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Preview Questions. Describe a typical prokaryote cell. Describe a typical eukaryote cell. Explain the differences between a prokaryote and eukaryote cell. How has the simplicity of prokaryotes affected their ability to adapt and survive / thrive? - PowerPoint PPT PresentationTRANSCRIPT
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 theory1. All living things are made of cells2. Cell can only come from other
cells3. 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
Prokaryotesfrom 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 blue-green algae
Prokaryote Characteristics1. 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 extra-
chromosomal DNA
http://www.bio.mtu.edu/campbell/prokaryo.htm
5. Strong cell walls: resistant to environmental changes
Bacterial Structure
Shapes3 basic shapes Cocci - sphere
Bacilli - rodsSpirilla – spirals
2 basic groupingsStaph - in clusters
Strep - in chains
Spiral
Rod shaped
SphericalStreptococcus sp. Chains of nearly-spherical bacteria.From The Rockefeller University.
This spiral shaped bacteria is the causitive agent of syphilis Treponema pallidum
Replication• Binary fission
– one cell splits into two cells, see diagram• offspring are genetically identical to parent
Bacterial conjugation– a form of sexual
reproduction where bacteria exchange genetic information before dividing
• offspring have new genes (and new traits)
Figure 1. Schematic drawing of bacterial conjugation. 1- Donor cell produces pilus; 2- Pilus attaches to recipient cell, brings the two cells together; 3- The mobile plasmid is nicked and a single strand of DNA is then transferred to the recipent cell; 4- Both cells recircularize their plasmids, synthesize second strands, and reproduce pili. Both cells are now viable donors.
http://parts.mit.edu/igem07/index.php/Boston_University/Conjugation
• Transformation – bacteria incorporate genes from dead
bacteria
• Transduction – viruses insert new genes into bacterial cells. – This method is used in biotechnology to
create bacteria that produce valuable products such as insulin
MovementSome prokaryotes
can't move, while others have long threadlike flagella.
If bacteria doesn’t move, how does it get from person to person?
E.Coli flagella
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.
Bacteria images / resources
• http://www.ulb.ac.be/sciences/biodic/ImBacterie2.html
• http://www.buckman.com/eng/micro101/bacteria.htm
• Discovery school video: Understanding Bacteria
EukaryotesFrom 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.)
Theories of the Origin or organelles• Symbiosis: two organisms live closely together • Endosymbiosis: one organism lives inside another (bacteria in
us)
Theory explaining why mitochondria and chloroplasts are found in cells:
• It's thought that mitochondria (m) and chloroplasts (c) were types of prokaryotic cells that lived inside other cells. The m & c helped keep the cell alive and so were retained.
• Evidence on relationship of mitochondria and chloroplasts to prokaryote cells:– a. mitochondria and chloroplasts are both surrounded by double
membranes (like bacteria are). – b. mitochondria and bacteria have similar size. – c. mitochondrial ribosomes resemble bacterial ribosomes. – d. mirochondria and chloroplast DNA is circular like bacteria.
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. 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.
1.
2.
3.
4.5.
Structure – animal cell
Structure – plant cell
reproduction*Mitosis – body cells
*Meiosis – gametes (egg &
sperm)
Movement Internal1. The centriole 2. The cytoskeleton 3. Actin and tubulin
proteins
External4. Flagella 5. cilia
1.
3.
2.
4.5.
images
• http://web.jjay.cuny.edu/~acarpi/NSC/13-cells.htm
• http://www.cellbio.com/images.html
Review
Prokaryote & Eukaryote similarities
Both have1. DNA 2. A cell membrane3. Ribosomes4. Diverse forms (meaning a lot of shapes
and sizes)
Prokaryotes & Eukaryotes differences
Prokaryotes Eukaryotes•Plasmid DNA•No membrane-bound 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 Eukaryote
Write the things that are Different here
Write things that are the Same here
Write the things that are Different here
Characteristic Prokaryote EukaryoteSize 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?