Water and its importance Flashcards
Structure of water
-polar molecule
-hydrogen bonds between water molecules as a result of dipoles formed by electronegativity
-individually weak, collectively strong
High specific heat capacity
- Important in stabilising internal body temp as the environment changes
- Keeping aquatic env. stable.
…to raise by 1 degree 1g of water
High latent heat of evaporation
-important in thermoregulation of mammals eg sweat
High cohesion between molcules
-important in transpiration stream and long continuous columns of H20 form in the xylem vessel
-Provides supportive role
-Mobility of aquatic animals
universal solvent
-important for polar molecules, ion transport, removing waste
-allowing chemical reactions to take place
Biofluids
-Intracellular eg. cytosol
-Extracellular eg fluid between cells
plasma, TF, lymph, serum, urine
Formation of lymph
excess tissue fluid drains back into the blood circulatory system via a network of lymph vessels
Composition of lymph
lymphocytes, small proteins, lipids, glucose (lower levels than plasma and TF), CO2 (higher levels than plasma and TF)
Role of lymph
-Important in immune response. Lymph nodes are where pathogens and foreign pathogens are filtered from lymph fluid and engulfed and destroyed
Urine
-Formed by kidney
-Ultrafiltration of blood followed by selective reabsorption
-Breakdown of excess amino acids and proteins, forms ammonia (highly toxic), then converts to urea which dissolves in water to form urine
-Urine removes urea, soluble waste products, excess water and ions
Serum
-Plasma with CF removed
-Contains antibodies, antigens, hormones, soluble proteins
Plasma
-straw-coloured mammalian biofluid
-Non cellular component of blood
-Water: transports dissolved substances, thermoregulation, regulation of blood pressure and volume
-Mineral ions: Osmotic balance, Ph buffering, regulation of membrane fluidity, eg calcium important in the clotting
-Plasma proteins (fibrinogen)
-Non cellular substances (digestion products, excretory products, hormones)
Functions of carbohydrates
SCEEM
Structural eg celulose
Cell markers eg receptors, antigens
Energy source eg glucose
Energy store eg. glycogen, starch
Macromolecules
Monosaccharides
-small soluble molecules
-eg. glucose, fructose, galactose
-glucose exists as linear and non linear
-Alpha glucose, beta glucose
-Difference, right-hand side. ABBA. OH group
-Glucose, fructose, galactose (identical to B glucose but left side=right side)
IMPORTANT
Structure of Monosaccharides
PAGE 47 BIBLE
Forming disaccharides
Joining 2 monosaccharides:
Condensation reactions makes glycosidic bond (1-4), and produces H20
Splitting a disaccharide
Hydrolysis, breaks glycosidic bond, addition of h20
glycosidic bond= type of covalent bond
Different disaccharides
alpha glucose + alpha glucose-> maltose + H20
alpha glucose + fructose -> sucrose + h20
alpha glucose + galactose-> lactose + h20
Polysaccharide: glycogen
PAGE 49!!
-Liver and skeletal muscles
-Formed by many condensation reactions between many a.glucose
FUNCTION= Storage of Glucose and Energy
- 1.4 glycosidic bond between adjacent a.glucose and at branching points, glycosidic bond formed at 1-6
Properties of Glycogen:
-Insoluble= doesn’t affect water potential
-Compact= can store large quantities of glc in 1 location
-Chemically inactive= does not take part in cell metabolism
Advantages of highly branched molecule:
-Many terminals ends for enzyme attachment for QUICK AND EASY addition or removal of glc
-Glc can be stored quickly
-More compact= takes up less space in cell
Polysaccharide: starch
PAGE 50!!
- Starch grains inside plant cells, seeds, storage organs.
- Also acts as a temporary energy store in leaves when glc made faster than it can be stored or moved
-amylose and amylopectin
(both made of many a.glc joined by many condensation reactions= glycosidic bonds)
Amylose- linear, smaller, less easily digested, more compact. 30% of starch, insoluble
Amylopectin- highly branched, larger, easily digested, less compact. 70% of starch, soluble
Reducing sugars
Sugars with ability to donate an e to another molecule. can reduce Cu2+ to Cu+
(glc, galactose, fructose, ribose)
How to test for reducing sugar (glc)
-Add Benedict’s reagent
-Place the boiling tube in 90 degrees water bath for 10 mins
-Observe colour of ppt form and estimate quantity of reducing sugar present
-Blue, green, yellow, red, brown (most)
Reducing sugar (reduced) + Cu2+ (blue) > Reducing sugar (oxidised) + Cu+
ppt= CuO
Benedicts reagent
Does not differentiate between reducing and non reducing sugars
Therefore, negative result initially only = no REDUCING SUGARS present
Making it more quantitive, filtration method
-React with excess Benedict’s solution
-filter to remove ppt
-Air dry ppt
-Weigh to constant mass
-Amount of ppt is proportional to amount of reducing sugar present
Making it more quantitive, Colorimeter method
-Select the appropriate filter
-zero colorimeter between readings
-stir solution between readings
-Filter and centrifuge to remove suspended material
-put sample into cuvette and take transmission and absorbance value
-Repeat and take colorimeter readings with known conc
-Plot calibration curve
what is a biosensor
an analytical device that uses biological molecule to detect presence of a specific chemical molecule
Different types of biosensors for glc
-Clinistrips (Clinistix for glc in urine)
Colour on test strip compared to colour charts
-Glucometers (presence of glucose in blood
Testing for non-reducing sugars (sucrose)
If the benedicts test shows a negative result, should not assume no sugars are present (only means there are no RS present, but could still be NRS)
-Add HCl
-place in 100 degrees water bath for 5 mins (Hcl hydrolyses glycosidic bond within disaccharide)… scr(NRS)-> glc + frc (both RS)
-+ sodium hydrogen carbonate to neutralise
-+ Benedicts reagent
-If NRS present= brick red cloudy ppt
-If it turns bright blue & clear= NO SUGARS PRESENT.
Testing for starch
KI-I solution
Yellow-brown -> blue-black
Testing for proteins
-Biuret solution
-Blue -> lilac
Testing for lipids
-Add Sudan III solution
-If lipids present, top layer will will be bright red
Osmosis
Movement of water molecules from an area of higher water potential to an area of lower water potential down a water potential gradient across a partially permeable membrane
Pure water= 0 kPa
Hypertonic solution
-higher number of solute molecules, so low water potential
Hypotonic
-lower number of solute molecules, so high water potential
Osmosis in erythrocytes
Rupture- cytolysed
Shrink- crenated
-Pressure exerted on csm when water moves in-
Osmosis in plant cells
Cell wall, protoplast and central vacuole
Same water potential- incipient plasmolysis» protoplast isn’t applying any pressure on the cell wall.
Lower water potential- flaccid, protoplasm shrinks and pulls away from cell wall
Higher water potential- TURGID= protoplasm exerts a force on cell wall as it inc in volume, cell wall does not rupture as cellulose is tough and inelastic. Prevents further h20 molecules from entering
