Degree: Biomedical Sciences (Bachelors) - University College London University
Hi! My name is Alisa and I am studying Biomedical Sciences at University College London. Having just attained the International Baccalaureate certificate in 2015 and also having a younger sister who I frequently help with her IB classes, I feel that I understand what topics and areas students find particularly difficult. As a result, I am able to explain them in a way that is easy to comprehend.
I have a background in tutoring as in my last two years of High School, I was inducted into the National Honor Society due to my academic records and one of my responsibilities was to tutor students who were having troubles in biology, maths, and chemistry.
What I can help with:
I can particularly help students who wish to have extra help in SL and HL Biology, and SL Chemistry.
In my first year of University studies, the classes that I have taken include Human Physiology, Genetics, Biochemistry, Chemistry, Pharmacology, and Cell Biology, and therefore have a strong understanding on the material that is present in IB Biology.
Furthermore, I took higher-level IB English Literature and therefore can help you to perfect your writing by peer-reviewing any written work. I can also give advice on how to structure coherent scientific essays as, especially in University, much of the marks attained for an assignment comes from not only the content of the material but also the structure of the essay itself.
Before each session, I will ask you to email me specific areas that you are having troubles with so that I will be able to make condensed study notes which you can print out after our session. By doing so, we will be able to make most of our time together and furthermore I will be able to make sure that we will be able to go through all the questions that you may have over the topic.
My tutoring times are currently flexible but may become more rigid once the academic year starts in September as I will have to plan my tutoring sessions between my classes. However, if asked in advance, I will be able to do a night tutoring session.
If you have any questions outside our session, do not hesitate to contact me!
|SL French B||Baccalaureate||7|
|HL English Literature||Baccalaureate||5|
|Extended Essay Biology||Baccalaureate||B|
|Before 12pm||12pm - 5pm||After 5pm|
Please get in touch for more detailed availability
Tanya (Parent) September 13 2016
Patrik (Student) January 12 2017
Transmitting Along Neurones
When a nerve cell is not stimulated, it is in a resting state. During this state, the inside of the axon is relatively more negative than outside of the axon, this is called the resting potential. The reason behind this negative charge is because of the distribution of the principal ions (Na+ and K+). In reality, there is a higher concentration of sodium ions outside the neurone while there is a higher concentration of potassium inside the neurone. This allows an electrochemical gradient to be generated, which is crucial for an action potential (AP) to be generated. During the resting state, there is a larger amount of positive ions (cations) on the outside of the neurone compared to the inside, thus giving it a relatively negative charge inside the axon. When there is a stimulus, this causes the Sodium (Na) channels located on the surface of the axon to open, causing an influx of sodium ions into the axon. This causes the charge within the axon to reverse and become positive, a process called depolarisation. Once the axon has depolarised over a certain threshold, this causes an AP.
The AP, a charge in the electrical potential associated with the propagation of an impulse along, in this case, the nerve cell, travels in one direction from the soma to the axon terminals. Thus, once the AP passes a certain area of an axon, that part must return back to its resting state. This is called repolarisation. During this period, the sodium ion channels that were previously open during depolarisation start to close slowly and simultaneously the potassium ion channels open, causing an efflux of potassium ions from within the axon, causing the charge within the axon to become less positive (and therefore more negative - returning back to the resting potential). But here we come to a problem. If all the ions keep being pushed out or into the axon, how can a second AP be generated? Will there be enough ions? In order to prevent a shortage of cations, there is a mechanism called the sodium potassium pump that is constantly working. It works by pumping 3 sodium ions out for every 2 potassium ions being pumped in, therefore maintaining and restoring the axon back to the resting potential.
Transmitting Between Neurones
Once the AP reaches the axon terminals, it must be converted into something else as an AP cannot cross interneuron space between the postsynaptic and presynaptic neurone, which is called the synaptic cleft. Thus, when the AP reaches the axon terminal, it releases a chemical messenger called a neurotransmitter (NT). This NT is released into the synaptic cleft and moves via diffusion from the presynaptic to the postsynaptic neurone where the NT binds to receptors on the postsynaptic neurone. Once they bind to receptors, this allows ion channels to open, causing an influx of cations (sodium ions), which may initiate an action potential depending on the amount of receptors that have been activated.see more
In genetics, sometimes it is not easy to tell if an organism is heterozygous (having two different alleles of a gene) for a certain trait or if it is a homozygous (having the same identical alleles of a gene). Therefore, we do not know if the phenotype (the characteristic) is due to homozygosity or heterozygosity. This is where the test cross comes in. In a test cross, we test a suspected heterozygote (A_ (the gap showing that it is a suspected heterozygote)) with a known homozygous recessive (aa) by crossing them together.
When we perform a test cross, we construct a punnet square, crossing the A_ with the aa. If after the cross, we get a result of 2 Aa and 2 aa pairs, then we know that the organism was in fact a heterozygote. However, if all of the results turn out to be heterozygote Aa, this means that the suspected heterozygote is a homozygous dominant.see more