Prokaryotes vs. Eukaryotes · Description Prokaryotes Eukaryotes When first evolved? Approx. 3.8...
Transcript of Prokaryotes vs. Eukaryotes · Description Prokaryotes Eukaryotes When first evolved? Approx. 3.8...
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