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IOE > intro to biomolecules 2 > Flashcards

intro to biomolecules 2 Flashcards

1
Q

what are nucleic acids

A
  • important class of macromolecules
  • essential to all forms of life
  • found on all types of cells
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2
Q

what does the term nucleic acid relate to overall

A
  • DNA and RNA (biopolymers composed of nucleotides)
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3
Q

what is a nucleotide made up of

A
  • nitrogenous base (A,T,G,C,U)
  • pentose sugar (ribose or deoxyribose)
  • phosphate group
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4
Q

what is a nitrogenous base and why is it named “base”

A
  • organic molecule
  • contains nitrogen
  • acts as a base in chemical reactions
  • provides the “basic” property of a nucleotide (its basicity driven from the nitrogen atom)
  • energy carriers in biochemical reactions
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5
Q

what are the 2 classes of nitrogenous bases

A

purines (double ring = A,T)

pyramidines (single ring = C,T,U)

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6
Q

what nitrogen is used to link the bases to sugar in a glycosidic bond

A

purines = N9

pyrimidines = N1

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7
Q

what is the name of RNA when the hydroxy group points in same direction as anomeric carbon

A

Ribose (beta-D-ribofuranose)

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8
Q

how are carbons numbered in the pentose sugar

A
  • anomeric carbon (1) on side where beta group is

- number with a prime (ie 5’)

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9
Q

what is the difference between ribose and deoxyribose

A

deoxy = H on the 2’ carbon instead of OH

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10
Q

what are nucleosides

A

structure formed by link of a nitrogenous base with a carbohydrate (typically a ribose or deoxyribose) at carbon 1’

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11
Q

which bond couples a nitrogenous base to D-ribose or 2’-deoxy-D-ribose and what does it form between

A

beta-N-glycosidic bond

  • between anomeric carbon 1’ of sugar and N9 of base
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12
Q

what nucleosides are found in rna and dna

A 
cytidine
uridine
adenosine
guanosine
- ADD deoxy to the front for dna and deoxythymidine instead of uracil
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13
Q

how does a nucleoside make a a nucleotide

A

link to 1+ phosphate group

nucleoTide = phosphorylated form of nucleoSide

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14
Q

what is the most common site of phosphorylation

A

hydroxyl group attached to 5’ carbon of ribose

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15
Q

how can we identify the state of phospohrylation (number of phosphate groups)

A 
monophosphate = dNMP
di = dNDP
tri = dNTP

ie - mono of adenosine is (AMP)
tri is ATP
mono of deoxyadenosine is dAMP

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16
Q

what are the major functions of nucleotides / nucleosides

A
  • important metabolites
  • form basic structural unit of nucleic acids
  • participants in energy transfer reactions (predominantly carried out by ATP)
  • encode, transmit express genetic info in living things
  • role in intermediary metabolism and biosynthesis of macromolecules
  • involved in cell signalling
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17
Q

how are nucleotides / nucleosides important in medicine

A
  • antiviral + anticancer agents

- some show high degree of potency + selectivity against herpes group of viruses

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18
Q

what functions do proteins have

A
  • catalysts
  • transport (haemoglobin)
  • communication (hormones)
  • cell structure (actin cytoskeleton)
  • give cells mobility (flagella)
  • body immunity
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19
Q

what do proteins exist of and how many of these exist

A
  • sub-units called amino acids
  • 20 types exist in the human body
  • so all proteins built from this selection of 20
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20
Q

what is the basic structure of amino acids

A
  • chiral carbon = the alpha carbon (in centre)
  • carboxyl group (COOH)
  • amine group (NH2)
  • Hydrogen
    the only part that differs:
  • R group = side chain, variable, provides each amino acids characteristic properties
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21
Q

what is the significance of the amino acid glycine

A
  • its R group is just a H atom

- so alpha carbon is NOT chiral (2 H groups)

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22
Q

what is the consequence of amino acids (except glycine) being chiral

A
  • exist in 2 mirror images
  • forms L and D
  • every amino acid in cells and proteins is in the L configuration (only a few exceptions)
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23
Q

what is the common approach to classifying amino acids

A

according to whether functional group on R side chain at neutral pH is 1) non-polar

2) polar but uncharged
3) polar but positively charged
4) polar negatively charged

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24
Q

what property do non-polar amino acids have

A

hydrophobic

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25
Q

what property do polar uncharged amino acids have

A

R groups soluble in water and hydrophilic
so seek contact with aqueous solutions
because their functional group forms H bond w water

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26
Q

what property do positively charged amino acids have

A

r group basic

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27
Q

what property do negatively charged amino acids have

A

r group acidic

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28
Q

so why does a slight change of amino acids exerts a profound effect on the structure + biological activity of proteins

A 
each has unique characteristics arising from
- size
- shape
- solubility
- ionisation property
of R group
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29
Q

what does a peptide bond form between and what is formed

A
  • carboxyl group of one amino acid and amine group of another
  • makes H2O
  • forms polypeptides and ultimately proteins
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30
Q

what physical property do lipids have so how is an organic compound classed as a lipid

A

solubility

- if they are more soluble in organic solvents than in water

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31
Q

what is included in the lipid category

A
  • fats (fatty acids)
  • triglycerides
  • oils
  • steroids
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32
Q

define lipids

A

molecules that are insoluble in aqueous solutions + soluble in organic solvents

33
Q

how do lipids contrast to proteins, nucleic acids and polysaccharides

A

NOT large macromolecular polymers

34
Q

what major groups are lipids classified into

A

1) fatty acids + its derivatives
2) cholesterol + its derivatives
3) lipoproteins

35
Q

how are lipids formed

A

chemical linking of several small constituent molecules

36
Q

where do fatty acids occur

A
  • rarely as free molecules in nature
  • usually as component of complex lipid molecules
    1) fats (energy storage compound)
    2) phospholipids (primary lipid component of cellular membrane)
37
Q

what are biological fatty acids composed of

A
  • hydrocarbon chain
  • 1 terminal carboxyl group / moiety
  • SO members of carboxylic acid class
38
Q

what are the 2 types of fatty acid

A 
saturated = no double bonds, commonly between 12+24 carbons long
unsaturated = 1+ carbon-carbon double bond
39
Q

which short chain saturated fatty acids are biochemically important

A 
butyric acids (contain 4 carbon)
caproic acids (contain 6 carbons)
both in milk
40
Q

how do we number fatty acid carbons

A

1 = carbon of the carboxyl (COOH) group (most reactive component)

41
Q

what properties do saturated fatty acids have

A

1) V stable - not prone to rancidity
2) straight chains stack tight
3) solid at room temp
4) in butter, animal fats, eggs, coconut oil, palm oil + BODY

42
Q

how can we determine number of double bonds in an unsaturated fatty acid

A

1) monounsaturated = one double bond

2) polyunsaturated = 2+ double bonds

43
Q

what configurations can the double bond of unsaturated fatty acid exist in

A
  • CIS (2 H atoms on carbons of double bond stick out on same side of chain)
  • TRANS (2 H atoms stick out on opposite side of chain)
44
Q

what is the structural difference between cis and trans-fatty acids

A

cis

  • causes chain to bend
  • restricts conformational freedom
  • more double bonds in the chain = less flexibility it has

trans

  • doesn’t cause the chain to bend much
  • shape is similar to straight saturated fatty acids
45
Q

which of cis or trans fatty acids are more common

A

CIS

in ALL biological unsaturated fatty acids

46
Q

what properties do unsaturated fatty acids have

A
  • double bonds prone to rancidity
  • double bonds cause bent chains which do not stack as tightly as saturated
  • liquid at room temp
  • in plant oils
47
Q

what are numerical symbols used to describe fatty acid chains

A

ratios
1st number - no of carbons in fatty acid chain
2nd = no of double bonds in chain
small numbers (to power of with delta symbol then a number) = position of the start of each double bond counting from carbon 1

48
Q

what is linolenic acids numerical symbol

  • 18 carbon
  • 3 double bonds starting at positions 9, 12, 15
A

18:3^delta9,12,15

49
Q

what is an essential fatty acid

A 
important
animals cannot synthesise them so obtain them in the diet from plant source
ie 
linoleic acid
linolenic acid
50
Q

what are

a) myristic acid
b) palmitic acid
c) arachidonic acid

A

a) attached to N-term of plasma membrane associated cytoplasmic proteins
b) end product of mammalian fatty acid synthesis
c) precursor for eicosanoid synthesis

51
Q

what are triglycerides

A
  • energy storage compound in form of fat droplets composed of triglycerides in specialised fat cells (adipose cells)
  • major components of stored fat (storing fatty acids in biological systems)
52
Q

what are phospholipids

A

primary lipid component of cellular membrane

53
Q

what is the structure of a triglyceride / triaglycerol

A
  • large triester molecule
  • derived from glycerol combined with 3 fatty acid molecules
  • each of 3 fatty acid molecules undergoes an esterification with 1 of the hydroxy groups of the glycerol molecule
  • forms 3H2O
54
Q

what is glycerol

A

a triol (alcohol that contains 3 hydroxy functional groups)

55
Q

where do triacyclglycerols accumulate in mammals

A

cytoplasm of adipose cells

56
Q

what do fatty acids provide when stored as energy

A

thermal insultion
- fat deposits under skin + throughout body cut heat loss by 2/3
protection against mechanical comparation

57
Q

why is triglycerides the preferrd form of energy storage over glucose

A

produce approximately 6x the amnt of usable energy

58
Q

why are triglycerides good in the body

A

efficient long term energy storage
large molecules so high potential energy
gram for gram MORE THAN 2x energy of carbs

59
Q

what are glycerophospholipids

A
  • similar basic structure to triglycerides

- carbon 3 of glycerol backbone = esterified to a phosphoric acid

60
Q

what is the building block of phospholipids

A

a phosphatidic acid

61
Q

how do phospholipids form the cell membrane

A 
ampithatic / amphiphilic = have hydrophilic (head - contains -vely charged phosphate group, miscible w + attracted to water) 
and hydrophobic (non-polar tail - interact w other none polar molecules turns away from water ) regions
SO
when added to water self-assemble into a bilayer with hydrophobic tails pointing towards interior
62
Q

what are the most important and abundant phospholipids in all mammalian cells

A

phosphatidylcholine (PC)
phosphatidylethanolamine (PE)
phosphatidylserine (PS)
phosphatidylinositol (PI)

63
Q

how are steroids defined

A
  • class of lipids

- defined by chemical structure - carbon skeleton consisting of 4 fused rings (3 six sided, 1 five sided)

64
Q

why do steroids vary in nature

A
  • different groups have functional group attached

- vary in nature of attached group and position of the groups

65
Q

a steroid is any…

A

class of natural or synthetic compounds characterised by molecular structure derived from the 4 fused rings

66
Q

give 3 examples of steroids

A

cholesterol
estradiol
testosterone

67
Q

what does the steroid group include

A

1) sex hormones
2) adrenal cortical hormones
3) bile acids
4) sterols of vertebrate
5) other physiologically active substances of animals + plants

68
Q

what synthetic steroids are of therapeutic value

A

large number of

1) anti-inflam agents
2) anabolic agents (growth stimulating)
3) oral contraceptives

69
Q

cholesterol is the precursor for the synthesis of what

A

1) vitamin D
2) testosterone
3) estrogen
4) progesterone
5) aldosterone
6) cortisol
7) bile salts

70
Q

what role does cholesterol have

A

in membrane structure

71
Q

how is over accumulation and abnormal deposition of cholesterol prevented

A

its synthesis + utilisation must be tightly regulated

72
Q

why is abnormal deposition of cholesterol and cholesterol-rich lipoproteins in coronary arteries clinically important

A

lead to atherosclerosis

73
Q

which vitamins are derived from steroids

A

ergosterol

vitamin D

74
Q

what are the 4 steroid hormones

A
  • pregnenolone
  • progesterone
  • estradiol
  • testosterone
75
Q

what is pregnenolone

A
  • produced directly from cholesterol

- precursor molecule for all C18, C19, C21 steroids

76
Q

what is progesterone

A
  • produced directly from pregnenolone
  • secreted from the corpus luteum
  • responsible for changes associated w luteral phase of menstrual cycle
77
Q

what is estradiol

A
  • estrogen principal female sex hormone
  • produced in ovary
  • responsible for female sex characteristics
78
Q

what is testosterone

A
  • androgen
  • synthesized in testes
  • responsible for secondary male sex characteristics

IOE (22 decks)

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