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