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What is the function of cellulose?

Primary structural component of cell wall of green plants
Lignin and cellulose (lignocellulose) most common biopolymer on earth
Only tunicates evolved the ability to create and use cellulose
Indigestible by humans so acts as hydrophilic bulking agent for faeces


Describe the structure of cellulose

Layered linear chains of B-1,4 linked D-glucose units packed into crystals (myofibrils)
Layers linked by H bonds


What is lactose?

Disaccharide of B-D-galactose and B-D-glucose linked through B-1,4


What are glycosaminoglycans? (GAGs)

Large, pure carbohydrates that are -ve charged, hydrophilic
Polysaccharides present on animal cell surface and in ECM


Describe the structure of GAGs

Disaccharide repeating unit containing glucosamine or galactosamine and uronic acid
At least one of the sugars has a -ve charged carboxylate or sulphate group - with exception of hyaluronic acid (no sulphate group)


What is a glycoprotein?

Macromolecule composed of protein and a carbohydrate which is added in posttranslational modification either at asparagine (N-glycosylation) or hydroxylysine/hydroxyproline/serine/threonine (O-glycosylation)


What is the function of glycoproteins?

Assist protein folding or improve stability
Immune cell recognition: antibodies (immunoglobulins) interact directly with antigens, moles of major histocompatibility complex (MHC) surface of cells interact with T-cells (adaptive immune response)


Explain N and O glycosylation

Glycosylation is the attachment of carbohydrate to AA side chain
N: attach to N of amide side chain (asparagine)
O: attach to O of OH side chain (hydroxylysine/hydroxyproline/serine/threonine)


What are proteoglycans?

Heavily glycosylated glycoproteins - core protein with several GAG chains


What are the functions of GAGs?

Structural: ECM and BM
Space-filling in cartilage
Modifiers/activators of effector proteins (growth factors, proteases)


What are the functions of proteoglycans?

Form large complexes in ECM with proteoglycans and fibrous matrix proteins (collagen)
Binding of cations and water
Regulation of movement of molecules through matrix


What is chondroitin sulphate?

Sulphate GAG composed of N-acetyl-galactosamine and glucuronic acid
Usually forms part of a proteoglycan


What is the function of chondroitin sulphate?

Major structural component in cartilage conferring resistance to compression
Dietary supplement for treatment of osteoarthritis


What is heparin?

Highly sulphated GAG used as injectable anticoagulant and used for inside of test tubes, renal dialysis machines


Describe the structure of peptidoglycan

Crystal lattice of linear chains of NAG and NAM
Each NAM has peptide chain usually containing AAs that do not occur in humans thought to protect against attacks by most peptidases


Describe the energy balance in humans

Balance between energy intake and energy expenditure


Describe the anabolism of glucose

Glucose enters cell, undergoes glycogenesis forming glycogen in liver and muscle cells
OR undergo lipogenesis and join FA chain


Describe the anabolism of FAs

FAs esterified to triglycerides in adipose tissue


Describe the anabolism of AAs

AAs undergo protein synthesis to form proteins in muscle


Describe the metabolism of glycogen

Glycogen undergoes glycogenesis forming glucose, undergoes glycolysis to pyruvate converted to acetyl-CoA enters TCA


Describe metabolism of triglycerides

Undergo lipolysis forming FAs, undergo B-oxidation to form acetyl-CoA enter TCA


Describe protein metabolism

Proteolysis converts to AAs either directly enter TCA or converted to acetyl-CoA


Describe glycogen stores and their mobilisation

In liver glycogen converted to glucose-6-P which is converted to glucose which can enter brain or back to glucose-6-P and used by muscles to produce lactate
Muscle cells produce glucose 6P then lactate


Describe the cori cycle

Lactate produced in muscle cell converted to pyruvate which can enter gluconeogensis to re-form glucose which can be recycled


Describe lipid stores and mobilisation

Triglyceride stored in adipose broken down to glycerol and FAs
Glycerol undergoes gluconeogenesis forming glucose, enters brain
FAs enter muscle or undergo ketogenesis forming ketone bodies utilised by brain or enter muscle


Describe protein utilisation

Undergo proteolysis produce AAs which can enter TCA, converted to Acetyl-CoA or undergo transamination (amino group moved)
Acetyl-CoA enter TCA or converted to ketone bodies
After transamination form pyruvate either enter TCA or gluconeogenesis


Describe glucose transport

Enters cells via facilitated diffusion by GLUTs
Uptake increased by increasing GLUTs in PM - insulin or exercise


Describe FA transport

Thought to diffuse across PM or may involve FA transporter proteins


How is energy stored in cells?

In chemical bonds
When cell has enough energy available it stores it by adding Pi group to ADP forming ATP


What are the stages of ATP production?