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Biology > Biological Molecules > Flashcards

Biological Molecules Flashcards

1
Q

Monomer is …

A

small, single molecule many of which can be joined together to form a polymer

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2
Q

Polymer is…

A

large molecule made up of many similar monomers joined together

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3
Q

A condensation reaction..

A

Joins 2 molecules together, eliminates a water molecules, forms a chemical bond

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4
Q

A hydrolysis reaction

A

Separates 2 molecules, requires addition of a water molecule, breaks a chemical bond

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5
Q

Disaccharide e.g.

A

glucose+glucose →maltose
glucose+fructose →sucrose
glucose+galactose →lactose

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6
Q

Monosaccharides are…

A

the monomers from which larger carbohydrates are made

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7
Q

What bond is formed from a condensation reaction between 2 monosaccharides

A

Glycosidic

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8
Q

Difference between alpha and beta glucose

A

OH group is below C1 on a-glucose, but above C1 on b-glucose
*remember ABBA (honourable mamma mia mention)
Alpha
Below
Beta
Above

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9
Q

Glycogen: function and structure

A

Energy store in animal cells
Polysaccharide of a-glucose with C1-C4 and C1-C6 glycosidic bonds so branched

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10
Q

Structure of glycogen related to its function

A

Branched; can be rapidly hydrolysed to release glucose for respiration to provide energy
Large polysaccharide molecule; cant leave the cell
Insoluble in water; water potential of cell isn’t affected

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11
Q

Starch: function and structure

A

-Energy store in plant cells
-Polysaccharide of a-glucose
-Mixture of amylose and amylopectin
-Amylose (C1-C4 glycosidic bonds)
-Amylopectin (C1-C6 glycosidic bonds) so branched

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12
Q

Structure of starch related to its function

A

Helical; compact for storage in cells
Large polysaccharide; can’t leave cell
Insoluble in water; water potential of cell not affected

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13
Q

Cellulose: function

A

Provides strength and structural support to plant cell walls

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14
Q

Structure of cellulose related to its function

A

-Every other beta glucose molecule is inverted in a long, straight, unbranched chain
-Many H bonds link parallel strands to form microfibrils
-H bonds are strong and high in number
-Providing strength and structural support to plant cell walls

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15
Q

Benedicts test for reducing sugars

A

-Add benedict’s reagent (blue) to sample
-Heat in boiling water bath
-Positive= green/yellow/orange/red (depending amount of reducing sugar conc)

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16
Q

Benedicts test for non reducing sugar

A

-Add a few drops on dilute HCl ( to hydrolyse sugar)
-Heat in a boiling water bath
-Neutralise with sodium bicarbonate
-Add Benedict’s and heat again
-Non reducing sugar present= green/yellow/orange/red (depending amount of reducing sugar conc)

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17
Q

Determining glucose concentration

A

-Produce a dilution series of glucose solutions of known concentrations
-Perform a Benedict’s test on each sample
-Use same amount for each solution
-Remove precipitate by filtering
-Using a colorimeter measure the absorbance and plot a calibration curve
-Calibrate using unreacted Benedict’s
-Use red filter
-Absorbance against glucose concentration
-Repeat with unknown samples and use graph to determine glucose concentrations

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18
Q

Iodine test for starch

A

-Add iodine dissolved in potassium iodide to solution and shake
-Blue/black colour =positive

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19
Q

Formation of triglycerides

A

Condensation of 1 glycerol and 3 fatty acids, forming an ester bond

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20
Q

Properties related to a triglycerides structure

A

-Energy storage molecule
-High ratio of C-H bonds to C atoms in hydrocarbon tail so more energy is released compared to the same mass of carbohydrates
-Insoluble in water so no effect on water. potential

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21
Q

Formation of phospholipids

A

One of the fatty acids of a triglyceride is substituted by a phosphate-containing group

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22
Q

Properties related to a phospholipids structure

A

-Form bilayer in cell membrane, allowing diffusion of non-polar, small molecules
-Phosphate heads are polar/hydrophilic
-Fatty acids tails are non-polar/hydrophobic

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23
Q

Emulsion test for lipids

A

Add ethanol and shake
Then add water
Positive; milky/cloudy white emulsion

24
Q

General structure of amino acids

A

-amine group
-carboxyl group
-R group (variable)
-CH

25
Q

Amino acids can form

A

-Dipeptides; 2 amino acids joined
-Polypeptide; many amino acids joined

26
Q

Structure of proteins

A

Primary; Sequence of amino acids in a polypeptide chains
Secondary; H bonding between amino acids causes polypeptide chain to fold into a repeating pattern (a-helix or b-pleated sheets)
Tertiary; Overall 3D structure of a polypeptide held together by interactions between amino acid side chains: ionic. bonds/disulphide bridges/H bonds
Quaternary; Some proteins made of 2+ polypeptide chains held together by more H, ionic and disulfide bonds

27
Q

Biuret test for proteins

A

-Add biuret solution; NaOH + CuSO4
-Positive= purple colour
-Detects presence of peptide bond

28
Q

Lock and key model (old)

A

-Active site is a fixed shape and is complementary to one substrate
-After a successful collision, an E-S complex forms leading to a reaction

29
Q

Induced fit model (accepted)

A

-Before reaction, enzyme AS isn’t completely complementary to specific substrate
-AS shape changes slightly as substrate binds and E-S complex forms
-This distorts bonds in sublate leading to a reaction

30
Q

The specificity of enzymes

A

-Enzymes have a specific tertiary stucture and active site (determined by the sequence of amino acids in primary structure)
-AS complimentary to specific substrate

31
Q

How does enzyme conc affect rate of enzyme controlled reactions

A

-Increasing enzyme conc., increases RoR
-More enzymes= more available active sites
-More successful E-S collisions and complexes
-Until RoR plateaus

32
Q

How does substrate conc affect rate of enzyme controlled reactions

A

-Increasing substrate conc, increases RoR
-More successful E-S collisions and complexes

33
Q

How does temperature affect rate of enzyme controlled reactions

A

-Increasing temp to optimum, increases RoR
-Increase in kinetic energy
-More successful E-S complexes and collisions
-Increasing temp above optimum, rate of reaction falls
-Enzymes denature; tertiary structure and active site changes shape
-Fewer E-S collisions and E-S complexes, as substrate can no longer bind

34
Q

How does pH affect rate of enzyme controlled reactions

A

-pH above/below optimum,RoR decreases
-Enzymes denature; tertiary structure and active site changes shape
-Fewer E-S collisions and E-S complexes, as substrate can no longer bind

35
Q

Competitive inhibitors

A

-Similar shape to substrate
-Compete to bind to AS so substrates cannot bind
-Fewer E-S complexes
-Increasing substrate conc reduces effect of inhibitor

36
Q

Non- competitive inhibitor

A

-Binds to allosteric site
-Enzyme tertiary structure/ changes shape so substrates can’t bind to AS
-Fewer E-S complexes

37
Q

Function of DNA and RNA

A

DNA- holds genetic information
RNA- transfers genetic info from DNA to ribosomes
-Ribosomes are formed from RNA and proteins

38
Q

The differences between DNA and RNA

A

-DNA nucleotides have the pentose sugar deoxyribose, whereas RNA nucleotides have the pentose sugar ribose
-DNA nucleotides have the bases thymine, whereas RNA nucleotides have uracil instead
-DNA has two strands, RNA is single stranded
-DNA has H bonds, RNA doesn’t
-DNA is longer, RNA is shorter

39
Q

Structure of DNA related to its function

A

-Double stranded; both strands can act as templates for semi-conservative replication
-Weak H bonds between bases; can be unzipped for replication
-Complementary base pairing; accurate replication
-Many H bonds between bases; stable molecule
-Double helix with sugar phosphate backbone; protects H bonds
-Long molecule; stores lots of genetic info
-Double helix; compact

40
Q

Semi conservative replication

A

-DNA Helicase breaks H bonds between bases, unwinds double helix
-2 strands act as templates
-Free floating DNA nucleotides attract to exposed bases by specific complementary base pairing, H bonds are formed
-DNA polymerase joins adjacent nucleotides by condensation, forms phosphodiester bonds
-Replication is semi conservative- each new strands formed contains one original
-Ensuring genetic continuity between generations of cells

41
Q

How does DNA polymerase move along DNA antiparallel strands

A

-DNA polymerase is an enzyme with a specific AS which can only bind two substrate with complementary shape
-Can only bind to the phosphate 3’ end

42
Q

Evidence for semi-conservative (Meselson and Stahl)

A

-Bacteria is grown in a nutrient solution contain heaving Nitrogen (15N) for several generations
-Nitrogen is incorporated into bacterial DNA bases
-Bacteria is transferred to a nutrient solution containing light Nitrogen (14N) and allowed to grow and divide twice
-During this process, DNA moves from different samples of bacteria was extracted, suspended in a solution in separate tubes and spun in a centrifuge.

43
Q

Structure of adenosine trisphosphate

A

-Ribose, a molecule of adenine, 3 phosphate groups
-Nucleotide derivative
-The structure of ADP= is the same as ATP, minus a phosphate

44
Q

ATP hydrolysis

A

-Catalyses by ATP hydrolase
-Inorganic phosphate releases can phosphorylate other compounds often making them more reactive

45
Q

ATP condensation

A

-Catalysed by ATP synthase
-Happens during respiration or photosynthesis

46
Q

Properties of ATP

A

-ATP cannot be stored
-ATP releasees energy in small, manageable amounts to reduce waste
-Only one bond hydrolysed, to release energy

47
Q

How does H bonding occur between water molecules

A

-Water is polar
-Slightly negative O atoms attract slightly positive H atoms of other water molecules
-So H bonds form

48
Q

Water: High SHC explanation and importance

A

Polar so many H bonds between water→allow water to absorb a large amount of heat energy before its temp change
-Good habitat for aquatic organisms
-Organisms mostly made of water so helps maintains a constant internal body temp

49
Q

Water: High LHE explanation and importance

A

Polar so many H bonds between water→allow water to absorb a lot of energy before breaking when water evaporates
-Evaporation of small amount of water is an efficient cooling mechanism
-Helping organisms maintain a constant body temp

50
Q

Water: Cohesive explanation and importance

A

Polar so many H bonds between water→so water molecules tend to stick together
-Columns of water don’t break
-Produces surface tension at an air water. surface so invertebrates can walk on water

51
Q

Water: Solvent explanation and importance

A

Polar so can separate ionic compounds
-Can dissolve other substance so water acts as a medium for metabolic reaction

52
Q

Water:Metabolite explanation and importance

A

Reactive
-Involved in condensation and hydrolysis reactions

53
Q

Role of phosphate ions

A

Attached to other molecules as a phosphate group e.g:
-DNA nucleotides, so nucleotides can join together and form phosphodiester bonds
-ATP; bonds between these store/release energy

54
Q

Role of Hydrogen ions

A

-Maintain pH levels in the body
-Affects rate of enzyme controlled reactions

55
Q

Role of Iron ions

A

-Component of Haem group of Haemaglobin
-Transports Oxygen around body, O2 bind stocks it temporarily and forms Fe3+

56
Q

Role of Sodium ions

A

-Co transport of glucose and amino acids across cell membranes
-Involved in generating nerve impulses and muscle contraction

Biology (9 decks)

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