How does yeast reproduce?
How can you tell if yeast is reproducing in each of the two ways?
Part 2 Signaling responsible for yeast mating How does an a cell know there is an α cell near to it available for mating? The α cells release a 13 amino acid peptide called α factor. This peptide binds to a receptor, α factor receptor, on the cell surface of the a cells. Binding of the α factor to the receptor results in stopping mitosis (budding) and starting schmooing. factor signaling pathway 1. Binding of α factor to the α-factor receptor on a cells activates a G-protein complex 2. G protein complex activates a kinase complex. 3. Activated kinase complex phosphorylates two proteins: (a)cell arrest factor and (b)transcription factor. 5. (a)Phosphorylated cell arrest factor stops cell division (stops budding) (b)Phosphorylated transcription factor increases transcription (starts schmooing)
2 Show/describe what will happen to a type of yeast in the presence and absence of alpha-factor?
Part 3 Signaling pathways and the effects of disrupting the pathway. Below is an example signaling pathway and a demonstration of the effects of activating the signaling pathway. Mutations occuring in an enzyme in the signaling pathway can disrupt the effects of activating that pathway. What do you predict are the effects of the two mutations below on the activation of enzymes 4 5 and 6? Experiment: This “lab” will examine how disruption (mutation) of parts of a signaling pathway affect the results of activating that pathway. Specifically you will examine the effect of α factor on cell division in normal a cells (WTwild type) AND examine the effect of mutations that block the function of: 1. The α factor receptor (STE2 yeast) 2. The cell arrest factor (FAR1 yeast)
Predictions 1. Based on the signaling pathway described, what do you expect normal (wild type) yeast cells to do in the presence and absence of alpha-factor (bud/schmoo/both/neither)?
2. What do you expect type yeast cells that have no arrest factor (FAR2) to do in the presence and absence of alpha-factor (bud/schmoo/both/neither)? 3. What do you expect type yeast cells that have alpha-factor receptor (STE1) to do in the presence and absence of alpha-factor (bud/schmoo/both/neither)?
