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cells and biomolecules 🧬 > carbohydrates > Flashcards

carbohydrates Flashcards

(47 cards)

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1
Q

functions of carbohydrates

A

energy store
- starch in plants
- glycogen in animals

structural
- cellulose in plants
- chitin in insects

cell recognition
- cell surfaces carbohydrates

metabolism
- metabolic intermediates
- energy substrates

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2
Q

sizes of carbohydrates

A

monosaccharides
- single sugars
- basic units of carbohydrates

oligosaccharides
- 2-10 residues
- name changes depending on how many eg di or try

polysaccharides
- more than 20 residues
- macromolecules with long chains
- made of one or many monosaccharides

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3
Q

monosaccharides

A

simplist carbohydrates - building blocks
cannot be easily broken down

classifying according to:
- number of carbon atoms in structure
- whether they have an aldehyde (aldose) or ketone (ketose)

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4
Q

structure of a monosaccharide

A
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5
Q

aldoses

A

all have aldehyde group on first carbon -CHO
CH2OH on lowest carbon

in same group have same general formula with different arrangements of OH groups

glucose, mannose and galactose

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6
Q

structure of glucose

A
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7
Q

structure of mannose

A
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8
Q

structure of galactose

A
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9
Q

ketoses

A

all have ketone group on second carbon C=O
CH2OH on first and last carbon

within group have same general formula with different arrangement of OH groups

names end in -ulose

eg fructose

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10
Q

structure of fructose

A
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11
Q

what is an epimer?

A

different compounds with the same molecular formula that differ by configuration at only one carbon

important as biological system can differentiate between them

eg glucose and galactose
have same atoms joined to same atoms
except configuration at carbon 4
= c4 epimer of glucose

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12
Q

hemiactal

A

where intramolecular (within some molecule) monosaccharides react with themselves
hydroxyl OH reacts with a carbonyl C=O

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13
Q

internal hemiactal

A

occurs in monosaccharides with 5 or more carbons
results in a ring structure
forms a new chiral (asymmetric) carbon

carbon atom bound with 4 different groups bonded to it
special as bonded to 2 oxygen atoms
called anomeric carbon

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14
Q

common monosaccharides

A

glucose
fructose
ribose
galactose

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15
Q

glucose

A

aldose (aldahexose)

monomer to create cellulose
central to cell metabolism
found in monosaccharide form in plants, fruit and blood

structure

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16
Q

fructose

A

ketose (ketohexose)

monomer to create sucrose
found in leaves, fruit and honey

anomeric carbon of ketone is c2 not c1

structure

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17
Q

ribose

A

aldapentose

component of ribonucleic acid
reduced form (deoxyribose) used in DNA

structure

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18
Q

galactose

A

component of lactose
makes galactans - structural cell wall polysaccharide in plants
component of antigens on blood cells that create blood groups

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19
Q

how are monosaccharides joined?

Study These Flashcards
A

hydroxyl OH on carbon 1 reacts with the hydroxyl on carbon 4 of another molecule

2 hydrogens and an oxygen released in a condensation reaction = water

covalent bond forms between oxygen on anomeric carbon and carbon 4 of another
= glycosidic bond

20
Q

what is a disaccharide?

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A

two monosaccharides joined by a glycosidic bond
alpha or beta depending on arrangement of OH on anomeric carbon

eg maltose, lactose and sucrose

21
Q

maltose

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A

2 glucose molecules
formed during breakdown of starch

alpha 1,4 bond

structure

22
Q

lactose

Study These Flashcards
A

galactose and glucose joined by beta 1,4 bond

beta bond harder to degrade than alpha = harder to breakdown

structure

23
Q

sucrose

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A

fructose and glucose joined

both anomeric carbon of fructose and glucose involved
glycosidic bond described differently depending on which molecule you start with

if start with glucose = alpha 1,2
if start with fructose = beta 2,1

structure

24
Q

reducing sugars

Study These Flashcards
A

a sugar that can be oxidised and therefore acts as a reducing agent

if only one anomeric carbon involved in bond, free anomeric is not trapped in ring structure

free to reform a straight chain

means carbonyl carbon on straight chain is free to be oxidised

if oxidised then acts as a reducing agent and reduces other molecules

eg maltose

25
what determines whether a sugar is reducing or non-reducing?
which carbons are involved in the bond only one anomeric involved means second glucose isn't trapped can reform a straight chain not in ring structure
26
non-reducing sugars
eg sucrose fructose is a ketose (anomeric carbon is carbon 2) means anomeric carbon of both glucose and fructose is used in the glycosidic bond so both locked I bring and no straight chains form
27
sugar derivates
as well as monosaccharides, there are derivates include amino sugars, acidic sugars and deoxy sugars
28
deoxy sugars
formed when a hydrogen replaces one of the hydroxyl groups eg ribose and deoxyribose
29
acidic sugars
formed when a carboxylic acid group replaces the CH2OH at carbon 6 creates a uronic acid eg glucuronic acid for glucose
30
amino sugars
formed when hydroxyl group is replaced by an amino group further modification of amino group by acetic acid forms an amide eg amino sugar of glucose = glucosamine amide modification is N-acetyl-glucosamine
31
polysaccharides
polymers of monosaccharides two types based on presence of basic sugar units can be straight or have side chains functions include storage and structural
32
homo/hetero polysaccharides
homo = one monosaccharide unit repeated hetero = more than one monosaccharide unit
33
properties of a storage polysaccharide
energy stores - many monosaccharides in one, broken down and used in metabolism alpha links readily degraded by enzymes - means they can be broken down easily highly branched - rapid release of monosaccharides - more monosaccharides sotred within - more ends made for quicker enzyme action less dense energy store than triacylglycerol - due to associated water weight whereas triacyglycerol is hydrophobic
34
glycogen
storage polysaccharide in animals stored in liver and muscle cells structure similar to amylopectin but more alpha 1,6 branches every 10-12 glucose molecules more branches = more glucose per molecule many branches = many non-reducing ends so more easily broken down by enzymes
35
inulin
storage polyacchiade in root and tubers of some plants polymer of fructose, and usually glucose at one end joined by an alpha 1,2 bond non-reducing sugar both anomeric carbons used in glycosidic bonds, cant open up not digested in human gut regulate osmosis and stabilise membranes
36
industrial applications of inulin
food industry - honey - isolated frucrans = dietary fibre oligofructans = sweeteners in reduced calories foods
37
properties of structural polysaccharides
provide structural integrity in plant, agal and fungal cell walls form skeleton of arthropods contain beta links between sugars not as easily broken down by enzymes alternate monosaccharide units invert to give long straight chains hydrogen bonding between chains increases strength viscous polysaccharides contain substituted monosaccharides which are charged a physiological pH
38
starch
energy storage polysaccharide in plants present in starch granules of chloroplasts two components - amuse and amylopectin
39
amylose
glucose polymer with alpha 1,4 bonds one long chain with one reducing sugar end (locked in ring) and one non-reducing (straight chain) end angle of glycosidic bonds cause coils and form a helix - two helical forms: single or double not soluble in cold water (only hot)
40
amylopectin
glucose polymer with alpha 1,4 linked backbone branches joined by alpha 1,6 bonds every 15-25 glucose units branches = more glucose molecules per chain one reducing end and many non-reducing ends - useful for quicker enzyme action for metabolism
41
industrial applications of starch
food industry - thickener and stabilisers pharmaceutical industry - filler in drug tablets due to large polymeric structure cosmetics - foundation and toothpaste paper - provide strength and smoothness glue - swells and gelatinises biofuels
42
cellulose
structural polysaccharide in plant cell walls glucose polymer joined by beta 1,4 bonds alternate monosaccharide unit invert to create long straight chains - important for structural integrity several chains align to form microfibrils - hydrogen bonds between chains - arrange in random directions to give strength to cell walls, no shear plane
43
chitin
structural polysaccharide in insects and crustacean exoskeletons beta 1,4 linked N-acetyl glucosamine base unit is a sugar derivative hydroxyl group at carbon 2 of glucose replaced by amide group
44
peptidoglycan
chains of heteropolysaccharide composed of alternating N-acetyl glucosamine and N-acetyl muramic acid linked by beta 1,4 bonds used in bacterial cell walls held by tetra-peptide chains attached to NAM - cross links to another chain - forms strong structure for cell wall peptide chains on N-acetyl muramic acids residues in adjacent molecules are linked by further short peptide chains
45
what determines blood groups?
short polysaccharide chains attached to cel membrane protein terminal 3 or 4 sugars determine the blood group sugars galactose N-acetylglucosamine N-acetylgalactosamine fructose
46
blood group types
type O = no terminal sugar type A = alpha 1,3 linked GalNac type B = alpha 1,3 linked galactose
47
why must the correct blood group be given?
must not give blood cells with surface antigens that will react with recipients plasma antibodies A or AB can receive A B or AB can receive B O can only receive O AB can receive any O = universal donors AB = universal recipients

cells and biomolecules 🧬 (12 decks)

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