure contains both alpha helix, and beta pleated sheets
60
3 Types of fibrous proteins?
Collagen Keratin Elastin All insoluble, strong and structural
61
Structure and function of the fibrous protein collagen?
Found in animal connective tissue (bone, muscle) Very strong, minerals can bind to increase it's rigidity
62
Structure and function of the fibrous protein keratin?
Found in external structures of animals, eg skin, hair and nails Can be flexible or very tough
63
Structure and function of elastin?
Found in elastic connective tissue, such as skin and large blood vessels Elastic so allows tissues to return to their original shape after being stretched
64
What's an ion with a positive charge called?
Cation
65
What's an ion with a negative charge called?
Anion
66
What does the inorganic ion Ca2+ do?
Involved in the transmission of nerve impulses Involved in release of insulin from pancreas Acts as a cofactor for many enzymes Important for many enzymess
67
What does the inorganic ion Na+ do?
Important in generating nerve impulses for muscle contraction Regulating fluid balance in the body
68
What does the inorganic ion K+ do?
Important in generating nerve impulses for muscle contraction Regulating fluid balance in the body Activates essential enzymes needed for photosynthesis
69
What does the inorganic ion H+ do?
Affects the pH of substances Important for photosynthesis reactions that occur in the thylakoid membranes inside chloroplasts
70
What does the inorganic ion NH4+ do?
Absorbed from soil by plants as an important source of Nitrogen
71
What does the inorganic ion NO3 - (nitrate) do?
Absorbed from soil by plants, and is an important source of Nitrogen
72
What does the inorganic ion HCO3- (hydrogen carbonate) do?
Acts as a buffer, which helps maintain the pH in the blood
73
What does the inorganic ion Cl- do?
Involved in the chloride shift, which helps maintain the pH of the blood during gas exchange Acts as a cofactor for amylase
74
What does the inorganic ion PO4(3-) do?
Involved in photosynthesis and respiration reactions Needed for synthesis of nucleotides
75
What does the inorganic ion OH- do?
Affects the pH of substances
76
What are reducing sugars?
All the monosacchardies, and the disacharides maltose and lactose
77
How do you test for a reducing sugar?
Add benedict's reagent and heat, will go from blue to brick red The higher the concentration of the reducing sugar, the further the colour change
78
How do you test for a non reducing sugar?
If the test for the reducing sugar is negative, then add dilute HCl and heat in a water bath Nuetralise it with Sodium Hydrogen carbonate Now do the Benedict's test again
79
What can be used to test for glucose?
Test strips
80
How can you test for starch?
Add Iodine dissolved in potassium iodide solution, if present, sample will change from browny orange to a dark blue/black colour
81
Can you test for proteins?
Use the Biruet test Solution needs to be alkaline, so add a few drops sodium hydroxide solution Add some copper sulphate solution, if it goes stays blue there's no protein, if goes purple protein is present
82
How do you test for lipids?
The emulsion test Shake the substance with ethanol then pour into water Solution will go milky if a lipid is present
83
How do you use calorimetry to measure the concentration of a glucose solution?
Create glucose concentrations using dilution factor 2 on 40m/M to create a 20, 10, 5 and 2.5 and a negative control of water You will have added benedict's reagent, so the higher the concentration gradient of glucose, the lower the absorbance as more benedict's reagent used up, as will have also remove precipitate by centrifuging it Now create a calibration curve by plotting absorbance on y axis, and concentration on x axis (use red filter) Now can use graph to find link the absorbance of a solution with an unknown concentration, with it's concentration
84
What's a biosensor?
A device that uses a biological molecule such as an enzyme
85
How would you use paper chromatography to identify unknown amino acids?
Have a mobile phase, a liquid solvent which allows the amino acids to move Have a stationary phase, where the molecules can't move eg chromatography paper Put concentrated dots of the amino acids at the end of the chromatography paper, put in solvent and they'll move up the paper at different rates so they'll seperate out Spray with ninhydrin spray, to make them purple so more visible Calculate the R value of each value (distance moved by amino acid/ distance moved by solvent) then compare R value with a data base to work out what amino acids they are)

Biology final (28 decks)

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