Unit 2: Cells & Viruses. SB1a. Explain the role of cell organelles for both prokaryotic and...

Unit 2: Cells & Viruses

Unit 2: Cells & Viruses SB1a. Explain the role of cell organelles for both prokaryotic and

eukaryotic cells, including the cell membrane, in maintaining homeostasis and cell reproduction.

SB1d. Explain the impact of water on life processes (i.e., osmosis, diffusion).

SB3d. Compare and contrast viruses with living organisms.

Vocabulary & Contents: Pg 11 Prokaryote / Eukaryote 12 nucleus / ribosome 13 endoplasmic reticulum / golgi apparatus 14 vacuole / lysosome 15 mitochondrion / chloroplast 16 cell wall / cell membrane 17 Venn Diagram: Plant & Animal Cells

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Vocabulary & Contents (continued): Pg 18 diffusion / osmosis 19 facilitated diffusion / isotonic 20 hypertonic / hypotonic 21 active transport / homeostasis 22 Passive Transport Diagram 23 virus / capsid 24 Venn Diagram: Viruses & Living Organisms

The origins of cell study

Individual cells are so small, they are seen in detail only with a :

microscope.

The first microscopeWas designed by Anton van

Leeuwenhoek in the 1600s.Really, it was a piece of glass. In 1665, Robert Hooke used a

compound microscope to see cork “cells”.

Current Study of Cells: Microscope Technology

Three Types:        Light Microscope (LM)Transmission Electron

Microscope (TEM)Scanning Electron Microscope

(SEM) 

Current Study of Cells: Microscope Technology

Light Microscope (LM)

Current Study of Cells: Microscope Technology

Transmission Electron Microscope (TEM)

Current Study of Cells: Microscope Technology

Scanning Electron Microscope (SEM)

insect wing

Development of the Cell Theory

Robert Hooke was the first to see and name “cells.”

Two other scientists, Shleiden (studied plants) and Schwann (studied animals),

were the first to write that living things are composed of cells.

Their conclusions contributed to what is now called the Cell Theory.

Development of the Cell Theory

The Cell Theory says:

All living things are made of one or more cells.

The cell is the basic unit of an organism.

All cells come from other living cells. 

Characteristics of Cells

Two main types: prokaryotes and eukaryotes.

Prokaryotes do NOT have a true nucleus.

Eukaryotes have a true nucleus. There are other differences as well…

Prokaryotic Cell

Cell membrane

Cell membrane

Cytoplasm

Cytoplasm

Nucleus

Organelles

Eukaryotic Cell

Section 7-1

Prokaryotic and Eukaryotic Cells

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Eukaryotic Cells Eukaryotic cells have internal membrane-

bound structures called organelles. Organisms that are eukaryotic can be uni- or

multi- cellular. Unicellular organisms are able to carry out all

of life’s functions. Multicellular organisms can have

specialization of cell groups (tissues). Examples: include fungi, amoeba, plants, and

animals.

Prokaryotic Cells Prokaryotic cells lack membrane-bound

organelles. They still have DNA, but no nucleus to

enclose it. Examples include: all bacteria.

Plant Cell

Nuclearenvelope

Ribosome(attached)

Ribosome(free)

Smooth endoplasmicreticulum

Nucleus

Rough endoplasmic reticulum

Nucleolus

Mitochondrion

Cell wall

CellMembrane

Chloroplast

Vacuole

Section 7-2

Figure 7-5 Plant and Animal Cells

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Vacuole

Chloroplast

CellMembrane

Cell wall

Golgi apparatusGolgi apparatus

Mitochondrion

Smooth endoplasmicreticulum

Ribosome(free)

Ribosome(attached)

Nuclearenvelope

Nucleolus

Nucleus

Rough endoplasmic reticulum

Cell membrane

Endoplasmicreticulum

Microtubule

Microfilament

Ribosomes Mitochondrion

Section 7-2

Go to Section:

Microtubule

Microfilament

Animal Cell

Centrioles

NucleolusNucleus

Nuclearenvelope

Rough endoplasmic reticulum

Golgi apparatus

Smooth endoplasmicreticulum

Mitochondrion

CellMembrane

Ribosome(free)

Ribosome(attached)

Section 7-2

Figure 7-5 Plant and Animal Cells

Go to Section:

Rough endoplasmic reticulum

CellMembrane

Nucleus

Nuclearenvelope

Nucleolus

Smooth endoplasmicreticulum

Golgi apparatus

Mitochondrion

Ribosome(attached) Ribosome

(free)

Centrioles

ProkaryotesEukaryotes

Cell membraneRibosomesCytoplasm

NucleusEndoplasmic

reticulumGolgi apparatusLysosomesVacuolesMitochondriaCytoskeleton

Animal Cells Plant Cells

LysosomesCentrioles

Cell membraneRibosomesNucleusEndoplasmic

reticulumGolgi apparatusVacuolesMitochondriaCytoskeleton

Cell WallChloroplasts

Venn Diagrams

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Viruses Non-living strand of genetic

material with a protein coat No organelles Do not move Cannot replicate on their own Size: 5 – 300 nm (nanometers – about

1 billionth of a meter)

HIV virus bursting out of white a blood cell

Viral Diseases AIDS

(caused by HIV) Herpes Measles Mumps Chicken Pox, Shingles Cold Influenza “the flu” “Swine Flu”

Warts Gastroenteritis Polio viral meningitis rabies Small Pox**

Hepatitis

More images of viruses

H1N1 virus

“Swine flu”

More images of viruses

Herpes virus

Tobacco mosaic virus

All about virusesWhere did viruses come from? Possibly parts of cells

– Genetic material of viruses is similar to that of cells

Viral Structure Covered by an outer layer of proteins called

a capsid Inside the capsid – genetic material –

could be DNA or RNA

Viral Infections Viruses do not have ribosomes or

mechanism for making proteins They cannot function or reproduce on their

own To replicate, viruses must infect host cells

– Two types of viral reproduction Lysogenic Lytic

Lytic Cycle Host cell makes copies of its own DNA

as well as viral DNA or RNA Invading genetic material instructs the

host cell to make more viral protein capsids & enzymes needed for viral replication

With those copies of DNA and protein, new viruses start to form

Host cell lyses or “explodes” and releases thousands of new viruses

Lysogenic Cycle Lysogenic = literally “can initiate a lysis of

the cell” but it doesn’t do it right away Viral DNA inserts into DNA of host cell DNA stays dormant (it hides/rests) for a

length of time Under the right conditions, the viral DNA is

activated and the Lytic Cycle begins Examples—chicken pox-> shingles,

HIV

http://www.geocities.com/madokagm/BIOL1551/lecture_notes_Nov_22_files/image002.jpg

Fighting Viral Disease Antibiotics are ineffective against viral

infections The only way to fight a virus is with the

immune system by:– Fighting an existing new viral infection– Preventing the severity of viral disease by

vaccination: A vaccine is a killed or weakened virus that is injected into a person so their immune system (1) gets a preview of what the virus looks like(2) Can respond quickly so that the virus will not

totally infect the person and make them ill

Virus Variations & more Retrovirus

– Has RNA instead of DNA– Ex. HIV Virus that causes AIDS

Prions– Proteins that can cause infectious diseasesFor example:– Mad Cow Disease, Creutzfeldt-Jakob Disease

How much do you know? What is the difference between a virus and

a retrovirus? What type of virus is HIV? Do prions have genetic material? Are viruses living? Give one reason why or

why not? Are viruses bigger or smaller than normal

cells? Do antibiotics work against viruses?