The Process Of Cell Division In Animals - Coursework Example

? work work 4. Explain the process of cell division in animals. Include a of interphase, mitosis and cytokinesis. Every eukaryotic cell has a repeating set of events known as cell cycle which results in cell growth and division into two daughter cells. The cell cycle comprises of four important stages. S stage is for synthesis and DNA replication occurs in this stage. G2 comes after and S phase and is the phase of DNA repair and correction of any mistakes made during DNA replication. Only the cells with repaired DNA are allowed to enter the M phase. M phase or mitosis is when nuclear and cytoplasmic division occurs culminating in the formation of daughter cells. Cytokinesis is the cytoplasmic division of the parent cells. When a fibrin ring called actin contracts around the center of the cell, it leads to pinching of the cell into two daughter cells, each containing one nucleus. Interphase is not technically a part of mitosis as it is the phase in which the cell is metabolically prepared for mitosis. Chromosomes are not clearly distinguished and the pair of centrioles starts appearing. 5. Suppose someone presented data from their research that showed the DNA of a newly discovered species was composed of: 30% adenine, 30% guanine, 20% thymine, 20% cytosine. Based on what you know about DNA structure, explain why these data do not make sense. The Chargaff’s rules indicate that the amount of adenosine equals the amount of Thymine and the amount of Guanine equals the amount of Cytosine. Therefore, the total purines equal the total pyrimidines. However, the rules only apply on double-stranded DNA or double stranded RNA and single stranded nucleic acids such as in viruses do not follow the Chargaff’s rule. The data presented shows 30% adenosine and 20% thymine, and 30% guanine in comparison to 20% cytosine. This data contradicts the Chargaff’s rule, indicating that it is not a double-stranded nucleic acid and most likely represents the base pairing of single-stranded nucleic acid, maybe in viruses. 6. What are the differences between a covalent bond and an ionic bond? In a covalent bond, the atoms are bound by the sharing of electrons. The electrons are shared either equally or unequally between the two atoms. If the electrons are shared equally between the two atoms, the covalent bond is said to be non-polar. If the electron is attracted more towards one atom than another, it leads to the formation of a polar covalent bond, for example the molecule of water H2O. In contrast, the ionic bond of two atoms is formed by the forces of attraction between oppositely charged ions. For example, NaCl is formed by the positively charged Sodium (Na) atom and the negatively charged Chloride (Cl) atom. 7. Water is crucial for life as we know it. One of the most important characteristics of water is its ability to act as a solvent. Explain why water is such a good solvent for polar and charged molecules. The physical and chemical composition of water makes it a very good solvent for polar and charged molecules. Water molecule is made up of positive electrical charge of Hydrogen atoms and the negative charge of Oxygen atom. This forms a very strong polar covalent bond and contributes it a property of being a good solvent, by disrupting the attractive forced between other charged molecules. The polar molecules are easily dissolved in water because the forces of attraction are disrupted between the solute. The positive charges are attracted towards the negative Oxygen pole of water and the negative charges of the solute are attracted towards the positive Hydrogen pole of water. The atoms of solute are then surrounded by water molecules, making it a good solvent for charged and polar molecules. 8. Suppose you are taking a cruise from California to Hawaii. About halfway there, the ship begins to sink. You are able to board a lifeboat, but now you are floating in the ocean waiting to be rescued. After several days, you are so thirsty that you bend over the side of the boat and drink lots of salty seawater. Explain what you think will happen to your body within a few hours of drinking the ocean water and what would be the biological basis for your answer. The human body is divided into two main body fluid compartments, intracellular fluid (ICF) and extracellular fluid (ECF). The electrolytes, sodium and potassium form the two main determinants of cell osmolality and homeostasis. The electrolytes are maintained in a state of equilibrium such that the concentration of sodium outside the cell is more as compared to the inside. In contrast, potassium is higher in concentration inside the cell. Intake of salty water would create a hypertonic environment outside the cell i.e. water is in low concentration as compared to the solute. According to the rules of diffusion, the water will move from higher concentration to lower concentration, making the water to diffuse from the ICF into the ECF. As the water concentration moves out of the cell into the ECF to maintain equilibrium, this would lead to shrinking of the cell. 9. DNA and RNA are similar yet distinct components of the cell. Describe three differences between RNA and DNA with respect to their chemical composition and structure. Provide a detailed description of each characteristic you chose in your response. DNA and RNA are nucleic acids which are polymers of nucleotides joined by phosphodiester bonds. Nucleotides are composed of nitrogenous bases combined with a sugar and phosphate group attached at the 5`carbon of the sugar. The nitrogenous bases include purines i.e. adenine and guanine, and pyrimidine i.e. cytosine, uracil and thymine. The difference in DNA and RNA is in their chemical composition and structure. DNA or deoxyribonucleic acid is composed of a deoxy ribose molecule while RNA has ribose sugar molecule. The pyrimidine is also different in DNA and RNA. DNA has a cytosine pairing with thymine while the RNA has a cytosine pairing with Uracil. The DNA is generally double stranded in eukaryotes and RNA is mostly single stranded. Two strands are linked together in DNA to form a double helical structure. Certain exceptions are seen in viruses, where DNA can be single stranded and RNA double stranded. 10. Why would you quickly die if not for the action of enzymes in your cells? Enzymes are the most essential elements in our body that are important for life. Enzymes are crucial for the formation as well as break down of different molecules in our body. Enzymes construct, synthesize and deliver essential for life body nutrients. Enzymes at the same time eliminate dangerous molecules from our body. Absence of enzymes in our digestive system will lead to inability of the body to produce glucose that is essential for life and body metabolism. This would lead to inability of human body to survive. Similarly, inability of the enzymes required to produce the nucleic acids would result in loss of formation of important genetic information leading to structural, chemical and physiological malformations. Although present in small quantities, enzymes are essential for life. Low quantities can produce certain diseases but absence of crucial enzymes leads to death. 11. List the four “large molecules of life.” Identify their composition and structure, and describe one function they perform in the cell. The four biological macromolecules are carbohydrates, lipids, proteins and nucleic acids. Carbohydrates are a major source of energy for the cell and are also stored in the form of glycogen to be used exercise, starvation or stress conditions. They are composed of monosaccharaides including glucose, fructose, disaccharides includes lactose, sucrose and polysaccharides including starch, glycogen. Proteins are the structural components of body parts and also function as storage molecules, hormones, antibodies, transport proteins and contractile proteins. Proteins are polymers of amino acids and are made up of 20 kinds of different amino acids arranged in different sets joined by peptide bonds. Lipids are hydrophobic molecules consisting of fats, oils, cholesterol, steroids and phospholipids. Lipids form important components of cell membranes, help in energy storage and insulation of our body. Steroids form the basic sex hormones which are testosterone and estrogen. Nucleic acids are the building components of chromosomes that contain the genetic material transferred from parents to offspring. Nucleic acids are of two types DNA and RNA that store genetic information as well regulate the formation and expression of different enzymes and important cellular function. Nucleic acids are polymers of nucleotides which comprise of nitrogenous bases, sugar molecule and phosphate molecule. Read More