Upon maturation the parent cell passes its genetic information to the bud which then becomes a genetic copy of the original cell and adds to the population. A growth curve demonstrates the four stages of population growth for a yeast cell as follows: Diagram 1 . Reference: Lag phase: Indicates the process of assimilation of nutrients by the initial population. Growth is restricted as the yeast are adjusting to their environment and synthesizing cellular macromolecules.
Exponential phase: Growth is increasing rapidly at this stage and competition for resources is minimal allowing for the yeast to bud at maximum capacity. Stationary phase: The population is now stabilizing as resources become depleted and competition increases; yeast cells are dying at a similar rate of budding due to the accumulation of zygotic wastes and metabolic byproducts, such as ethanol, are produced. Death phase: Due to the exhaustion of resources and increasing levels of toxic waste the population of yeast starts to decrease. Budding cannot occur at this mint as there is limited space for growth reducing the population over time.
Use appropriate biological knowledge and understanding When considering the growth of yeast cells it is important to understand other factors involved in enzyme activity when metabolism sugars that can directly affect the ability if yeast to reproduce via budding . An enzyme substrate process within the cells affects the metabolism of yeast by which enzymes and substrates move freely about in the cell and in doing so collide with each other. The concentration of both enzymes and substrates will detect the rate in which reactions take place within a east cell.
The collision theory indicates they have specific binding sites for substrates during collision and in doing so substrate material is taken in by the cell. It is then released by the active site after this transfer of material. Kinetic theory is also influential in yeast growth as more energy causes an increase in enzyme movement within the cell and will affect the rate of collision with substrates and therefore increase yeast growth and reproductive activity. Enzymes are proteins with a tertiary structure of globular shapes of a folded polypeptide chain held together by hydrogen bonds, ionic bonds and sulfuric bonds.
Enzymes have an optimal temperature for activity and when this is surpassed administration of that enzyme can occur causing the active site to be destroyed and the enzyme to become inactive. Acidity and alkalinity can also a factor in the population growth of yeast as there is an optimum pH for enzyme activity. A concentration of hydrogen ions significantly above or below the optimum will lead to a complete loss in enzyme activity and administration. Select ideas from the information relevant to the investigation All organisms have optimum temperatures for growth as defined by their specific physiology.
Some grow optimally at low temperatures (acropolises) and some at high temperatures (thermopiles). Baker’s yeast is a mesospheric microorganism and grows optimally at ICC because the majority of its metabolic processes have evolved to function at these temperatures. The same can be said for Baker’s yeast in relation to the optimum pH on its metabolic processes. As discussed a pH level that is significantly higher or lower will also affect the strength of non-covalent bonds which are required or tertiary and quaternary structure of proteins.
Link your ideas together to suggest an explanation At sub-optimal temperatures, the slower movement of molecules in the culture medium and cytology leads to a slower metabolic rate and therefore growth of the yeast population. At supra-optimal temperatures, the increased kinetic energy is detrimental as the cellular macromolecules begin to become denatured and bonds between the active site of enzymes and their substrates are coincidentally weakened. To counteract the denaturing effects of supra-optimal temperatures, many yeast pieces synthesis heat-shock proteins.
This takes away from resources for growth, also causing a reduction in growth rate. State precisely in a hypothesis the most appropriate explanation As stated previously, any supra-optimal temperature will be detrimental to metabolic processes and therefore cell growth and division. The hypothesis is that at temperatures within the optimal growth range of Baker’s yeast, 30 to 40 co, and population growth will be at a maximum; whereas any temperature exceeding this will result in a decreased growth rate. AAA- Plan a procedure Using suitable equipment and Hammertoe’s
Cover slip Microscope Pipettes materials Solution of 1% glucose and 1% yeast solution Water baths (30 and 60 co) Test tubes Select a suitable range for the independent variable or suggest conditions for the experimental treatment For this experiment I will be using a range of 30 CO to 60 co at 10 degree intervals to provide 5 temperatures to sample from Communicate an ordered sequence to follow procedure 1. 1% glucose and 1% yeast solutions placed in separate test tubes and incubated in 30 co and 60 co water baths for 24 hours 2. Grid cells will be located on a hammertoe’s using a microscope 3.
A dropper will be used to agitate the solutions before taking a sample from the centre of the solution 4. I will use the pipettes with solution to place a drop on the cell grid of the hammertoe’s to allow the cover slip to draw the solution in via capillary action. 5. Using the top left rule of counting I will select ICC squares at random to count the number of yeast cells in each 6. The hammertoe’s will then be cleaned and the method repeated for the alternative temperature Which provides a fair test? The only varied factors in this experiment are the temperature of the water baths for the investigation.
The controlled variables are as follows: Concentration of glucose Population incubated for 24 hours The pH remains the same by using a buffer The same species of yeast (bakers yeast) is used Top left rule of C cell counting Predict a result of the test of the hypothesis It is my hypothesis that the yeast population will be greater at 30 co and lesser 60 co and null hypothesis that there is no significant difference in the yeast population at ICC and 60 co AAA- Planning tort analysis Clearly state what must be recorded The number of yeast cells counted in 5 randomly selected B squares each containing randomly selected C squares at 30 co and 60 co per 0. 00025mm3 and an average taken for both that will be multiplied by 4000 to give the number of yeast cells per mm What format will be used to present the results?
This will allow the standard deviation of results to work out the confidence limits and determine if there is a significant difference between the two temperatures being used and give a statistical analysis of our results. Table 2. Class table showing results for the average number of yeast cells per mm in 1% yeast and 1% glucose solution, after being incubated for 24 hours in water baths of ICC Name Average number of yeast cells present at ICC Average number of yeast cells present at ICC Mean number of yeast cells per mm Decide now much replication is required tort stressful analysis I nave determined that the optimal amount of replication of the results to prove or disprove the null hypothesis is 30 times for successful analysis.
Consider the feasibility of replication given the time and materials available Unfortunately due to time and equipment limitations in conducting the experiment only temperatures of 30 co and 60 co were used to derive results 82- Recording and communicating Organization of the raw data with the dependent variable in the body of the table and treatments or range of the independent variable as columns or rows Table 3. Table of personal results showing the number of yeast cells in 1% yeast and 1% glucose solution; per B and C square after being incubated for 24 hours at temperatures of 30 and 60 degrees B squares 15 19 28 27 8 20. 4 3. 92 104 1. 57X104 Table 4.