A2 biology
A2 Biology Coursework
A1- Develop a hypothesis
Outline your biological knowledge or research related to the problem under investigation
Yeast are eukaryotic species and make up approximately one percent of species in the kingdom Fungi. One of the most well studied yeast species, Saccharomyces cerevisiae, commonly known as bakers yeast, and also used in the fermentation of alcohols, is a model species for the study of eukaryotic cells. They are known to reproduce either sexually, by mitosis, or asexually, by budding, depending on environmental conditions. Yeast grow and reproduce by producing enzymes to catabolise polysaccharides. 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: http://classconnection.s3.amazonaws.com/33/flashcards/602033/jpg/bacterial_growth_curve1320203184633.jpg
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 synthesising 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 stabilising as resources become depleted and competition increases; yeast cells are dying at a similar rate of budding due to the accumulation of cytotoxic 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 point 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
A1- Develop a hypothesis
Outline your biological knowledge or research related to the problem under investigation
Yeast are eukaryotic species and make up approximately one percent of species in the kingdom Fungi. One of the most well studied yeast species, Saccharomyces cerevisiae, commonly known as bakers yeast, and also used in the fermentation of alcohols, is a model species for the study of eukaryotic cells. They are known to reproduce either sexually, by mitosis, or asexually, by budding, depending on environmental conditions. Yeast grow and reproduce by producing enzymes to catabolise polysaccharides. 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: http://classconnection.s3.amazonaws.com/33/flashcards/602033/jpg/bacterial_growth_curve1320203184633.jpg
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 synthesising 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 stabilising as resources become depleted and competition increases; yeast cells are dying at a similar rate of budding due to the accumulation of cytotoxic 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 point 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