Chapter 3 - Biological Molecules Flashcards
Explain why phenolphthalein indicator was able to detect the breakdown of triglycerides
Triglycerides is broken down into fatty acids.
The pH will fall as more break down occurs, and if pH drops below 8.3 there is a colour change; pink to colourless
M - C55H98O6
N - C18H30O16
which of the formula, M or N, corresponds to triglyceride
Explain your answer
M because there is a high ratio of hydrogen to oxygen
Explain how the structure of phospholipids allows them to form the bilayer of a plasma membrane.
Phospholipids have hydrophilic heads and hydrophobic tails.
The hydrophobic tails are repelled by water
The hydrophilic heads form H bonds with the water
State 2 ways in which the molecular structure of cholesterol in similar to the molecular structure of glucose.
They both contain carbon and hydrogen atoms
They also contain oxygen atoms
State the physical property of glucose that allows it to be easily transported in the bloodstream
Glucose is soluble in water
Mammals convert the monosaccharide glucose into a highly branched polysaccharide called glycogen, which gets stored in liver cells.
Explain why mammals store glycogen instead of glucose.
- Glycogen is metabolically inactive
- Glycogen is compact so lots can be stored in a small space
- Glycogen can be broken down quickly to release glucose
DNA sequences in genes code for polypeptide molecules such as pepsin and titin
Explain why a process known as transcription is necessary for polypeptide synthesis
The DNA is transcribed to mRNA.
Then the RNA is translated at the ribosome.
The DNA is too large to not be able to leave the nucleus as it cannot fit through the nuclear pores.
Titin is a fibrous protein. Explain the properties and functions of fibrous proteins in the human body.
Fibrous proteins are insoluble, strong and elongated strands.
Fibrous proteins are used for protection e.g. keratin in skin/hair/nails
It is used for contraction e.g. actin in muscle
It is also used to give elasticity e.g. elastin in the alveoli
Pepsin is a globular protein
Explain the properties and functions of globular protein in the human body.
Globular protein are soluble, spherical in shape, tertiary structure and hydrophilic on outside
Globular proteins are used to transport substances in blood e.g. haemoglobin there are iron II present in the haem groups which are able to combine reversible with an oxygen molecule. This enables hemoglobin to transport O2 around the body.
It can be used to catalyse reactions and lower activation energy.
E.g. catalase, the prescence of iron II allow catalase to interact with hydrogen peroxide and speed up its breakdown.
Describe the role of cholesterol in cell surface membranes in the human body?
Cholesterol binds to phospholipid fatty acid tails, increasing the packing of the membrane, therefore reducing the fluidity of the membrane.
The students were provided with 3 different fruit juices labelled A,B an C.
The Benedict’s test was carried out on each fruit juice and samples were prepared for the colorimeter.
Explain how the students would use the calibration curve to estimate the glucose concentration of the fruit juices.
Follow the absorbante value (y axis) across to the calibration curve and then down to the x axis to find the concentration corresponds to this absorbance
Identify the ion that plays the role :
Production of nitrate ions by bacteria
NH4+
Identify the ion that plays this role:
Loading of phloem
H+
Identify the ion that plays this role:
DNA structure
PO4 3-
Identify the ion that plays this role:
Cofactor for amylase
Cl-
Outline the properties of water which make it an ideal habitat for an amphibian
Water is a good solvent has a high specific capacity
Ice is less dense than water
Living organisms have many uses for triglycerides, one of which is the production of phospholipids.
Name 3 other functions of triglycerides in living organisms
- Thermal insulation
- Electrical insulation
- Energy Storage
Phospholipid molecules also contain fatty acids
Explain how the fatty acids in phospholipids allow the formation of membranes
Fatty acids are hydrophobic so they repel from water causing them to point inwards and the hydrophilic heads to point outwards, forming a phospholipid bilayer.
What is the formation of cellulose
Condensation polymerisation of beta glucose molecules
Why is the ability of water to act as a solvent important for the survival of organisms?
It is a medium for metabolic reactions
Organisms can absorb minerals or ions
Able to dilute toxic substances
Sulfur atoms are required for the synthesis of which type of biological molecule?
Protein
A student mixed an unknown substance with water and ethanol.
A white suspension formed in the tube
What is occurring?
Lipid is present
What is amylopectin made up of
It contains 1-4 and 1-6 glycosidic bonds between a - glucose monomers
Name the carbohydrate molecules used to store energy in plants and animals
Plants - starch
Animals - glycogen
Glycogen storage disease type IV occurs when the liver is unable to catalyse the addition of branches of glucose molecules. People with this disease may develop liver damage over time.
Suggest why this disease may result in liver damage.
Glucose deposit is is in long chains and so not compact which damages liver cells
State 2 properties of water in blood plasma and explain their significance
High specific heat capacity : maintenance of stable temperature
Solvent : transport polar chemicals
How could you confirm the presence of protein in a sample of blood plasma
Carry out a biuret test and if protein present a purple colour will be seen
What type of biological molecule is glycogen
Polysaccharide - carbohydrate
Describe how the structure of glycogen allows it to perform its function and explain the advantage to animals of using glycogen as an energy storage
Gkycogen contains alpha glucose which is used in respiration and glycogen can be broken down by enzymes
Glycogen is a polysaccharide which is insoluble and does not affect water potential.
They also have 1-6 glycosidic bond which are branched and breakdown really quickly so glucose can be made
Animals have a higher metabolic rate and the animals lifestyle required atp
