4 Sugars, lipids and cellular barriers

Question 1

Carbohydrate group

Answer 1

CH2O

Question 2

Sugars - role of 5C

Answer 2

DNA / RNA / ATP

Question 3

Sugars - role of 6C

Answer 3

Energy roles and structure

Question 4

Alpha glucose polymers (3)

Answer 4

amylose (1,4)
amylopectin (1,4 1,6)
glycogen (1,4 1,6)

Question 5

Beta glucose polymer

Answer 5

cellulose (1,4)

Question 6

Chitin

Answer 6

N-acetyl glucosamine

Question 7

Glycobiology - where do glycans attach

Answer 7

Glycans attatched to the asn, ser, the = glycoproteins

Question 8

Glycan roles - structural

Answer 8

mucous proteins (glycans containing sialic acid)

Question 9

Glycan roles - functional

Answer 9

ABO blood groups —> glycans attatched to cell surface proteins + lipids

Question 10

Glycan roles - proteoglycans

Answer 10

important features of extracellular environemnt - forms collagen / structural bases that holds cells and tissues into place / shock absorbing / lubrications

Question 11

What is the extracellular matrix rich in (ECM)

Answer 11

Glycans

Question 12

Lipids - fats, oils and waxes

Answer 12

More reduced than carbohydrates - more efficient energy store (larger energy release)

Question 13

Trans-fats

Answer 13

more similar to saturated fats although theyre unsaturated C=C

Question 14

Phospholipids

Answer 14

2FA and a phosphate group attatched to an alcohol - the alcohol is often charged) has a polar and charged end VS the unipolar uncharged FA end

Lipid head (hydrophilic) faces out and FA tail (hydrophobic) faces inwards

Question 15

The first cells

Answer 15

Inside and outside - fatty acids may be available on the early earth

Question 16

Eukaryotic cells

Answer 16

Specialisations help them to grow large and complex

Energy - mitochondria (and chloroplasts)

Complex internal and external membranes

Sophisticated transport systems and internal skeleton (cytoskeleton)

Question 17

Membrane structure

Answer 17

flexibility and fluidity (yet strong)

Fluid mosaic model - lipids and membrane proteins can move in the plane of the membrane. Fluidity can be affected by temperature and unsaturation

Membrane composition varies between species and between membranes within a cell - bacterial cells are the most uniform and have the highest proportion of PtdEtn (PtdEtn is responsible for the maintenance of mitochondrial integrity and assembly of lactose permease and other membrane proteins)

Question 18

Membrane composition can vary as follows…

Answer 18

Inner and outer face can vary (eg. animal cells plasma membrane)

Cytoplasmic face + Extracellular face

Mechanism for ‘flipping’ phospholipids

Question 19

Cholesterol in membranes

Answer 19

moderator of membrane fluidity (adding cholesterol fills in some of the gaps and makes the membrane less fluid

Led to the idea of Lipid rafts (self organised regions of membrane)

Question 20

Proteins in membranes

Answer 20

Transmembrane domains (intergration proteins)

Peripheral proteins (can be anchored to a phospholipid - only present on one side —> GPI anchor is a linkage via a phospholipid)