Prokaryotes vs. Eukaryotes
Cell Theory
Cell Theory
In the 1800s, hundreds of scientists report seeing cells whenever they looked at living organisms through microscopes.
Based on these observations, researchers developed: Cell theory
– All living things are composed of cells
– The cell is the basic unit of structure and function in living things
– New cells are produced from existing cells
Description Prokaryotes Eukaryotes
When first evolved?
Size:
Types of organisms
# of cells:
Nucleus present?
Ribosomes present?
Mitochondria present?
DNA?
Type of chromosome:
Type of cell division:
Compare/Contrast: Prokaryotes & Eukaryotes
Turn to the back page of your packet
Eukaryotic Cells Have Organelles
• Organelles are internal membranes that partition the cell into different compartments
• Organelles isolate different chemical reactions thereby increasing efficiency
Eukaryotic Cells
Prokaryotic Cell (Bacteria)
2
Eukaryotic Cells Have Membrane-bound Organelles and Compartmentalization
Prokaryotic Cells Have No Organelles and No
Compartmentalization
All activities take place in the cytoplasm
Compare and Contrast Eukaryotic and Prokaryotic Cells
Size: Eukaryotic cells are larger
About 1,000 bacterial cells could fit inside a eukaryotic cell
Both have DNA made of the same 4 monomers: A, T, C, G
Prokaryotes have a single circular chromosome
Eukaryotes have multiple, linear chromosomes
Prokaryotes• No nucleus• Reproduction via binary
fission (a type of cloning)• No membrane-bound
organelles
Eukaryotes• Nucleus• Reproduction via mitosis
or meiosis• Has membrane-bound
organelles
Prokaryotes vs Eukaryotes
Prokaryotic Cells Eukaryotic CellsBacteria & Archaebacteria Plant, Animal, Protista, Fungi
Prokaryotic vs. Eukaryotic Cells
• Bacteria and Archaea-bacteria
• Bound by a plasma membrane
• Chromosomes carrying genes in the form of DNA
• Ribosomes: make proteins
• No nucleus, DNA concentrated in a region called nucleoid, lacks most organelles
• Smaller
• Protists, plants, fungi, animals
• Bound by a plasma membrane
• Chromosomes carrying genes in the form of DNA
• Ribosomes: make proteins
• Nucleus and has many organelles (such as mitochondria and chloroplasts)
• Typically ten times bigger than bacteria
Description Prokaryotes Eukaryotes
When first evolved? Approx. 3.8 billion years ago
Approx. 2.2 billion years ago
Size: 1/10 the size 10 times as big
Types of organisms Bacteria only Fungi, plants, animals, protists
# of cells: Single only Single and multicellular
Nucleus present? No Yes
Ribosomes present? Yes Yes
Mitochondria present? No Yes
DNA? Yes Yes
Type of chromosome: Single, circular Multiple, linear
Type of cell division: Binary fission Mitosis and meiosis
Compare/Contrast: Prokaryotes & Eukaryotes
Endosymbiotic Theory• Mitochondria has a double membrane, just as bacteria do.
• They also have their own unique set of DNA completely separate from the Eurkayotic cell they are in.
• That DNA has a lot more in common with bacterial DNA than that of Eurkaryotes
Endosymbiotic Theory• Chloroplasts also have their own unique DNA independent of
the plant cells they inhabit.
• That DNA is very similar to cyanobacteria
• In fact, the entire structure of a chloroplast is very similar to a bacteria that was engulfed and modified
Endosymbiotic Theory
1. What does the endosymbiotic theory claim about the origin of mitochondria & chloroplasts?
2. The DNA of chloroplasts is most closely related to:
3. The DNA of mitochondria is most closely related to:
4. List three lines of evidence in support of the theory:
Endosymbiosis Theory EvidenceMitochondria and Chloroplasts: • Have their own DNA, which has shape
(circular) and gene-structure like bacteria• Have their own ribosomes• Can copy themselves by binary fission
What is unique about the structure of mitochondria?
Evolution connection: Mitochondria
What is unique about the structure of mitochondria?
Evolution connection: Mitochondria
• their own DNA – a circular chromosome
Photo from Christian Kukat, Christian A. Wurm, Henrik Spåhr, Maria Falkenberg, Nils-Göran Larsson,
and Stefan Jakobs. Super-resolution microscopy reveals that mammalian mitochondrial nucleoids
have a uniform size and frequently contain a single copy of mtDNA. PNAS 2011 108 (33) 13534-
13539
What is unique about the structure of mitochondria?
Evolution connection: Mitochondria
• their own ribosomes
Image from Sukhjit Kaur, Reynald Gillet, Wen Li, Richard Gursky, and Joachim Frank. Cryo-EM
visualization of transfer messenger RNA with two SmpBs in a stalled ribosome PNAS 2006 103 (44)
16484-16489.
What is unique about the structure of mitochondria?
Evolution connection: Mitochondria and Plastids
• multiply by binary fission
Mitochondria image © Rockefeller University Press, 1970; originally published in the Journal of Cell
Biology 47:373-383. Chloroplast image from Shin-ya Miyagishima. Mechanism of Plastid Division:
From a Bacterium to an Organelle. Plant Physiol. 2011 155: 1533-1544.
What is unique about the structure of mitochondria?
Evolution connection: Mitochondria and Plastids
• The size of bacteria
What is unique about the structure of mitochondria
Evolution connection: Mitochondria
• double membrane
Why are mitochondria so weird?
Evolution connection: Mitochondria and Plastids
Because of their evolutionary history! Both evolved via
endosymbiosis.
Endosymbiosis in a series
Evolution connection: Mitochondria and Plastids
Endosymbiosis in a series
Evolution connection: Mitochondria and Plastids
Our house is compartmentalizedEven the rooms in our house are compartmentalizedEach compartment has a different functionEach compartment has a different formIncompatible activities can therefore go on simultaneously
- Food can stay frozen, while other food is cooked- This increases efficiency of important proceses
FreezerKeeps food frozenLong-term storage
FridgeKeeps food coldShort-term storage
Garbage CanStores wasteCan be removed
Cupboards Keeps dry & canned foods organized
Stove/OvenHeats foodCooks food
SinkDelivers fresh waterRemoves waste water
http://www.youtube.com/watch?v=yF7esxWJj1Q
Mitochondrial-DNA
• Inherited only from the egg (maternal-line)• You have the same mitochondrial DNA as mother,
grandmother, etc.• Sons inherit their mitochondrial DNA only from
mom as well
Mutation in mitochondrial DNA 40,000 years ago: Saami of Lapland
Mitochondrial DNA
• https://www.youtube.com/watch?v=ru7Wyt778QQ
Plant cells have:A cell wall, large central vacuole, chloroplasts
Eukaryotic Cells Have Organelles
• Organelles are internal membranes that partition the cell into different compartments
• Compartments can have very different environments
• Compartments allow incompatible processes to go on simultaneously inside the same cell
Cell Part Structure FunctionNucleus
Endoplasmic reticulum
Ribosomes
Golgi apparatus
Vesicles
Mitochondria Bean-shaped, has two membranes, inner membrane with many folds to increase surface area
Supplies energy to the cell: chemical reactions to convert food molecules into energy
Vacuole
Lysosomes
Cell Wall
Chloroplast