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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
10
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
Go to Section:
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
Go to Section:
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
Go to Section:
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?