Preview Questions
1. Describe a typical prokaryote cell.
2. Describe a typical eukaryote cell.
3. Explain the differences between a prokaryote
and eukaryote cell.
4. How has the simplicity of prokaryotes affected
their ability to adapt and survive / thrive?
5. How has the complexity of eukaryotes affected
their ability to adapt and survive / thrive?
Cell theory
1. All living things are made of cells
2. Cell can only come from other
cells
3. All functions of a living thing are
carried out in cells
•
Reminder: the functions of living things are:
respiration, metabolism, growth, adaptations to
the environment, reproduction, homeostasis
and interdependence
Different Types of
Cells
An overview
There are two main groups of cells,
prokaryotic and eukaryotic cells.
Similarities: all are alive, all belong to one of the five life
kingdoms.
Differences: appearance, structure, reproduction, and
metabolism.
–
.
biggest differences are between cells of different kingdoms
Where to begin?
• Prokaryotes are
simpler, so we will
start with them.
VS
Diagrams courtesy - http://www.cod.edu/people/faculty/fancher/ProkEuk.htm
Prokaryotes were formed about
3.5 billion years ago,
or 3,500,000,000 years
Prokaryotes
from the Greek meaning “before nuclei”
Why “before nuclei?”
• Prokaryotic cells have no nucleus.
– Prokaryote’s DNA is circular (it has no
ends).
– Small circlets of DNA are called
Plamids.
• Prokaryotic DNA is “naked” – it has no
histones associated with it and does NOT
form chromosomes
All Prokaryotes are in the
monera kingdom
domains Bacteria and Archaea
– bacteria
– Cyanobacteria
• also known as bluegreen algae
Prokaryote Characteristics
1. Simplest organisms: Very small size.
2. Lack membrane-bound organelles inside the cell
3. have few internal structures that are distinguishable
under a microscope.
4. genetic information is in a circular loop called a
plasmid (instead of having chromosomal DNA)
5. Strong cell walls: resistant to environmental changes
1. Size
• Bacterial cells are very small,
• about 1-2µm in diameter and 10 µm long
– One micrometer = 1/1000 mm.
• Imagine looking at a dime from its thinnest side
and trying to slice it into a thousand pieces; that is
the same as 1 µm.
2. Lack membrane-bound
organelles inside the cell
3. have few internal structures
that are distinguishable under a
microscope.
http://www.umanitoba.ca/science/biological_sciences/lab3/biolab3_2.html#Examine
4. genetic information is in a
circular loop called a plasmid
• E. coli cell dividing.
• E. Coli Grows in
human intestine;
– Has a single, circular
chromosome
– contains DNA as
plasmids
• Plasmids are extrachromosomal DNA
http://www.bio.mtu.edu/campbell/prokaryo.htm
5. Strong cell walls: resistant to
environmental changes
Bacterial Structure
Shapes
3 basic shapes
Cocci - sphere
Bacilli - rods
Spirilla – spirals
Spiral
This spiral
shaped
bacteria is the
causitive
agent of
syphilis
Treponema
pallidum
Rod shaped
2 basic groupings
Staph - in clusters
Strep - in chains
Spherical
Streptococcus sp.
Chains of nearlyspherical bacteria.
From The
Rockefeller
University.
Replication
• Binary fission
– one cell splits into two cells, see diagram
• offspring are genetically identical to parent
Movement
Some prokaryotes
can't move, while
others have long
threadlike flagella.
E.Coli flagella
If bacteria doesn’t
move, how does it
get from person
to person?
Prokaryote Functions
•
•
•
•
decomposers
agents of fermentation
play important roles in digestive systems
involved in many nutrient cycles
– ex: the nitrogen cycle, which restores nitrate into the soil for
plants.
• diverse array of metabolic functions.
– For example, some bacteria use sulfur instead of oxygen in their
metabolism.
Eukaryotes
From the Greek for “true nucleus”
Example cells from the plantae and
animalia kingdoms
Plant (elodea)
animal cells (blood vessel lining)
Eukaryote characteristics
All eukaryotes have …
1) A Cell
membrane
2) A Central nucleus
3) Organelles in cytoplasm (like
ER, vacuoles, mitochondria,
etc.)
size and shape are related to cell function.
For Example:
1. birds’ eggs are large because they
contain all the nutrient material that
the developing bird embryo will
need during its growth to a young
chick.
2.
1.
2. Muscle cells are long, so that they
can contract and shorten up,
thereby moving body parts.
3. Nerve cells are also long — they need to
transmit nerve signals to different parts
of the body
4. epithelial cells are broad and flat
5. red blood cells are especially small
because they need to get through
the smallest capillaries of the
circulatory system.
3.
4.
5.
Structure – animal cell
Structure – plant cell
reproduction
*Mitosis – body cells
*Meiosis – gametes (egg &
sperm)
Movement
Internal
1. The centriole
2. The cytoskeleton
3. Actin and tubulin
proteins
External
4. Flagella
5. cilia
1.
2.
3.
4.
5.
Review
Prokaryote & Eukaryote
similarities
Both have
1. DNA
2. A cell membrane
3. Ribosomes
4. Diverse forms (meaning a lot of shapes
and sizes)
Prokaryotes & Eukaryotes
differences
Prokaryotes
Eukaryotes
•Plasmid DNA
•No membranebound organelles
•Few things inside
(are simple)
•Nuclear bound DNA
•Has membrane
bound organelles
•Many things inside
(Are complex)
**Organelles are tiny structures inside cells that do a
certain job.
Complete this Vinn Diagram
worksheet and turn it in
Prokaryote
Write the
things that are
Different here
Write things
that are the
Same here
Eukaryote
Write the
things that are
Different here
Characteristic
Prokaryote
Eukaryote
Size
1-10um
10-100um
Nuclear Envelope
Absent
present
Chromosomes
Single, circular, no
nucleus
Multiple, linear, wound on
nucleosomes
Golgi apparatus
Absent
Present
ER, Lysosomes
Absent
Present
Mitochondria
Absent
Present
Chlorophyll
Not in chloroplasts
Present in chloroplasts
Ribosomes
Relatively small
Relatively large
Microtubules,
filaments,
microfilaments
Absent
Present
Flagella
Lack microtubules
Contain microtubules
Review Questions
1. Describe a typical prokaryote cell.
2. Describe a typical eukaryote cell.
3. Explain the differences between a prokaryote
and eukaryote cell.
4. How has the simplicity of prokaryotes affected
their ability to adapt and survive / thrive?
5. How has the complexity of eukaryotes affected
their ability to adapt and survive / thrive?