Biology Unit 3 Questions Megathread

[HERculina]

ummmm well Pr = inactive form. so when it meets red light (natural light) it becomes activated into Pfr. as an enzyme  triggers synthesis or activation of specific proteins in specific cells or altering transcription of genes, eventually causing a response. The amount of phytochrome in each form will enable plant to measure daylenght/nightlength =  involved in photoperiodism.
And when Pfr meets with far red light (in the dark), it become inactivated again and is now Pr.

EDIT: just read q. again. ok, so when it absorbs red light it becomes activated in Pfr. When the enzyme did things to lead to a response i think this could have included stem elongation.
but with "The result will be stem elongation as Pfr prevents stem elongation" - i dont think that makes sense? 

[WhoTookMyUsername]

But what does Pfr and Pr mean?, that one phytochrome can be converted into another?


What are bacterial cell wall composed of, I thought it was mainly complex polysaccharides but nob says lipid compounds or teichoic acid ( gram -,+) and amino acids and di saccahridrs?

[HERculina]

peptidoglycan. but gram positive have a thicker cell wall (this includes teichoid acid + more amino acids + disaccharides) and gram negative has a multilayered cell wall, having an additional outer membrane layer of lipids (without teichoic acid + less amino acids and disaccharides). this helps determine what type of antibiotics would work on the bacteria. For example gram positive bacterias are more susceptible to penicillin than gram negative.

With cell mediated immunity, when interleukin-2 activates cytotoxic T cell to proliferate does it mean it devides rapidly into same cytotoxic T cells or does it mean it differentiates into those 4 type of T cells through clonal expansion

[Lesliel1]

do loaded acceptor molecules carry electrons or hydrogen ions? cuz in the electron transport stage it says the electrons and hydrogen ions are passed into cytochromes..but i dont know where the electrons come from D=

[HERculina]

the electrons are from the Hydrogen ions. Ions have protons and then electrons orbiting around nucleus.

[amun]

whats the difference between hypolgycamemia and hyperglycameia ?

[lexitu]

Hypoglycaemia = low blood glucose levels
Hyperglycaemia = high blood glucose levels

[amun]

whats the difference between glucagon and glucogen?

[lexitu]

glucagon hormone which promotes glucose release into bloodstream, glycogen stored form of CHO in animals

[amun]

oh ok thanks , how much of hormones do we need to know ? am i wasting my time learning them into the detail?

[lbeste12]

Just to clear things up.
Does a protein have a quaternary structure when it has two or more polypetide chains?

[lbeste12]

Or is it one?
Two different sources are telling me two different things! :|

[Kaille]

I think it would be beneficial to know one hormone really well. Eg. Insulin. They might ask you to name one then describe how it causes a change in a cell (signal transduction) or draw a negative feedback model.

[HERculina]

Quaternary structures = two or more polypeptide chains

What are the lymphocytes that undergo clonal expansion/selection theory?
is it B cells and helper T cells
or
B cells, helper T cells and cytotoxic T cells?

[Kaille]

Quaternary structures = two or more polypeptide chains

What are the lymphocytes that undergo clonal expansion/selection theory?
is it B cells and helper T cells
or
B cells, helper T cells and cytotoxic T cells?

i think b lymphocytes, t helper and cytotoxic t cells undergo clonal expansion because they all have memory cells i think.....