biological molecules BAILEY Flashcards
define monomers
small molecular unit
define polymerisation
process of forming a polymer from many monomers
define a condensation reaction
when a monomer is joined to another monomer forming a chemical bond and a molecule of water
define hydrolysis reaction
polymers can be broken down into monomers by using water to break chemical bonds
name one monosaccharide
glucose
name 3 polysaccharide
glycogen
starch
cellulose
name the polymer made out of amino acids
polypeptides
(proteins)
name one type of proteins
enzymes
name a polynucleotide
DNA
RNA
write a method of how to test for reducing sugars
(all monosaccharides all disaccharides)
- equal volumes of sample and Benedict’s solution
- HEAT gently for 5 mins
if the sample stays blue this is the negative result and means there no reducing sugars in the sample
sample could change colour
RED (strongest concentration of sugar)
ORANGE
YELLOW
GREEN
Name one issue with using Benedict’s to test for reducing sugars
it’s semi quantitative
colours can be subjective
What is a more accurate way to measure the amount of reducing sugar
use a colourimeter to measure how much light passes through the sample
list 2 positives of using a colourimeter
it is quantitative
standardises
when testing how much sugar there is in a precipitate after drying and filtering it
What does the mass mean
more mass = more reducing sugars
what elements are carbohydrates made up out of
C H O
in a condensation reaction with 2 monosaccharides what is formed
disaccharide
name one disaccharide
sucrose
maltose
lactose
what is the general formula for monosaccharides
CnH2nOn
name 3 monosaccharides
glucose
galactose
fructose
name 2 reducing sugars
maltose
lactose
name the 2 isomers of glucose
beta glucose
alpha glucose
state the formula for hexose
C6H12O6
what type of sugars are all made out of alpha glucose
all disaccharides are made out of alpha glucose
give 2 properties of glucose, galactose, fructose
soluble
sweet tasting
describe how disaccharides are formed
disaccharides are 2 monosaccharides joined together by a condensation reaction (forming a new glyosidic bond and a water molecule is released)
when the react 2 alpha glucose molecules what is formed as the products
alpha glucose + alpha glucose = maltose + water
name the reactants to form sucrose + water
glucose + fructose
name the reactants to form lactose + water
galactose + glucose
name the reactants to form maltose + water
glucose + glucose
give the method to test for non reducing sugars
- heat if the sample stays blue then no reducing sugars are present
- add sample and HCl (hydrolyses the glyosidic bond producing a reducing sugar) and boil for 5 mins
- add NaHO3 to neutralise the sample
- add Benedicts reagent and heat
- no non reducing sugars in sample will stay blue as this is a negative result
- the colour change will be green, orange, red and then a non reducing sugar is present
How are polysaccharides created
Polysaccharides are created by condensation reactions between many glucose monomers
What are the monomers of starch
Alpha glucose
In starch what are the bonds between monomers
1-6 and 1-4 glycosidic bonds in amlopectin
Where is starch located
In starch grains in plant cells
What is the function of starch
Insoluble store of glucose
What is the structure of starch
2 polymers
Amylose- unbranched helix
Amylopectin- a branched molecule
Explain how the structure of starch leads to its function
Helix can compact to fit a lot of glucose into a small space
Branched surface increases the surface area for rapid hydrolysis back to glucose
What are the monomers of cellulose
Beta glucose
What are the bonds between the monomers in cellulose
1-4 glycosidic bonds
What is the function of cellulose
Structural strength to cell wall
Where is cellulose located
Cell wall of plant cells
Describe the structure of cellulose
Long straight chains of 1-4 glycosidic bond are held together in parallel by many hydrogen bonds (fibrils)
Explain how the structure of cellulose leads to its function
Many hydrogen bond provide collective strength
What are the monomers of glycogen
Alpha glucose
What are the bonds between monomers in glycogen
1-4 and 1-6 glycosidic bonds
What is the function of glycogen
Insoluble store of glucose
Where is glycogen located
Muscle and liver cells in animals
What is the structure of glycogen
A highly branched molecule (has more 1-6 glycosidic bonds)
Explain how the structure of glycogen leads to its function
Branched structure increases the surface area for rapid hydrolysis (faster hydrolysis back to glucose)
And then glucose provides the respiratory substrate for energy release
Insoluble so does not affect water potential
Helix is compact
Describe 2 differences between the structure of cellulose molecule and a glycogen molecule
Glycogen is a highly branched molecule but cellulose is in long straight chains
Cellulose is made out beta glucose and glycogen is made out of alpha glucose
Glycogen has 1-4 glycosidic bonds and 1-6 glycosidic bonds but cellulose only has 1-4 glycosidic bonds
Describe and explain 2 features of starch that makes it a good storage molecule
- helix can compact to fit a lot of glucose into a small space
- branched surface increases the surface area for rapid hydrolysis of starch into glucose
list the 2 types of lipids
Phospholipids
Triglyceride
List the 5 roles of lipids
- phospholipids form cell membranes
(Flexible and transfer soluble substances) - energy source
(When oxidised release 2x the energy of carbohydrates) - protection
(around organs) - waxy cuticle/oils from sebaceous glands in the skin
(Waterproofing) - insulation
(warmth, myelin sheath around neurona allows electrical impulses to be transmitted quickly)
list 3 characteristics of lipids
- C H O but less than in carbohydrates
- insoluble in water so doesn’t affect water potential
- soluble in organic solvents (alcohol)
