bb10a cells biomolecules genetics 2003 semester 1 n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
BB10a: Cells, Biomolecules & Genetics, 2003 Semester 1. PowerPoint Presentation
Download Presentation
BB10a: Cells, Biomolecules & Genetics, 2003 Semester 1.

Loading in 2 Seconds...

play fullscreen
1 / 25

BB10a: Cells, Biomolecules & Genetics, 2003 Semester 1. - PowerPoint PPT Presentation


  • 84 Views
  • Uploaded on

BB10a: Cells, Biomolecules & Genetics, 2003 Semester 1. Thursday 2 Oct. Lecture 4 Structures & functions of common carbohydrates Andrew Pearson. BB10A: Common carbohydrates. Basic units: called monosaccharides  are simple sugars such as glucose and fructose.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'BB10a: Cells, Biomolecules & Genetics, 2003 Semester 1.' - sage


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
bb10a cells biomolecules genetics 2003 semester 1
BB10a: Cells, Biomolecules & Genetics, 2003 Semester 1.
  • Thursday 2 Oct.
  • Lecture 4
  • Structures & functions of common carbohydrates
  • Andrew Pearson
slide2

BB10A: Common carbohydrates

Basic units: called monosaccharides

 aresimple sugars such as glucose and fructose.

The structures of monosaccharides can be drawn

in different ways, to highlight different aspects:

the Fischer projection is best for showing the

stereoisomerism of the various substituents;

but the Howarth projection is more useful

to biochemists because it approximates the 3-D

structures and helps explain stabilities.

slide3

BB10A: Common carbohydrates

Fischer projections

slide4

Properties of monosaccharides.

Containing many hydroxyl groups:

sugars interact easily with water:

they are hydrophilic & water-soluble.

Containing many hydroxyl groups:

sugars are highly oxidised and can be easily hydrolysed into fragments.

Containing many hydroxyl groups:

sugars are easily derivatised to give related molecules, including aminosugars, acetylated sugars, dimers, oligomers and polymers.

BB10A: Common carbohydrates

slide8

The relationship between the various isomers of sugars is not complicated to biochemists:

Biomolecules like sugars are selected because of their 3-D structure, and the wrong isomer simply does not fit into binding sites.

The distinction between D- and L- glucose is not something that many biochemists concern

themselves with nowadays: some bacterial products contain the odd L-sugar, all others are D-.

BB10A: Common carbohydrates

slide9

Precise 3dimensional fit between a substrate and enzyme.

Ionic

interaction

“Hydrophobic

Interaction”

H-bond

Adapted From

Voet & Voet

slide11

Disaccharides:

two monosaccharides joined by

O-glycosidic bond.

Three occur naturally in stable form,

Lactose in breast milk (sugar transport)

Sucrose in plant sap (plant transport sugar)

Trehalose in fungi and insect heamolymph (for transport)

all others shown in books are digestion products of something bigger.

BB10A: Common carbohydrates

slide13

BB10A: Common carbohydrates

Disaccharides

maltose

trehalose

sucrose

cellobiose

lactose

slide14

BB10A: Common carbohydrates

Glycogen, in animals, is similar but has a

greater degree of branching.

slide15

BB10A: Common carbohydrates

Cellulose is a linear homopolymer of glucose, but unlike amylose the O-glycosidic bond is beta in cellulose; alpha in amylose.

slide16

Cellulose: note the H-bonds.

A tetrasaccharide from heparan sulphate: note the substituted sugars.

Repeating unit of chitin: from insects and crustaceans

slide17

The raffinose series at the end of a number of “unusual” plant storage polysaccharides. Our intestinal digestive enzymes are unable to cleave stachyose into smaller units – but anaerobes in our lower intestines can..

BB10A: Common carbohydrates

slide19

The difference in size between proteoglycans

which are giant macromolecules

and glycoproteins,

which are small soluble protein macromolecules.

BB10A: Common carbohydrates

slide21

Functions of Monosaccharides

    • broken down for energy (by either fermentation or respiration)
    • interconverted/carbon skeleton used for biosyntheses
    • solvation of hydrophobes: in aqueous transport media such as serum
    • transport form of energy in animal serum, plant sap and intracellularly in general.  

BB10A: Common carbohydrates

slide22

Oligosaccharides:

  • short branched heteropolymeric chains of
  • monosaccharides, often derivatised,
  • with high informational content in their normal
  • hydrated state.
  • Functions:
  • markers for outer surface of cell membranes
  • protein targeting markers in endoplasmic reticulum system
  • prevention of membrane protein flip-flop
  • formation of glycocalyx

BB10A: Common carbohydrates

slide23

Polysaccharides:

long chains of monosaccharides,

sometimes branched, either

Homopolymers (only one type of monosacch.)

(e.g. cellulose, glycogen, amylose, amylopectin)

or heteropolymers(more than one monosacch.)

(e.g. glycosaminoglycans, algal cell wall gels,

peptidoglycan, chitin)

BB10A: Common carbohydrates

slide24

BB10A: Common carbohydrates

  • Functions:
  • energy reserves in plants:
  • (starch and some of the flatulogenic polymers)
  • energy reserves in animals:
  • glycogen
  • structural in all except animals:
  • chitin, celluloses, peptidoglycan
  • lubrication and shock-absorbing
  • in synovial fluids, connective tissues
slide25

CHO function table

BB10A: Common carbohydrates