The Structure of Sugars Flashcards
Carbohydrates always contain…
Carbon, hydrogen and oxygen
Carbohydrates with five or more carbons tend to…
Form rings
Most sugars have a carbon with four or more different groups attached. This means they are…
Chirally active
Carbohydrates contain two or more ? groups
Hydroxide (-OH)
Carbohydrates have either a ? or ? group
Aldehyde or ketone
Carbons are numbered starting from the…
Aldehyde or ketone group
Carbohydrate rings are not flat, but instead form a…
Non-planar chair configuration
If the ring structure results in different stereochemistry at the carbonyl carbon (C1 in aldoses, C2 in ketoses), it is an…
Alpha or beta anomer (but considered the same sugar)
Because most sugars are chirally active, they can form enantiomers (mirror image molecules) in which ? are reversed
H and OH
Chirally active sugars can exist in D and L forms. Most sugars are found in the ? form
D
Stereoisomers where the configuration around one of the non-carbonyl asymmetric carbons differs are known as…
Epimers
Epimers are considered ( the same / different ) sugars
Different
An example of an epimer is galactose, which is a…
C4 epimer of glucose
Disaccharides are polymers of ? sugar molecules
2
Oligosaccharide is a somewhat imprecise term which usually refers to polymers of between X - Y sugars in length
2-10
Sugars are often…
Modified 🛠
The bond formed between a hemiacetal group of one sugar and the oxygen of a hydroxyl group of another is known as a…
Glycosidic bond
Glycosidic bonds are formed by X and broken by Y (type of reaction)
X = Condensation reactions Y = Hydrolysis reactions
Glycosidic bonds between sugars are typically between carbons…
1 and 4 (1,4 glycosidic bond)
There are a huge range of possible carbohydrate structures which arise from variations in (5)…
- Composition
- Branching
- Multiple glycosylation sites
- Isomeric forms
- Sialic acids
Carbohydrates are ? rich molecules
Information 📖
The main roles of carbohydrates are (6)…
- Main source of metabolic energy 🔥
- Energy storage & transport 🚚
- Structures in plants, bacteria, fungi & animals 🌱
- Components of DNA & RNA 🔬
- Cell-to-Cell communication 📞
- Host-pathogen recognition 👀
The storage molecules in plants and animals are…
Starch and glycogen (respectively)
Both starch and glycogen share the structure of (2)…
Alpha 1,4-glycosidic bond backbone with alpha 1,6-glycosidic bond branch points
The reducing end of a carbohydrate is the…
Unattached terminal sugar (C1), ring can open
The non-reducing end of a carbohydrate is where…
The terminal sugar is involved in a glycosidic bond
The alpha linkages result in a…
Helical structure
Helical structure is advantageous because it allows molecules to be (2)…
Densely packed and easily accessible to enzymes
Cellulose is a polymer of…
Beta glucose
Cellulose gains its strength from…
Cross-linking hydrogen bonds between chains
Second generation biofuels require the conversion of cellulose into…
Glucose
Peptidoglycan, bacterial cell wall, is a rare occurrence of…
D-amino acids
Gram positive bacteria have ? of peptidoglycan cell wall…
40+ layers
Gram negative bacteria have ? of peptidoglycan cell wall…
1 or 2 layers
Glycoconjugates are carbohydrates…
Covalently linked to other chemical species (eg. lipids, proteins)
Glycolipids are (hydrophilic / hydrophobic / amphiphilic)
Amphiphilic
Glycolipids act as receptors for…
Cell recognition 👀
GlcNAc is a…
Glycoprotein
Glycosylated proteins (glycoproteins) can be either…
N (nitrogen) linked or O (oxygen) linked
N-linked glycoproteins are joined by the amide group of…
Asparagine (G)
O-linked glycoproteins are joined by the hydroxyl of either…
Serine (S) or Threonine (T)
Mucins are O-linked glycoproteins which (2)…
Protect epithelial surfaces and provide lubrication
Proteoglycans are mostly (N-linked / O-linked )
O-linked
Proteoglycans bind with many water molecules to form a hydrated gel, able to withstands…
High compression within joints 🏃♂️
Proteoglycans are heavily…
Sulphated
Glycosyltransferases (GTs) transfer sugars from…
Nucleotides to acceptor molecules
Glycosyltransferases (GTs) are responsible for building most (molecule type)…
Complex carbs 🍞
Notably, the presence or absence of different types of glycosyltransferases is responsible for…
Blood groups 🅰️🆎🅱️🅾️
On the surface of a flu virus, the glycoprotein hemagglutinin is responsible for ( binding to / release from ) host cell
Binding to
On the surface of a flu virus, the glycoprotein neuraminidase is responsible for ( binding to / release from ) host cell
Release from
Tamiflu inhibits ( neuraminidase / hemaglutinin / transpeptidase)
Neuraminidase
Penicillin inhibits the enzyme ?, which is responsible for…
Transpeptidase - building cross-links which give bacterial cell wall its strength
