Week 2 - Macromolecules, nutrients & metabolism Flashcards
What is an oligosaccharide?
When 2-10 monosaccharides link covalently (glycosidic linkage).
What is the difference between homo and heteropolysaccharides?
Homo are polymers of single polysaccharides whereas hetero and composed of different polysaccharides.
What 2 components make up starch?
Amylose and amylopectin
What are the 4 functions of carbohydrates in living organisms?
- Provide energy
- They offer cells external protection (Cellulose).
- Attached to proteins and lipids, they help cells to recognise molecules or other cells in their surroundings.
- They are part of every building block of nucleic acids (as ribose or deoxyribose).
How can you distinguish a ‘saturated’ from an ‘unsaturated’ fatty acid?
Saturated all carbons are linked by single bonds whereas unsaturated there are double bonds
What is the most abundant lipid category?
Triglycerides
How many vitamins are there, and how are they split?
13 vitamins - split into water and fat soluble
Name the 9 water soluble vitamins
Vitamin B1/thiamine
Vitamin B2/riboflavin
Niacin
Vitamin B6/pyriodoxine
Vitamin B12/cobalamin
Folate
Pantothenate
Biotin
Vitamin C/ascorbate
Name the 4 fat soluble vitamins
Vitamin A/retinol
Vitamin D/cholecalciferol
Vitamin E/a-tocopherol
Vitamin K/phylloquinone
What is metabolism?
The sum of the chemical reactions occurring in a living organism or part of it
What is the ‘free energy’ of a reaction effected by?
Temperature, pressure, initial amounts of reactants and products, and pH.
What is catabolism?
Large molecules -> small molecules (releases energy for synthesis of ATP)
What is anabolism?
Small molecules -> large molecules(Synthesis of molecules)
What are the 3 ways in which molecules/ions can move across membranes?
Simple diffusion
Passive transport/Facilitated diffusion
Active transport
What is saltatory conduction?
Propogation of Aps from one node of ranvier to another - much faster than continuous conduction
What is exocytosis?
When vesicles containing neurotransmitters fuse with the presynaptic membrane and discharge their contents into the synaptic cleft
How does the nervous system control contractile force?
Through the number of motor units recruited
What are the 2 components of muscle cell?
Sarcolemma - plasma membrane
Sarcoplasm - cytoplasm
Describe the sliding filament theory
When sarcomere contracts, the length of thick and thin filaments don’t change, but their overlap increases. Therefore, contraction is caused by active sliding of thick and thin filaments past each other.
What 2 proteins overlap during muscle contraction?
Actin and myosin
How does calcium control muscle activity?
By permitting binding of myosin to F-actin, via tropnonin and tropomyosin
Which of the following statements are true of myosin:
a) forms attachment with actin
b) hydrolyses ATP
c) undergoes conformational change, resulting in powerstroke
All of them
How is the reservoir of Ca2+ maintained in the sarcoplasmic reticulum?
Via the Ca2+ ATPase pump & Via hydrolysis of ATP.
Which protein predominantly constitutes the sarcomere “M line”?
Myomesin
During muscle contraction, which event is thought to initiate troponin/tropomyosin movement to facilitate myosin and actin binding?
Ryanodine receptor mediated release of Ca2+ from the sarcoplasmic reticulum.
What are ‘thick’ filaments mostly made out of?
Myosin
What are ‘thin’ filaments mostly made out of?
Actin, tropomyosin and troponin.
What 2 forms foes actin exist in?
Globular actin & Fibrous actin
What does F actin do?
Interwine and form trunk of thin filaments to which tropomyosin and troponin attach.
F actin greatly increases ATPase activity of myosin by increasing the rate at which ADP & Pi are released from active site.
How does calcium control muscle contraction?
By permitting binding of myosin to F-actin, via troponin and tropomyosin.
What does the transmisson of an AP across T-tubules cause?
The opening of a Ca2+ channel called the ryanodine receptor.
What happens when AP passes T-tubule?
Ryanodine receptor closes, preventing Ca2+ efflux from the SR, Ca2+ ATPase returns resting gradient
