biological molecules Flashcards
how much water does our bodies lose, and through what?
our bodies lose up to 3l of water daily, mostly through sweat and urine production
how does dehydration occur in humans?
it happens when the volume of water lost is not balanced by the water intake through eating and drinking.
what are the symptoms of dehydration?
feeling faint, losing focus, dry and irritated eyes, cracked lips and sore throat, constipation, pungent and dark-coloured urine
why is water important in humans in terms of regulating body temperature?
-water has a high heat capacity and is used to transport heat around the body
-when water in sweat evaporates,the latent heat of vapourisation removed from the skin helps keep the body cool
why is water important in humans in terms of maintaining blood pressure?
water makes up half the volume of blood
-too little water and blood becomes too viscous
-too much water and blood vessels may burst
why is water important humans in terms of medium of transport?
water being a universal solvent allows for efficient transport of many soluble substances throughout the body
why is water important in humans in terms of solvent for chemical reactions?
water makes up more than half the volume of the cell cytoplasm and is where most chemical reactions occur in the cell
why is water important in humans in terms of lubrication?
fluid at the joints and tears on the eye reduce the wear and tear these surfaces experience
why is water important in humans in terms of preventing constipation?
undigested food should be passed out in a semi-solid form with some water present
why is water important in humans in terms of excretion?
the kidneys remove toxic metabolic waste from the body by diluting it in water and excreting it in urine
why is water important in plants in terms of regulating temperature?
when plants lose water vapour via transpiration, the latent heat of vapourisation removed helps keep the plant cool
why is water important in plants in terms of medium if transport?
water being a universal solvent allows for the efficient transport of many soluble substances via the xylem and phloem
why is water important in plants in terms of solvent for chemical reactions?
water makes up more than half the volume of the cell cytoplasm and is where most chemical reactions occur in the cell
what are carbohydrates, proteins, and fats called, and what do they all contain in common?
they are biological molecules
they all similarly contain carbon, hydrogen, and oxygen atoms in varying ratios
in carbs, what are the polysaccharides?
starch, cellulose, glycogen
in carbs, what are the monosaccharides?
glucose, galactose, fructose
in carbs, what are the disaccharides?
maltose, lactose, sucrose
what is the element composition of carbs?
carbon, hydrogen, oxygen only
hydrogen and oxygen always 2:1
what is the basic unit in carbs?
monosaccharide (C6H12O6)
simplest carbohydrate molecule
what is the role in organism of carbs?
all carbohydrates consumed are ultimately broken down into glucose
substrate for cellular respiration
substrate for lipid and amino acid synthesis
what are some examples of glucose?
honey, raisins, dates
what are some examples of galactose?
honey, celery, plums
what makes maltose and what are some examples of it?
glucose+glucose
malt sugar
apples, sweet potatoes, edamame
what are some examples of fructose?
honey, pear, mango
what makes lactose and what are some examples of it?
galactose+glucose
milk sugar
milk, yoghurt, cheese
what are reducing sugars?
glucose, galactose, fructose, maltose, lactose
what makes sucrose and what are some examples of it?
fructose+glucose
table sugar
sugar cane, maple syrup, gula melaka
what sugar isnt a reducing sugar?
sucrose
how to carry out the benedicts test?
if presented with solid sample grind with a mortar and pestle then add distilled water
-add 2cm3 of benedicts solution to 2cm3 of the liquid/aqueous sample
-heat the mixture for 5 minutes in a boiling bath
what do the results of the benedicts test mean?
remains clear blue=reducing sugars absent
turns brick-red=reducing sugars present
what are polysaccharides made out of?
polysaccharides are made out of many repeating subunits of glucose chemically bound together
where is starch commonly found?
starch is the storage in plants
where is glycogen commonly found?
glycogen is the storage in animals
where is cellulose commonly found?
cellulose is the structural support for the plant cell wall
how to carry out the iodine test for starch?
add 3 to 5 drops of iodine solution to the sample
what do the results of the iodine test mean?
remains yellowish-brown=starch absent
turns blue-black=starch present
which class of biological molecules do fats belong to?
lipids (which also include many other important molecules such as phospholipids;cell membrane, and hormones;oestrogen and testosterone)
what is the element composition of fats?
carbon, hydrogen, and oxygen
no fixed ratio of hydrogen and oxygen
what is the basic unit of fats?
one glycerol backbone with three fatty acid tails
what is the role in organism in fats?
long-term energy storage, insulation beneath the skin surface, cushion and protect internal organs from impact, major component of cell membrane, solvent for fat-soluble vitamins
what are saturated fats?
solid at room temperature, increases risk of heart diseases
what are unsaturated fats?
liquid at room temperature, lowers risk of heart diseases
how does the ethanol-emulsion test for fats occur?
add the food sample to a beaker of ethanol and shake thoroughly to allow any fats present to dissolve
-filter the mixture and pour 2cm3 of the residue to 2cm3 of water
what do the results of the ethanol-emulsion test for fats mean?
remains clear and colourless=fats absent
cloudy white emulsion formed=fats present
what are proteins?
proteins account for more than 50% of the dry mass of most cells and are crucial for the basic functioning of a cell. proteins help to speed up chemical reactions, transport substances, and allow cells to move
how are proteins formed?
there are 20 amino acids that can be chemically bound together in various lengths and sequences to form thousands of different proteins
for proper functioning, how many proteins does a normal human have?
10000 different proteins for an estimated total of 400000 proteins for proper functioning
what do amino acids contain?
they all consist of an amino group, a carboxyl group, and a hydrogen atom.
what differs in amino acids?
the variable group that gives rise to the 20 different amino acids
what do those 20 different amino acids do?
these 20 different amino acids come together in various lengths and sequences to form polypeptides which subsequently fold to become the proteins essential for life
what are some products rich in proteins?
meat and dairy products, as well as leafy vegetables. eggs, nuts and beans
what is the element composition of proteins?
carbon, hydrogen, oxygen and nitrogen
some amino acids have sulfur and phosphorus
what is the basic unit of amino acids?
amino acid
what is the role in organism in proteins?
enzymes speed up chemical reactions, antibodies and antigens protect cell from pathogens, hormones regulate various processes, contractile and motor proteins allow for movement
how does the biuret test for proteins occur?
-add 2cm3 of sodium hydroxide solution to 2cm3 of the liquid/aqueous sample and shake thoroughly to mix
-add a 3 to 5 drops of copper(II) sulfate solution, shaking the mixture between drops
what do the results of the biuret test for proteins mean?
remains blue=proteins absent
turns violet=proteins present
what are enzymes?
enzymes are biological catalysts that speed up the rate of chemical reactions and remain chemically unchanged at the end of each reaction
how do enzymes work?
-all enzymes are proteins and function best at their optimal temperatures and pH
-enzymes provide an alternative reaction pathway with a lower activation energy
-only a small amount of enzymes are needed as they remain chemically unchanged at the end of each reaction and can therefore be reused
what is activation energy?
the minimum amount of energy reacting molecules need to have to undergo a reaction. the lower the activation energy, the more easily the reaction proceeds
what is the ‘lock and key’ hypothesis?
substrate molecules have a complementary shape to fit into the active site of an enzyme. enzymes ensure specificity by having a unique active site that can only bind to a complementary substrate molecule. upon forming the enzyme-substrate complex, the substrate now requires a lower activation energy to undergo a reaction and can proceed to form new products by breaking or forming bonds
what is the complementary substrate molecules for amylase?
starch
what is the complementary substrate molecules for sucrase?
sucrose
what is the complementary substrate molecules for protease?
proteins
what is the complementary substrate molecules for lipase?
lipids
how does temperature affect enzyme-cataylsed reactions?
being proteins, enzymes are sensitive to changes in temperature, and their ability to catalyse reactions will diminish when the conditions are too far from the optimal
what is the optimum temperature of enzymes found in the human body?
around 37 degrees celsius
what does the point below optimum temperature in the graph mean?
enzymes (and substrates) have insufficient kinetic energy
enzymes are inactive and enzyme activity is low
what does the point at optimum temperature in the graph mean?
enzymes have the perfect of kinetic energy to bind to substrates and catalyse the reaction
what does the point above optimum temperature in the graph mean?
enzymes denature and are no longer complementary to their substrates
what does the trend below optimum temperature in the graph mean?
as temperature increases, reacting molecules have more kinetic energy and move faster
the frequency of effective collisions increase, causing more enzyme-substrate complexes to form more quickly for a greater rate of reaction
what does the trend at optimum temperature in the graph mean?
enzymes are most active and have the greatest rate of reaction
what does the trend above optimum temperature in the graph mean?
-too much kinetic energy disrupts the bonds holding the three-dimensional structure of the enzyme
-the specific shape of the active site is damaged, and the enzyme is no longer complementary to its substrate
-enzymes are denatured and cannot catalyse the reaction
what is the effect pH has on enzyme-catalysed reactions?
enzymes are also sensitive to changes in pH, and their ability to catalyse reactions will diminish when the conditions are too far from the optimal
what is the pH of stomach enzymes?
2 (very acidic)
what is the pH of pancreatic enzymes?
8 ( a little basic/alkali)
what does the point below optimum pH in the graph mean? (pH)
enzymes are denatured and no longer complementary to their substrates
what does the point at optimum pH in the graph mean? (pH)
enzymes are most active
what does the point below optimum pH in the graph mean? (pH)
enzymes are denatured and no longer complementary to their substrates
what does the trend below optimum pH in the graph mean?
-deviations from the optimal pH disrupts the bonds holding the three-dimensional structure of the enzyme
-the specific shape of the active site is damaged, and the enzyme is no longer complementary to its substrate
-enzymes are denatured and cannot catalyse the reaction
what does the trend at optimum pH in the graph mean?
enzymes are most active and have the greatest rate of reaction
what does the trend above optimum pH in the graph mean?
-deviations from the optimum pH disrupts the bonds holding the three-dimensional structure of the enzyme
-the specific shape of the active site is damaged, and the enzyme is no longer complementary
how does substrate concentration affect the rate of enzyme-catalysed reactions?
-at low substrate concentrations, enzyme activity increases rapidly when substrate concentration increases
-at high substrate concentrations, enzyme activity plateaus as all enzyme active sites are occupied and substrate molecules must wait for a free active site
how does enzyme concentration affect the rate of enzyme-catalysed reactions?
-at low enzyme concentrations, enzyme activity increases rapidly when enzyme concentration increases
-at high enzyme concentrations, enzyme activity plateaus as all substrates have already formed enzyme-substrate complexes and there are no available substrates
how does the size of the sample affect the rate of enzyme-catalysed reactions?
-large chunks of food have small surface to volume ratios, decreasing the effectiveness of enzyme reactions
-small pieces of food have large surface area to volume to ratios, increasing the effectiveness of enzyme reactions
