Biology Ch. 7 Ms. Haut

Robert Hooke Used early compound microscope to look at slices of cork Named the tiny chambers “cells” after rooms in monasteries iques/Robert_Hooke_archivos/Robert_Hooke.jpg media/68/ AF8F9553.jpg

Anton van Leeuwenhoek Dutch janitor with hobby of ocular grinding (making lenses) Used single-lens microscope to look at raindrops Found living organisms

Schleiden concluded plants were made of cells (1838) Schwann concluded animals were made of cells (1839) Virchow concluded new cells could only be produced from existing cells (1855) Principles of 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.

The light microscope enables us to see the overall shape and structure of a cell Figure 4.1A Image seen by viewer Eyepiece Ocular lens Objective lens Specimen Condenser lens Light source Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings Red blood cells teaching.path.cam.ac.uk/partIB_pract/NHP1/

Invented in the 1950s They use a beam of electrons instead of light The greater resolving power of electron microscopes allows greater magnification reveals cellular details websemserver.materials.ox.ac.uk/cybersem/getf...

Electron beam scans cell surface Used to see detailed structure of cell surface Figure 4.1B Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings Red blood cells ls.jpg

Transmits electrons through specimen Used to examine the internal structures of a cell Figure 4.1C Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings Red blood cell in capillary commons.wikimedia.org/wiki/Image:A_red_blood_...

Cell size is limited by metabolic requirements Lower limits: Enough DNA to program metabolism Enough ribosomes, enzymes, & cellular components Upper limits: Surface area and plasma membrane large enough for cell volume to allow exchange of nutrients and wastes

Prokaryotes Smaller cells Simpler structure Cells do not have a nucleus Cells do not have membrane bound organelles Single celled organisms Eukaryotes Larger cells More complex structure Cells have a nucleus Cells have membrane bound organelles Single celled organisms—Protists Multicellular organisms All Cells: 1.Are surrounded by a cell membrane 2.At some time during their life contain DNA

Single cell Enclosed by a plasma membrane Usually encased in a rigid cell wall The cell wall may be covered by a sticky capsule Inside the cell are its DNA and other parts Ribosomes Figure 4.4 Capsule Cell wall Plasma membrane Prokaryotic flagella Nucleoid region (DNA) Pili Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings

All other life forms are made up of one or more eukaryotic cells These are larger and more complex than prokaryotic cells Eukaryotes are distinguished by the presence of a true nucleus

Structure: Nuclear envelope: double membrane perforated with pores Contains most of cell’s DNA in form of chromatin (DNA and protein) Houses nucleolus Makes ribosomal parts Function: Control center of cell Directs protein synthesis

Structure: RNA and proteins found throughout cytoplasm and attached to endoplasmic reticulum Function: Site of protein synthesis Cells that are active in making proteins have lots of ribosomes

Structure: Channels made of membranes Smooth ER Synthesizes lipids, phospholipids, and steroids Carbohydrate metabolism Detoxifies drugs & poisons Rough ER Protein synthesis Membrane production

Have lots of Smooth ER Extract many harmful materials from the blood and excrete them in the bile or from the kidneys. 8/0_300_er.jpg

Structure: Stack of membranes Function: Modify, sort and package proteins and other molecules for storage in cells or secretion out of cells DB80.jpg

Structure: Small membrane sack filled with enzymes Function: Digestion of lipids, carbohydrates, and proteins Break down worn out organelles

Structure: Small membrane sack filled with enzymes Function: Contain enzymes for specific metabolic pathways; all contain hydrogen peroxide Contain catalase 2H 2 O 2 catalase 2H 2 O + O 2

Structure: Saclike structures of membrane Function: Store materials like water, salts, proteins, and carbohydrates

Stores food for digestion once lysosome fuses with it

Stores organic compounds Stores inorganic ions May contain pigments May contain poisons Plays role in plant growth & elongation

Protists may have contractile vacuoles These pump out excess water Figure 4.13B Nucleus Contractile vacuoles Copyright © 2003 Pearson Education, Inc. publishing Benjamin Cummings Collapsing contractile vacuole of Protozoa

Structure: Enclosed by double membrane Contains ribosomes and own DNA (maternal) Function: Responsible for Cellular Respiration (converts chemical energy in glucose into chemical energy in ATP) Grows and reproduces by itself

Structure: Enclosed by double membrane Contains ribosomes and own DNA Function: Site of photosynthesis in plants (converts solar energy into chemical energy in glucose) organelles/organelles/chloroplast-b.gif

Structure: Network of protein filaments Microfilaments-made of actin Microtubules-hollow tubules made of tubulin Function: Helps maintain cell shape

Microfilaments Tough, flexible framework that supports cell Cell movement-assembly and disassembly for cytoplasmic movement Microtubules Form mitotic spindle for separating chromosomes Form cilia and flagella for cell movement Amoeba