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biology > Biological Molecules > Flashcards

Biological Molecules Flashcards

1
Q

Describe how to carry out benedict reagent and how it works.

A

Add Benedicts reagent and heat.

Cu2+ ions are reduced to become Cu+
Copper oxide precipitate forms that is brick red

Semi quantitative test

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2
Q

How to test for non-reducing sugars

A

Boil in HCl
Neutralise with sodium hydrogen carbonate
Test with benedicts (heat)

Acid hydrolysed to reveal reducing centre

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3
Q

Describe test for protein.

A

Add equal amounts of biuret reagent (NaOH + CuSO4) and sample.

Blue to purple in presence of peptide bonds

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4
Q

Draw basic amino acid

A 
H.         H.         O
     |.           |.          ||
     N.  —-  C. —-  C
     |.            |.          | 
     H.           R.       OH

Tetrahedral shape
Amine group and carboxyl group

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5
Q

How do biological molecules provide evidence for evolution?

A

Animals share common chemistry (bio molecules)

Share common ancestor

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6
Q 
Describe 
Primary 
Secondary 
Tertiary 
Quaternary structure
A

1) sequence of amino acids
2) alpha helix and beta pleated sheets, hydrogen bonds
3) chain folds again, ionic hydrogen and disulphides bonds
4) interactions between multiple polypeptide chains. Prosthetic groups (non-protein)

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7
Q

How does change to one amino acid affect function of protein?

A

Determines position of H Ionic and S bonds.

Affects shape of protein

Affects function

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8
Q

Why do saturated fatty acids have a higher MP than unsaturated fatty acids?

A

Unsat: double bonds between carbon atoms, kink means not compact. Weaker intermolecular forces mean a lower MP, less energy needed to break bonds

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9
Q

Link celluloses structure to function

A

Beta glucose = alternating = straight chains = compact + micro/macrofibrils = strong

Hydrogen bonds = strong

Inward pressure prevent too much osmosis

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10
Q

Test for starch

A

+iodine

Yellow/orange to blue-black

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11
Q

Functions of carbohydrates

A

Structure and energy storage

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12
Q

Glucose + glucose = A
Glucose + fructose = B
Glucose + galactose = C

A 
A= maltose 
B= Sucrose 
C= Lactose
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13
Q

Link phospholipid properties to function

A

Polar (hydrophilic head, hydrophobic tail)= sits upright out of water = plasma membrane

+carbohydrate = glycolipid (cell recognition

Hydrophilic head holds cell surface membrane.

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14
Q

Link triglyceride properties to function

A

Non polar + insoluble + large= doesn’t affect water potential of cell

Lots of carbon hydrogen bonds = 2x as many calories as carbs and protein

Low mass: energy= light storage molecule

Condensation reaction= metabolic water source

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15
Q

Why are phospholipids polar molecules?

A

Two regions that behave in different ways

Hydrophobic tails
Hydrophilic head

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16
Q

Why are lipids not polymers?

A

No identical repeating units.

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17
Q

How and why are the monomers in cellulose arranges?

A

Beta glucose molecules alternate

So OH groups adjacent for condensation reaction.

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18
Q

Name macromolecules and monomers and polymers

A

Lipid-glycerol + fatty acid chains

Carbohydrates - monosaccharides = polysaccharides

Proteins - amino acids= polypeptides

Nucleic acids- nucleotides = polynucleotides

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19
Q

Name bonds formed by condensation of

Lipids
Proteins
Monosaccharides
Nucleotides

A

Ester
Peptide
Glycosidic
Phosphodiester

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20
Q

What’s an isomer

A

Same chemical formula different structure

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21
Q

Link starches structure to its function

A

Helical= compact storage of energy

Branched = more glycosidic bonds hydrolysed at once= fast release of glucose

Large, insoluble and uncharged= won’t affect water potential of cell

Alpha glucose= easily transported and readily used in respiration

22
Q

What are the roles of lipids

A

Waterproofing (hydrophobic)= sebum or waxy cuticle

Energy source = C-H bonds

Plasma membranes (phospholipids) = flexibility

Thermal + electrical insulation= poor conductor of heat and electricity

Protection of internal organs

23
Q

Why do lipids store more energy than carbs and protein?

A

Higher amount of hydrogen carbon bonds

Higher
O:H and O:C

24
Q

What are lipids soluble in?

A

Organic solvents (contain carbon)

25
Q

What’s the main storage molecule in animals?

A

Lipids

26
Q

Define r group

A

Carbon containing side chain bonded to alpha carbon

27
Q

Define starch

A

Alpha glucose monomers joined by glycosidic bonds

28
Q

Describe water potential

A

Measure of how freely water molecules can move

29
Q

Define disulphide bond

A

Covalent bond between sulphur atoms in R group of amino acids

30
Q

Define glycosidic bond

A

Covalent Bond between two monosaccharides

31
Q

Define osmosis

A

Movement of water molecules from an area of high water potential to an area of lower water potential through a selectively permeable membrane

32
Q

Define glycerol

A

Sugar alcohol made of two polyols

33
Q

What does biurets agent detect

A

Peptide bonds

34
Q

Explain how change in primary structure of globular protein will cause different 3D shape

A

Different sequence of amino acids

Bonds form in different places.

Polypeptide folds differently

35
Q

Explain how structure and function are related in fiborous proteins

A

Alpha helix + beta pleated sheets, folds again
Quaternary structure = fibres and sheets
H and disulphide bonds forms fibres and sheets
Fibres= strength and flexibility
Sheet= flexibility
E.g keratin in hair/ collagen in bones
Insoluble due to non-polar external r-groups

36
Q

Difference between fiborous and globular proteins

A

Fiborous = insoluble, structural functions

Globular= soluble, metabolic functions

37
Q

Name bonds in tertiary structure

A

Ionic, hydrogen and disulphide

38
Q

What makes an amino acid charges?

A

Presence of C=O- or NH+ in r group

39
Q

Draw peptide bond

A

O. H
||. |
C—— N

40
Q

What’s the test for lipids?

A

Emulsion test
Cloudy white emulsion I’d present .

Add ethanol, agitate vigorously.
Add water shake gently

41
Q

Explain results of positive emulsion test

A

Lipids molecule suspended in water

Light refracts going through boundary between lipid and water= cloudy white

42
Q

What’s the difference between amylose and amylopectin?

A 
Amylose= helical 
Amylopectin = branched
43
Q

Difference between starch and glycogen

A

Starch is storage molecule in plants
Glycogen is storage molecule in organisms not including plants

Glycogen more highly branched

44
Q

How does glycogens structure link to its function?

A

Highly branched = more glycosidic bonds can be hydrolysed at once, fast energy release

Alpha glucose= readily used in respiration, easily transported

Large + insoluble= won’t diffuse out of cell or affect water potential

45
Q

What does a buffer do?

A

Maintain a constant PH

46
Q

Which is soluble and insoluble out of glucose and starch.

A

Glucose (monosaccharide) is soluble

Starch (polysaccharide) = insoluble

47
Q

What is the function of cellulose in plant cells?

A

Inward pressure = turgid = resist Osmosis and provide max SA for Photosynthesis

48
Q

Name the methods of measuring amount of reducing sugar in a solution after benedict rest

A

Colorimeter
Colour standards
Filtering, drying and weighing precipitate

49
Q

What proteins are found in chromatin + how many?

A

Histones 8

50
Q

Is benedict test quantitative or qualitative?

A

Semi-quantitative

biology (28 decks)

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