Enzymes Flashcards
What is metabolism?
It’s the sum of all the chemical reactions that take place within an organism
What reactions are involved in metabolism?
Growth, movement, repair, response to stimuli and reproduction
What do all changes/reactions require?
Energy to be released or absorbed
Why is metabolism necessary?
To control the chemical and energy requirements of a cell, by doing this it maintains a balanced internal state [homeostasis] within an organism
What is the most important controllers of cellular reactions?
Enzymes
Solar energy
The primary source of energy is sunlight. Some of the energy in sunlight is trapped by organisms that contain pigments which can absorb light [chlorophyll]. Green plants use solar energy to form chemical bonds of carbohydrates and other biomolecules = form of energy conversion is known as photosynthesis
Cellular energy
If refers to sources of energy that are capable of being released by reactions within a cell [energy stored in bonds of biomolecules]
Each organism breaks down energy-rich biomolecules in the process of respiration. This releases energy, some of which is used by cells and the rest is released into the environment as heat
What is a catalyst?
It is a substance that speeds up chemical reactions without being used up in the reaction
What are enzymes?
Proteins that speed up a reaction without being used up in the reaction
What does the shape of an enzyme mean?
The 3D shape of an enzyme [globular folding] means it will fit neatly and react only with a substance of a shape that matches the enzyme
What happens if the shape of an enzyme is changed?
It will reduce the efficiency of the enzyme to speed up a reaction
What will change the shape of enzymes?
Changing the PH or temperature of a reaction will change the shape of enzymes
What would occur at normal cell temperature in the absence of enzymes?
Reactions would occur too slowly for the cell to stay alive
What is the substrate?
It’s the substance with which an enzyme acts on [reacts]
What is the product?
It’s the substance the enzyme forms
Features of enzymes
Made of protein
Enzymes have a complex, three dimensional shape in order to fit with a substrate
Enzyme reactions are reversible = can cause a reaction to proceed in either direction. Any enzyme can be anabolic or catabolic
Enzymes are named by adding the ending ase to the name of their substrate
What is the role of enzymes?
Control metabolic reactions
Give an example of a catabolic enzyme?
Amylase - it converts starch into maltose. It breaks down a substance into simpler parts
Give an example of amylase in plants and animals
Animals - produced by salivary glands in mouth and pancreas. Converts starch to maltose
Plants - seeds contain starch and when seeds germinate the enzyme amylase converts the starch to maltose
Give an example of an anabolic enzyme
DNA polymerase which forms and repairs DNA. It converts simpler molecules into more complex from.
Enzymes that control photosynthesis = convert water and c02 into glucose
What affects enzyme activity
Temperature
PH
Enzyme concentration
Substrate concentration
How does temperature affect enzyme activity?
At low temps, ice forms and the cell contents become solid + enzymes cannot work
As temperature increase, the molecular movement increases so the substrate molecules and enzymes bump into eachother more often and therefore the rate of reaction increase
Above a certain temperature, enzymes begin to lose 3D shape so the rate of reaction falls
When will an enzyme denature?
When the shape of enzyme is fully lost
What is a denatured enzyme?
A denatured enzyme has lost its shape and can long carry out its function
How does PH affect enzyme activity?
Narrow PH range - 6-8
Optimum PH - 7
If it’s outside this range it’s active site is altered and therefore becomes denature and loses its shape [activity begins to fall]
What is bioprocessing?
It’s the use of enzyme controlled reactions to produce a product
What is a bioreactor?
It’s a vessel or container in which living cells or their products are used to make a product
What does bioprocessing produce?
antibiotics, vaccines, drugs, vitamins, amino acids
Since mid 1950’s how has bioprocessing been carried out?
Cells [micro-organisms] replaced by purified enzymes
How are enzymes wasted in a bioreactor?
Use of enzymes freely dissolved in a bioreactor to carry out a biological reaction is wasteful because the enzymes are removed from the bioreactor at the end of the process and it is not normally possible to isolate the enzymes for reuse
How is the problem of enzymes being wasted resolved?
Enzymes are immobilised or fixed = insoluble and easier to reuse
What are immobilised enzymes?
Enzymes that are attached or fixed to each other or to a inert material [or enclosed in gel]
Methods of immobilising enzymes
Adsorption - physically attached to inactive supports [glass beads, ceramics]
Trapping enzyme gel - sodium alginate which is prepared form algae and is permeable to entry of substrate and exit of products. The enzyme is prevented from leaving cell.
What are the advantages of immobilised enzymes?
Can be reused - cost of replacing enzymes are high
Can be recovered - after process is done in bioreactor, it allows the product to be purified easily
Increases stability - reduces amount of enzymes needed
Production process is cheaper
Uses of immobilised enzymes
Soft drinks are sweetness with fructose. Immobilised enzyme = glucose isomerase converts glucose to fructose
Lactase [immobilised in porous beads] converts lactose into sweeter tasting sugars [glucose and galactose] used to replace condensed milk into soft toffee and caramel
Identify a non-metallic element in proteins
Sulfur
What is the approximate percentage of water by mass in a human cell?
70-95%
Name two processes that occur in plant or animal cells that require the use of enzymes
Photosynthesis and digestion
Some biological washing powders contain enzymes similar to the ones found in our digestive system; why are such enzymes found in washing powders?
Break down food stains
What is the enzymes chemical nature?
Protein
What is the molecular shape of enzymes?
Folded
Why is it necessary to keep PH constant in the experiment of the rate of temperature
Need only one variable - temp
Why are enzymes essential for metabolism?
Control the rate of metabolic reactions
Is the conversion of ADP to ATP anabolic of catabolic
Anabolic
Is the conversion of ATP to ADP anabolic of catabolic
Catabolic
Give two features of a denature enzyme?
Changed structure, lost function
What terms describes the shape of an enzyme?
Folded
What is optimum activity?
Working at its most efficient, maximum rate
Diagram for temperature and Ph enzymes!!
Check book!! Pg 95
Name the compound from which immobilising beads are formed in the lab?
Alginate
How did you vary the temperature in the course of the investigation of denaturing of enzyme?
Using waterbath
What is meant by the specificity of an enzyme?
Enzyme acts on only a particular substrate
Describe how you carried out imobilisation id enzyme
- add sodium alginate and water in beaker and mix with glass rod
- add yeast to water [yeast = sucrase, enzyme to be immobilised] and stir
- dissolve calcium chloride in water
- mix alginate and yeast solutions in beaker and using syringe, draw some of the mixture
- slowly add stream of alginate and yeast drops to calcium chloride solution
- a gel of calcium alginate forms, immobilising yeast cells
- allow harden
Briefly outline how you investigated the activity of the immobilised enzyme
- control = free yeast added to water and poured into sep funnel
- pour beads of immobilised yeast into 2nd sep funnel
- dissolve sucrose in water and add to each sep funnel
- test products using glucose test strips [diastrix] and continue testing every min until glucose is formed
- formed quicker - free yeast in sep funnel, takes longer for sucrose penetrate alginate beads and for glucose to emerge from beads. However once start producing glucose, imm enzymes can be reused easily
What was the result of the investigation to determine the effect of temperature on enzyme action
More foam - more activity
Less foam - less activity
States - activity varies with temperature
What term best describes the shape of an enzyme?
Folded
What is the purpose of sodium alginate?
Trap enzymes
What is the purpose of calcium chloride?
Form beads
In investigation of effects of ph and temperature, what was used to vary/keep constant : ph
PH buffer solution
In investigation of effects of ph and temperature, what was the substrate?
Hydrogen peroxide
In investigation of effects of ph and temperature, what was the enzyme?
Catalase
In investigation of effects of ph and temperature, what was the source of the enzyme
Celery
In investigation of effects of ph and temperature, what were the products?
Water and oxygen
In investigation of effects of ph and temperature, what was the purpose of adding washing up liquid?
Trap oxygen that is released to form forth
Describe how to investigate the effect of PH on the rate of catalase activity
- Place PH buffer solution im graduated cylinder
- add drops of washing up liquid to the graduated cylinder
- blend stalks of celery and add water
- filter solution and add to graduated cylinder
- use syringe, add hydrogen peroxide to a test tube
- stand graduated cylinder and test tube in water bath for few mins
- pour hydrogen peroxide into graduated cylinder
- note and record volume in graduated cylinder
- repeat using different PH buffer’s
Describe how to investigate the effect of PH on the rate of catalase activity
- Place PH buffer solution im graduated cylinder
- add drops of washing up liquid to the graduated cylinder
- blend stalks of celery and add water
- filter solution and add to graduated cylinder
- use syringe, add hydrogen peroxide to a test tube
- stand graduated cylinder and test tube in water bath for few mins
- pour hydrogen peroxide into graduated cylinder
- note and record volume in graduated cylinder
- repeat using different PH buffer’s
What would be the control of the experiment : Describe how to investigate the effect of PH on the rate of catalase activity
Do not add celery - no catalase is present therefore no froth is formed
