Cell Structure and Function Chapter 7

7-1I.Life is Cellular A. Discovery of the Cell 1. Robert Hooke a used simple microscope to look at thin layer of cork b. called them empty “chambers” or “cells” 2. Anton Van Leeuwenhoek a. used single lens microscope to observe pond water b. found a new world of living things

Cells- the basic units of life Cell Theory – Cell Theory – a. all living things are composed of cells b. cells are the basic units of structure and function in living things c. new cells are produced from existing cells

B. Exploring the Cell 1.Compound Light Microscope a. More than one lens or objective b. Uses a light source 2. Electron Microscope a. 1000x as powerful as a light microscope sends beams of electrons through specimen 3. SEM’s (scanning electron microscope) 3. SEM’s (scanning electron microscope) a. produces 3-D images electrons scan surface of object 4. Confocal Light Microscope a. scans cells with laser beam

C.Prokaryotes vs Eukaryotes NUCLEUS- membrane bound organelle that contains genetic information (DNA). Also, controls the cells activities. NUCLEUS- membrane bound organelle that contains genetic information (DNA). Also, controls the cells activities. 1. Prokaryotes: a. cells that do not contain a nucleus b. no membrane bound organelles c.DNA is found within (no specific area) Example: bacteria 2.Eukaryotes: a.cells that contain a nucleus b.DNA is found in nucleus has other membrane bound organelles Example: animal cell, plant cell

7-2 Eukaryotic Cell Structure A.Comparing the Cell to a Community 1.The organelles - Nucleus - Ribosome - Endoplasmic Reticulum (smooth or rough) - Golgi Apparatus - Lysosome - Vacuoles - Mitochondria - Chloroplasts - Cytoskeleton

Checkpoint! 1. Which of these is not part of the cell theory? –A. all cells are made up of living things –B. cells are the basic structure and function of living things –C. cells come from existing cells –D. all living things are made of cells

Nucleus How it connects: – School House What it does: –Controls the cells processes and contains the hereditary information of DNA What it is: –Surrounded by the nuclear envelope which allows material to move in and out Also contains: – Chromatin- consists of DNA bound to proteins – Nucleolus- where the assembly of the ribosomes begins

Ribosomes How it connects: –Workers What it does: –Site of protein assembly What it is: – small particles of RNA and protein found throughout the cytoplasm

Endoplasmic Reticulum How it connects: – Assembly line What it does: –Site where lipid components of the cell membrane are assembled for export from the cell –Rough: synthesis of proteins –Smooth: synthesis of membrane lipids, detoxification of drugs using enzymes What it is: –Rough: part of the ER that have ribosomes on the surface; proteins chemically modified –Smooth: no ribosomes on its surface (found in liver cells)

Checkpoint! 1. Which organelle is responsible for DNA? –A. ribosomes –B. nucleus –C. smooth ER –D. rough ER 2. What is the job of rough ER? –A.

Golgi Apparatus How it connects: –Packaging center What it does: –Modifies, sorts and packages proteins and other materials from the ER for storage or secretion What it is: –A stack of closely apposed membranes

Lysosome How it connects: –The trash cleanup crew What it does: –Digestion, or breakdown of lipids, carbohydrates, and proteins into small molecules that can be used by the rest of the cell –Also can break down organelles and remove “junk” from the cell What it is: –Small organelles filled with enzymes

Vacuoles How it connects: –Storage facility What it does: –Store materials such as water, salts, proteins, and carbohydrates –In plants, they provide structure to the cells –In paramecium, they maintain homeostasis What it is: –A saclike structure that is often filled with liquid

Mitochondria How it connects: –The power company What it does: –Convert chemical energy stored in food into compounds that are usable to cells What it is: –Enclosed by two membranes- outer and inner membrane- the inner is folded up inside Extra info: –In humans, they are inherited from the cytoplasm of the egg

Chloroplasts How it connects: –Solar Power Plant What it does: –Capture the energy from sunlight and convert it into chemical energy for photosynthesis What it is: –Two membranes- inside there are stacks of other membranes containing chlorophyll

Cytoskeleton How it connects: –Roads, streets and highways What it does: –Helps cells maintain shape –Assists in movement What it is: –A network of protein filaments, called microfilaments and microtubules

Centrioles How it connects: –City Planner What it does: –Helps organize cell division What it is: –Formed by tubulin

7-3 Cell Boundaries A. Cell membrane 1. regulates what enters and exits the cell and provides protection 2. made of two layers- phospholipid bilayer a. phosphate heads (hydrophilic) b. lipid tails (hydrophobic) c. proteins d. cholesterol (a lipid) (helps with structure)

Figure 8.1 Artificial membranes (cross sections)

Figure 8.2 Two generations of membrane models

Figure 8.6 The detailed structure of an animal cell’s plasma membrane, in cross section

B. Cell Wall 1. Provides support and protection 2. Made of cellulose a. carbohydrate fiber (wood and paper is made from) 3.found in plants, algae, fungi, and many prokaryotes 4. found on outside of cell membrane

C. Diffusion Through Cell Boundaries 1. Diffusion- movement of molecules across a membrane 2. Concentration- mass of solute/volume of solution a. molecules will move from an area of HIGH concentration to an area of LOW concentration b. molecules will continue to move until they’re equal ****Diffusion requires NO energy****

Figure 8.11 Osmosis

D.Osmosis- Diffusion of water through a selectively permeable membrane (pg 186) 1. Isotonic solution- concentrations of solutes is the same inside and outside of the cell 2. Hypertonic solution- solution has a higher solute count than the inside cell (cell shrinks) 3. Hypotonic solution- solution has a lower solute concentration than the cell (cell will balloon up) 4. Osmotic Pressure- pressure that builds up inside the cell (good and bad)

Figure 8.12 The water balance of living cells

Figure 8.14 Two models for facilitated diffusion

Figure 8.13 The contractile vacuole of Paramecium: an evolutionary adaptation for osmoregulation

Animation How Diffusion Works.mht Animation How Diffusion Works.mht How Osmosis Works.mht How Osmosis Works.mht

E. Active Transport- the process of moving molecules against the concentration gradient 1. Small molecules are carried across the membrane by TRANSPORT PROTEINS. 2. Large molecules are actively transported 1 of 2 ways a. Endocytosis- taking material into cell by engulfing the membrane around the molecule b. Exocytosis- pushing material out of cell ****REQUIRES ENERGY****

Figure 8.16 Review: passive and active transport compared

7-4 Diversity of Cellular life A. Unicellular- organism made of one cell only B. Multicellular- organism made of more than one cell or many 1. Specialized cells- cells that perform a specific task. Ex. Red blood cells carry O2 Ex. Red blood cells carry O2

C. Levels of Organization 1. Cells- basic unit of life 2. Tissues- a group of similar cells 3. Organs- a group of tissues 4. Organ systems- a group of organs 5. Organisms- a group of organ systems

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