Mitochondria and The Golgi Complex
Work Book Section II a(i) Mitochondria a(ii) The structure and shape of the shape in the diagram suggested to me that it was a mitochondria cell. The structure of the all round shape and also the inner walls to the mitochondria cell. b(i) Golgi Complex b(ii) and 1c A membrane bound compartment in the interior of a cell. This compartment is involved in modifying, sorting and packaging lipid, carbohydrate and protein molecules for secretion or for delivery to other organelles. www.lsdn.com/glance_glossary.shtml One of the organelles that is in both the animal and the plant cells is the golgi apparatus. In this organelle, the endoplasmic reticulum (ER) sends vesicles(The function of the vesicles are to mainly transport proteins and other cellular material between cells and organelles) to the Golgi complex where they fuse with the cell membrane. Their membrane, which has now added to the membrane of the sacs of the golgi, empties it's contents of it into the golgi sac. Audesirk, Teresa; Audesirk, Gerald; "Fifth Edition Biology Life on Earth" Prentice-Hall; 1999 The Molecular Biology of The Cell. Second Edition. New York. Garland Publishing, Inc. 1989 d Single-membrane structure. The thickness of structure C shows to be only a single membrane cell. Also the structure when compared to other similar looking cells on the diagram, such as structure D, looks less rigid and
Most cells are very small. What physical and metabolic constraints limit cell size? What problems would an enormous cell encounter? What adaptations might help a very large cell survive?
Assignment 2: Most cells are very small. What physical and metabolic constraints limit cell size? What problems would an enormous cell encounter? What adaptations might help a very large cell survive? The cell is an amazing structure. A single cell, alone, can function as a single entity: independently acquiring the nutrients it needs to survive, adapting to its environment, and eliminating the wastes it accumulates. Other cells, however, would rather be a part of a community of cells, like a tissue or higher organism. These cells often become specialized; they may specialize in motility, or they may be better suited for absorption and secretion. Whether these cells are suited for autonomous living, or become specialized for a specific function, the size of the cell is a general feature that relates to its function. Some cells, like bacteria, can be as small as a few microns. Other cells, like neurons, have axonal extensions that can travel a few meters long in some organisms. For the most part, however, cells are very small. So, what are the constraints that limit the cell to its small physical size? What types of problems would a cell that diverges from these constraints encounter? Finally, how do those cells that are very large, compared to the majority of cells, adapt to their larger size? These are the questions that will be explored. Cells are small. The
Prokaryotes and Viruses
Prokaryotes and Viruses . Eukaryotic cells tend to be complex in nature. They make up the structures of complex organisms such as animals, plants, fungi and protoctista. The name eukaryotes itself means 'true-nucleus',1 this is because of the nature of its DNA being enclosed in a nuclear membrane. This leads to one of the features that make eukaryotic cells distinctive. That is compartalization; this is very distinct in eukaryotic cells this is the separation between different organelles and groups. The organelles maintain their groups to ensure processes such as respiration and protein synthesis don't mix chemicals. Various compartments are nucleus, plasma membrane and cytoplasm. Leading on from compartalization the cell structure it is quite complex, it consists of a various organelles that may differ depending on the organism the cells are in. Normally they contain organelles such as nucleuses, mitochondria, ribosome's and countless others. Eukaryotic cells are also able specialize, this is when cells adapt to their environment and perform specific processes and actions, such as the red blood cell which carries oxygen or the nerve cell which carries impulses.2 2. Gram staining is a method of staining used to indentify and classify different bacteria. The process itself is used to differentiate between two major cell wall types present in bacteria. These are gram negative
PoMC cell function
POMC and Human Pigmentation Proopiomelanocortin or POMC and the neuropeptides derived from it, participate in several cardinal processes that control the central nervous system and peripheral tissues. Although, POMC regulates melanocortin or MC receptors in their local activation process, its role in extracellular proteolytic processing has been largely ignored. Several research scientists have been investigating important mechanisms that have significance in controlling the bio-availability of adrenocorticotropin and hormones that stimulate cutaneous melanocyte. This has been done in the context of peptidases like neprilysin - or neutral endopeptidase or NEP, and the ACE or angiotensin - converting enzyme (König et al, 2006, Pp. 751 - 761). The skin constitutes a source, as well as a target organ for the actions of neuropeptides derived from proopiomelanocortin or POMC. These peptides are ACTH, ?-melanocyte stimulating hormone or ?-MCH, and ß-endorphin. The levels of POMC genes and corticotropin releasing hormone peptides or CRH peptides are not constant in the skin. Their levels vary due to several factors, like the physiological changes relating to hair cycles, which are at their zenith during the anagen phase; physiological changes resulting from exposure to ultraviolet radiation; cytokine releases; and the incidence of cutaneous pathology (Slominski et al, 2000, Pp.
What is HIV?
HIV/AIDS Srabonti Ali The world is plagued by the HIV infection which almost always precedes AIDS . If you are HIV positive, that doesn't mean you have AIDS. However, having AIDS means that you most definitely are HIV positive. HIV or Human Immunodeficiency Virus, basically breaks down your immune system until it eventually cannot function properly anymore. AIDS (Acquired Immune Deficiency Syndrome) never really kills anyone, instead it is a disease like pneumonia or something similar that the body cannot fight because its immune system is shot. (1) The first reported case of AIDS in the United States was in 1981. Nearly 900,000 American citizens are have the HIV virus and about 600,000 Americans have the AIDS virus itself. (3)HIV and AIDS are rapidly growing throughout not only the nation, but the entire world. The most common way to get infected with HIV is through sexual contact with an infected person. Other ways of getting infected are through intravenous needles, blood transfusions. Also, sometimes a pregnant mother can pass on the infection to her fetus before it is born. After the baby is born it is also possible for the baby to get infected through breast-feeding. (1) Most people do not have any distinct symptoms early on. Two months after the first exposure to the virus infected persons may experience flu-like symptoms such as fever, headache, depression and
Translocation of soluble products of photosynthesis occurs in the part of the vascular tissue known as the phloem.
Transport system in a plant is concerned with the movement of materials from source to sinks. According to Lacher .W 1985, a source is a region of a plant, which is manufactures sugars during photosynthesis and supplies materials of any kind to the transport system (e.g leaves) and a sink as a region where the sugars and minerals are being removed or lost from the system to be used up or stored (for example the root and production of fruit). Transport of soluble products of photosynthesis is called translocation. Translocation of soluble products of photosynthesis occurs in the part of the vascular tissue known as the phloem. The phloem is the principle food conducting tissue associated with xylem in the vascular system. The basic components of phloem are sieve elements, companion cells and phloem parenchyma and phloem fibres. It is placed outside the cambium of the vascular bundle (www./http://infotrac.thomsonlearning.com). It is well known that soluble products of photosynthesis formed in the photosynthetic tissue, enter the sieve tubes by active transport. The movement of materials once they are in the sieve tubes is still under debate as to which and what is the driving force. Although sugars and amino acids tend to move along concentration gradients the speed at which they travel is too fast to be explained simply by diffusion. There presently four proposals of
Explain how the action potential is generated and is transmitted along the axon. Include information about the effect of myelin on the speed of transmission.
. Explain how the action potential is generated and is transmitted along the axon. Include information about the effect of myelin on the speed of transmission. 655 words The brain and the spinal cord form the central nervous system (CNS). The CNS processes information using millions of nerve cells (or neurones). In order to understand their function and process, a description of the neurones and their environment seems necessary. This will lead to the second part which will cover the neurone's actual action potential generation and transmission. Neurones are constituted of an outer membrane, a cell body (or soma) and a nucleus. These characteristics are common to all body cells. Nevertheless, other fundamental features are needed in order to respond to environmental changes: the dendrites that surround the soma and receive nerve impulses. The axon, connected to the soma by the axon hillock, is composed of myelin and nodes of Ranvier, through which the impulses pass. Finally, the impulses reach the axon terminal, and through the synapse, get transmitted to the next neurone. The neurone's resting membrane potential represents its stability, when not stimulated or firing. The cell's charge is -70 mV, the cell is negatively charged whereas the outside is less. The membrane controlling ions moving in and out the cell through ion channels using ion pumps (sucking in or
Animal Physiology - The Nervous System - To understand Resting and Action Potential
Animal Physiology The Nervous System AIM: To understand Resting and Action Potential All living cells have electrical differences across the membrane this is called the membrane potential and is defined as the electrical potential measured from within the cell relative to the potential of the extracellular fluid. Only some cells (neurones and muscle)have the ability to change the membrane potential and are known as Excitable cells. Neurone signals start as a change in the electrical gradient across the membrane , the signal is then transmitted along the length of the neuron to the axon tip. The gradient depends on the ion flow across the membrane (The ions move through ion channels in the membrane) An unexcited neurone is at its resting state - refer to figures 21,22 booklet 1. Figure 22 shows that the invertebrates may have large neurones as in the giant squid, they are good model systems. NB: The electrical currents of membrane potentials are formed from the net flux of charged particles that move across the membrane. Resting Membrane Potentials (RMP) The RMP arises as a small build up of negative charges forming just inside the neurone, there is also an EQUAL build up of positive charges on the outside of the neurone. The RMP is measured in millivolts (mV) and typically lies between -40 and -90 mV. The RMP arises from differences in the ion concentrations
Describe the Mechanism of Peptide Bond Hydrolysis by Serine Proteases and discuss the specificity of these enzymes
Describe the Mechanism of Peptide Bond Hydrolysis by Serine Proteases and discuss the specificity of these enzymes. Proteins are essential for all living systems and once used they need to be broken down into peptides and amino acids. These amino acids can then be recycled for the synthesis of more proteins. Berg et al (2002) stated that proteolytic reactions are also important in regulating the activity of certain enzymes. The hydrolysis of peptide bonds in the absence of a catalyst is extremely slow and a typical peptide bond in a neutral pH will have a hydrolysis half-life of between 10-1000 years (Berg, 2002). Berg (2002) explained that the resonance structure that accounts for the planarity of a peptide bond makes such bonds resistant to hydrolysis. This is because for every pair of amino acids linked by a peptide bond there are six atoms that lie in the same plane. Therefore it is essential to use a proteclytic enzyme or a protease to promote peptide bond cleavage. Serine proteases are used in the hydrolysis of peptide bonds and include chymotrypsin, elastase and trypsin. Proteases catalyse peptide bonds in polypeptides and proteins and according to Mathews et al (2000) serine proteases are distinct because they all have a serine residue that plays a critical role in the catalytic process. These serine proteases all have a similar three-dimensional
Nucleotide Excision Repair
The Importance of DNA Repair Systems and Process of Nucleotide Excision Repair Name: Thien Nguyen ID: 20299974 TA: Kristyna Wilson Bio 130 Tutorial Tuesday, November 10th 2009 As we go about our daily lives, our cells are hard at work to maintain our well-being. Whether it is providing the energy required doing everyday tasks or just repairing what has been damaged from the constant bombardment of harmful forces, the cell is a formidable force on its own. And it should, because within every cell, DNA enclosed, which is the genetic information that houses the instructions for an organism to function and also a very vulnerable part of the cell to harmful alterations. With radiation, the backbone of a DNA is broken, when exposed to reactive chemicals or UV light; the DNA's bases can be altered structurally (Karp, 2008). While there are many mechanisms for repair for DNA, the nucleotide excision repair (NER) is one of the most effective and versatile repair systems within the cell that acts on the DNA. The reasons for this is because of its ability to recognize, remove a wide variety of alterations in the DNA called lesions, and replacing the damaged part of the DNA (Leibeling et al, 2006). Before this system can do any work on the damaged part of the DNA, it must recognize the lesion first. There are two ways pathways in which the nucleotide excision repair can