Chapter 2 notes BIOS 2250 Genetics
Chapter 2 notes BIOS 2250 Genetics Bios 2250
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This 5 page Class Notes was uploaded by hw767714 on Monday February 1, 2016. The Class Notes belongs to Bios 2250 at Ohio University taught by Dr. Sugiyama in Winter 2016. Since its upload, it has received 42 views. For similar materials see Genetics in Human Society in Biology at Ohio University.
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Date Created: 02/01/16
BIOS 2250 – GENETICS IN HUMAN SOCIETY __________CHAPTER 2 – HUMAN CELLS__________ Cells are the basic functional units of all living things. Cells can differ greatly depending on the function of the cell, but the basic structures of each kinds of cells are similar. All human cells have these four components: ▬ Cytoplasm ▬ Nucleus – The nucleus is enclosed by a double layered nuclear membrane called a nuclear envelope. The nucleus also contains a majority of our genes. ▬ Organelles (this consists of the endoplasmic reticulum, secretory vesicles, ribosomes, golgi complex, lysosomes, and mitochondria) ▬ Cytosol The cell has a plasma membrane that is made up by lipids, proteins, and carbohydrates. The lipid bi-layer, which is made of double layered lipids, is selectively permeable and embedded with proteins. The protein channels regulate the exchange of the materials. The carbohydrates within the plasma membrane give it its molecular identity. Cystic fibrosis is a genetic disorder associated with a change in the Cl- protein channel on the plasma membrane. The abnormality in this specific protein channel can cause issues with sweat, mucus, and digestive enzyme production. There is a thick mucus that clogs the ducts of the pancreatic enzyme that can cause poor digestion and pancreatic degeneration. The symptoms of cystic fibrosis are slow growth, a small body, thick mucus, coughing, and early death. There is no complete cure yet, but a combination of treatments can increase life expectancy. Gaucher’s disease is a genetic disease that causes brittle bones and problems in the liver, spleen, and bone marrow. Gaucher’s disease is caused by a deformity in the lysosome where the lysosome lacks an enzyme that breaks down lipid membranes. Gaucher’s disease has two treatments: an injection of a digestive enzyme or a bone-marrow transplant. Both have pro’s and con’s. Mitochondrial disorders are also genetic. Many of the mitochondrial disorders include fatigue, memory loss, vision problems, and more. This is due to the lack of BIOS 2250 – GENETICS IN HUMAN SOCIETY ATP production. Since we receive mitochondria from our mothers, Mendel’s rule doesn’t apply to this. The cell cycle describes the history of a cell. The cell cycle consists of 3 parts: interphase, mitosis, and cytokinesis. ▬ Interphase is the time between each division. Interphase is broken up into 3 stages: G1 (Gap 1), S (Synthesis), and G2 (Gap 2). ▬ Mitosis is the division of the cell’s DNA to produce two genetically identical cells. Mitosis is divided up into 4 different parts: Prophase, Metaphase, Anaphase, and Telophase. ▬ Cytokinesis is the process of cytoplasmic division that happens right after the cell’s division. Cytokinesis is when the cleavage furrow forms and deepens and the cytoplasm divides. The two daughter cells become separated completely. Prophase – This is when the chromosomes become visible. They become easily recognizable and become shorter and thicker. Each chromosome is now in two strands of replicated DNA known as sister chromatids. In this phase, the spindle fibers begin to form and the nuclear envelope begins to break down. Metaphase – In this phase the spindle fibers have attached and the chromosomes have moved into the middle of the cell. In this stage the chromosomes are in their most tightly condensed form. Anaphase – In this phase the attachments binding the sister chromatids breaks and each half of the chromosome is pulled toward opposite ends of the cell. Telophase – By this phase the chromosomes have reached opposite ends of the cell. The chromosomes begin to uncoil, the spindle fibers begin to break down, and a new nuclear envelope begins to form. Mitosis has been completed and cytokinesis can now begin. Interphase Mitosis and Cytokinesis BIOS 2250 – GENETICS IN HUMAN SOCIETY Meiosis – The process of cell divisions where one chromosomal replication is followed by two cell divisions to produce 4 haploid cells. Instead of each daughter cell having 46 chromosomes, meiosis leaves each daughter cell with 23 chromosomes. One replication of the DNA is followed by 2 divisions of the nucleus. Meiosis ONLY occurs on germ line cells! Once a cell becomes a gamete it can’t go back. BIOS 2250 – GENETICS IN HUMAN SOCIETY There are some genetic diseases related to cell division. ▬ Progeria syndrome is caused by a gene malfunction in the nuclear envelope. This gene malfunction causes the cells to divide rapidly and person ages too fast and has an early death. BIOS 2250 – GENETICS IN HUMAN SOCIETY ▬ Most cases of Down syndrome are caused by meiosis. This is due to an extra chromosome. Cells have different names depending on their makeup and their intended duty. ▬ Haploid cells – When each chromosome is represented once in a cell. It doesn’t belong to a pair. ▬ Diploid cells – When each chromosome is represented twice as a homologous pair within a cell. ▬ Gametes – Sex cells (these are eggs or sperm) ▬ Germ line cells – cells designated to become a gamete ▬ Somatic cells – cells that aren’t germ line cells ▬ Homologous chromosomes – two of the same types of chromosomes. (For example, two chromosome 1’s are homologous chromosomes.) ▬ Sister chromatids – Two identical copies of a chromosome that are made by DNA replication.
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