The oxygen atom has a slight negative charge while the hydrogen atoms are slightly positively charged, so it has negative and positive poles
What is a hydrogen bonding in water?
The positive pole of one water molecule is attracted to the negative pole of another. They are relatively weak bonds but in water, there are huge numbers creating a significant force responsible for many of water’s unusual properties
High specific heat capacity
Acts as a buffer against sudden temperature changes
High specific Latent heat of vaporisation
results in sweating being effective at cooling the body
strong cohesion and surface tension in water
Allows water to be pulled up xylem tissues in continuous columns in plants
Solvent
It’s a polar molecule so polar Substances dissolve in water easily so metabolic reactions can take place faster in solution. Substances can be transported easily around organism
Metabolite
Used in many metabolic reactions like hydrolysis and formed in condensation reactions. Also used in photosynthesis
What is a polymer?
A polymer is a large molecule made up of repeating subunits called monomers.
What reaction joins monomers together?
Condensation reactions
Polymers are broken into monomers through which reaction?
Hydrolysis
What are the 3 monosaccharides?
Glucose, fructose, galactose
Chemical formula of monosaccharides?
C6H12O6
What makes maltose?
Maltose is made from two glucose molecules.
Sucrose?
Glucose + fructose
lactose?
Glucose + galactose
What are the 2 isomers of glucose?
Alpha glucose and beta glucose.
What is the difference between alpha and beta glucose?
The main difference between alpha and beta glucose is the position of the hydroxyl group on the first carbon atom. In alpha glucose, the hydroxyl group is below the ring, while in beta glucose, it is above the ring.
Two monosaccharides joined together is called what?
Disaccharide
What is the bond Called between monosaccharides?
Glycosidic bond
What are the 3 polysaccharides?
Starch, glycogen, cellulose
What are they used for?
Starch and glycogen- energy storage
Makes plant cell walls (structural)
Polysaccharides are monomers of either alpha glucose or beta glucose. Cellulose is made from beta glucose whereas starch and glycogen are made from alpha glucose
Starch and cellulose are found in plant cells, glycogen in animal cells
What two polymers is starch made from?
Amylose and Amylopectin
What does amylose form.?
A compact helical chain to store large numbers of glucose molecules in a small space
Amylopectin?
Branched so allows amylopectin to be quickly hydrolysed by amylase enzymes to form maltose then glucose for respiration
Describe structure of glycogen
More branches than amylopectin so an energy storage molecule in animals found in liver and muscle cells.
Why are starch and glycogen both suited to their function?
Coiled so compact and so store lots of glucose in a small space
large and insoluble so can’t diffuse out cells
insoluble so no osmotic effect
Glycogen and amylopectin both quickly hydrolysed to provide glucose for respiration. Branching creates more ends available to enzymes
inert so not involved in cell’s chemical reactions
How do two beta glucose molecules link together?
the molecule on the left has to flip over
Why is cellulose suited to its function?
Major component of plant cell wall
made of straight unbranched chains
chains run parallel to each other and h bonds form cross linkages between chains
Many h bonds collectively are strong and so provide high tensile strength making cell wall rigid and prevents osmotic lysis
cellulose molecules are grouped to form microfibrils
What is the test for starch?
The test for starch is the iodine test, which turns the starch solution blue-black in colour from brown/orange
What’s the test for reducing sugars?
Benedict's test.
add benedicts
heat
sample goes from blue to brick red
Test for non reducing sugars?
Sucrose is a non-reducing sugar
Boil sample with dilute acid like HCL
neutralise with alkali
Reheat with Benedict’s solution so it will now turn brick red due to sucrose being hydrolysed into its monosaccharides glucose and fructose
What are some issue with the Benedict's test?
Non specific- a positive result only tells us a reducing sugar is present but not which one
It’s qualitative- colour change is used to determine the result so no value is obtained for the concentration of reducing sugar. The test can be described be as semi-quantitative because the colour change depends on the amount of reducing sugar present. Allows an estimate for how much reducing sugar is present. e.g red = high
Subjective
How can a biosensor be useful?
it can test for specific sugars e.g a glucose biosensor will only detect glucose and no other sugar.
What can a colorimeter do?
It can quantify results. A serial dilution of a glucose solution can be carried out producing a set of known concentrations. Carry out Benedict’s and measure colour intensity using the colorimeter. A calibration curve is then produced. Absorbance on x axis, concentration on y axis
Role of hydrogen ions
Affect pH levels
Role of iron ions
Component of haemoglobin in red blood cells
Role of phosphate ions
Component of DNA, ATP and phospholipids and to make molecules more reactive
Role of sodium ions
Co transport with glucose and amino acids in small intestine