What Are Some Fundamental Concepts in Biology?

[nemzy]

1) what is diff between osmolarity and molarity?

is osmolarity the difference of molarity in a cell and the outside?

2) are both enzymes and substrates pH specific?

i know that enzymes are, but are substrates pH specific too?

3) increassing enzyme concentration increases the enzymatic reaction if substrate concentration is held constant right?

4) I know that yeast cells can undergo both respiration and fermentation, does that mean yeast cells have mitochondria too?

5) In a mitotic phase, i know that 90% of the time the cell is in prophase, but what about the other 10%? Are metaphase, anaphase, and telephase happening in equal proportions?

6) how is optical density diff than absorbance?

 

[iansmith]

1) what is diff between osmolarity and molarity?

is osmolarity the difference of molarity in a cell and the outside?

osmolarity is equal to the molarity times the number of particles per molecule whereas the molarity is the number of moles per litre of a molecule.

2) are both enzymes and substrates pH specific?

i know that enzymes are, but are substrates pH specific too?

I will depend on the substrate. Protein configuration is affected by pH. The enzyme recognize a certain configuration. the enzyme might be active at a pH but the configuration of the protein is incorrect.

3) increassing enzyme concentration increases the enzymatic reaction if substrate concentration is held constant right?

Yes but the enzyme reaction will plateau past a given concentration of enzyme for a given substrate concentration. There only so much substrate for a a certain number of enzyme

4) I know that yeast cells can undergo both respiration and fermentation, does that mean yeast cells have mitochondria too?

Yes, yeast have mitochondria. Every eucaryotes type cells have mitochondria. It is one of the key feature.

5) In a mitotic phase, i know that 90% of the time the cell is in prophase, but what about the other 10%? Are metaphase, anaphase, and telephase happening in equal proportions?

It is not equally divided and it will change depending on the species but in general the anaphase and telophase are the shortest steps but my memory might be play trick on me.

6) how is optical density diff than absorbance?

In biology it is not consider the same. You take absorbance reading but you express it as an optical density (OD) after you remove the absorbance of the blank. My old supervisor told me once and did not pay enough attention. In biology always express it as OD when talking about culture growth.