Chapter 3 - Chapter 3 Cells and Tissue Part 1: Cells I....

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Chapter 3 – Cells and Tissue Part 1: Cells I. Overview of the Cellular Basis of Life o made up primarily of C, H, O, and N o also Fe, Na, K o 60% H 2 O o Vary in length – 1/12,000 /inch to over 3 ft. (nerve cells) o Many different shapes and functions II. Anatomy of a Generalized Cell - 3 main regions – 1) Nucleus 2) Cytoplasm 3) Plasma Membrane A. The Nucleus – “control center” o Contains the DNA – genetic material o Code for building proteins – protein synthesis o 3 regions 1) Nuclear Membrane – a double membrane barrier around the nucleus - ** Selectively permeable
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- encloses jelly like nucleoplasm 2) Nucleoli – round bodies in the nucleus. - sites where ribosomes are built 2) Chromatin – bumpy threads of DNA combined with protein o ** found in cells not dividing o Chromosomes – formed by chromatin in cells that are dividing B. The Plasma Membrane – fragile, transparent barrier – separates the cell from its environment. o ** has a core of two lipid (fat) layers and floating protein molecules o lipid layers – mainly phospholipids – also has cholesterol o Proteins - have specialized functions - ex – Some are enzymes - ex 2 – many are receptors for chemical messages - ex 3 – many are involved in transport functions - “sugar-proteins” – called glycoproteins – they help determine your blood type 1) Specializations of the Plasma Membrane a) Microvilli – “little shaggy hairs”
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1) tiny fingerlike projections - ** increase the surface area – line the small intestine b) Membrane Junctions 2) Tight Junctions – like a zipper – make impermeable 3) Desmosomes – anchoring – found in the skin – keep cells from being pulled apart 4) Gap Junctions – found in the heart – allow communication C. The Cytoplasm – cellular material outside of the nucleus and inside the plasma membrane o 3 parts – cytosol , organelles , inclusions o Cytosol – semitransparent fluid – suspends the other elements - Organelles – specialized parts - Inclusions – not functioning units – “little organs” – chemical substances – ex – stored nutrients or cell products - 3.5 pg 58 – Generalized Cell
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Cytoplasmic Organelles a) Ribosomes – tiny, round dark bodies - made of proteins and ribosomal RNA - ** sites of protein synthesis b) Endoplasmic Reticulum – (ER) – fluid filled tubules of canals - **serves as a minicirculatory system for the cell - carry material from one part of the cell to another - Types – 1) Rough ER – contains ribosomes 2) Smooth ER – cholesterol synthesis & breakdown, fat metabolism and detoxification c) Golgi Apparatus – stack of flattened sacs - ** major function – modify and package proteins as sacs fill with protein , they will pinch off and from secretory vesicles - also form lysosomes d) Lysosomes – “break-down bodies” - “bags” – contain digestive enzymes - function as “demolition sites” - white blood cells – contain many lysosomes – engulf bacteria and other harmful substances
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Chapter 3 - Chapter 3 Cells and Tissue Part 1: Cells I....

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