A_Tour_of_the_Cell_and_its_Membranes

A Guided Tour of the Cell : 

A Guided Tour of the Cell BIOLOGY:

Cells : 

Cells Definition: The smallest, basic unit of living material capable of carrying on all the activities necessary for life. Average sizes: 1. Bacteria—1-10 micrometers 2. Eukaryotic cells—10-100 micrometers a. average plant cell—40 m b. average animal cell—15 m

Discovery of the Cell : 

Discovery of the Cell 1665—Robert Hooke described the structure of cork, actually the remains of dead plant cells, through his compound microscope. He gave us the word “cell.” 1673—Anton van Leeuwenhoek described microscopic organisms he viewed through his simple microscope.

The Cell Theory : 

The Cell Theory The three statements of the cell theory: 1. All living things are composed of cells and cell products. 2. The cell is the basic unit of structure and function of all living things. 3. Every cell comes from a preexisting cell. One of the unifying concepts of biology 1838—Matthias Schleiden—botanist 1839—Theodor Schwann—zoologist 1855—Rudolf Virchow

The first way to study cells is with light microscopy. : 

The first way to study cells is with light microscopy.

The second way to study cells is with electron microscopy. : 

The second way to study cells is with electron microscopy. TEM – Transmission Electron Microscopy SEM – Scanning Electron Microscospy

We study organelles by a process called cell fractionation. : 

We study organelles by a process called cell fractionation.

Slide 8: 

What is the benefit of cells being so small? Why don’t just keep growing?

Prokaryotic Cells : 

Prokaryotic Cells Etymology of name: Greek before, kernel Lack a membrane-bounded nucleus. Structurally simple. Average size is 1.1-1.5 m wide by 2-6 m long. Can be divided into two domains: Bacteria Three Shapes Bacillus (rod) Coccus (spherical) Spirilla (spiral) Archaea Live in extreme habitats such as extremely salty and/or hot aqueous environments. May have been first type of cell to evolve.

Prokaryotic Cells : 

Prokaryotic Cells Cell Envelope Glycocalyx - helps prevent drying out and aids in resisting a host’s immune system. Either: Capsule – Well-organized layer. Compact. Slime Layer—if diffuse and can be washed off Cell wall—maintains shape of cell; is composed of peptidoglycan. Cell membrane phospholipid bilayer with internal pouches called mesosomes that increase surface area for metabolic activities.

Prokaryotic Cells : 

Prokaryotic Cells Cytoplasm Inclusion Bodies - Stored granules of various substances. Contains enzymes DNA found in the nucleoid (a single coiled strand) and in plasmids (small circular loops) -- Ribosomes -- thylakoids (Cyanobacteria) — Were probably first photosynthetic organisms. Appendages Flagella—one or more; locomotion. Fimbriae—small, bristle-like fibers on the surface; help attach to surfaces. Sex Pili—rigid, tubular structures used to pass DNA from cell to cell. Can obtain new DNA by conjugation (sex pili), transformation (taking up DNA from outside), and transduction (carried in by viruses).

Figure 7.4x2 E. coli & Figure 27.x1 Prokaryotic conjugation : 

Figure 7.4x2 E. coli & Figure 27.x1 Prokaryotic conjugation

Eukaryotic Cells : 

Eukaryotic Cells Found in members of the domain Eukarya (Protists, Fungi, Plantae, and Animalia). Contain membrane-bounded nucleus. Contain specialized organelles. Contain plasma membrane—phospholipid bilayer. Some protists, fungi, and plants have cell walls.

Organelles : 

Organelles Origin of Organelles: Invagination of plasma membrane could have created the nuclear envelope and endomembrane system (ER, Golgi apparatus, and vesicles) Endosymbiosis—independent prokaryotes took up residence in a larger cell. Are now mitochondria and chloroplasts. Organelles of endomembrane system communicate with one another and are self-sufficient. Compartmentalization allows eukaryotic cells to be larger than prokaryotic cells.

Nucleus & Nucleolus : 

Nucleus & Nucleolus Nucleus: Contains chromatin (DNA, protein, and some RNA) in semifluid nucleoplasm. Condense to form chromosomes. Separated from cytoplasm by double-membrane nuclear envelope. Nuclear pores permit passage in and out of the nucleus. Nucleolus - Dark region of chromatin where ribosomal RNA (rRNA) is produced and subunits of ribosomes are made

Ribosomes : 

Ribosomes 20 X 30 nm in size. Composed of large and small subunits that serve in protein synthesis. Subunits made in nucleolus. Occur singly and in groups, and may be found loose in the cytoplasm or may become attached to endoplasmic reticulum .

Endomembrane System : 

Endomembrane System Consists of nuclear envelope, membranes of endoplasmic reticulum, Golgi apparatus, and several types of vesicles. Restrict enzymatic reactions to specific compartments within cell. Endoplasmic Reticulum Rough - Studded with ribosomes. Smooth - No ribosomes.

Endomembrane System : 

Endomembrane System Golgi Apparatus Consists of flattened, curved saccules. Modifies proteins and lipids and packages them in vesicles.

Endomembrane System : 

Endomembrane System Lysosomes Membrane-bounded vesicles produced by the Golgi apparatus. Engage in digestion of molecules and apoptosis (programmed cell death).

Peroxisomes and Vacuoles : 

Peroxisomes and Vacuoles Peroxisomes are membrane-bounded vesicles that enclose enzymes. Enzymes are cell-specific Vacuoles are membranous sacs that are larger than vesicles. Store substances Plants cells typically have a central vacuole that functions in storage of nutrients and waste products.

Chloroplasts : 

Chloroplasts Adenosine triphosphate (ATP) is used for all energy-requiring processes in cells. Chloroplasts use solar energy to synthesize carbohydrates. Photosynthesis Chloroplasts are green due to the green pigment chlorophyll. Stroma —fluid containing enzymes Granum —stack of coins; individual membranes called thylakoids

Mitochondria : 

Mitochondria Mitochondria are involved in cellular respiration. Produce most of ATP utilized by the cell. Cristae– folded inner membranes that enclose the matrix. Matrix –fluid containing DNA, ribosomes, and enzymes that break down nutrient molecules.

Cytoskeleton : 

Cytoskeleton Cytoskeleton maintains cell shape and assists in movement of its parts. Actin Filaments —twisted double chain for chloroplast movement and pseudopods Intermediate Filaments —ropelike assembly of fibrous polypeptides support nuclear envelope & plasma membrane Microtubules —hollow tubes of tubulin maintain the shape of the cell and act as tracks along which organelles can move

Figure 7.21 Motor molecules and the cytoskeleton : 

Figure 7.21 Motor molecules and the cytoskeleton

Centrioles, Cilia, and Flagella : 

Centrioles, Cilia, and Flagella Centrioles - short cylinders with a 9 + 0 pattern of microtubule triplets that may give rise to basal bodies of cilia and flagella. Cilia and flagella are hair-like projections with a 9 + 2 pattern of microtubules that aid in cell movement. (cilia are shorter).

Slide 28: 

Centrioles, Cilia, and Flagella

Cell Membrane : 

Cell Membrane

Plant Cell Wall : 

Plant Cell Wall