Biology_review-Cell

    21. Salty water is a hypertonic solution to a cell, and water will move out of the cell, while pure water, a hypotonic solution, will cause water to move into the cell. Turgor pressure is water pressure.
     22. Diffusion is the process by which molecules of a substance move from places of higher concentration to places of lower concentration. Mixing the combining of different substances. Osmosis is the diffusion of water molecules through a selectively permeable membrane which continues until equilibrium is reached. Active transport is an energy-requiring process that allows materials to move across a cell membrane against a concentration difference. This is made possible by either membrane-associated pumps or movements of the cell membrane itself. These relate to homeostasis by helping the cell keep its environment balanced.
     23. Autotrophs are organisms which can make its own food, such as all green plants, which make their food directly from sunlight. Heterotrophs are the eaters of autotrophs or other heterotrophs. They gain energy from consuming.
Chemotrophs are organisms which make their own food from chemicals, such as sulfur. These organisms, often bacteria, are found in volcanoes or in volcanoes in the ocean.
     24. Aerobic means with oxygen, and anaerobic means without oxygen. When you exercise strenuously, your cells do not receive enough oxygen, and so produce energy using fermentation instead of cellular respiration and produce alcohol or lactic acid, which makes muscles sore.
     25. DNA differs from RNA because DNA has a double-helical structure and is formed of units called nucleotides. RNA are the messengers which carry information from the DNA and ribosomes. DNA is made of deoxyribose and RNA is made of ribose, DNA is in the shape of a double helix and RNA can twist into loops, and RNA has uracil instead of guanine in the base pairs. The DNA is located inside the nucleus of the cell, and the RNA appears during transcription.
Body cells have 2 sets of chromosomes (are diploid), but the sex cells (gametes) have only one set of chromosomes (are haploid) because in fertilization, one gamete from the father and one gamete from the mother will join, so that they form a new organism with the two sets of chromosomes. Only in the sex cells are there haploid cells; all other body cells are diploid.
      26. Mitosis is the splitting of autosomal body cells, resulting in two identical daughter cells. These cells are exactly the same as the original cell, and mitosis happens every day, all the time. Meiosis is the forming of gametes; a diploid cell splits into two haploid gamete cells, each with only half the set of chromosomes from the original cell.
      27. Many diseases and syndromes occur because of faulty meiosis, called non-disjunction. Down syndrome is a genetic disorder because of an extra 21st chromosome that resulted from non-disjunction. People with down syndrome are slow learners and look different than �normal� people. Other diseases like Kleinfelder�s are also a result of non-disjunction.