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BIOL 235 Midterm 1-Version B Tips Athabasca University
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BIOL 235 Midterm 1-Version B Tips Athabasca University
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By: marvin03nurse • 6 months ago
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Chap 1. -Positive feedback: Strengthen or reinforce a change in one of the body’s controlled conditions. Control center provides a physiological response that adds to or reinforces the initialchange in the controlled condition—continues till interrupted by some mechanism.
Frontal plane: Divides the body into anterior (front) and posterior (back) portions.
Chap 2. -Water molecule bond: One atom of oxygen shares electrons with two atoms of hydrogen. Polar covalent bond, sharing of electrons is unequal=nucleus of one atom attracts the shared electrons more strongly than the nucleus of the other atom. Oxygen atom attracts the electrons more strongly than the hydrogen atoms=oxygen atom has greater electronegativity.
*Inorganic compounds =structurally simple, water/salts/acids/bases, cannot be used by cells to perform biological functions, carbon dioxide
Organic compounds – always contain carbon(carbon not easily dissolved in water, useful for body structures), covalent bonds, large molecules. Carbs/lipids/proteins/ATP/nucleic acids. They carry out complex functions within the body. *Covalent bonds =can form between atoms of the same element, can be polar or non-polar, forms when electrons are shared, and most common chemical bond in the body
*Atomic number of an element =proton # in nucleus
Mass number – protons plus neutrons Isotopes – atoms that have the same number of protons but different numbers of neutrons (different mass #) most are stable. If an atom is an isotope, its chemical properties remain the same, this only changes if the electron number is different, as electrons determine chemical properties of that element.
Atomic mass – amount of all naturally occurring isotopes. Non-polar bond – a covalent bond where atoms share electrons equally
Polar bond – a covalent bond where atoms do not share electrons equally. One atom has more electronegativity. (H20 is a polar covalent bond. O attracts electrons more)
Hydrogen bond – partially positive hydrogen attracts partially negative atoms. (usually O or N)
They result from attraction of positive and negative charges. They are weak. They help link other molecules together. Enzymes - Properties of enzymes: protein molecules that speed up chemical reactions in organisms. They are catalysts, they decrease the amount of energy required for a reaction to occur. Consist of two parts: (1) protein portion (apoenzyme), (2) non protein portion (cofactor).
Three properties: (1) Enzymes are highly specific (enzyme matched to particular substrate), (2) Enzymes are very efficient, (3) Enzymes are subject to a variety of cellular controls. End in ‘ase’. ATPases split ATP. Proteases break down proteins. *Fibrous proteins =form muscle fiber, tendons, connective tissue, and bone. (Actin, collagen, dystrophin, elastin, keratin, myosin, tropomyosin, tubulin, and fibrin). Insoluble in water
*Globular proteins =more water soluble than other classes of proteins and they may have several functions including transporting, catalyzing, and regulating. Hemoglobin, lipoproteins, albumin, enzymes, antibodies. Chap 3. -Facilitated diffusion: when solutes are too polar or highly charged to move through the lipid bilayer by simple diffusion they can cross the plasma membrane by passive process(no cell energy) or facilitated diffusion(cell energy). Integral membrane protein assists a specific substance across the membrane via channel or carrier. (Active processes uses atp – active transport, transport in vesicles)
-Lipid bilayer: Basic structural framework of the plasma membrane, two back to back layers made up of three types of lipid molecules—phospholipids, cholesterol, and glycolipids. Lipids are amphipathic molecules=both polar and non polar parts. Polar part = head = hydrophilic = water loving. Non-polar = tails = hydrophobic = water fearing. Cytosol on inside, extracellular fluid on outside. Highly permeable to nonpolar molecules such as oxygen, carbon dioxide, and steroids, moderately permeable to small uncharged polar molecules like water/urea, and impermeable to ions and large, uncharged polar molecules like glucose. Uncharged on the inside of cell Tonicity – a measure of a solutions ability to change the volume of cells by altering the cells water content. Hypertonic fluid used for cerebral edema. Sports drinks used to rehydrate are hypotonic. Transport in vesicles – active process, three types, receptor mediated endocytosis, phagocytosis, and bulk phase.
Receptor mediated Endocytosis diagram – steps: binding, vesicle formation, uncoating, fusion with endosome, recycling of receptors to plasma membrane, degradation in lysosomes.
Transcytosis – movement of substances into a cell, through it, and out of the cell. Occur most often in endothelial cells (line blood vessels), for materials to move from blood into interstitial fluid. -Cell diffusion diagram – simple diffusion, channel-mediated facilitated diffusion, carrier-
mediated facilitated diffusion. -Membrane proteins: Integral or peripheral—form ion channels or pores/carriers/receptors/are enzymes/linkers /cell-identity markers. -Integral proteins : extend into the lipid bilayer and are firmly embedded in it. Most are transmembrane proteins and span the entire lipid bilayer and protrude into both the cytosol and extracellular fluid. Amphipathic and are tightly attached to one side of the bilayer by covalent bonding to fatty acids. Consist of glycoproteins, proteins with carbohydrate groups attached to the ends that protrude into the extracellular fluid. -Peripheral proteins : not as firmly embedded in the membrane. Attached to the polar heads of membrane lipids or to integral proteins at the inner or outer surface of the membrane. Support plasma membrane, anchor integral proteins, move materials within cells. - Three main parts of the human cell: plasma membrane, cytoplasm(cytosol/organelles), and nucleus.
- Cytoplasm: consists of organelles, lysosomes, cytoskeleton (centrosomes that help hold the cell together), and cytosol. -Nucleus: stores cells DNA. contains ribosomes, chromatin, nucleolus, and DNA. Has its own cytoplasm called the nucleoplasm.
-Nucleolus: makes mRNA where they get sent to the nuclear envelope where they are fully assembled into ribosomes. Formed by proteins, RNA, and DNA.
-Nucleoli – produce ribosomes
*Messenger RNA: directs protein synthesis.
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