Cell Structure and Function Chapter 7

The Discovery of the Cell Robert Hooke – first to see and identify cork “cells.” 7-1

The Cell Theory Cell Theory: 1.All living things are composed of cells. 2.Cells are the basic units of structure and function in living things. 3.New cells are produced from existing cells. Schleiden Schwann Virchow 7-1

Who said “All plants are made of cells?” A.Hooke B.Schleiden C.Schwann D.Virchow

Prokaryotes and Eukaryotes Nucleus – large membrane- enclosed structure that contains the cell’s genetic information. Prokaryotes – cells that do not contain nuclei. (Bacteria) Eukaryotes – cells that contain nuclei. (All other organisms) 7-1

Eukaryotic Cell Structure Organelles – structures in a cell that act like “little organs.” Cytoplasm – the jelly-like fluid that the organelles “float” in

Inside the Nucleus Nuclear Envelope – membrane that surrounds the nucleus. Chromatin – consists of DNA wrapped around proteins. “Ball of string” Chromosomes – condensed string- like structure that forms from DNA just before the cell divides. Nucleolus – structure within the nucleus that makes ribosomes

Inside the Nucleus Nuclear Envelope Chromatin Nucleolus 7-2

Ribosomes Ribosomes – made of RNA and protein. Make Proteins! 7-2

Ribosomes Ribosome 7-2

Endoplasmic Reticulum (ER) Endoplasmic reticulum – internal membrane system of the cell. –Lipids, proteins, and other products are made here. –Rough ER – has ribosomes –Smooth ER – no ribosomes 7-2

Endoplasmic Reticulum (ER) Rough ER Smooth ER 7-2

Golgi Apparatus Golgi Apparatus – modifies, sorts, and packages proteins

Golgi Apparatus 7-2

Lysosomes Lysosomes – small organelles filled with enzymes. –Digest molecules to be used by the cell

Vacuoles Vacuoles – store materials

Vacuoles 7-2

Mitochondria Mitochondria – organelle that converts chemical energy stored in food into compounds that are more convenient for the cell to use. –“Powerhouse of the Cell!” 7-2

Mitochondria 7-2

Chloroplasts Chloroplasts – organelles that capture energy from sunlight and convert it into chemical energy. (Photosynthesis) –Found only in plants

Chloroplasts Chloroplast 7-2

Cytoskeleton Cytoskeleton – helps cell to maintain shape, move, and move organelles. Centrioles – help organize cell division. Not found in plants

Cytoskeleton 7-2

Cell Boundaries Cell membrane – thin, flexible membrane that surrounds the cell. Cell walls – rigid layer around the membrane found only in bacteria, fungi and plants

Cell Membrane Controls what enters/leaves cell, provides support/protection. Lipid Bilayer – double-layered sheet of phospholipids. Two layers! 7-3

Diffusion and Osmosis Diffusion – movement of particles from an area of high to low concentration. Osmosis – the diffusion of water through a selectively permeable membrane. –Water will move into/out of a cell to equalize concentrations

Osmosis Practice Cell 90% H2O 10% NaCl 90% H2O 10% NaCl Concentrations are equal, so no net movement of water! Isotonic Solution

Osmosis Practice Cell 90% H2O 10% NaCl 80% H2O 20% NaCl Concentration of water is greater in the cell than out, so water will move out! Hypertonic Solution

Osmosis Practice Cell 80% H2O 20% NaCl 90% H2O 10% NaCl Concentration of water is greater outside the cell than in, so water will move In! Hypotonic Solution

Facilitated Diffusion and Active Transport Facilitated diffusion – when the plasma membrane “helps” particles pass through protein channels. –No energy used. Active transport – when the plasma membrane uses energy to move particles against a concentration gradient. –Uses Transport Proteins 7-3

Facilitated Diffusion and Active Transport 7-3

Organization in Multicellular Organisms Tissues Organs Organ System Organism Cells 7-4