Prokaryotic and Eukaryotic Cell Structure And a Little Taxonomy too!

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Prokaryotic and Prokaryotic and Eukaryotic Cell Eukaryotic Cell Structure Structure And a Little Taxonomy too!

Transcript of Prokaryotic and Eukaryotic Cell Structure And a Little Taxonomy too!

Page 1: Prokaryotic and Eukaryotic Cell Structure And a Little Taxonomy too!

Prokaryotic and Eukaryotic Prokaryotic and Eukaryotic Cell StructureCell Structure

And a Little Taxonomy too!

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TaxonomyTaxonomy

The science of classification of living organisms.– So we can identify and understand relationships

between organisms.

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Linnaean SystemLinnaean System First developed by Carolus Linnaeus (1707-1778).

– Method of classifying things in a hierarchical structure from most general to most similar.

– Binomial System (2 names) Domain

– Kingdom (most general)– Phylum or Division – Class – Order – Family– Genus– Species

Ex. Eschericia coli

or E. coli

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Classification Classification

Domains constitute a level of classification above the kingdom.

Domains are further subdivided into kingdoms etc.

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The 3 DomainsThe 3 Domains

1. Archaea 2. Bacteria 3. Eukarya - animals

- plants

- algae

- protozoa

- fungi

Prokaryotes Eukaryotes

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5 Kingdoms 5 Kingdoms

Based on similar morphology, geographic distribution, and if multicellular, the ability to interbreed.

Bacteria

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Bergey SystemBergey System

Another system for classifying Prokaryotes.Still use kingdom, division or phylum,

class, order, family, genus, species.Classification based on similar

morphological and biochemical characteristics.

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Eukaryotic and Prokaryotic CellsEukaryotic and Prokaryotic Cells

How are they different and

how are they the same?

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What Is a Cell?What Is a Cell?

It is the fundamental unit of all living matter.

Has all characteristics of life.Can live independently of other cells.

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All Cells Have the Following:All Cells Have the Following: Enzymes

– A protein that speeds up a chemical reaction. DNA – deoxyribonucleic acid

– A large molecule that stores genetic information. RNA – ribonucleic acid

– A large molecule involved in protein synthesis. ATP – adenosine triphosphate

– The main energy currency of a cell. Amino Acids

– Proteins are composed of basically the same 20 amino acids.

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Eukaryotic Cell StructureEukaryotic Cell StructurePossess membrane-bound organelles.10-30µm in diameter.Eukaryote = “true nucleus”

– Their DNA is enclosed by a double membrane.

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Eukaryotic Cell StructureEukaryotic Cell StructureCell Membrane

– Phospholipid (fatty chain with a phosphate) bi-layer with different types of proteins interspersed.

– Separates inside of cell from external environment.

– It has selective permeability. Only certain things can get in and out.

– Other organelle membranes are similar in structure.

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Cell MembraneCell Membrane

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Eukaryotic Cell StructureEukaryotic Cell Structure Nucleus

– Controls the functions of the cell (“the control center).

– Nuclear membrane – surrounds nucleus.– Nucleoplasm – gelatinous matrix.– Chromosomes – linear DNA molecules and

proteins.– Gene – specific DNA segment on the

chromosome that contains the information for making a gene product, usually a protein.

– Nucleolus – where rRNA is made and is used to make a structure called ribosomes.

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Eukaryotic Cell StructureEukaryotic Cell Structure

Cytoplasm– A semi-fluid, gelatinous, nutrient matrix.– Contains storage granules and cell organelles.– Most of cell’s metabolism occurs.– Often called the cytosol.

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Eukaryotic Cell StructureEukaryotic Cell StructureEndoplasmic Reticulum (ER)

– An irregular maze of spaces enclosed by a membrane.

– “Assembly Line”– Rough ER

Contains ribosomes Involved in making proteins

– Smooth ER Does not contain ribosomes Involved in lipid metabolism (fat storage)

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Eukaryotic Cell StructureEukaryotic Cell Structure

Ribosomes– Are important in protein synthesis.– Are found in the Rough ER.

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Eukaryotic Cell StructureEukaryotic Cell Structure

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Eukaryotic Cell StructureEukaryotic Cell Structure

Golgi Complex– “packaging plant.”– Stacks of flattened, membranous sacs.– Completes and packages newly formed proteins

and lipids.– Packages them so that they are ready for

storage within the cell or outside of the cell.

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Eukaryotic Cell StructureEukaryotic Cell Structure Lysosomes

– “garbage disposal system”– 1 µm diameter– Contain lysozyme and other enzymes that break down

foreign material.– Particles may enter cell by phagocytosis.– Also involved in programmed cell death called autolysis or

apoptosis. Peroxisomes

– Membrane-bound vesicles that generate and break down hydrogen peroxide (a dangerous and highly reactive chemical).

– Used to break down lipids (fats) and destroy toxic molecules.

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Eukaryotic Cell StructureEukaryotic Cell Structure

Mitochondria – “the power plant of the cell”– 0.5 – 1 µm in diameter, 7 µm in length– Where ATP (adenosine triphosphate) is

formed. ATP is the energy currency of the cell.

– ATP is formed during a reaction called cellular respiration.

– ATP is formed from our food sources.

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Eukaryotic Cell StructureEukaryotic Cell Structure

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Eukaryotic Cell StructureEukaryotic Cell Structure

Plastids– Site of photosynthesis.– Contain photosynthetic pigments.

Photosynthesis – converting light energy into a source of chemical energy for organism.

– Chloroplasts – type of plastid that contains chlorophyll.

Chlorophyll – a green photosynthetic pigment.

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Eukaryotic Cell StructureEukaryotic Cell Structure- Plant Cell- Plant Cell

micro.magnet.fsu.edu/cells/plants/plantmodel.html

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Eukaryotic Cell StructureEukaryotic Cell Structure

Cell Wall– External structure that provides rigidity, shape,

and protection.– May be composed of cellulose, pectin, lignin,

chitin, and some mineral salts.– Usually simpler than prokaryotic cells.

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Eukaryotic Cell StructureEukaryotic Cell Structure

Cells stained green (DNA) and red (keratin)

www.newworldencyclopedia.org/entry/Cell_(biology

Illustration by Robert Hooke (c.1665)

askabiologist.asu.edu/.../rhooke.html

Plant Cells

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Cell WallsCell Walls

Cell Walls

Present

•Plants

•Algae

•Fungi

•Most Bacteria

Absent

•Animals

•Protozoa

•Mycoplasma species (type of bacteria)

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Eukaryotic Cell StructureEukaryotic Cell Structure

Flagella– An organelle of movement.– Long, thin structure that moves like a whip to propel organism

through liquid environment. – Can be found in some species of protozoa, spermatozoa, and

algae. Cilia

– Organelle of locomotion.– Usually short, hair-like structures that beat in coordinated,

rhythmic movement.– Can be found in some species of protozoa and types of cells

that line respiratory tract.

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Eukaryotic Cell StructureEukaryotic Cell Structure

Euglena – sp. Protozoa. Notice the flagella.www.biologie.uni-erlangen.de/.../fotonm3_eng.htm

Paramecium – sp. Protozoa. Notice the cilia.microbewiki.kenyon.edu/index.php/Paramecium

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Prokaryotic Cell StructureProkaryotic Cell Structure

More simple than eukaryotic cells.Can perform all functions necessary for life.Prokaryotes comprise all bacteria and

archaeans.Do NOT contain membrane-bound

organelles.Typical E. coli cell is about 1 µm wide and

2-3 µm long.

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Prokaryotic Cell StructureProkaryotic Cell Structure

Bacterial Cell Wall – Provides rigidity, strength, and protection.– More complex than eukaryote cell walls.– Composed of peptidoglycan (polymer of sugars and amino

acids)– Gram-positive bacteria

Thick layer of peptidoglycan with some other molecules.

– Gram-negative bacteria Thinner layer of peptidoglycan with an outer membrane composed of

lipid macromolecules.

– Genus Mycoplasma do not have cell walls.– Archaens have cell walls but not composed of peptidoglycan.

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Prokaryotic Cell StructureProkaryotic Cell Structure

Cell Membrane– Similar to eukaryotic cells.– Contains proteins and phospholipids.– Selectively permeable.– It is very flexible and thin.

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Prokaryotic Cell StructureProkaryotic Cell Structure Glycocalyx

– Thick, slimy, gelatinous material produced by the cell membrane and secreted outside the cell wall.

– Some bacteria have it.– 2 types of glycocalyx

1. Slime Layer– Is not highly organized or firmly attached to cell wall.

– Allows bacteria to glide or slide along surfaces. 2. Capsule

– Highly organized and firmly attached to cell wall.

– Chemical composition allows scientists to determine different types of bacteria.

– Prevent bacteria from being phagocytized by phagocytic white blood cells.

– Can attach bacteria to a wide array of surfaces.

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Prokaryotic Cell StructureProkaryotic Cell Structure

diverge.hunter.cuny.edu/~weigang/Lecture-syll.

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Prokaryotic Cell StructureProkaryotic Cell StructureProkaryotic Chromosome

– Single, long, supercoiled, circular DNA molecule.

– Embedded in cytoplasm.– Found in nuclear region of cell.– Does not have a nuclear membrane.– Contains all the information for carrying out

life processes.– Plasmids may also be found in prokaryotic

cells.

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Prokaryotic Cell StructureProkaryotic Cell Structure

Plasmid– Small, circular molecule of double-stranded

DNA.– Not part of the chromosome.

Called extrachromosomal DNA.

– Found in the cytoplasm.– May contain 10-100s genes.– Number varies per cell.

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Prokaryotic Cell StructureProkaryotic Cell Structure

Cytoplasm – Semiliquid interior of cells.– Consists of water, enzymes, dissolved oxygen

(in some bacteria), waste products, nutrients, proteins, carbohydrates, and lipids.

– Everything necessary for its metabolic functions.

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Prokaryotic Cell StructureProkaryotic Cell Structure

Cytoplasmic Particles– Ribosomes are found in the cytoplasm.– They are important in protein synthesis.– Some substances are stored in cytoplasmic

granules. Such as starch, lipids, sulfur, or iron. The type of substance stored depends on the species

of organism.

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Prokaryotic Cell StructureProkaryotic Cell Structure

diverge.hunter.cuny.edu/~weigang/Lecture-syll.

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Prokaryotic Cell StructureProkaryotic Cell Structure

Flagella– A mechanism for

movement for some bacteria.

– Bacteria can be classified and identified by the arrangement of their flagella.

– Nonflagellated bacteria are usually considered to be nonmotile.

Although there are exceptions.

Pseudomonas fluorescens – aerobic soil bacteria.www.scienceclarified.com/As-Bi/Bacteria.html

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Prokaryotic Cell StructureProkaryotic Cell Structure

Pili (Fimbriae)– Not associated with motility.– Thin, rigid, hair-like structure.– Arise in cytoplasm and extend through the plasma

membrane, cell wall, and capsule (if present).– 2 types of pili

1. Adhesins - allows bacteria to adhere to surfaces. 2. Sex pilus

– Allows for the transfer of genetic material through a process called conjugation.

– One bacteria attaches its sex pilus to another cell and transfers its genetic material to the other cell usually in the form of a plasmid.

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Prokaryotic Cell StructureProkaryotic Cell Structure

Adhesin bacterial cell with pili (fimbriae) ultr23.vub.ac.be/.../fimbrialadhesion.html

Bacterial conjugation with sex pilus. www.cbs.dtu.dk/.../roanoke/genetics980309.html

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Prokaryotic Cell StructureProkaryotic Cell Structure

Spores (Endospores)– Bacterial spores called endospores.– Usually found in 2 genera: Bacillus and Clostridium.– Form through the process sporulation.

A copy of the chromosome and some cytoplasm is enclosed in a thick protein coat.

– This occurs when moisture and nutrients are low.– Endospores are resistant to heat, cold, drying, and most

chemicals.– If adequate conditions are present, the endospore can

become an active bacteria.

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EndosporeEndospore

Clostridium difficil forming an endospore.

Associated with antibiotic related diarrhea caused by toxins produced

Red structure is endospore forming. www.chem.wayne.edu/feiggroup/research.htm

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Prokaryotic Cell Reproduction Prokaryotic Cell Reproduction

Binary Fission– One parent cell splits to become 2 daughter

cells.– This process produces a clone of the parent cell.– During this process, its chromosome is

replicated in a process called DNA replication.– Generation time

The time it takes one parent cell to become 2 identical daughter cells.

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Binary FissionBinary Fission

www.uic.edu/.../bios100/lecturesf04am/lect06.htm

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The EndThe End