A codon is basically a "word" in the genetic code.
Let's start at the base. A base is the smallest unit of information in genetics. It is a chemical represented by either A, T , C, G or U.
These genetic "letters" are combined into "words" which are called codons. What is useful is that each codon is only made of 3 bases. You'll have CCT, GAT, TTA etc. So what do these words represent? Well they can be instructions, like START or STOP, but usually they represent an amino acid, the LEGO building blocks of proteins. There are around 20 AAs but a bit of maths tells us we have a lot more codon combinations than AAs. This means we have some synonyms where several codons can represent one AA.
To take the analogy further, the codons combine into "sentences" and then "chapters". The chapters are a gene, usually instructions for a complete protein, but some of the sentences are useless and will be ignored when translating into a protein.
Then we have the "Book" which is the chromosome. The reason I like to think of it as a book is that at this point it is a contained unit, a massive molecule. You can separate up your books and even lend one to a friend, but you can't do that with a chapter unless you destroy the book.
Finally you have you "library" or genome. It's not a big collection, 46 books in total, and in fact you have 2 copies of each. It's like inheriting 2 sets of encyclopaedias from your parents. They both have the same information, it is just explained in different ways.
And there is my book analogy of genetics. It's not perfect but works when used on small children.
Answer:
It is likely that Jeremy’s<u> basal nuclei</u> is producing less <u>dopamine </u>than it needs to.
Explanation:
Parkinson's disease is caused by less production of neurotransmitter dopamine from basal nuclei present in the cerebrum of the brain. Lower levels of dopamine have caused Jeremy's mental health. He needs to smoke more than earlier to fight depression caused by lower dopamine levels.
Dopamine imbalance would also affect his balance and coordination of muscles. He would not be able to perform the routine tasks by himself.
I believe it is C but not sure.
A cell membrane is semi-permeable. This means that it is size-specific. It allows only a particular maximum size of particles to pass through it. Large molecules such as plasma proteins and lipid molecules cannot therefore penetrate while small moecules such as glucose will easily diffuse across it.
Secondly, a cell membrane is charged. The charge is as a result of a difference in ionization between the intracellular fluid and the extracellular fluid. Substances that have the same charge as the fluid into which they are diffusing will be hard to asorb due to repulsion effect. On the other hand, substances that have opposite charge as the fluid into which they are diffusing will be absorbed easily and faster.
Finally, the cell membrane is made of two layers. Lipid layer and phospholipid layer. Inside these layers, there are embedded particles and substances such as enzymes, receptors, hormones and ion channels. During diffusion of substances across cell membrane, some substances are speeded up by these substances. For instance, Translocase enzyme in the membrane of mitochondria speeds up the transfer of Carnitine transferase into the mitochondrial matrix.
