Tutor profile: George H.
Subject: Biomedical Science
What is a gene?
A gene is the specific section of a chromosome which contains the order of amino acids required to make a specific protein. The entire collection of genes from one organism is called the genome, but a single part of that genome which codes for a single protein is called a gene. Transcription is the process which begins the formation of a protein from a specific gene.
Subject: Basic Chemistry
What is an atom? What is a molecule?
An atom is a usually made of a cluster of protons and neutrons, with a group of rotating electrons moving around the outside. An exception to this rule is the centre of the hydrogen atom (the atom's centre is called the 'nucleus') which is made up of a single proton. The number of protons is equal to the number of surrounding electrons, which means the overall charge of an atom is 0. This is because protons have a positive charge and electrons have a negative charge. In chemistry, a molecule is more than one atom joined together into a single unit. Furthermore some atoms prefer to join with other specific atoms. For example, carbon tends to be attached to hydrogen when they are together in a molecule.
How does a cell create itself? Where are the instructions?
First, lets imagine a balloon filled with water. Inside you have some small objects, all of which have different shapes and sizes. We could say they are 'suspended' in the water, because they do not move around much and each float in a different section. This is exactly how a cell looks close up, but much smaller. This is important to understand because some drawings of a cell make it look flat, when it is actually 3-dimensional. Around the outside of the cell is a membrane, which is a layer that protects the cell's contents but lets some molecules and ions (charged particles) move in and out. Inside the cell, the different structures each have a different job. The scientific name for each structure is 'organelle'. One of these organelles is called the nucleus, and it contains the instructions for making different parts of the cell, as well as molecules that can send messages, either inside the cell or outside. The instructions in the cell are made from two different molecules called 'DNA' and 'RNA'. The instructions in the nucleus can also tell the cell to split into two, and this is called 'mitosis'. When a sperm and egg cell join together, they begin to split into two over and over again, eventually creating a small group of cells, which eventually grows in size until it is a baby. This does not stop at birth, or even when we become adults. The cells inside our body keep being made by splitting into two, until we die. In some parts of the body, this happens very slowly, but in other parts, this happens quickly. An example of cells splitting into two very quickly is the skin. This means that we shed a layer of dead skin cells constantly. In summary, the nucleus contains the instructions for making all the different parts of the cell. It can also instruct the cell to split into two, and this is called 'mitosis'. The cells in our body are constantly dividing, although some do this quicker than others. Finally, the different structures inside the cell are called 'organelles'. Some questions to test yourself: 1. What is the scientific name for the different structures in a cell? 2. Where are the instructions for the cell found? 4. What is it called when a cell divides into two?
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