Saturday, October 9, 2010
CHAPTER 7: Respiration
Respiration may refer to:
- Cellular respiration, the process in which nutrients are converted into useful energy in a cell
- Respiration (physiology) and Breathing, the physiological process that enables animals to exchange carbon dioxide, the primary product of cellular respiration, for fresh air.
- Anaerobic respiration, cellular respiration without oxygen
- Aquatic respiration, the process of animals extracting oxygen from water
- Carbon respiration, a concept used in calculating carbon (as CO2) flux occurring in the atmosphere
- Ecosystem respiration, measure of gross carbon dioxide production by all organisms in an ecosystem
- Root respiration, exchange of gases between plant roots and the atmosphere
- Maintenance respiration, the amount of cellular respiration required for an organism to maintain itself in a constant state.
click here for subtopics: 7.1, 7.2, 7.3, 7.4
CHAPTER 5: Cell Division
Cell division is the process by which a parent cell divides into two or more daughter cells. Cell division is usually a small segment of a larger cell cycle. This type of cell division in eukaryotes is known as mitosis, and leaves the daughter cell capable of dividing again. The corresponding sort of cell division in prokaryotes is known as binary fission. In another type of cell division present only in eukaryotes, called meiosis, a cell is permanently transformed into a gamete and cannot divide again until fertilization. Right before the parent cell splits, it undergoes DNA replication.
For simple unicellular organisms such as the amoeba, one cell division is equivalent to reproduction-- an entire new organism is created. On a larger scale, mitotic cell division can create progeny from multicellular organisms, such as plants that grow from cuttings. Cell division also enables a sexually reproducing organisms to develop from the one-celled zygote, which itself was produced by cell division from gametes. And after growth, cell division allows for continual construction and repair of the organism. A human being's body experiences about 10,000 trillion cell divisions in a lifetime.
The primary concern of cell division is the maintenance of the original cell's genome. Before division can occur, the genomic information which is stored in chromosomes must be replicated, and the duplicated genome separated cleanly between cells. A great deal of cellular infrastructure is involved in keeping genomic information consistent between "generations".
*Definition from http://en.wikipedia.org/wiki/Cell_division
Click here for slide show (Meiosis)
Click here for slide show (Mitosis)
Saturday, May 1, 2010
CHAPTER 4: Chemical Composition of the Cell
Hydrogen, oxygen, nitrogen, carbon, sulfur, and phosphorus normally makeup more
than 99% of the mass of living cells.
- Ninety-nine percent of the molecules inside living cells are water molecules.
- Cells normally contain more protein than DNA.
- Homogenous polymers are non-informational.
- All non-essential lipids can be generated from acetyl-CoA.
- Like certain amino acids and unsaturated fatty acids, various inorganic elements are dietarily "essential".
- Most all diseases in animals are manifestations of abnormalities in biomolecules, chemical reactions, or biochemical pathways.
Sunday, April 18, 2010
difference between seizures and epilepsy
Seizures are a symptom of epilepsy. Epilepsy is the underlying tendency of the brain to produce a sudden burst of electrical energy that disrupts other brain functions. Having a single seizure does not necessarily mean a person has epilepsy. A number of factors, including high fever, severe head injury and lack of oxygen, can affect the brain enough to cause a single seizure. Epilepsy, on the other hand, is an underlying condition that affects the delicate systems that
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First Seizures: Many people have a single seizure at some point in their lives. Often these seizures occur in reaction to anesthesia or a strong drug, but they also may be unprovoked, meaning that they occur without any obvious triggering factor. Unless the person has suffered brain damage or there is a family history of epilepsy or other neurological abnormalities, these single seizures usually are not followed by additional seizures. One recent study that followed patients for an average of 8 years found that only 33 percent of people have a second seizure within 4 years after an initial seizure. People who did not have a second seizure within that time remained seizure-free for the rest of the study.
Febrile Seizures: Sometimes a child will have a seizure during the course of an illness with a high fever. These seizures are called febrile seizures (febrile is derived from the Latin word for "fever") and can be very alarming to the parents and other caregivers. In the past, doctors usually prescribed a course of anticonvulsant drugs following a febrile seizure in the hope of preventing epilepsy. However, most children who have a febrile seizure do not develop epilepsy, and long-term use of anticonvulsant drugs in children may damage the developing brain or cause other detrimental side effects. Experts at a 1980 consensus conference coordinated by the National Institutes of Health concluded that preventive treatment after a febrile seizure is generally not warranted unless certain other conditions are present: a family history of epilepsy, signs of nervous system impairment prior to the seizure, or a relatively prolonged or complicated seizure.
Nonepileptic Events: Sometimes people appear to have seizures, even though their brains show no seizure activity. This type of phenomenon has various names, including nonepileptic events and pseudoseizures. Both of these terms essentially mean something that looks like a seizure but isn't one. Nonepileptic events that are psychological in origin may be referred to as psychogenic seizures. Psychogenic seizures may indicate dependence, a need for attention, avoidance of stressful situations, or specific psychiatric conditions. Some people with epilepsy have psychogenic seizures in addition to their epileptic seizures. Other people who have psychogenic seizures do not have epilepsy at all. Psychogenic seizures cannot be treated in the same way as epileptic seizures. Instead, they are often treated by mental health specialists. Other nonepileptic events may be caused by narcolepsy, Tourette syndrome, cardiac arrythmia, and other medical conditions with symptoms that resemble seizures.
Eclampsia: Eclampsia is a life-threatening condition that can develop in pregnant women. Its symptoms include sudden elevations of blood pressure and seizures. Pregnant women who develop unexpected seizures should be rushed to a hospital immediately. Eclampsia can be treated in a hospital setting and usually does not result in additional seizures or epilepsy once the pregnancy is over.
source: http://neurology.health-cares.net/epilepsy-seizures-difference.php
Saturday, April 10, 2010
CHAPTER 3: Movement of Substances Across the Plasma Membrane
The plasma membrane or cell membrane surrounds the cell contents in all types of cells. It is a multipurpose covering composed of phospholipids and proteins.
Apart from the plasma membrane, an eukaryotic cell also shows intracellular and subcellular membranes around its organelles and vacuoles. Such membranes are also found all over the cytoplasm as a network called endoplasmic reticulum. These membranes thus, compartmentalize the cell into discrete functional units. The plasma membrane and the subcellular membranes are involved in the flow of selected materials across the cell, as and when the cell needs them.
Click here for the slides
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