Tutor profile: Sarah B.
Subject: Organic Chemistry
What is a free radical?
All stable atoms normally exist with all the electrons in their outermost shell (valence electrons) in pairs. A free radical is an atom that has unpaired valence electrons. This makes it unstable and therefore highly reactive as it is incomplete and looking to make a complete pair with electrons from other atoms or molecules or even from itself. Free radicals can play an important role in various chemical reactions or processes but biologically can cause damage when they occur in the human body. A common chemical reaction that uses free radical chemistry is when a halogen is needed to be added to a hydrocarbon, for example Chlorine. Can you think of how we would make a Chlorine radical?
Subject: Basic Math
What does it mean to find the 'square root' of a number?
The square root of a number is whatever number is multiplied by itself to get the number that you have. Let's say that you have the number 9. The square root of 9 is 3 because 3 multiplied by itself (ie 3x3) equals 9. Now you have a go, what do you think the square root of 25 is (ie what number multiplied by itself equals 25)?
What is DNA?
DNA (deoxyribonucleic acid) is molecule that carries genetic information and is found in the cells of all living organisms and many viruses. It is a very long molecule made of two strands joined together and is coiled very tightly, like a spring, in what is known as a double helix (show picture). The information that this DNA carries is to do with the growth, development, functioning and reproduction of it's owner. Basically, anything involved in the physical working of your body is found in your DNA - your hair colour, eye colour, gender etc. called 'traits'. Each trait is determined by a section of DNA called a gene. Can you think of other 'traits' that are decided by genes that you have?
needs and Sarah will reply soon.