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

Chapter: Cells

Table of ContentsTable of Contents

Section 3: Viruses

Section 1: Cell Structure

Section 2: Viewing Cells

• Cell - smallest unit that is capable of performing life functions.

• Cell Membrane - outer covering

• Cytoplasm - gelatinlike material inside cell

Common Cell Traits

Cell StructureCell Structure

11

• Nerve cell - could be a meter long.

• Human egg cell – the size of dot on an i

Comparing Cells


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• 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


11

• 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


11

• protective layer around all cells

• found inside of cell wall

Cell Membrane


11

• regulates interactions between the cell and environment.

• gelatinlike substance inside cell

• contains cytoskeleton

• made of tubes and fibers of protein

Cytoplasm


11

• Organelles – membrane bound structures

• found in Eukaryotic cells

• directs all cell activities

• largest organelle

• contains DNA – strands of hereditary information

Nucleus


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• 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


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• Mitochondria - organelles that break down glucose to release energy

Energy-Processing Organelles


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• Ribosomes – make proteins

• found in cytoplasm and on endoplasmic reticulum

Manufacturing Organelles


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• Endoplasmic reticulum (ER)

Processing, Transporting, and Storing Organelles


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• 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


11

Recycling Organelles


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• Lysosomes - contain digestive chemicals that break down molecules

From Cell to Organism


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• 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


11

Click box to view movie.

• A group of organs working together to perform a certainfunction 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 CheckSection Check

11

Answer

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


11

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.


11

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.


11

Magnifying Cells

Viewing CellsViewing Cells

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• 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


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• Magnification•Eyepiece x Objective = Total Magnification

Electron Microscopes

• Scanning electron microscopes (SEM) produce a realistic, three-dimensional image.

• Can only observe surface of sample


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• Uses a magnetic field in a vacuum to direct beams of electrons

Electron Microscopes


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• 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”


22

• Schleiden & Schwann (1830’s) – all living things are made of cells

• Virchow - cells divide to form new cells.

Cell Theory


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22Section CheckSection Check

Question 1Who developed a microscope using a tiny glass bead for a lens?

A. Antonie van LeeuwenhoekB. Edward JennerC. Matthias SchleidenD. Theodor Schwann


Answer

The answer is A. His microscope could magnify up to 270 times.


Question 2How many lenses does a simple microscope have?

A. 0B. 1C. 2D. 4


AnswerThe answer is B. A simple microscope is similar to a magnifying glass.


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


A. Cell TheoryB. Koch’s RulesC. Law of Independent Assortment D. Principles of Natural Selection


AnswerThe 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

VirusesViruses

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• 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

VirusesViruses

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• Causes the host cell to make new viruses.

Click image to view movie.

Latent Viruses

VirusesViruses

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• It does not immediately make new viruses or destroy the cell.

Click image to view movie.

How do viruses affect organisms?

VirusesViruses

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• 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

VirusesViruses

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• Vaccine - weakened virus particles that can’t cause disease anymore.

The First Vaccine

VirusesViruses

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• 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

VirusesViruses

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• 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.


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Question 2

Which happens to the host cell after the active virus is duplicated?

A. It divides through cell divisionB. It is destroyedC. It functions normallyD. It continues to produce more and more new viruses


Answer

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


Question 3Who developed the first vaccine?

A. Edward JennerB. Gregor MendelC. Reginald C. PunnettD. Theodor Schwann


AnswerThe answer is A. A vaccine is made from weakened virus particles that can’t cause disease anymore.

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

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