Image

§112.4A & C, 5B

Introduction to Cells & Viruses

All living things on the planet are made of cells. The basic

unit of all life is the cell; viruses, however, are not cells.

In this unit, WE will identify the different types of cells, the

parts within cells, and how different cells perform different

functions.

We will compare the structure of cells to the structure of

viruses.

On the following slides, the orange sections are the main

points; summarize the slides for your notes. Underlined words

= vocabulary!

Image

Cells All living things are composed of one

or more cells.

In 1665, the scientist Robert Hookediscovered plant cells in cork tissue.

Hooke coined the term "cells“ because the boxlike cells of cork reminded him of the cells of a monastery.

The cell is the considered the basic unit of life and organization.

http://es.wikipedia.org/wiki/Robert_

Hooke

Hooke, Robert: cork cell structure and sprig of sensitive plant.

Photograph. Encyclopædia Britannica Online. Web. 26 Sep. 2010

Image

What is a cell?http://www.nature.com/

naturejobs/2007/07060

7/images/nj7145-748a-

i1.0.jpg

http://www.alternative-

cancer.net/images/Cancer_cell,%20brain.jpg

http://ww

w.alterna

tive-

cancer.n

et/Cell_p

hotos.ht

m

Image

Cell Theory Years after Hooke’s cell discovery, other scientists

continued to study cells and added new information

to the initial observations.

The major concepts surrounding cells are now

known as the cell theory.

The cell theory states:

All living things are composed of cells.

Cells are the basic units of structure and

function in living things.

New cells are produced from existing cells.

Image

Prokaryotes

Prokaryotic cells are simply one cell holding genetic material.

They contain no nucleus (DNA is free in the cell).

They are unicellular organisms known commonly as

bacteria (they are not plants or animals).

Remember: N“O” for No Nucleus

http://library.thinkquest.org/03oct/00520/gallery/photos/prokar

yote.jpg

Image

Example:

Escherichia coli

(E coli) bacteria is

the common cause

of food poisoning.http://www.greenfacts.org/images/glossary/bacteria.jpg

Image

Eukaryotes Unlike prokaryotes,

eukaryotic cells are much more complex.

They have membrane-bound internal structurescalled organelles (little organs).

Eukaryotes have anucleus that controls all the functions of the cell.

Remember: “U” for n”U”cleus

http://www-micro.msb.le.ac.uk/109/Prokaryotes3.gif

Image

Eukaryotes cont. Eukaryotes can be either unicellular (one cell) or

multicellular (many cells).

Eukaryotic

cells are

found in:

Animals

Plants

Fungus

Us!

http://content.answers.com/main/content/wp/en/thu

mb/e/e7/370px-Cytoskeleton-color.gif

Image

Viruses A virus is an infectious agent

made up genetic material (DNA

or RNA) and surrounded by a

protein coat.

They are NOT cells!

No nucleus

Cell membranes

No organelles

They are parasites and have to

live off of other cells; than can

only survive and reproduce by

infecting living cells.

Common viruses include

herpes, the common cold, and

HIV/AIDS.

http://oceanworld.tamu.edu/resources/oceanograph

y-book/Images/BacteriophageCartoon.jpg

Image

Viral

Discoveries In 1892, 28 year old Russian

biologist Dmitri Ivanovskiidentified a disease that infects tobacco plants.

Later, in 1897, Dutch scientist Martinus Beijernick named this disease causing agent a “virus”.

Much later, in 1935, Wendell Stanley, an American biochemist, crystallized the tobacco mosaic virus (see E) and inferred that viruses were not alive (living organisms do not crystallize).

Electron micrographs of highly purified preparations of some viruses. (a)

Adenovirus. (b) Rotavirus. (c) Influenza virus (courtesy of George Laser).

(d) Vesicular stomatitis virus. (e) Tobacco mosaic virus. (f) Alfalfa mosaic

virus. (g) T4 bacteriophage. (h) M13 bacteriophage.

Image Copyright © The McGraw-Hill Companies. All rights reserved.

Image

Cell Organelles

A structure inside the cell that is surrounded by a membrane that performs a specific function is called anorganelle (“little organ”).

http://u

plo

ad.w

ikim

edia

.org

/wik

ipedia

/com

mons/thum

b/6

/63/B

i

olo

gic

al_

cell.

png/3

50px-B

iolo

gic

al_

cell.

png

Image

Lynn Margulis Lynn Margulis is an American

Biologist known for her research on organelles, the tiny structures within some cells.

She graduated from the University of Chicago and gained a PhD from Berkeley. She teaches at UMASS.

Her research contributed to the theories of the history of cellular life and the origins of eukaryotic cells.

She continues to research cellular life. http://www.geo.umass.edu/margulislab/Margulis_L

ab_Site/News_files/lynnmargulisloyola.jpg

Image

Cell Wall

The cell wall is present in plants, algae, fungi, and

many prokaryotes (bacteria!).

Its function is to provide support and protection for

the cell; it surrounds the cell membrane.

http://www.enchantedlearni

ng.com/subjects/plants/cell/

anatomy.GIF

Image

Cell

Membrane

The cell membrane is a thin layer of lipids and proteins (phospho-lipid bilayer) that surrounds cell and regulates the traffic in and out of the cell.

http://www.cs.utexas.edu/users/s2s/latest/cell1/src/images/cell_membrane.jpg

Image

Phospholipid

Bilayer

Image Copyright © The McGraw-Hill

Companies.

All rights reserved.

Image

Cytoplasm

Cytoplasm is the material

between the cell

membrane and nucleus.

It is a thick fluid made

mostly of water; jello like.

The function of the

cytoplasm is to contain

the organelles.

http://www.daylilies.org/ahs_dictionary/cytoplasm.gif

Image

Cytoskeleton

The network of thread-like protein fibers (microfilaments)

and hollow tubes of protein (microtubules) extending

through cytoplasm is called the cytoskeleton (shown in

yellow).

This “skeleton” gives cell shape and support, helps to

transports materials through cell, and sometimes enables

cell to move.

http://www.immediart.com/catalog/images/big_images/SPL_

6_P780110-Fibroblast_cells_showing_cytoskeleton.jpg

Image

Nucleus

The nucleus contains

the genetic

information (DNA)

and controls the cells

activities.

It is surrounded by a

double membrane

called the nuclear

envelope.

http://library.thinkquest.org/06aug/01942/plcells/thinkquest/nu

cleus.jpg

Image

Nucleolus The nucleolus is inside the nucleus where

ribosomes are produced.

http://micro.magnet.fsu.

edu/cells/nucleus/imag

es/nucleusfigure1.jpg

Image

Ribosomes Ribosomes are found loose in cytoplasm or bound to

other organelles.

They produce (or make) proteins from instructions within

RNA.

http://www.biotechnologyonline.gov.au/images/co

ntentpages/cellwithlabels.jpg

Image

Mitochondria

Mitochondria convert

chemical energy from

carbohydrates and

lipids into cell energy

A mitochondrion

contains DNA.

http://www.microscopy.fsu.edu/cells/mitochond

ria/images/mitochondriafigure1.jpg

Image

Chloroplasts

Chloroplasts also

contain their own DNA

and capture energy from

sunlight to convert it to

cell energy

(photosynthesis).

They are found only in

plants and certain

bacteria.

http://botit.botany.wisc.edu/images/130/Plant_Cell/Elodea/Ch

loroplasts_face_side_MC.jpg

Image

Lysosomes Lysosomes are

sac like organelles

filled with

enzymes.

Lysosomes help

to digest and

recycle materials

within the cell (to

breakdown

carbohydrates,

proteins, and

lipids into H, O, C,

etc). lysosome: intracellular digestion. Art. Encyclopædia

Britannica Online. Web. 26 Sep. 2010

Image

Endoplasmic Reticulum The endoplasmic

reticulum is a folded

network of

membranes.

Rough ER –

studded with

ribosomes

Smooth ER – no

ribosomes

The ER builds lipids

and proteins for the

cell.

Enzymes here also

clean up harmful

substances in the cell.

http://fog.ccsf.cc.ca.us/~mmalacho/physio/oll/Lesson2/images/3

Slide11.GIF

Image

Golgi Apparatus

The Golgi apparatus

is a series of flat,

membrane-bound

sacs.

The Golgi modifies,

sorts and packages

materials for storage

or to exit the cell.

http://www.bact.wisc.edu/Microtext

book/images/book_4/chapter_2/2-

59.gif

Image

Vacuoles

Vacuoles are the storage compartments for water,

proteins, lipids, and waste within cells.

Plants often have 1, large vacuole, while animals have

many small ones.

Some forms of single-celled life use vacuoles to pump

excess water out of the cell.

http://www.btinternet.com/~stephen.

durr/parameciumtwo.jpg

Image

Cilia Cilia (1 cilium) are tiny, hair like

projections on the surface of some cells.

Some forms of single-celled life use cilia

for movement.

Cilia are found in the Fallopian tubes of

mammals to move ova to the uterus as

well as in the respiratory system to clean

debris and move fluid.

http://f

aculty.p

lattsburg

h.e

du/jose.d

eondarz

a

/researc

h/P

hoto

s/P

ara

meciu

m.jpg

Image

Flagella (1 flagellum) are long, whip like structures that some cells use for movement.

Some forms of single-celled life use flagella that spin like a propeller.

Mammalian sperm have these long tails to help them reach an ova.

Flagella

http://www.ldeo.columbia.edu/users/menke/blogs/flagella.jpg

Image

In Conclusion In this unit, we learned that all living things on the

planet are made of cells.

The two different types of cells are:

Prokaryotes (no nucleus)

• Bacteria

Eukaryotes (nucleus)

• All other life (Animals, Fungi, Plants, Protists)

Inside certain cells there are organelles that perform

certain functions.

Viruses are not living cells, but must infect living

cells in order to reproduce.