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22 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Three components of typical cell
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- plasma membrane (plamalemma)
- cytoplasm - organelles |
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Histones
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DNA binding proteins, often cause folding of long DNA strings; control reproduction and repair: histones are the chief protein components of chromatin. They act as spools around which DNA winds, and they play a role in gene regulation. Without histones, the unwound DNA in chromosomes would be very long.
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Ribosomes
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Ribosomes (from ribonucleic acid and "Greek: soma (meaning body)") are complexes of RNA and protein that are found in all cells. The ribosome functions in the expression of the genetic code from nucleic acid into protein, in a process called translation. Ribosomes do this by catalyzing the assembly of individual amino acids into polypeptide chains; this involves binding a messenger RNA and then using this as a template to join together the correct sequence of amino acids. This reaction uses adapters called transfer RNA molecules, which read the sequence of the messenger RNA and are attached to the amino acids.
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Endoplasmic reticulum
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The endoplasmic reticulum, or ER, is an organelle found in all eukaryotic cells that is an interconnected network of tubules, vesicles and cisternae. These structures are responsible for several specialized functions: protein translation, folding and transport of proteins to be used in the cell membrane (e.g. transmembrane receptors and other integral membrane proteins), or to be secreted (exocytosed) from the cell (e.g. digestive enzymes); sequestration of calcium; and production and storage of glycogen, steroids, and other macromolecules. The surface of the rough endoplasmic reticulum is studded with protein-manufacturing ribosomes giving it a "rough" appearance (hence its name). The surface of the rough endoplasmic reticulum is studded with protein-manufacturing ribosomes giving it a "rough" appearance (hence its name).
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Golgi apparatus
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The primary function of the Golgi apparatus is to process and package the macromolecules such as proteins and lipids that are synthesized by the cell. It is particularly important in the processing of proteins for secretion.
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Mitochondria
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Mitochondria are sometimes described as "cellular power plants" because they generate most of the cell's supply of adenosine triphosphate (ATP), used as a source of chemical energy. In addition to supplying cellular energy, mitochondria are involved in a range of other processes, such as signaling, cellular differentiation, cell death, as well as the control of the cell cycle and cell growth.
The inner mitochondrial membrane contains proteins with four types of functions: 1. Those that perform the redox reactions of oxidative phosphorylation 2. ATP synthase, which generates ATP in the matrix 3. Specific transport proteins that regulate metabolite passage into and out of the matrix 4. Protein import machinery. |
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Vacuoles
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Vacuoles are found in the cytoplasm of most plant cells and some animal cells. When they are found in animal cells, they are represented as many smaller ones rather than one large one like in a plant cell. Vacuoles are membrane-bound compartments that can serve a variety of secretory, excretory, and storage functions.
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Lysosomes
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Lysosomes are organelles that contain digestive enzymes (acid hydrolases). They digest excess or worn-out organelles, food particles, and engulfed viruses or bacteria. The membrane surrounding a lysosome allows the digestive enzymes to work at the 4.5 pH they require. Lysosomes fuse with vacuoles and dispense their enzymes into the vacuoles, digesting their contents. They are created by the addition of hydrolytic enzymes to early endosomes from the Golgi apparatus. At pH 4.8, the interior of the lysosomes is more acidic than the cytosol (pH 7.2). The lysosome's single membrane stabilizes the low pH by pumping in protons (H+) from the cytosol via proton pumps and chloride ion channels. The membrane also protects the cytosol, and therefore the rest of the cell, from the degradative enzymes within the lysosome. For this reason, should a lysosome's acid hydrolases leak into the cytosol, their potential to damage the cell will be reduced, because they will not be at their optimum pH. Some important enzymes in these are:
- Lipase, which digests lipids - Carbohydrases, which digest carbohydrates (e.g., sugars) - Proteases, which digest proteins - Nucleases, which digest nucleic acids - phosphoric acid monoesters. |
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Cellular receptors
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Protein molecules that are capable of recognizing/binding with ligands (a molecule that can be sent or received to transmit messages). Receptors can be found on the membrane, in the cytoplasm or in the nucleus.
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There are a number of types of cell to cell communication:
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Endocrine: secretory cell exudes ligand (hormone) into circulatory system.
Exocrine: secretory cell exudes ligand (enzyme) into duct. Paracrine: secretory cell exudes ligand into interstitial space which interacts with nearby cells. Autocrine: intracellular communication by exuding a ligand into interstitial space which acts on the emitting cell. Synaptic - a specialized form of paracrine signalling in which a neurotransmitter is emitted from the endplate of a neural axon into the synapse of a neighboring cell. |
Endocrine
Exocrine Paracrine Autocrine Synaptic |
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Passive transport across a cellular membrane
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diffusion - movement across a semipermeable membrane from an area of higher concentration to lower.
hydrostatic pressure - liquid is pushed across a membrane by fluid pressure. osmosis - diffusion of water from high concentration to lower concentration, thus more dilute solutions (higher conc. of water) become more concentrated as they lose water to more concentrated solutions. |
diffusion
hydrostatic pressure osmosis |
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Active transport across cell membrane
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Active transport is the mediated process of moving particles across biological membranes at the molecular scale or below. Specialised trans-membrane proteins recognise the substance to be transported and allow it (or, in the case of secondary transport, expend energy on forcing it) to cross the membrane when it otherwise wouldn't, either because it is one to which the bilipid layer of the membrane is impermeable or because it is moved against the concentration gradient. The last case, known as primary active transport, and the proteins involved in it as pumps, uses the chemical energy of, usually, ATP. The other cases require no source of energy, are known as secondary active transport and involve pore-forming proteins which form channels through the cell membrane.
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Epithelial tissue
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Covers most internal and external surfaces, and attaches to a basement membrane. There are 3 types:
- smooth (inside of blood vessels) - microvilli (inside of intestine) - cilia (respiratory tract) |
smooth
microvilli cilia |
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Connective tissue
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A wide variety of structure and function, it is the structure on which epithelial cells cluster, there is usually a great deal of extracellular matrix.
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Muscle tissue
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Highly contractile (when depolarized) followed by relaxation. There are three types:
- skeletal: under voluntary control - smooth: involuntary, usually controlled by autonomic nervous system - cardiac: hybrid, has inherent rhythmicity and can initiate depolarization itself |
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Neural tissue
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Receive and transmit electrical impulses across a synapse.
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Atrophy
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Decrease in cell size. If enough cells atrophy, organ will shrink. Atrophy can result from disuse, nutritional deprivation, physiological stimulation.
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Hypertropy
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Increased cell size. A result of increased protein, not increased water. Heart and kidney particularly susceptible. Sometimes is normal.
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Hyperplasia
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Increased number of cells due to increased cell division.
- normal (physiologic) compensatory or hormonal - pathological due to: abnormal proliferation of normal cells (endometrium is most common site); results from failure of growth control leading to a malignant transformation. |
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Dysplasia
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Atypical hyperplasia, abnormal changes in size, shape and organization. Often seen in epithelial cells of the cervix and resp. tract. Reversible when the inciting stimuli are removed.
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Metaplasia
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Reversible replacement of one mature cell type by another. Reverses if inducing stimuli are removed (prolonged exposure leads to malignant transfromation.
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Ischemia vs hypoxia
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Ischemia is a decrease in blood flow to tissue. It can be one cause of hypoxia (loss of supply of oxygen to tissue). Ischemia is the same as decreased perfusion.
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