Genetics Standard 2

In standard two of genetics we learned about the human body with the same genes and cells that are in it, the differences between mitosis and meiosis, the different stages of meiosis, different types of reproduction, and patterns of inheritance.

In the human body we are made up of many little things. To figure out about genetic recombination, first we should know what is being recombined. There are a few main cells in our body, germ cells and somatic cells. Germ cells are the cells in your reproductive organs. These cells are found in the ovaries or testes. They are also called gametes. The germ cells develop into either eggs or sperm. Which then help make a baby.

Somatic cells are known as body cells. They are all the other cells in your body. You would find somatic cells in your tissue and organs. Somatic cells, however, do not get passed down, but the germ cells (eggs and sperm) do get passed down to your children.

After passing down genes to your child, he/she will be left with 23 pairs of chromosomes or 46 chromosomes. In doing so, for each pair one gene will be passed from the mother and the other will be passed from the father, also called homologous chromosomes.

In the process of meiosis they start in the first stage “prophase I,” which is when the nuclear membrane is starting to break down, preparing itself to be split in half. Then “metaphase I,” the chromosomes line up against the line going through the middle. Next, “Anaphase I,” they start to separate, and the sister cells are still together. “Telophase I,” is when they finally split, making 2 eggs. Once Meiosis I is over, there is now meiosis II. Meiosis II is just like meiosis I, but instead it makes 4 haploid cells.

Although ever single person is made the same way, no one has exactly the same genes unless they are identical twins. You may ask yourself why full blood siblings look similar but not exactly the same, I mean they are from the same parents so they should look alike right? You would think that that would happen, but because of things like genetic recombination, no one is ever going to look completely the same.

One way to mix the genes of an offspring is crossing over. Crossing over is when pieces of a chromosome break off and attach to another homologous chromosome. When this happens it is mixing the parts of the chromosome giving it a kind of “twist” that will eventual make the child more unique but mixing it to slightly change an appearance of a feature. When crossing over, it’s not just two random chromosomes, it is a piece from each chromosome that are matched together in a chromosome pair. Crossing over helps

make a feature different that a possible sibling or even someone who may have genes that may be very closely related.

The other ways to show genetic variation is though mutations. There are two mutations that I am aware of that go on in chromosomes. The first one is deletion.

Deletion is when there is a line of genetics and while they are being copied there are few genes that are just randomly taken out of the line of genes. This shows genetic variation because the genes that are deleted aren’t purposefully deleted so it would be extremely rare for someone to have the exact same gene type as the person whose genes went through deletion. I think that missing a set of genes may be fatal if those genes missing were required to function.

There is another type of mutation; this kind is called duplication of genes. This is when the homologous chromosomes are being copies and then an extra pair of one of the homologous structures are copied into the gene line and added on. This also would be very rare just like the deletion of genes. In most cases I would guess that having an extra set of genes wouldn’t make that much of a difference.

Deletion and duplication of genes are important because scientist can manual do this. Doing so they can find genes that trigger things like autoimmune diseases or things like cancer. If they take genes and compare and contrast them with and without a certain disease they can them take that gene from the chromosome, deletion, and find what counteracts with the gene that cause the disease and then add those genes that cure the illness and then inject patients with it and add, duplicate, the gene into their body so they may hopefully no longer have the sickness.

The last kind is genetic linkage. Genetic linkage is when genes are inherited together because they are on chromosome. Genetic linkage only happens when they are inherited together. So a gene from a completely different chromosome can’t link to a different one because they are not close together. If they are close together then they are inherited together.

Genetic diversity and variation is very important. With variation, the genes that are more successful are going to be passed down and give us a higher chance of surviving because they are being passed down. Variation is also key because if someone has a week

respiratory system or immune system then the healthier system will be passed down. It also causes mating success.