Biological molecules + movement of substances Flashcards
2.7-2.13 2.15-2.17
What are the chemical elements present in Carbohydrates
CHO - Carbon, hydrogen, oxygen
Lipids
CHO - Carbon, hydrogen, oxygen
Protein
CHON - Carbon, hydrogen, oxygen, nitrogen
Structure of carbohydrates
Basic unit of carbs is simple sugars (glucose)
How do you test for the presence of glucose
- Add Benedict’s solution to the sample solution in a test tube
- Heat in a boiling water bath for 5 minutes
- Take the test tube out of the water bath and observe the colour
- pos = brick red
What is the positive result for glucose
Brick red
How do you test for protein
- Add drops of Biuret solution to the food sample
What is the positive result for protein
Violet
How do you test for lipids?
- Mix the food sample with 4cm3 of ethanol and shake
- Allow time for the sample to dissolve in the ethanol
- Strain the ethanol solution into another test tube
- Add the ethanol solution to an equal volume of cold distilled water (4cm3)
What is the positive result for lipids?
Cloudy
What are enzymes
Enzymes are proteins and biological catalysts that speed up a chemical reaction.
- They do not get used up.
- They are made of amino acids
Explain how an enzyme works
- Enzymes and substrates randomly move
- A specific enzyme and substrate collide, substrate binds into enzymes active site
- The enzyme splits substrate and is released from the active site
How does temperature affect enzyme function
- Enzymes work fastest at their optimum temp
- High temps will make the enzymes lose its shape and denature it
- Low temps cause enzymes to work slower
- how to test temp and enzyme activity
How does pH affect enzymes
- low and high pH level denatures enzyme
- if pH changes beyond enzymes optimum level (7) it denatures the enzyme
Structure of proteins
- long chains of amino acid
Structure of lipids
- fatty acids + glycerol
What is diffusion
Diffusion is the net movement from high conc to low conc
- does not require energy (passive transport)
- molecules move randomly
What is the difference in concentration called
conc gradient
What is osmosis
Osmosis is the net movement of water from high water potential to low water potential through a partially permeable membrane
What is active transport
Active transport is the movement of molecules against the conc gradient by using energy
What are the 4 factors affecting the rate of movement of substances into and out of cells
temperature
- high temp = more kinetic energy, faster rate
surface area to volume ratio
- larger sa to vol ratio = increased rate of diffusion
distance
- shorter the distance, faster the rate of diffusion
concentration gradient
- Higher gradient = faster movement
- higher conc = more collisions against membrane
Diffusion practical
- Make up a dilution series of sugar solutions in the range of 0.2M – 1.0M
- Cut six potato cylinders of approximately 4cm in length
- Blot dry and find the mass of each to the nearest 0.1g
- Place the cylinders in each concentration of sugar and leave for 40 minutes
- Calculate the percentage change in mass.
- Record all data in a suitable table
- Plot a graph of the percentage change in mass against the concentration of the sugar solution
Osmosis practical
- Prepare a range of sucrose (sugar) solutions ranging from 0 Mol/dm3 (distilled water) to 1 mol/dm3
- Set up 6 labelled test tubes with 10cm3 of each of the sucrose solutions
- Using the knife, cork borer and ruler, cut 6 equally-sized cylinders of potato
- Blot each one with a paper towel and weigh on the balance
- Put 1 piece into each concentration of sucrose solution
- After 4 hours, remove them, blot with paper towels and reweigh them
