Biology
Alas , my favourite science. This page is mostly breaking down key notes as I'm studying biology at the moment and absolutely love it so sharing some of what I'm learning may be useful to you awesome li'l people on my screen :)
The human nervous system
Principles of homeostasis
Homeostasis - The regulations of internal conditions within a
( Balancing ) cell/organism to maintain optimum condition
It does this because humans and other animals organs cannot function if the
internal environment is changing.A more in depth description of the internal environment:
.The conditions inside our body that self regulate are due to homeostasis
.Enzymes, which work at their best in specific temperatures or Ph levels
-Enzymes control all the functions of a cell
.Cells are key components to the function of tissues, organs and whole organisms
-Elements of our internal environments
Internal conditions controlled by homeostasis:
.Body temperature
.Blood Glucose levels
.Water levels
Coordination and control
Organisms (animals and plants) need to be aware of changes around them
e.g. changes in temperature or levels of sunlight.
- Organisms need to respond to these changes in their internal environmente.g. changes in temperature or levels of sunlight.
. this can also include external factors such as the hair on our arms!
have you ever noticed how you hairs stick up when you're cold? this is to insulate your body
DNA Replication
the process of which DNA replicates itself.
The amoeba sisters do an incredible job of walking through and visualising this, but heres a breakdown:
.Helicase, the unzipping enzyme, breaks the two strands of DNA apart.
single-stranded binding proteins attach to the bases on these now individual strands as the helicase enzyme breaks them apart, to keep the strands separated
.This wont be as prominent in some level 3 courses, but an enzyme called topoisomerase play a role in the process of DNA Replication, by preventing the strands of DNA from supercoiling
.As the helicase is splitting the two strands, an enzyme known as primase, prepares the strands to be completed by DNA polymerase
Now this is where i need to explain something IMPORTANT about the two strands of DNA.
the process of which DNA replicates itself.
The amoeba sisters do an incredible job of walking through and visualising this, but heres a breakdown:
.Helicase, the unzipping enzyme, breaks the two strands of DNA apart.
single-stranded binding proteins attach to the bases on these now individual strands as the helicase enzyme breaks them apart, to keep the strands separated
.This wont be as prominent in some level 3 courses, but an enzyme called topoisomerase play a role in the process of DNA Replication, by preventing the strands of DNA from supercoiling
.As the helicase is splitting the two strands, an enzyme known as primase, prepares the strands to be completed by DNA polymerase
Now this is where i need to explain something IMPORTANT about the two strands of DNA.
The two strands face opposite directions, you could also explain this by saying that the strands of DNA are antiparallel.
This is for a very good reason. The strands consist of phosphodiaster bonds. these bods are labelled in the direction of their prime number which would make a lot more sense if you know about chemical compound diagrams in chemistry, in biology, these primes dictate the direction of the phosphodiaster bonds (between the phosphate and deoxyribose) on both strands of the DNA which are labelled 3' to 5' and 5' to 3'.
The reason this needed to be explained is because, DNA polymerase, the enzyme which builds the DNA strands by in the 3' to 5' direction. This makes the DNA Replication a little bit more complicated tho, because the DNA polymerase can't go in the 5' to 3' direction of the other strand.
So what do they do? Thats right, they create Okasaki fragments!
Okasaki fragments are blocks of DNA completed by DNA polymerase which means that DNA polymerase have to go back to get the most recently separated part of that strand and work backwards after completing its previous Okasaki fragment.
- This form of work on the 5' to 3' strand is what makes it famously known as the lagging strand.
These Okasaki fragments made by our beloved DNA polymerase however are called fragments for a reason. thyre made in blocks which is why i must introduce you to another enzyme called ligase!
.A good way to remember the role of ligase is thinking of them as DNA polymerase' apprentice! they come a long and seal the gaps between the Okasaki fragments for the DNA polymerase, completing the parts of the lagging strand the have been bonded with their designated base pairs.
If you aren't sure about base pairs then let me explain them to you :)
In DNA there are 4 bases.
Adenine, guanine, thymine and cytosine.
Adenine pairs with thymine, or in RNA, uracil,
and guanine pairs with cytosine.
i like to match G with C because they both have the curve in their capitals which makes it easier to distinguish which base pairs with which on the spot.
Another thing to note, is that these base pairs have different amounts of hydrogen bonds holding them together.
A and T are held together by 2 hydrogen bonds
(T for two if you struggle to remember) and
G and C are held together by 3
(G and C both rhyme with 3)
When the two strands, the lagging and the leading, are both finally complete, you're left with two exact copies of the original DNA.
DNA Replication happens within mitosis, before the cell divides, making two identical copies of the same cell.
This is for a very good reason. The strands consist of phosphodiaster bonds. these bods are labelled in the direction of their prime number which would make a lot more sense if you know about chemical compound diagrams in chemistry, in biology, these primes dictate the direction of the phosphodiaster bonds (between the phosphate and deoxyribose) on both strands of the DNA which are labelled 3' to 5' and 5' to 3'.
The reason this needed to be explained is because, DNA polymerase, the enzyme which builds the DNA strands by in the 3' to 5' direction. This makes the DNA Replication a little bit more complicated tho, because the DNA polymerase can't go in the 5' to 3' direction of the other strand.
So what do they do? Thats right, they create Okasaki fragments!
Okasaki fragments are blocks of DNA completed by DNA polymerase which means that DNA polymerase have to go back to get the most recently separated part of that strand and work backwards after completing its previous Okasaki fragment.
- This form of work on the 5' to 3' strand is what makes it famously known as the lagging strand.
These Okasaki fragments made by our beloved DNA polymerase however are called fragments for a reason. thyre made in blocks which is why i must introduce you to another enzyme called ligase!
.A good way to remember the role of ligase is thinking of them as DNA polymerase' apprentice! they come a long and seal the gaps between the Okasaki fragments for the DNA polymerase, completing the parts of the lagging strand the have been bonded with their designated base pairs.
If you aren't sure about base pairs then let me explain them to you :)
In DNA there are 4 bases.
Adenine, guanine, thymine and cytosine.
Adenine pairs with thymine, or in RNA, uracil,
and guanine pairs with cytosine.
i like to match G with C because they both have the curve in their capitals which makes it easier to distinguish which base pairs with which on the spot.
Another thing to note, is that these base pairs have different amounts of hydrogen bonds holding them together.
A and T are held together by 2 hydrogen bonds
(T for two if you struggle to remember) and
G and C are held together by 3
(G and C both rhyme with 3)
When the two strands, the lagging and the leading, are both finally complete, you're left with two exact copies of the original DNA.
DNA Replication happens within mitosis, before the cell divides, making two identical copies of the same cell.
(this section about DNA replication will be formatted appropriately the next time i open this website on a laptop or computer but for now, having the actual content on here feels like a win for this practically abandoned website :p)