Yacoubb's Bio 3+4 Questions

[Irving4Prez]

In the studydesign it states "disorders of the human immune response including the allergic response and autoimmune diseases"
Does this mean we should only know the details on allergic response and autoimmune disease?
Or must we know all the disorders of the human immune response such as Rhesus incompatibility, immunodeficiency, etc?

Information about specific examples would be provided within the stem of the question. You should know about the allergic response and autoimmune disease.

[vox nihili]

This is from Lisa Chem, 2006.

For the 2nd row my answers were as follows:

Carbohydrates ... ... Glucose
I initially thought I could have written proteins but the description provided, "organic catalyst used in glycolysis" suggested it wasn't, as enzymes can't be consumed in a reaction.

But the answers suggested they were, protein and amino acids.

Confused 

Anything that says organic catalyst is referring to an enzyme (or an RNA but that's out of the course). Carbohydrates are the substrates.

[Yacoubb]

Would it be accurate to say that a regulatory gene is a unit of DNA that codes for a polypeptide, that in turn, regulates the activity of another gene.

Also:
* The leading strand is synthesised continuously in a 5' to 3' direction because the replication fork immediately exposes the leading strand DNA template
* The lagging strand is synthesised discontinuously in a 5' to 3' direction because the replication fork does not immediately expose the lagging strand DNA template. As a result, short okazaki fragments are produced, which are then ligated by DNA ligase to form a continuous polynucleotide strand.

^ Is that accurately expressed?

[Irving4Prez]

Hey guys, how would you infer that lethal alleles are involved within this question,

[Yacoubb]

Is mRNA longevity just a reference to how long mRNA is able to last? And by regulating mRNA longevity, is energy conserved by the cell? Because if the mRNA lasts a shorter time, then it would not be continually translated and thus polypeptides that are not required will not be produced.

[Yacoubb]

Few questions:

1) Does interferon just cause cells to produce an enzyme that inhibits the biosynthesis of viral particles, if the virus were to enter the cell?

2) If I were asked to indicate HOW the immune system cells distinguish 'self' from 'non-self', would this be acceptable:
* Cells of the immune system possess receptors that are able to recognise different MHC markers, and thereby be able to distinguish self from non-self.

3) Plant defence mechanisms - should I only know a couple:
E.g. thick (intact) waxy cuticle, hairy epidermal layer, and more active responses like the production of galls to trap pathogens.

[Smiley_]

Few questions:

1) Does interferon just cause cells to produce an enzyme that inhibits the biosynthesis of viral particles, if the virus were to enter the cell?

2) If I were asked to indicate HOW the immune system cells distinguish 'self' from 'non-self', would this be acceptable:
* Cells of the immune system possess receptors that are able to recognise different MHC markers, and thereby be able to distinguish self from non-self.

3) Plant defence mechanisms - should I only know a couple:
E.g. thick (intact) waxy cuticle, hairy epidermal layer, and more active responses like the production of galls to trap pathogens.

1. you could say they are antiviral agents
secreted by activated T cells
Their production and secretion is triggered by the presence of double-stranded RNA, which does not occur in uninfected cells
Interferons act by preventing the synthesis of viral RNA and therefore
the produc tion of viral proteins. They have little or no effect on uninfected
cells.

2. sounds good

3. as long as you can apply your knowledge to situations

[Irving4Prez]

secreted by activated T cells

You'd want to avoid definitives. They can also be produced by cells that are affected by a virus in an attempt to warn other cells and hence the production of an anti viral protein coat within non affected cells.

[Russ]

You don't need to know the specifics of #1 and #2

[Scooby]

Russ is right. All you need to know is that interferons are proteins released by virus-infected cells that trigger surrounding cells to produce anti-viral enzymes

[Yacoubb]

Definition of reflex arc:
A reflex arc is a pathway of nerves, from a receptor to an effector, that involves the electrical impulse bypassing the brain.
^ Is that accurate? It definitely needs a bit of touching up, so if anyone has anything I could incorporate into that/remove, it would be much appreciated.

Also, would an advantage of a reflex arc over a normal stimulus-response model be that a reflex arc is a rapid response to a stimulus that would minimise tissue damage, in events like touching a hot plate, standing on a pin, etc?

Thanks!

[vox nihili]

Definition of reflex arc:
A reflex arc is a pathway of nerves, from a receptor to an effector, that involves the electrical impulse bypassing the brain.
^ Is that accurate? It definitely needs a bit of touching up, so if anyone has anything I could incorporate into that/remove, it would be much appreciated.

Also, would an advantage of a reflex arc over a normal stimulus-response model be that a reflex arc is a rapid response to a stimulus that would minimise tissue damage, in events like touching a hot plate, standing on a pin, etc?

Thanks!

It's a hard one to define, but that should suffice

And yeah, the advantage is speed

[swagsxcboi]

Hey guys, how would you infer that lethal alleles are involved within this question,

We know that 'When the hairy dogs are mated, they tend to produce larger litters and never produce hairless offspring" meaning that they must be homozygous recessive.

The hairless dogs can be either heterozygotes or homozygous dominant.
(but their litters are smaller, which suggests something is different)

if you add up all the hairless offspring, you get 16.
If you add up all the hairy offspring, you get 8. 
A ratio of 2:1 hairless to hairy. "Other breeders of Mexican hairless dogs always obtained similar overall ratios." suggests that this 2:1 ratio is reliable.

If you label the hairless dogs as HH, draw a punnet square, you'll see that their offspring will be 100% HH, which we know is not true (due to the difference of the ratio of phenotypes)

If you label the hairless dogs as Hh, draw a punnet square, you'll see that their offspring will be 25% homozygous dominant (HH),  50% heterozygous (Hh), and 25% homozygous recessive (hh). Since we can infer that the genotype of a hairy dog is hh, the genotype of hairless dogs must be Hh. The ratio 2:1 reinforces that HH is a lethal allele.

(apologies if this doesn't help!)

[Irving4Prez]

We know that 'When the hairy dogs are mated, they tend to produce larger litters and never produce hairless offspring" meaning that they must be homozygous recessive.

Alternatively, couldn't they be homozygous dominant? That's where my confusion lies

[swagsxcboi]

Alternatively, couldn't they be homozygous dominant? That's where my confusion lies

(by logic, yes) But not every hairy dog will be homozygous dominant, and if we cross heterozygous and heterozygous, we'll end up with a 25% chance of a hairless offspring, which is untrue.