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The Cell cont. Chapter 7 Sections 3 & 4 Cell Boundaries Cell Membrane A thin flexible barrier that surrounds all cells. It contains pumps and channels made of proteins. It regulates what enters & leaves the cell. It provides protection and support. Cell Boundaries Cell Wall A strong supporting layer around the cell membrane that is usually made of tough fibers. It provides protection for the cell. Plants, algae, fungi, & many prokaryotes have cell walls. Cell Boundaries Cytoplasm It contains a solution of many different substances in water. A solution is a mixture of 2 or more substances. Homeostasis Ideal conditions; a balance (feedback system) Sweat, shiver, heart rate (to deliver more Oxygen). Particle Transport Passive Transport Diffusion Osmosis Facilitated Diffusion Active Transport Passive Transport Moves down a gradient; particles move from Higher concentration to lower concentration Energy is not required Diffusion A process that occurs because molecules constantly move & collide with one another. Particles move from an area of high concentration to an area of low concentration. Energy is not used or required. Diffusion Equilibrium – when the concentration of the solute is the same throughout a system. All organisms move towards & maintain equilibrium. When this is reached, particles of a solution will continue to move across the membrane in both directions. Done by Osmosis & Diffusion Osmosis The diffusion of water through a selectively permeable membrane. Energy is not used or required. Isotonic- “same strength”- movement of water in & water out. Equal concentration Hypertonic- “above strength”- water out. Hypotonic- “below strength”- water in. (soil hypo to root hyper) Osmosis Osmotic Pressure- pressure that is caused during osmosis on the hypertonic side of a selectively permeable membrane. The cell contains salts, sugars, proteins, and other molecules and when put into fresh water, it will almost always be hypertonic and cause the cell to swell and possibly burst. Facilitated Diffusion The process in which channels facilitate or help make it easier for certain molecules to cross the cell membrane. Protein channels- they are made of protein & help move materials from one side to the other side. Energy is not used or required. Active Transport A process in which cells must sometimes move materials in the opposite direction – against the concentration difference. Energy is required. (ATP) A pump is used to take large molecules and force them through the membrane. Against a gradient Active Transport Endocytosis- wraps or absorbs; taking into cell by infolding or pocketing. Phagocytosis- enguls it after surrounding it; “cell eating” Pinocytosis- take up liquid. Exocytosis- discharge of large particles; surrounding & fusing with cell membrane. Diversity of Cellular Life Unicellular organisms Multicellular organisms Unicellular Organisms Consists of a single cell. It carries out all of the essential functions that a larger organism does such as: grow, respond, react to environment, reproduce, & transform energy. Ex. – yeast, algae, bacteria. Multicellular Organisms Are made up of many cells. The cells are specialized to perform different tasks. Ex. – muscle cells, blood cells, pancreatic cells. Cell specialization – when cells have different jobs in an organism. Ex- blood cells transport oxygen, muscle cells contract and relax muscles. Levels of Organization Individual cells- the first level of organization. Tissues- similar cells grouped together to perform a particular function. Ex.- muscle, epithelial, nervous, connective. Organs- a group of tissues that work together. Ex.heart, stomach, lungs. Organ systems- a group of organs that work together to perform a specific function. Ex.- nervous system, digestive system, circulatory system.