Eukaryotes have a much more complex cell structure than prokaryotes. Essential Idea Eukaryotes have a much more complex cell structure than prokaryotes.

All cells share certain characteristics ♦ Cells tend to be microscopic. ♦ All cells are enclosed by a membrane. ♦ All cells are filled with cytoplasm. ♦ Plasma membrane ♦ Chromosomes (carry genes) ♦ Ribosomes (make proteins)

There are two cell types: 1. Prokaryotes 2. Eukaryotes nucleus organelles cell membrane

Prokaryotes Assessment Statement Draw and label a diagram of the ultrastructure of Escherichia coli (E. coli) as an example of a prokaryote. The diagram should show the cell wall, plasma membrane, cytoplasm, pili, flagella, ribosomes and nucleoid (region containing naked DNA).

Draw and label a prokaryote

E. Coli – A representative prokaryote (bacteria) Prokaryotes are cells that do not have a nucleus The do not have any membrane bound organelles All bacteria are prokaryotes

Diagram of E. Coli

Prokaryotes The general size of a prokaryotic cell is about 1-2 um. Note the absence of membrane bound organelles There is no true nucleus with a nuclear membrane The ribosome's are smaller than eukaryotic cells The slime capsule is used as a means of attachment to a surface Only flagellate bacteria have the flagellum Plasmids are very small circular pieces of DNA that maybe transferred from one bacteria to another.

Prokaryotes Example Eshericha coli (E. coli) In a prokaryotic cell, DNA is circular and in the cytoplasm called the nucleoid

Prokaryote cellular structure function Assessment Statement Annotate the E. coli diagram with the functions of each named structure.

Annotate: Label & Function

Prokaryote cellular structure function Cell Wall: Made of a murein (not cellulose), which is a glycoprotein or peptidoglycan (i.e. a protein/carbohydrate complex). There are two kinds of bacterial cell wall, which are identified by the Gram Stain technique when observed under the microscope. Gram positive bacteria stain purple, while Gram negative bacteria stain pink. The technique is still used today to identify and classify bacteria. We now know that the different staining is due to two types of cell wall Plasma membrane: Controls the entry and exit of substances, pumping some of them in by active transport. Cytoplasm: Contains all the enzymes needed for all metabolic reactions, since there are no organelles. Ribosome: The smaller (70 S) type are all free in the cytoplasm, not attached to membranes (like RER). They are used in protein synthesis which is part of gene expression. Nucleoid: Is the region of the cytoplasm that contains DNA. It is not surrounded by a nuclear membrane. DNA is always a closed loop (i.e. a circular), and not associated with any proteins to form chromatin.

Prokaryote cellular structure function Flagella: These long thread like attachments are generally considered to be for movement. They have an internal protein structure that allows the flagella to be actively moved as a form of propulsion. The presence of flagella tends to be associated with the pathogenicity of the bacterium. The flagella is about 20nm in diameter. This structure should not be confused with the eUkaryotic flagella seen in protoctista. Pilli: These thread like projections are usually more numerous than the flagella. They are associated with different types of attachment. In some cases they are involved in the transfer of DNA in a process called conjugation or alternatively as a means of preventing phagocytosis. Slime Capsule: A thick polysaccharide layer outside of the cell wall, like the glycocalyx of eukaryotes. Used for sticking cells together, as a food reserve, as protection against desiccation and chemicals, and as protection against phagocytosis. In some species the capsules of many cells in a colony fuse together forming a mass of sticky cells called a biofilm. Dental plaque is an example of a biofilm.

Prokaryote cellular structure function Plasmids: Extra-nucleoid DNA of up to 400 kilobase pairs. Plasmids can self-replicate particularly before binary fission. They are associated with conjunction which is horizontal gene transfer. It is normal to find at least one anti-biotic resistance gene within a plasmid. This should not be confused with medical phenomena but rather is an ecological response to other antibacterial compounds produced by other microbes. Commonly fungi will produce anti-bacterial compounds which will prevent the bacteria replicating and competing with the bacteria for a resource. conjugation Direct contact between bacterial cells in which plasmid DNA is transferred between a donor cell and a recipient cell. There is no equal contribution to this process, no fertilisation and no zygote formation. It cannot therefore be regarded as sexual reproduction.

Binary Fission – Asexual Reproduction in Prokaryotes Prokaryotes reproduce by binary fission They copy their circular chromosome The cell grows longer with the two chromosomes attached to the inside membrane The membrane pinches together in the centre Two daughter cells are formed

Prokaryote Binary Fission (a). Reproduction signal: The cell receives a signal, of internal or external origin that initiates the cell division. E.coli replicates about once every 40 minutes when incubated at 37o C. If however we increase the concentration of carbohydrate nutrients that the cell is supplied with then the division time can be reduced to 20 minutes. There is a suggestion here that an external signal (nutrient concentration) is acting as the reproductive signal. (b). Replication of DNA: bacterial cells have a single condensed loop of DNA. This is copied by a process known as semi-conservative replication to produce two copies of the DNA molecule one for each of the daughter cells. The replication begins at a single point (ori)on the loop of DNA. The process proceeds around the loop until two loop have been produced, each a copy of the original. The process finishes at a single point on the loop of DNA called the ter position.

Prokaryote Binary Fission (c). Segregation of DNA: One DNA loop will be provided for each of the daughter cells. As the new loops form the ori site becomes attached to some contractile proteins that pull the two ori sites, and therefore the loops, to opposite ends of the cell. This is an active process that requires the bacteria to use energy for the segregation. (d). Cytokinesis: Cell separation. This occurs once the DNA loop replication and segregation is complete. The DNA completes a process of condensing whilst the plasma membrane begins to form a 'waist' or constriction in the middle of the cell. As the plasma membrane begins to pinch and constrict the membrane fuses and seals with additional new membrane also being formed.

Prokaryote cell Pili Nucleoid Ribosomes Plasma membrane Cell wall Bacterial chromosome Capsule Flagella A typical rod-shaped bacterium A thin section through the bacterium Bacillus coagulans (TEM)

Binary Fission Animation http://www. classzone

Prokaryotes Animation Watch Animation of Prokaryotes Structure and function. http://www.wiley.com/legacy/college/boyer/0470003790/animations/cell_structure/cell_structure.swf http://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::500::500::/sites/dl/free/0073375225/594358/BinaryFission.swf::BinaryFission

Eurkaryotic Cell Characteristics Eukaryotic cells have a nucleus that contain its DNA Eukaryotic cells have membrane-bound organelles. Nucleus Mitochondria Chloroplasts (plants only) Eukaryotes are bigger than Prokaryotes Animal and plant cells are eukaryotes

Human Liver Cells

Draw a Eukaryotic Liver Cell Assessment Statement Draw and label a diagram of the ultrastructure of a liver cell as an example of an animal cell. The diagram should show free ribosomes, rough endoplasmic reticulum (rER), lysosome, Golgi apparatus, mitochondrion and nucleus. The term Golgi apparatus will be used in place of Golgi body,

Draw a Eukaryotic Liver Cell N: Nucleus PM: plasma membrane M: mitochondria rER: Rough endoplasmic reticulum GA: Golgi apparatus L: Lysosome MV: Microvilli

Annotate Diagram Assessment Statement Annotate the E. coli diagram with the functions of each named structure.

Annotate: Label & Function

Nucleus Nucleus: This is the largest of the organelles. The nucleus contains the chromosomes which during interphase are to be found the nucleolus. The nucleus has a double membrane with pores(NP). The nucleus controls the cells functions through the expression of genes. Some cells are multi nucleated such as the muscle fibre

Plasma Membrane Plasma membrane: controls which substances can enter and exit a cell. It is a fluid structure that can radically change shape. The membrane is a double layer of water repellant molecules. Receptors in the outer surface detect signals to the cell and relay these to the interior. The membrane has pores that run through the water repellant layer called channel proteins.

Mitochondria:.. Mitochondria: location of aerobic respiration and a major synthesis of ATP region.. Double membrane organelle. Inner membrane has folds called cristae. This is the site of oxidative phosphorylation. Centre of the structure is called the matrix and is the location of the Krebs cycle. Oxygen is consumed in the synthesis of ATP on the inner membrane The more active a cell the greater the number of mitochondria.

Rough endoplasmic reticulum (rER). rER form a network of tubules with a maze like structure. In general these run away from the nucleus The 'rough' on the reticulum is caused by the presence of ribosomes. Proteins made here are secreted out of the cell

Ribosomes: the free ribosome produces proteins for internal use within the cell.

Golgi apparatus. Modification of proteins prior to secretion. proteins for secretion are modified possible addition of carbohydrate or lipid components to protein packaged into vesicles for secretion

Lysozyme: Vesicles in the above diagram that have formed on the golgi apparatus. Containing hydrolytic enzymes. Functions include the digestion of old organelles, engulfed bacteria and viruses.

Vocabulary Practice (12 mnutes) free ribosomes, rough endoplasmic reticulum (rER) lysosome, Golgi apparatus, mitochondrion and nucleus 3 minutes – One student gives function –the other identifies organelle 3 minutes -- Switch 3 minutes – One student gives organelle –the other describes function

IB Assessment Statement Identify structures from liver in electron micrographs of liver cells.

Videos Video about Animal Cells http://www.youtube.com/watch?v=cj8dDTHGJBY&feature=BFa&list=PL3EED4C1D684D3ADF&lf=context Video about Plant Cells http://www.youtube.com/watch?v=9UvlqAVCoqY&list=SP3EED4C1D684D3ADF Video about Cells in general https://www.youtube.com/watch?v=yZu6DfcPHr8&feature=player_embedded#t=6

Self Test: What organelle is it?

Self Test: What organelle is it?

Self Test: What organelle is it?

Self Test: What organelle is it?

Self Test: What organelle is it?

IB Assessment Statement 2.3.4 Compare prokaryotic and eukaryotic cells.

Prokaryote vs. Eukaryote Only organisms of the domains Bacteria and Archaea consist of prokaryotic cells Protists, fungi, animals, and plants all consist of eukaryotic cells

Prokaryote cell Pili Nucleoid Ribosomes Plasma membrane Cell wall Bacterial chromosome Capsule 0.5 µm Flagella A typical rod-shaped bacterium A thin section through the bacterium Bacillus coagulans (TEM)

ENDOPLASMIC RETICULUM (ER Eukaryote cells ENDOPLASMIC RETICULUM (ER Nuclear envelope Flagellum Rough ER Smooth ER Nucleolus NUCLEUS Chromatin Centrosome Plasma membrane CYTOSKELETON Microfilaments Intermediate filaments Microtubules Ribosomes: Microvilli Golgi apparatus Peroxisome Mitochondrion Lysosome In animal cells but not plant cells: Lysosomes Centrioles Flagella (in some plant sperm)

Prokaryotes vs. Eukaryotes nucleus cell membrane organelles cytoplasm

Prokaryotic vs. Eukaryotic

Prokaryotic vs. Eukaryotic

IB ASSESSMENT STATEMENT State three differences between plant and animal cells.

All eukaryotes have the same following components: Ribosomes Mitochondria Nucleus Endoplasmic Reticulum (ER) Rough ER Golgi body apparatus

Eukaryotic: Plant vs. Animal Plants Cell Wall Chloroplasts General Rectangular Shape Large Vacuoles Stores polysaccharide in the form of STARCH Animals NO cell wall NO Chloroplast Irregular shape Small Vacuoles Stores polysaccharide in the form of Glycogen

ENDOPLASMIC RETICULUM (ER LE 6-9a ENDOPLASMIC RETICULUM (ER Nuclear envelope Flagellum Rough ER Smooth ER Nucleolus NUCLEUS Chromatin Centrosome Plasma membrane CYTOSKELETON Microfilaments Intermediate filaments Microtubules Ribosomes: Microvilli Golgi apparatus Peroxisome Mitochondrion Lysosome In animal cells but not plant cells: Lysosomes Centrioles Flagella (in some plant sperm)

LE 6-9b Nuclear envelope Rough endoplasmic reticulum NUCLEUS Nucleolus Chromatin Smooth endoplasmic reticulum Centrosome Ribosomes (small brown dots) Central vacuole Golgi apparatus Microfilaments Intermediate filaments CYTOSKELETON Microtubules Mitochondrion Peroxisome Plasma membrane Chloroplast Cell wall Plasmodesmata Wall of adjacent cell In plant cells but not animal cells: Chloroplasts Central vacuole and tonoplast Cell wall Plasmodesmata

A representative plant cell and a diagram of a ‘’Typical’’ Plant Cell

Other Eukaryotes – Protists Paramecium and Ameoba

Plants vs. Animals

Plant Vs. Animal

Nature of Science Developments in scientific research follow improvements in apparatus—the invention of electron microscopes led to greater understanding of cell structure. (1.8)

http://www. history-of-the-microscope http://www.history-of-the-microscope.org Assignment: History of the Microscope Webquest

The electron microscope Invented in Germany (1930’s) Able to view samples 200 times smaller than light microscopes Invention of the electron microscope revealed a whole new level of cellular detail.

Resolution - comparison Millimetres (mm) Micrometres ( m) Nanometres (nm) Eye 0.1 100 100,000 Light Microscope 0.0002 0.2 200 Electron microscope 0.000001 0.001 1 Table taken from page 18, your biology textbook