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Biological Molecules Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Reaction from monomer to polymer

A

Condensation reaction, a water molecule is produced and monomers are left covalently bonded.

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2
Q

Reaction from polymer to monomer.

A

Hydrolysis reaction, requires the addition of a water molecule which splits into OH and H to join with monomer and break their covalent bond

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3
Q

What are the 2 isomers of glucose

A

Alpha glucose
Beta glucose

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4
Q

What is an isomer?

A

Compound with the same formula but different atomic arrangement

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5
Q

What is the general formula for monosaccharides?

A

(CH2O)n

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6
Q

What is the difference between a monosaccharide, disaccharide and polysaccharide?

A

Mono= one chain of sugar
Di- two chains
Poly= many chains

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7
Q

What are reducing sugars?

A

Sugars that give up electrons to the reagent used in testing for sugars, causes a colour change

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8
Q

What is the test for reducing sugars?

A

Method
1. Crush food sample
2. Add distilled water
3. Add a similar volume of Benedict’s reagent
4. Put into a water bath to heat up
5. Positive result= colour change
Blue= none
Green/ yellow= traces
Orange= moderate amount
Brick red= large amounts

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9
Q

What is maltose?

A

2 glucose molecules bonded together (alpha glucose)
Found in food, natural
Cannot be absorbed into blood

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10
Q

What is sucrose?

A

1 glucose, 1 fructose bonded together
Bonded by a glycosidic bond between the two monosaccharides

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11
Q

What is lactose?

A

1 galactose and 1 glucose boned together

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12
Q

What are 5 examples of monosaccharides?

A

Glucose
Fructose
Galactose
Deoxyribose
Ribose

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13
Q

What is always released when two monosaccharides are bonded together?

A

H2O, water

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14
Q

What are non-reducing sugars?

A

Ones that dont really give up their electrons to reduce the copper sulphate in the Benedict’s solution

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15
Q

What is the test for non-reducing sugars?

A
  1. Add 2cm3 of your sample to a test tube with 10 drops of HCL
  2. Heat to boiling point for 2 mins (the acid causes the hydrolysis)
  3. Add sodium hydrogen carbonate spatula by spatula until the fizzing stops to neutralise the acid (Benedict’s doesn’t work under acidic carbonate)
    Test with PH paper to confirm it is neutral/ slightly alkaline
  4. Retest with Benedict’s to observe a colour change
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16
Q

What is starch?

A

Store of energy in plants and main energy source in humans diet

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17
Q

What are the two types of starch?

A

Amylose
Amylopectin

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18
Q

What is the structure of starch?

A

Made of alpha glucose monomers bonded through condensation reaction. (h2o emitted)
Glycosidic bonds between oxygen atoms
Helical structure by hydrogen bonds of hydroxyl groups

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19
Q

How does the structure of starch lead to its function?

A

-Large molecule= insoluble
Doesn’t affected water potential, doesn’t allow water into the cell (pressure)
Cannot diffuse out of cells (made inside the cell)
- Helix structure= insoluble
Lots can be stored within chloroplasts which is a small place
-Hydrolysed into alpha glucose
Easily transported through the organism
Readily used when needed for respiration
-Branched amylopectin structure= many ends to the molecule
Lots of areas for enzymes to act and hydrolyse the polymer simultaneously and release glucose quickly

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20
Q

Test for starch

A

Add food sample to a test tube
Add a few drops of iodine
Contains starch= blue/black colour change

Limitation= doesn’t indicate the amount of starch in the sample

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21
Q

Structure of glycogen

A

Similar structure to starch but smaller chains with more branches
Made of alpha glucose monomers bonded through condensation reactions

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22
Q

How does the structure of glycogen lead to function?

A

-Large molecule= insoluble
Doesn’t affected water potential, doesn’t allow water into the cell (lysis)
Does not diffuse in and out of cells
-compact
Lots can be stored within a small space (muscles and liver)
-hydrolysed into alpha glucose
Easily transported throughout organism
Readily used when needed for respiration
-highly branched structure- many ends to the molecule
Lots of area for enzymes to act and hydrolyse the polymer simultaneously and release glucose quickly, more important to animals than plants.

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23
Q

Structure of cellulose?

A

Formed of beta glucose where alternating monomers are upside down to facilitate the glycosidic bonds
No coils or branches, it forms long straight molecules that run parallel to each other, held in place with hydrogen bonds
Molecules held together by hydrogen bonds, forming cross bridges

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24
Q

What is the structure of cellulose?

A

Linear, unbranching chains are held together with hydrogen bonds
Chains group together to form microfibrils, those are arranges in alternate directions to give strength to cell walls.

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25
Q

What are lipids?

A

Contain C, H and O
Insoluble in water
Soluble in organic solvents, such as acetone and alcohol
Fats solid at room temperature, oils liquid at room temp (triglycerides)

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26
Q

Main functions of lipids

A

Energy source- oxidised to release more than twice the energy stored in carbohydrates
Insulation- poor conduction of heat to insulate heat and also to insulate electrical impulses in nerve cells (myelin sheath)

Protection- physical protection around certain organs
Waterproofing- insoluble property used in plant waxy cuticles and animal sebaceous glands

27
Q

Triglyceride structure

A

One glycerol molecule bonded to three fatty acid molecules
Ester bond (forms between an alcohol and an acid) forms from a condensation reaction also forming a water molecule from each bond (total of 3)

28
Q

Variation in triglycerides

A

Glycerol molecule is always the same in a triglycerid3
Over 70 different fatty acids
You can form 3 of the same fatty acids forming a simple trig.
Varying properties of trig are a result of the combination of fatty acids

29
Q

What is a saturated fatty acid?

A

No double carbon bonds, bonded to as many H atoms as possible already

30
Q

What is a monounsaturated fatty acid

A

One double bond between carbons

31
Q

What is a polyunsaturated fatty acid?

A

Multiple double bonds between the carbons

32
Q

Properties of lipid structure

A

-high energy source
High ratio of C-H bonds to C atoms
-good storage molecule
Low mass compared to energy stores in bonds means more energy can be stored in a small volume, most beneficial to animals carrying mass.
-insoluble molecules
Large and non-polar, doesn’t affect water potential of cells or osmosis
-important source of water
High ratio of H to O atoms, releasing water when oxidised, especially important for animals in hot environments

33
Q

What is a phospholipid structure?

A

A glycerol backbone attached to only 2 fatty acids with phosphate group bonded to the other end of the glycerol
Hydrophilic head- phosphate and glycerol, is attracted to water, does mix with fat.
Hydrophobic tail- fatty acids, orientates away from water, can mix with fats.

This is a polar molecule (2 poles behave differently`) and wil position themselves relative to water
Triglycerides are extremely hydrophobic

34
Q

Phospholipids properties

A

Polar molecules interacting with water
-hydrophilic and hydrophobic ends of molecules allow a bilayer to form as the cell membrane, the polarity causes a barrier between the inside and outside of the cell

Can form glycolipids
Sugar can bond to the phospholipid molecule to form a glycolipid on the outside of the cell membrane- helps maintain membrane stability and used in cell recognition

35
Q

Test for lipids

A
  1. Label the test tubes suitably for the foods to be tested
  2. Chop solid food on a tile or grind with a pestle and mortar
  3. Add the food to a labelled test tube to a depth of about 1cm. For olive oil add 2 drops.
  4. Add 3cm^3 of ethanol to each test tube
  5. Put a clean bung into each test tube and shake carefully at least 10 times. This will help nah lipids deissolve in the ethanol
  6. Allow time for food particles to settle. You may proceed when the ethanol above the food has cleared.
  7. Use the wash bottle to dispense about 3cm of distilled water into the test tubes.
  8. Observe and note any changes
36
Q

What are monomers

A

Small units which are components of larger molecules

37
Q

What is a polymer

A

Molecules made from many monomers joined together

38
Q

What are the 4 main types of biological molecules

A

Carbohydrates
Lipids
Proteins
Nucleic acids

39
Q

What is a primary structure?

A

-Order of amino acids in the polypeptide
-20 amino acids and polypeptides contain usually 100s of them- countless combinations
-determined by DNA
-peptide bond between each amino acid

40
Q

What is a secondary structure?

A

-the amine group has a positive charge and the O from C=O has a negative charge
-they attract one another from a weak hydrogen bond
-bonds form the first part of the 3D structure of a polypeptide

41
Q

What are beta pleated sheets

A

Looping backwards and forwards

42
Q

What is a tertiary structure?

A
  • alpha helices can be further twisted to give a more specific and 3 dimensional shape
    -held together with many bonds
    -location and type of bonds depends on the primary structure
43
Q

Bonds in tertiary structure-

A

-hydrogen bonds, weak but plentiful
-ionic bonds, between carboxylate and amino groups, easily broken by PH change
-disulphide bridges, ionic bonds specifically between sulphur atoms from the R group of a specific amino acids and polypeptides

44
Q

Properties of globular protein shape

A

Roughly circular
Irregular and wide range of R groups
Physiological/ functional, metabolically
Examples: haemoglobin, enzymes, insulin, immunoglobulin
Generally soluble in water

45
Q

Properties of fibrous/ structural

A

Long strands
Repetitive with a limited range of R groups
Structural
Examples: collagen, keratin, myosin, actin, fibrin
Generally insoluble in water

46
Q

Structure/ function of collagen

A

-repeating sequence of amino acids in primary structure
-Tightly wound alpha- helix in secondary structure
-tertiary structure is another wound helix
-quaternary structure is three fibres (some in opposing directions) wound together.
- collagen molecules are then bundled together to form stronger fibres

47
Q

What is quaternary structure?

A

More than one amino acid chain

48
Q

What is the structure of haemoglobin?

A

Haem “prosthetic group”
4 iron
Prosthetic group= non protein groups

49
Q

What is the test for proteins?

A
  • biuret reagent (sodium hydroxide and dilute copper sulfate)
    -can be done in test tubes or dimple tiles
    -protein= purple
    -no protein= blue
50
Q

What are the 3 conditions required for a chemical reaction to occur?

A
  1. Collision, the reactants must collide
  2. Orientation, the reactants must align properly to break and form bonds
  3. Energy, the reactants must have enough activation energy
51
Q

How do enzymes work?

A

They reduce the amount of activation energy required for a reaction to take place meaning they can take place at a lower temperature (37°) otherwise these reactions would occur too slowly to sustain life

52
Q

What are some examples of enzyme controlled reactions?

A

Digestion
Photosynthesis
Metabolic reactions

53
Q

What is the enzyme substrate complex?

A

-when the substrate binds to the enzymes active site it is held to place briefly by temporary bonds between the two molecules
-when the reaction is over those temporary bonds are broken and the products are released from the active site

54
Q

What is the lock and key model?

A

-one key= one lock
-one substrate will fit one enzyme
-supported by evidence that enzymes are specific to the reactions they catalyse

-enzymes are not rigid like a lock, molecules have been viewed bonding to an area of an enzyme that isn’t an active site which causes enzyme action to change

55
Q

What is the induced fit model?

A

-an enzyme-substrate complex is still formed but a change of shape in the enzyme and substrate us required.
-the distortion of the substrate puts a strain on one/some of the bonds in the molecule and lowers the activation energy required to break it

56
Q

What are enzymes that act outside the cells?

A

Extracellular

57
Q

What are enzymes that act inside cells?

A

Intracellular

58
Q

How do we measure rate of reaction?

A

How long foes it take for a certain amount of product to be formed or reactants to be used up

59
Q

What is the effect of temperature on enzymes?

A
  • rising temp= increased kinetic energy and more collisions
  • optimum temperature gives highest rate of reaction
  • continues temp rise can break hydrogen bonds and others amongst the polypeptide chains
  • active site can be altered in shape so substrate no longer fits
    -human enzymes start this at 45° and are completely denatured by 60°
60
Q

What is the effect of pH on enzymes?

A

-each enzyme has its own optimum pH
-narrow bell curve on graph
-subtle changes to pH can alter changes on amino acids in the active site due to concentration of H atoms- can prevent enzyme- substrate complex forming
-bonds of tertiary structure may break= enzyme changes shape and denature it

61
Q

What is the effect of enzyme concentration?

A
  1. Low enzyme concentration
    -lots of excess substrate with no enzymes to collide and reactive with so low rate of reaction.
  2. Medium enzyme concentration
    -more available active sites to built to substrates and break them down so increased rate of reaction.
  3. Excess enzymes when all available substrates are already binding/ reacting. Rate of reaction limited by concentration of substrate
62
Q

What are competitive inhibitors?

A

-similar shape to substrate
-occupy active site but not permanently bound
-low conc- little impact
-high conc- more likely that multiple inhibitors will collide and inhibit enzyme in a low before the substrate binds so activity can be greatly reduced

Examples- penicillin, active site inhibitor as it disrupts the ability for cell walls to be built in bacteria

63
Q

What are non- competitive inhibitors?

A

-different shape to substrate
-binds to different place on enzyme but induces a change in shape to the active site so substrate no longer fits
-increasing the substrate conc. does not decrease the effect of the inhibitor as they are not competing for the same place

Biology (7 decks)

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