Chapter 1: BIOLOGICAL MOLECULES: activation energy and catalysts ,reaction rates,investigating enzyme activity , water and ions , transcription and translation process in DNA Flashcards
As enzymes can not cause a reaction but speed it up reactions already happening
How do they speed up reactions already happening?
This is done by lowering activation energy
How is activation energy lowered by enzymes ?
Give 2 points
1 bringing substrates closer to active site so bonds are easier to form
2 by putting strain on bonds in the substrate to break them
Breaking bonds
For a chemical reaction to take place bonds must be …………….., which requires ………….
Reactions can be speeded up by ………….. or ……….
………….
Heating is an example of ………….. energy
Which can speed up a reaction
However this cannot be done in all living things as it can cause damage
How do can this problem be solved ?
Broken, energy
Adding , lowering energy
Adding
Answer:
This problem is solved by lowering the amount of envy needed so a reaction can take place
Explain detail why organisms require enzymes
Because biochemical reactions are too slow at the temp in which living things survive
So enzymes provide a lower energy pathway so substrates can be tuned into products
Which is done by binding the substrate and providing a environment which makes a reaction more likely to take place
Rate of enzyme catalysed reactions slows down as substrate is used up so to get true measure or reaction rate what should be measured first ?
Initial rate should be measured first
Investigating rates : in 1 possible experiment protease can be used explain in 5 steps as to how the initial rate can be calculated
1) Protease ( what happens ?)
2) As cloudiness …………. measured with , taking a reading of the ………….. every few seconds
3) Results are plotted on as…………on …. against time ….
4) What is calculated?
5) Then as a result what can be calculated from this?
Answer :
1)Protease is used to bread down a cloudy protein solution
2) Decrease in cloudiness is measured with coloromiter taking an absorbance reading every few seconds
3) Results can be plotted as absorbance (y) against time (x)
4) The gradient of the straight line graph is calculated
5) From this the initial rate is calculated
The effect of enzyme concentration
Measure the ……. …… for each ……. ………… plotting these ………gives a graph showing the ……… of ……….. …………….. on ……
…….. ……….
measure the initial rate for each enzyme concentration. Plotting these results gives a graph showing the effect on enzyme concentration on initial reaction rate
Reaction rate
What are three incorrect things to remember about time and rate ?
1 ) A Time taken is not a rate!
2) 1/time gives an indication of rate but it is time
3 ) Experiment learnt in this book does not give true rates as the units are Arbitrary AU
To convert to treat this must be broken down per second for example converting to mg
How to calculate rate maths skills in reaction rates for enzymes?
Rate is change in absorbance over time for example change over 60 seconds is 1.0 AU. So rate is one unit min-1 at 1% enzyme concentration
Investigating enzyme activity:
Variables
What does DV stand for and what is it?
What does IV stand for what is it
what does CV stand for and what is it?
Dependent variable is the thing to be measured this case it would be the initial rate of reaction
Independent variable is the factor that you have selected from a table
Control variables will be all the factors from the table that are not the independent variable
What to do if the factor is a controlled variable for pH, temperature, enzyme concentration, substrate concentration
Explain each point
PH: use a buffer solution in the correct range for the enzyme use and as near to the optimum as possible
Temperature: use a thermostatically controlled water bath set in the correct range for the enzyme used and as near to the optimum as possible
Enzyme concentration: should be in excess if substrate concentration is the IV
Substrate concentration: should be in excess if enzyme concentration is the IV
What are the skilled needed for enzyme activity experiment ? List 4 points
Use Appropriate apparatus to record mass time volume temperature and pH
Use a colorimeter
Use a laboratory glassware
Use a data logger to collect data and software to process data
Water and ions
Water is perfect medium for transporting nearly everything a living thing needs.
What 3 things are water ?
Water is a polar molecule explain?
Water is liquid at room temp?
Water easily dissolved charged molecules explain?
Water is polar, liquid at room temp and easily dissolves
Polar molecules have uneven charge distribution. One end is slight positive and the other end is slightly negative
Water is liquid at room temp - the 3 water molecules are joined to each other by H bonds
Water easily dissolves- sodium and chloride ions in common salt (NaCl) are pulled apart by water molecules and then surrounded by them
What are the 4 properties of water ?
Explain the properties as well
High specific heat capacity -
Due to H bonds keeps the temp in bodies of water fairly constant from season to season
High surface tension - due to H bonds means ther is a “skin” over the water, helps organisms to move across its surface
Incompressible - as it’s liquid
Maximum density at 4. ▪️C - means ice will float and insulate liquid water below allowing living things to survive
Dissolution gives ions
When substances dissolve in water 💦 they are pulled apart forming ions
List what ions plants need 4 of these and what for
Nitrate ions (No 3-) makes amino acids and nucleotides in DNA and RNA
Calcium ions (Ca 2 +) to form calcium pectate in the middle Pamela, glue between plants 🌱
Magnesium ions ( Mg 2 +) to produce chlorophyll molecules
Phosphate ions (PO 4. 3 +) to make DNA 🧬, RNA, ADP and ATP
