chapter 3 - biological molecules Flashcards
what are the three main single sugars / monosaccharides?
- glucose
- galactose
- fructose
“great girl friends”
what are the three main double sugars / disaccharides?
- Maltose = glucose + glucose
- lactose = glucose + galactose
- sucrose = glucose + fructose
maltose = glucose + _____________
glucose
lactose = glucose + _____________
galactose
why do we need food?
the nutrients in the food provide us with energy and materials needed by the body
sucrose = glucose + _____________
fructose
galactose is commonly found in _____________
milk from mammals
glucose is commonly found in ______________
plants and animals
fructose is commonly found in ___________
plants
(very rare in animals)
what is the test for reducing sugars?
Benedict’s test (using benedict’s solution)
what are the reducing sugars?
- glucose
- galactose
- fructose
- lactose
- maltose
“great girl friends like me”
if the benedict’s solution remained blue, _______________ reducing sugar
no reducing sguar
if the benedict’s solution turned from blue to green, _____________ reducing sugar
traces of
if the benedict’s solution turned from blue to yellow/orange, _____________ reducing sugar
moderate amount of
if the benedict’s solution turned from blue to red, _____________ reducing sugar
large amount of reducing sugar
traces of reducing sugar: benedict’s solution _________
turns from blue to green
moderate amount of reducing sugar: benedict’s solution _________
turns from blue to yellow/orange
no reducing sugar: benedict’s solution _________
remains blue
large amount of reducing sugar: benedict’s solution _________
turns from blue to red
what are the three complex carbohydrates / polysaccharides?
- starch
- glycogen
- cellulose
what is the main function of carbohydrates?
needed as an immediate source of energy
what are the chemical elements that make up carbohydrates?
carbon, hydrogen, oxygen
in carbohydrates, the hydrogen and oxygen atoms are present in the ratio __________
2:1
starch, glycogen and cellulose are polysaccharides make up of numerous __________ molecules
glucose
disaccharides are created when _______________
two monosaccharides are joined together through a condensation reaction
what is the role of starch (2 pts) and where does it occur (1 pt)?
- a storage form of carbohydrates in plants
- digested to glucose when needed
- found in storage organs of plants, e.g. potato, tapioca
what is the role of glycogen? (2 pts)
- a storage form of carbohydrates in mammals
- digested to glucose when needed
what is the role of cellulose? (2 pts)
- cellulose cell wall protects plant cell from bursting/damage
- serve as a dietary fibre that prevents constipation
why are glucose and starch used as storage materials?
- insoluble in water (they are osmotically inactive so they do not change water potential in cells)
- large molecules (cannot diffuse across cell membranes, so they will not be lost from cell)
- easily hydrolysed to glucose when needed for respiration
- have compact shapes (occupy less space than sum of individual glucose molecules)
what is the meaning of hydrolysed
breakdown in the presence of water
starch is broken down by ___________ to form maltose
amylase
maltose is broken down by _________ to form glucose
maltase
what is the test for starch ?
iodine test (using iodine solution)
for solid food samples, crush the food using _____________
a mortar and pestle
what elements are proteins made up of?
carbon, hydrogen, oxygen and nitrogen
each protein molecule is made up of smaller basic units called ___________
amino acids
(amino acids are the building blocks of protein)
amino acids are made up of _________, __________ & _____________.
amino group, acidic group & a side chain
amino acids ——-> ____________———> _____________
polypeptides
proteins
what happens when proteins are denatured?
they lose their unique 3D shape and lose their ability to function
what are the functions of proteins? (5)
- synthesis of new cytoplasm for growth and repair of worn-out cells
- synthesis of enzymes and some hormones
- formation of antibodies to combat diseases
- source of energy during EXTREME starvation when carbohydrate and fat reserves are depleted.
- proteins are used for muscle development.
what is the test for proteins?
biuret test (using biuret solution)
in the absence of protein, the biuret solution will __________________.
remain blue
in the presence of protein, the biuret solution will _________________.
turn from blue to violet
what elements are fats made up of?
carbon, hydrogen, oxygen
unlike carbohydrates, fats contain ________ oxygen compared to hydrogen
MUCH less
fats can be broken down into ________ & _________ by _________
fatty acids & glycerol by lipase
what are the functions of fats? (5)
- a long-term storage of energy
- insulating material that prevents excessive heat loss
- solvent for fat-soluble vitamins and hormones
- they form cell membranes
- oily substance secreted by skin glands reduce rate of evaporation and heat loss from skin surface
what is the test for fats?
ethanol emulsion test (using ethanol + water)
during an ethanol emulsion test, in the presence of fats, _________________ is formed.
a cloudy white emulsion
(ethanol emulsion test) in the absence of fats, ______________
solution will remain clear.
