Same And Different
Environment makes a difference
Almost all of your features are affected by the information you inherit from your parents. Some features are the result of only your environment such as scars and tattoos.
But most of your features are affected by both your genes and your environment. For example your weight depends on your inherited information, but if you eat too much you become heavier.
If you look at cells under a microscope you can see the nuclei. Inside each nucleus are long threads called chromosomes. Each chromosome contains thousands of genes. It is genes that control how you develop.
What are chromosomes made of?
Chromosomes are made of very long molecules of DNA. DNA is short for deoxyribonucleic acid. A gene is a section of DNA molecule.
How do genes control your development?
A fertilised egg cell has the instructions for making every protein in a human being. Genes are instructions for making protein. Each gene is the instruction for making a different protein.
Structural proteins – To build the body, e.g. collagen, the protein found in tendons
Functional proteins –To take part in the chemical reactions of the body, for example, enzymes such as amylase
Genes control which protein a cell makes. This is how they control what the cell does and how an organism develops.
Same But Different
Identical twins are formed when a fertilised egg cell starts to divide and splits forming two babies instead of one. Each baby has the same genetic information. This means any differences between them will be caused by the environment.
Genetically identical organisms are called clones. So identical twins are human clones. Plant clones are quite common. Strawberry plants and spider plants are just two sorts of plant that make identical plant clones at the end of runners. Bulbs, like daffodils, also produce clones.
It’s easy for people to clone plants artificially. This can be done by taking cuttings. A piece of adult plant is cut off. It soon forms new roots and stems to become a small plant genetically identical to the original parent. The new plant is a clone. It has the same genes as the parent.
You can also make clones from tiny pieces of plants grown in special jelly, called agar. In this way you can make hundreds of clones from a single plant.
What Makes You The Way You Are?
Huntington’s disease is an inherited disorder. You can’t catch it. The disease gets passed on from parent to offspring (child). The symptoms of Huntington’s disease don’t appear until the middle age. First they have problems controlling their muscles. This shows up as twitching. Then gradually the sufferer becomes forgetful and find it harder to understand things. People with Huntington’s tend to have mood changes. After a few years they can’t control their movement. The condition is fatal.
How do you inherit your genes?
Parents pass on their genes in their sex…