BIO Doubts..here..everyone!!

[xIshtar]

Okkay I have a doubt !!
describe the sites of
production and the roles of
oestrogen and progesterone
in
- the menstrual cycle
- pregnancy

anyone??

Oestrogen cause the thickening of the uterus lining, in preparation for implantation. It also prevents the further secreting of FSH or another egg being released.
Progesterone maintains the lining of the uterus during pregnancy.

They are produced in the ovaries.

 

[gadgetcrazy]

Could someone please explain the difference between meiosis and mitosis plzzz??

Thanks!

 

[Divalicious]

Could someone please explain the difference between meiosis and mitosis plzzz??

Thanks!

Meiosis:
1- Happens in reproductive organs (gonads [testis, ovaries, anther]) to produce gametes (haploid - half number of chromosomes, 23 in humans)
2- Causes variation due to crossing over of non-sister chromatids and independent assortment of chromosomes.

Mitosis:
1-Happens in all cells for growth. Produces diploid cells - having full number of chromosomes (46 in humans)
2-Doesn't cause variation.

If there's something I missed someone remind me.

 

[xIshtar]

Could someone please explain the difference between meiosis and mitosis plzzz??

Thanks!

Meiosis:
1- Happens in reproductive organs (gonads [testis, ovaries, anther]) to produce gametes (haploid - half number of chromosomes, 23 in humans)
2- Causes variation due to crossing over of non-sister chromatids and independent assortment of chromosomes.

Mitosis:
1-Happens in all cells for growth. Produces diploid cells - having full number of chromosomes (46 in humans)
2-Doesn't cause variation.

If there's something I missed someone remind me.

Didn't miss anything too important, just remember that mitosis is a form of asexual reproduction whereas meiosis is used in sexual reproduction.

 

[cHeStEr]

Okkay I have a doubt !!
describe the sites of
production and the roles of
oestrogen and progesterone
in
- the menstrual cycle
- pregnancy

anyone??

Oestrogen thickens the uterus lining for implantation of zygote .. It also prevents further release of FSH or eggs .. FSH follicle simulating hormone .
Progesterone maintains the lining during pregnancy !!
I hope this helps !

 

[Divalicious]

Uhm there's something confusing in contraceptive pills. It says they contain progesterone which stops secretion of LH by negative feedback mechanism, and also contains oestrogen. But doesn't oestrogen actually stimulate LH secretion?

 

[xIshtar]

Uhm there's something confusing in contraceptive pills. It says they contain progesterone which stops secretion of LH by negative feedback mechanism, and also contains oestrogen. But doesn't oestrogen actually stimulate LH secretion?

Basically, they contain the hormones which would normally be secreted during pregnancy, such as oestrogen. This prevents further eggs being produced.

 

[Divalicious]

Uhm there's something confusing in contraceptive pills. It says they contain progesterone which stops secretion of LH by negative feedback mechanism, and also contains oestrogen. But doesn't oestrogen actually stimulate LH secretion?

Basically, they contain the hormones which would normally be secreted during pregnancy, such as oestrogen. This prevents further eggs being produced.

But Oestrogen is produced by Graafian follicles without pregnancy anyway, actually is it even produced during pregnancy?. I know progesterone stops FSH (which develops more eggs) and LH (which causes ovulation). But the presence of oestrogen too seems to cancel what progesterone does(since it stimulates FSH, which stimulates LH too)?

 

[Ahmad95]

Scab formation

Actually, when you get cut, the platelets release thrombokinase which acts as an enzyme in the conversion of prothrombin to thrombin and the thrombin is used to convert soluble fibrenogen to insoluble fibrin, the insoluble fibrin forms a mat around the wound which traps red blood cells forming a clot which causes scab formation. Just thought I'd add information..

The syllabus states that you should only know the Fibrenogen > Fibrin part so the rest is just general information..

 

[xIshtar]

Uhm there's something confusing in contraceptive pills. It says they contain progesterone which stops secretion of LH by negative feedback mechanism, and also contains oestrogen. But doesn't oestrogen actually stimulate LH secretion?

Basically, they contain the hormones which would normally be secreted during pregnancy, such as oestrogen. This prevents further eggs being produced.

But Oestrogen is produced by Graafian follicles without pregnancy anyway, actually is it even produced during pregnancy?. I know progesterone stops FSH (which develops more eggs) and LH (which causes ovulation). But the presence of oestrogen too seems to cancel what progesterone does(since it stimulates FSH, which stimulates LH too)?

Basically, oestrogen doesn't simulate FSH, oestrogen prevents the production of further eggs or the releasing of FSH, I understand your confusion. Infact, I wasn't aware that knowledge of LH was required. You are right, during pregnancy oestrogen is not produced, but rather progesterone. You are simply over confusing the topic. Just notice that it prevents another egg being produced, which again, means that LH or FSH are not secreted.

On another note, could you give me the full name of LH, it isn't in my book, much like Follicle stimulation hormone is not, but I learnt their effects through past papers

 

[HyDraZin3]

Can anyone tell me the use of hormones in food production?
THANKS

 

[xIshtar]

Can anyone tell me the use of hormones in food production?
THANKS

Read back, already posted..

Simply

Rennin for cheese coagulation.
Pectinase for juice extraction.
Amylase for starch -> Maltose
Isomerase which converts glucose into fructose.

 

[Alpha45]

Can anyone tell me the use of hormones in food production?
THANKS

Key idea:

- These animal hormones can be used to increase the yeild of animals .
- BST which is a common hormone given to cows to make more milk . so farmers make more milk with less cows

 

[Xenarra]

Hey,

Thank you to everyone who answered my "blood clotting" question.

I have a doubt about whether we have to go through all the detailed parts of the animal cell or not? Like the endoplasmic reticulum, mitochondria etc etc.

BR,
Xenarra

 

[Xenarra]

Hey,

I don't know if there is any doubts coming from "Drugs" so if there is something that is important, could someone please mention it??
Thanks!

BR,
Xenarra

 

[Alpha45]

Nope its nope in the syllabus but you need to know about mitochondria , which helps to release energy in cell and this energy can be used in cell division and usually active transport .

 

[Xenarra]

Nope its nope in the syllabus but you need to know about mitochondria , which helps to release energy in cell and this energy can be used in cell division and usually active transport .

Thank you : )

 

[Alpha45]

Hey,

I don't know if there is any doubts coming from "Drugs" so if there is something that is important, could someone please mention it??
Thanks!

BR,
Xenarra

DRUGS : A substance which alters bodies metabolism . (is destroyed in liver)


* Heroin :
- It was used as a medicine
- Reduces pain
- Slows down CNS (central nervous system)
- Causes addiction
- Transfer of HIV due to sharing of unsterilized needles
- Slow down breathing ( respiration also)

* Alcohol :
- It causes adiction
- Slows down CNS
- causes double vision
- damage to brain
- damage to liver ( cirrhosis)
- Aggression

* Anti-Biotics

- They kill bateria by damaging there cell wall
- can cause mutation of bacteria if used allot

 

[Xenarra]

Hey,

I don't know if there is any doubts coming from "Drugs" so if there is something that is important, could someone please mention it??
Thanks!

BR,
Xenarra

DRUGS : A substance which alters bodies metabolism . (is destroyed in liver)


* Heroin :
- It was used as a medicine
- Reduces pain
- Slows down CNS (central nervous system)
- Causes addiction
- Transfer of HIV due to sharing of unsterilized needles
- Slow down breathing ( respiration also)

* Alcohol :
- It causes adiction
- Slows down CNS
- causes double vision
- damage to brain
- damage to liver ( cirrhosis)
- Aggression

* Anti-Biotics

- They kill bateria by damaging there cell wall

Thankx....got most of it...guess nothing major in that area : )

 

[Divalicious]

Basically, oestrogen doesn't simulate FSH, oestrogen prevents the production of further eggs or the releasing of FSH, I understand your confusion. Infact, I wasn't aware that knowledge of LH was required. You are right, during pregnancy oestrogen is not produced, but rather progesterone. You are simply over confusing the topic. Just notice that it prevents another egg being produced, which again, means that LH or FSH are not secreted.

On another note, could you give me the full name of LH, it isn't in my book, much like Follicle stimulation hormone is not, but I learnt their effects through past papers

Actually yea I got confused, Oestrogen doesn't stimulate FSH, it stimulates LH, which is Luteinizing Hormone that causes ovulation. Now I think having oestrogen in contraceptive pills doesn't matter, since even it stimulates LH, ovulation wont occur since there're no produced eggs(no FSH due to progesterone).