Compendium Review #2 (Unit one)

Genes are a unit of heredity existing as alleles on the chromosomes (Mader G-8). These genes are in the form of DNA molecules, which allow cells and other organisms to reproduce and replicate (Mader pg.4). Before a cell can reproduce, DNA has to be copied in its exact form in order to make genes that are passed on to our children (Mader pg.4). Genes start to develop in the nucleus, which contains threadlike microscopic bodies known as chromosomes (Unknown). Each species has a different number of chromosomes, but human typically have 46 or two pairs of 23 (Unknown). These chromosomes are made up of a large macromolecule from DNA (Psych book). They contain genes and other nucleotide sequences important for living organisms (psych book). Sperm and eggs from men and women both carry genes contributed by each person. When a sperm fuses with an egg, this combination of genes allow for the reproduction of offspring (Mader pg.4).

Genes and Chromosomes

In order to reproduce a cell, the cell needs to undergo mitosis. By definition, mitosis is a type of nuclear division which is called duplication division because each new nucleus contains the same number and kind of chromosomes as the former cell (Mader pg.379). During this process the sister chromatids of each chromosome separate and become to daughter nuclei (Mader pg.379).
Mitosis
Cell metabolism is all of the chemical reactions that occur in a cell (Mader G-12). DNA holds one of the most important roles in cell metabolism, because of its ability to replicate and make genes that make every human being different from one another. Cell metabolism also often requires metabolic pathways that are carried out by enzymes, and arranged in order (Mader pg 53). Another aspect that is very important to cell metabolism is cellular respiration. This is the process of producing ATP (Mader pg 53).
Cell Metabolism
Many biotechnological products are genetically engineered from bacteria, plants and animals (Mader pg 460). Genetically engineering is bacteria that can be selected for their ability to degrade a particular substance, which can be enhanced through this process (Mader pg 460). According to the text, genetically engineering could help in a situation where naturally occurring bacteria that eats oil do a more extensive job, such as clean whole beaches and oil spills (Mader pg 460). This engineering process is also known as recombinant DNA technology and are used to produce transgenic bacteria that are grown in large vats called bioreactors (Mader pg 460).

Bacteria Bioreactor plants Recombinant DNA
Cancer is defined as a malignant tumor whose non-differentiated cells exhibit loss of contact inhibition, uncontrolled growth, and the ability to invade tissue and metastasize (Mader G-3). According to the text, cancer is a genetic disease (Mader pg 405). In order to go from interphase to mitosis, a molecule known as cyclin needs to be present (Mader pg 405). When cancer actually begins to develop, the cell cycle repeats itself, mainly due to mutations in two types of genes (Mader pg 406). These two types of genes are Proto-oncogenes, and Tumor-suppressor genes. The Proto-oncogenes are what code for proteins that promote the cell cycle, and are considered the cause of acceleration of the cells cycle (Mader pg 406). The Tumor-suppressor genes also code for proteins, and are often considered the inhibit acceleration of the cells cycle (Mader pg 406).
Cancer cell
In early fetal development, there are three main stages a fetus goes through. These stages include the Germinal Stage, the Embryonic Stage, and the Fetal Stage (Feldman pg 75). The Germinal stage occurs from fertilization to two weeks of age. This is the shortest stage of prenatal development, but important because this is when the placenta is able to be used for nutrients and waste disposal through the umbilical cord (Feldman pg 74). The Embryonic stage occurs two weeks to eight weeks following fertilization (Feldman pg 75). This is the most important stage because the entire development of a child occurs during this stage (Feldman pg 75). There are three layers that form a different set of structures as a child’s development proceeds (Feldman pg 75). These layers are called the ectoderm, endoderm, and mesoderm. The ectoderm is where skin, hair, teeth, sense organs, the brain, and spinal cord will develop (Feldman pg 75). The endoderm produces the digestive system, liver, pancreas, and respiratory system (Feldman pg 75). Lastly, the mesoderm is where the muscles, bones, blood, and circulatory system are formed (Feldman pg 75). The last stage in fetal development is the fetal stage. This occurs from eight weeks until birth. Now the child is considered a fetus, and this is where labor comes into play (Feldman pg 75).
Fetal Development
During all of these stages genes and chromosomes will be passed down to a child, and different aspects of their life are inherited (Feldman pg 125). Genes are what makes us look, and where different aspects of our behavior come from (Feldman pg 125). Chromosomes also play a very important role, and without even just one of them could cause several problems. For example, Fragile X syndrome occurs when a particular gene is injured on the X chromosome, which results in mild to moderate mental retardation (Feldman pg 56). Down syndrome can also occur when the presence of an extra chromosome is on the 21st pair. Another disorder is Klinefelter’s syndrome. Klinefelter’s syndrome occurs when there is the presence of an extra X chromosome, which accounts for genetic ‘gender’ related abnormalities (Feldman pg 56). These abnormalities occur from receiving the improper number of sex chromosomes (Feldman pg 56). In conclusion, having the correct amount of chromosomes and properly working genes can mean a huge difference in people’s lives.

Down syndrome chromosome Klinefelter’s syndrome Fragile X syndrome

Citations:
Mader, Sylvia. Human Biology 10th edition. 2008
Feldman, Robert. Development across the life span 4th edition 2006.
Unknown. Basic genetics:. http://www.dnatesting.biz/Basic_Genetics/basic_genetics.html
Picture citations:
Gene and chromosomes - http://people.na.infn.it/~nicodem/research/cell_genes.jpg
Mitosis - http://www.dartmouth.edu/~cbbc/courses/bio4/bio4-lectures/images/mitosis.JPG
Cell metabolism - http://www.hopkinsmedicine.org/bin/n/v/CellMetabolismArt.jpg
Bacteria - http://www.scharfphoto.com/fine_art_prints/archives/199812-026-Staph-Bacteria.jpg
Bioreactor plant - http://www.pharmaceutical-technology.com/projects/sbl_vaccin/images/sbl1.jpg
Recombinant DNA - http://www.gene.com/gene/research/biotechnology/images/expressionofdna.jpg
Cancer cell - http://www.hlb.com/inovlog/archives/Cancer%20cell1.jpg
Fetal development - http://www.orwelltoday.com/babyub2.jpg
Down syndrome - http://library.thinkquest.org/04oct/00880/plaatjes/trisomie-21-180.jpg
Klinefelter’s syndrome - http://www.healthofchildren.com/images/gech_0001_0002_0_img0156.jpg
Fragile X chromosomes - http://www.ikm.jmu.edu/Buttsjl/ISAT493/Fragile%20X%20Syndrome/fragilearea.jpg