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Molecules and Cells- Biochemistry > Proteins, Polysaccharides and Lipids > Flashcards

Proteins, Polysaccharides and Lipids Flashcards

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Organic Chemistry 101 flashcards
1
Q

What is the primary structure of a protein?

A

Amino Acid chain linked together by peptide bonds

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2
Q

What are the 3 types of secondary protein structures?

A

-Alpha Helix
-Beta Sheet
-Triple Helix

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3
Q

Describe the alpha helix structure of a secondary protein
Structure?
Where are they found?
What are they stabilised by?
The Co of each amino acid is bonded to what?
How many residues per turn

A

-Rod like, right handed
- Found in strong, extensible proteins
-Stabilised by Hydrogen Bonds
-CO of each amino acid is H bonded to NH of amino acid four residues ahead in sequence
-3.6 Residues per helix/ turn

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4
Q

Give examples of alpha helix secondary proteins

A

Haemoglobin, Myoglobin, Keratins, Fibrins, Myosin

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5
Q

Describe the Beta Pleated sheet structure of secondary proteins and where are they found

A

-Zigzag chains
-Place several chains side by side, CO and NH groups align, H-bonding occurs → sheet-like structure
-Parallel: chains run in same direction
-Anti-parallel: chains run in opposite
directions
-Found in proteins where flexibility needed eg. silk fibroin (anti-parallel arrangement

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6
Q

Describe the triple helix structures of secondary proteins

A

-Collagen only
-Major component of connective tissue (skin, bone, tendon)
-Very strong, water-insoluble fibres
-Three chains wound round each other (rope) → tropocollagen
-~ 1000 amino acids per chain
-No H bonds in each chain

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7
Q

What repeating structure does each chain have in triple helix secondary proteins?

A

X- Pro- Gly

OR

X- Hyp- Gly

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7
Q

What repeating structure does each chain have in triple helix secondary proteins?

A

X- Pro- Gly

OR

X- Hyp- Gly

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8
Q

By what bonds are the three strands in triple helix secondary proteins held together by?

A

Hydrogen bonds by HYP and Hydroxylysine residues

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9
Q

By what bonds are the three strands in triple helix secondary proteins held together by?

A

Hydrogen bonds by HYP and Hydroxylysine residues

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10
Q

What sits inside the helix and what projects out of the helix of triple helix secondary proteins?

A

-Small Gly residues sit inside helix
-BulkyR groups either side of Gly project outwards

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11
Q

How is the triple helix intra and intermolecularly cross linked?

A

By covalent bonds between Lys and His

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12
Q

Describe fibrous proteins.

A

Insoluble, Metabolically unreactive

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13
Q

What are fibrous proteins mainly? Give examples.

A

Structural Proteins;

-collagen
-keratin (skin, hair, nails, fur, wool)
-fibrin (bloot clots)
-elastin (elastic fibres of connective tissue eg. arterial walls)
-myosin (muscle)

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14
Q

Describe globular proteins

A

Spherical

Backbone folds on itself

Water-soluble, compact structures

Usually have 3º and 4º structures eg. myoglobin and actin (3º), haemoglobin (4º)

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15
Q

What does the interior of myoglobin contain?

A

Entirely non-polar residues except for two polar His residues (attachment and function of Haem group)

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16
Q

What is myoglobin used for?

A

Oxygen storage in muscle

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17
Q

What type of protein is myoglobin and what structures is it associated with?

A

Globular, associated with 3º structures

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18
Q

How Many chains does myoglobin have?

A

Single chain (153 aa)

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19
Q

How Many chains does myoglobin have?

A

Single chain (153 aa)

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20
Q

How many helical regions in myoglobin

A

8 (75% of all aa)

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21
Q

Is there beta pleated sheet regions in myoglobin?

A

No

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22
Q

How are the helical segments of myoglobin joined?

A

Regions of random coiling where chain makes major directional change

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23
Q

What group does myoglobin contain and how is it bound/ where is it?

A

in hydrophobic pocket, held in position by hydrophobic interactions between haem porphyrin ring and non-polar side chains of aa in surrounding helical segments

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24
Q

What happens to myoglobin if harm group is absent

A

apoprotein, not as tightly folded

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25
Q

Haemoglobin function?

A

oxygen Transport

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26
Q

What structures is haemoglobin associated with?

A

Quaternary Structures

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27
Q

How many polypeptide chains are in haemoglobin and what do they look like?

A

Two pairs of polypeptide chains ( 2 Alpha 2 beta) folded into a similar shape to myoglobin

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28
Q

Shape of haemoglobin molecule?

A

Spheroidal Molecule

29
Q

How many ham groups in haemoglobin and where do they lie in the molecule?

A

Four Haem groups, lie on surface of molecule in individual pockets, far apart

30
Q

How many amino acids on alpha chains of haemoglobin?

How many amino acids on beta chains of haemoglobin?

A
  • Alpha- 141
  • Beta- 146
31
Q

What is each alpha unit in contact with in haemoglobin?

A

Both Beta Chains

32
Q

Describe the structure of each chain and what forms when they are fitted together

A

α1β1 and α2β2 half-molecules irregular in shape → central open channel when fitted together

33
Q

What are peripheral membrane proteins located?

A

Lie on membrane surface

34
Q

Where are integral membrane proteins located?

A

Within Lipid Bilayer

35
Q

What do channel proteins do?

A

Form a channel in membranes and facilitate movement of small molecules across the membrane (simple diffusion)

36
Q

What do carrier proteins do?

A

Bind to transported molecules (facilitated diffusion)

37
Q

Give an example of messenger proteins

A

Hormones

38
Q

What is the function of hormones?

A

Allows cells to communicate with each other

39
Q

Give 3 modes of action of hormones

A
  1. Influence rate of synthesis of enzymes and other proteins
  2. Affect rate of enzymatic catalysis
  3. Alter permeability of cell membranes
40
Q

What does each hormone have?

A

Its own corresponding receptor

41
Q

Describe the action of hormones binding to receptors?

A

Hormone binds receptor → message relayed to inside of cell → cascade of events → cellular action

42
Q

Give examples of hormones

A

Insulin
Glucagon
Human Growth Hormone

43
Q

What is the function of insulin?

A

Sugar uptake by cells from bloodstream

44
Q

What is the function of Glucagon

A

Sugar release by cells into bloodstream

45
Q

Hormones can be what?

A

-Protein/Polypetide
-Amino Acid Derivatives
-Steroid

46
Q

Describe Enzymes;

What are they?
Protein Type?
Function?
Specificity?

A

-Biological Catalysts
-Globular Proteins
-Increase reaction rates up to 10^20
-Highly Specific (reaction, substrate)

47
Q

Give examples of muscular contraction messenger proteins ? and their type

A
  • Myosin- fibrous
  • Actin- globular
48
Q

Give examples of messenger proteins used in immune protection

A

-Cytokines
-Antibodies

49
Q

What are the monomers of polysaccharides?

A

Monosaccharides

50
Q

What are two functions of polysaccharides?

A

-Storage
-Structure

51
Q

Give examples of two storage polysaccharides

A

Glycogen, Strarch

52
Q

Give examples of three Structure Polysaccharides

A

Cellulose, Chondroitin, Sulphate, Peptidoglycan

53
Q

What are two types of monosaccharides?

A

-Aldoses
-Ketoses

54
Q

What are aldoses?

A

Monosaccharides that contain the aldehyde (CHO) group

55
Q

What are ketoses?

A

Monosaccharides that contain the ketone (CO) group

56
Q

What are monosaccharides?

A

The building blocks of complex carbohydrates

57
Q

give a example of a monosaccharide

A

GLUCOSE

58
Q

Formation of Disaccharides?

A

Dehydration reactions of monosaccharide units form complex carbohydrates

59
Q

Breakdown of Disaccharides?

A

Hydrolysis reactions of monosaccharide units catabolise complex carbohydrates

60
Q

What are polysaccharides

A

Isomers of monosaccharides give rise to a huge variety of polysaccharides

61
Q

what are the monomers of lipids?

A

Fatty acids

62
Q

What are the main types of lipids?

A

Triglycerides
Diglycerides
Sterols

63
Q

Give 2 functions of lipids

A

-Storage
-Membrane Structure

64
Q

What are glycerides based on

A

Glycerol

65
Q

What are
-Glycerides
-Diglycerides
-Triglycerides

made up of

A

GLYCEROL FATTY ACID

1 1
1 2
1 3

66
Q

Glyceride structure diagram;

A
67
Q

Give an example of a diglyceride and its function

A

phosphoatidylcholine- a major phospholipid of membranes

68
Q

What are triglycerides role?

A

Storage compounds

69
Q

What are diacylglycerides used for?

A

Major components of biological membranes

70
Q

The degree of saturation of fatty acids (acyl lipids) affects what?

A

-Van der Waals forces
-Changes lipid physical properties

71
Q

Sterols function?

A

some have essential biological activity
Others are important constituents of biological membranes

Molecules and Cells- Biochemistry (4 decks)

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