Rishi's Biology Thread

[slothpomba]

Why do hormones require a second messenger protein in order to have their signal detected within a cell?
Is it because they are soluble in water?

The majority of hormone classes can squeeze through the membrane but keep in mind peptide hormones are hydrophillic (lipophobic) to a degree. This class of hormones usually attaches to receptors on the surface of the cell which in turn produces a second messenger (because they would find it difficult to get into the cell itself). As mentioned, amplification of the signal is another reason as well.

[Rishi97]

Could someone please kindly check my answer


1)What occurs in the body when glucose levels are
a.High?
Cells in the pancreas detect rise
Beta cells produce INSULIN
Insulin stimulates muscles + liver cells to absorb glucose
Glucose is converted to glycogen
b.Low?
Cells in the pancreas detect drop
Alpha cells produce GLUCAGON
Glucagon stimulates the liver to release glucose
Glycogen is converted to glucose
2)What are the hormones involved in the regulation of glucose levels in the blood?
Insulin and glucagon
3)What are the glands that produce the hormones that regulate glucose?
The pancreas is a gland that regulates glucose levels by producing insulin and glucagon
4)What is meant by the terms hypoglycaemia and hyperglycaemia?
Hypoglycemia is a condition in which the blood glucose levels in the body are lower than the required range
Hyperglycemia is a condition in which the blood glucose levels in the body are higher than the required range.
5)What is negative feedback?
The negative feedback system is a system of control which detects a change in a variable (e.g.: decrease) and action occurs to produce a change in the opposite direction (e.g. increase)
6)Be able to write a flow chart including, sensors, stimulus, effector and response. (including negative feedback)Stimulus  sensors  effector  response
              Stimulus  Receptor  Effector  Signal transduction  Response
7)What is signal transduction? How does it differ depending on the type of hormone?
Signal transduction is a chain of events that transmits and amplifies a signal to get a particular cellular response.
How it works:
-The receptor receives a stimulus (protein or lipid)
-The G-protein detects this stimulus and changes shape
-The G-protein transmits the message to the secondary messengers
-The secondary messengers amplify the required response so it occurs in less time

Types of hormones:-   
PROTEIN- If the hormones are proteins, then it cannot travel through the cell membrane since it’s not lipid soluble. Protein hormones (stimulus) have receptors on the cell membrane. When leaving a cell, the protein hormones use vesicles.
-LIPIDS- If the hormones are lipids, then it can travel through the cell membrane since it is lipid-soluble. Lipid hormones (stimulus) have receptors inside the cell/ in the cytoplasm. 

[Rishi97]

List the major steps involved in humoral immunity

Thanks

[Reus]

List the major steps involved in humoral immunity

Thanks

Note that B-cells have membrane bound IgM and IgD that have the same antigen specificity.

When B-cells encounter their antigen at least two membrane bound antibodies must attach to it. This will initiate endocytosis of the antigen, and digestion of its peptide portions for presentation on MHC-II.

Circulation activated T-helper cells can then recognize MHC-peptide complex on their surface and secrete IL-4 which helps activate the B-cell.

The B-cell can then divide and differentiate into plasma cells which secrete antibody and into memory cells.

Memory cells in circulation can form germinal centers around follicular dendritic cells in the lymph nodes and spleen where they can undergo affinity maturation and class switching.

[Rishi97]

Note that B-cells have membrane bound IgM and IgD that have the same antigen specificity.

When B-cells encounter their antigen at least two membrane bound antibodies must attach to it. This will initiate endocytosis of the antigen, and digestion of its peptide portions for presentation on MHC-II.

Circulation activated T-helper cells can then recognize MHC-peptide complex on their surface and secrete IL-4 which helps activate the B-cell.

The B-cell can then divide and differentiate into plasma cells which secrete antibody and into memory cells.

Memory cells in circulation can form germinal centers around follicular dendritic cells in the lymph nodes and spleen where they can undergo affinity maturation and class switching.

Wow..that is some sophisticated vocab.I haven't even heard half these words :/
This is what I wrote:
- Macrophages engulf pathogens and display the pathogen's anitigens on their surface
- T-helper cells are attracted to the macrophage and stimulate B-cells
- The B-cells produce plasma cells and memory cells
- The plasma cells produce antibodies which form antibody-antigen complexes
- The B-memory cells stay in the body until there is a second infection. It reacts more vigorously towards the pathogen the second time round.

Is this right?
Thanks

[Reus]

Wow..that is some sophisticated vocab.I haven't even heard half these words :/
This is what I wrote:
- Macrophages engulf pathogens and display the pathogen's anitigens on their surface
- T-helper cells are attracted to the macrophage and stimulate B-cells
- The B-cells produce plasma cells and memory cells
- The plasma cells produce antibodies which form antibody-antigen complexes
- The B-memory cells stay in the body until there is a second infection. It reacts more vigorously towards the pathogen the second time round.

Is this right?
Thanks

That's perfect! Nothing wrong with that, just if willing, learn some biological terminology to enhance your answer's credibility!

[simpak]

I actually think it can be better to use simple/less complex terminology in VCE Biol...otherwise it's easier to make a mistake and difficult for the examiner to mark. The examiner is only looking for things in the study design. There's nothing wrong with what either of you wrote but you won't get extra marks for mentioning things like affinity maturation or class switching, nor will it enhance your answer, because (afaik, or at least when I did VCE Biol) they're not in the study design.  Good job being enthusiastic about immuno though

[Scooby]

Wow..that is some sophisticated vocab.I haven't even heard half these words :/
This is what I wrote:
- Macrophages engulf pathogens and display the pathogen's anitigens on their surface
- T-helper cells are attracted to the macrophage and stimulate B-cells
- The B-cells produce plasma cells and memory cells
- The plasma cells produce antibodies which form antibody-antigen complexes
- The B-memory cells stay in the body until there is a second infection. It reacts more vigorously towards the pathogen the second time round.

Is this right?
Thanks

I'd write that subsequent expose to that antigen results in greater/faster production of specific antibodies due to the presence of memory B cells. "More vigorous" is a bit too vague

[Reus]

I'd write that subsequent expose to that antigen results in greater/faster production of specific antibodies due to the presence of memory B cells. "More vigorous" is a bit too vague

I'm not too sure about Rishi, but my teacher reiterated that it was more 'vigorous' and the Nelson Biology or NoB not too sure which one I recall it from, states that it acts more vigorously! Just saying

[Scooby]

I'm not too sure about Rishi, but my teacher reiterated that it was more 'vigorous' and the Nelson Biology or NoB not too sure which one I recall it from, states that it acts more vigorously! Just saying

Well, yeah, the immune response is more vigorous, but you're unlikely to be awarded marks for writing that if you get a question about memory cells. It doesn't really demonstrate any understanding of the concept. You've gotta be specific!

[Rishi97]

How can you acquire immunity through natural and passive strategies?

[Reus]

How can you acquire immunity through natural and passive strategies?

This should definitely help
http://classes.midlandstech.edu/carterp/Courses/bio225/chap17/17-01_AcqImmunity.jpg

[Rishi97]

This should definitely help
http://classes.midlandstech.edu/carterp/Courses/bio225/chap17/17-01_AcqImmunity.jpg

Omg just what I needed
Thanks Reus

[Rishi97]

1) Why are hormonal responses generally longer lasting?
2) What is the difference between hormones and pheromones?

Thanks guyysss

[Tyleralp1]

1) Why are hormonal responses generally longer lasting?
2) What is the difference between hormones and pheromones?

Thanks guyysss

1. The Humoral Response creates a large number of antibodies specific to the antigen, and a large number of Memory B-Cells. This is longer lasting in terms of immunity as next time the antigen invades, a form of defence mechanism is ready.

2. Hormones are chemical signalling molecules which travel in the blood stream directly to their target tissues to induce a specific response. This works within the means of the organism itself. Pheromones however, are chemical signalling molecules which travel through the atmosphere, causing a change in behaviour on members on the same species.