Chapter: Cells Table of Contents Section 3: VirusesViruses Section 1: Cell Structure Section 2: Viewing CellsViewing Cells

Cell - smallest unit that is capable of performing life functions. Cell Membrane - outer covering Cytoplasm - gelatinlike material inside cell Common Cell Traits Cell Structure 1 1

Nerve cell - could be a meter long. Human egg cell – the size of dot on an i Comparing Cells Cell Structure 1 1 Human red blood cell - 1/10 size of a human egg cell. Bacterium - 8,000 bacteria fit inside one red blood

Prokaryotic - without membrane-bound structures 2 Cell Types Cell Structure 1 1 Eukaryotic - with membrane-bound structures

Cell walls tough, rigid outer coverings protect the cell and give it shape. found in plants, fungi, and bacteria made of cellulose Cell Organization—Cell Wall Cell Structure 1 1

protective layer around all cells found inside of cell wall Cell Membrane Cell Structure 1 1 regulates interactions between the cell and environment.

gelatinlike substance inside cell contains cytoskeleton made of tubes and fibers of protein Cytoplasm Cell Structure 1 1 Organelles – membrane bound structures found in Eukaryotic cells

directs all cell activities largest organelle contains DNA – strands of hereditary information Nucleus Cell Structure 1 1

In plant cells, food is made in green organelles in the cytoplasm called Chloroplasts found in plant cells Chlorophyll – green pigment make food (glucose) Energy-Processing Organelles Cell Structure 1 1

Mitochondria - organelles that break down glucose to release energy Energy-Processing Organelles Cell Structure 1 1

Ribosomes – make proteins found in cytoplasm and on endoplasmic reticulum Manufacturing Organelles Cell Structure 1 1

Endoplasmic reticulum (ER) Processing, Transporting, and Storing Organelles Cell Structure 1 1 a series of folded membranes process and move materials inside cell Smooth ER – NO ribosomes Rough ER - ribosomes

Golgi bodies sort proteins and other cellular substances package them into membrane-bound transport molecules called vesicles Vacuole – large storage organelle Processing, Transporting, and Storing Organelles Cell Structure 1 1

Recycling Organelles Cell Structure 1 1 Lysosomes - contain digestive chemicals that break down molecules

From Cell to Organism Cell Structure 1 1 Tissue - a group of similar cells that work together to do one job. Organ - made up of two or more types of tissues

From Cell to Organism Cell Structure 1 1 Click box to view movie. A group of organs working together to perform a certain function is an organ system. Your heart, arteries, veins, and capillaries make up your cardiovascular system.

Question 1 Which of these cells is found in a bacterium? Section Check 1 1

Answer Prokaryotic cells are only found in one-celled organisms, such as bacteria. Prokaryotic cells are cells without membrane-bound structures. Section Check 1 1

Question 2 Answer Which part of the cell protects the cell and gives it shape? Cell walls are tough, rigid outer coverings that protect the cell and give it shape. The cells of plants, algae, fungi, and most bacteria are enclosed in a cell wall. Section Check 1 1

Question 3 Answer In what part of the cell is the cytoskeleton found? Cytoplasm is the gelatinlike substance within the cell. The cytoskeleton is found throughout the cytoplasm. Section Check 1 1

Magnifying Cells Viewing Cells 2 2 Mid 1600s - Antonie van Leeuwenhoek, a Dutch fabric merchant, made a simple microscope with a tiny glass bead for a lens. Could magnify up to 270 times.

Modern Microscopes Simple Microscope – 1 lens Compound Microscope – Uses 2 lenses at once Eyepiece and Objective lens Viewing Cells 2 2 Magnification Eyepiece x Objective = Total Magnification

Electron Microscopes Scanning electron microscopes (SEM) produce a realistic, three-dimensional image. Can only observe surface of sample Viewing Cells 2 2 Uses a magnetic field in a vacuum to direct beams of electrons

Electron Microscopes Viewing Cells 2 2 Transmission electron microscopes (TEM) produce a two-dimensional image of a thinly- sliced specimen. Scanning tunneling microscopes (STM) are able to show the arrangement of atoms on the surface of a molecule.

Cell Theory Robert Hooke (1665) cut a thin slice of cork and looked at it under his microscope – looked like “cells” Viewing Cells 2 2 Schleiden & Schwann (1830’s) – all living things are made of cells Virchow - cells divide to form new cells.

Cell Theory Viewing Cells 2 2

2 2 Section Check Question 1 Who developed a microscope using a tiny glass bead for a lens? A. Antonie van Leeuwenhoek B. Edward Jenner C. Matthias Schleiden D. Theodor Schwann

2 2 Section Check Answer The answer is A. His microscope could magnify up to 270 times.

2 2 Section Check Question 2 How many lenses does a simple microscope have? A. 0 B. 1 C. 2 D. 4

2 2 Section Check Answer The answer is B. A simple microscope is similar to a magnifying glass.

2 2 Section Check Question 3 The conclusions listed in this table are known as the _______.

2 2 Section Check A. Cell Theory B. Koch’s Rules C. Law of Independent Assortment D. Principles of Natural Selection

2 2 Section Check Answer The answer is A. The research and conclusions of Robert Hooke, Matthias Schleiden, Theodor Schwann, and Rudolf Virchow contributed to the development of the cell theory.

What are viruses? Virus - strand of hereditary material surrounded by a protein coating Viruses 3 3 make copies of themselves. Host cell – cell infected by a virus It can either be active or it can become latent, which is an inactive stage

Active Viruses Viruses 3 3 Causes the host cell to make new viruses. Click image to view movie.

Latent Viruses Viruses 3 3 It does not immediately make new viruses or destroy the cell. Click image to view movie.

How do viruses affect organisms? Viruses 3 3 The virus and the place where it attaches must fit together exactly. Because of this, most viruses attack only one kind of host cell.

Vaccines have been made to prevent many diseases, including measles, mumps, smallpox, chicken pox, polio, and rabies. Fighting Viruses Viruses 3 3 Vaccine - weakened virus particles that can’t cause disease anymore.

The First Vaccine Viruses 3 3 Edward Jenner - first vaccine in 1796 for smallpox Interferons proteins created by infected cells cause non-infected cells to produce protective substances

Research with Viruses Viruses 3 3 Gene therapy substitutes normal hereditary material for a cell’s defective hereditary material. The new hereditary material replaces the defective hereditary material.

Question 1 Answer A _______ is a nonliving strand of hereditary material surround by a protein coating. The answer is virus. Viruses do not have a nucleus or other organelles. Section Check 3 3

3 3 Question 2 Which happens to the host cell after the active virus is duplicated? A. It divides through cell division B. It is destroyed C. It functions normally D. It continues to produce more and more new viruses

3 3 Section Check Answer The answer is B. Latent, or inactive, viruses do not destroy the host cell until they become active.

3 3 Section Check Question 3 Who developed the first vaccine? A. Edward Jenner B. Gregor Mendel C. Reginald C. Punnett D. Theodor Schwann

3 3 Section Check Answer The answer is A. A vaccine is made from weakened virus particles that can’t cause disease anymore.

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