Chapter 2 The Cell

Limits of microscopes - Eukaryotic cells are measured in µm (100-10µm) End light microscope viewing power - Eukaryotic cells are measured in µm (100-10µm) Micrometer is 10-6 of a meter.

2 types of Electron Microscopes Transmission EM (TEM) Requires ultrathin sections See internal structures 2D image Scanning EM (SEM) Sweeps across surface of specimen See surface anatomy 3D image

Figure 2.1 Different Techniques, Different Perspectives LM  400 TEM  2400 SEM  14,000 Cells as seen in light microscopy (respiratory tract) Cells as seen in transmission electron microscopy (intestinal tract) Cells as seen in scanning electron microscopy (respiratory tract)

Virus budding from cell Which is TEM? SEM?

Plant cells: you can see 3 different cells and internal structures M= mitochondria, G= golgi apparatus, Vac= vacuole PM= plasma membrane CW = cell wall ER= Endoplasmic reticulum

Head of an Antarctic mite magnified 1500x

Termite Head

Fly foot

Human Adipose tissue

lung

Spongy bone

skin

Connective Tissue

collagen

Human hair

Nerve fibers

Nerve fiber close up

Skeletal muscle fiber: pink are mitochondria

Nerve cell White blood cell liver cell osteoblast

Generalized Eukaryotic Cell

Plasma Membrane (Plasmalemma) Composition: lipids, proteins and carbohydrates. phospholipid bilayer, cholesterol & glycolipids, glycoproteins, integral proteins, peripheral proteins Label parts of the membrane

Different types of Endocytosis

Receptor mediated endocytosis LDL tutorial

Exocytosis Examples?

Microvilli: extensions of plasma membrane

Cytoplasm: interior of the cell Cytosol jelly-like fluid inside the cell. Differs from outside in ion concentrations & molecular make-up (proteins, carbohydrates etc) Organelles: nucleus ribosomes ER golgi complex mitochondria lysosomes peroxisomes cytoskeleton

Nucleus “little nut”

Figure 2.11 Ribosomes Nucleus Free ribosomes Small ribosomal subunit Large ribosomal subunit Endoplasmic reticulum with attached fixed ribosomes An individual ribosome, consisting of small and large subunits TEM  73,600 Both free and fixed ribosomes can be seen in the cytoplasm of this cell.

Endoplasmic Reticulum • .

Functions of ER Smooth ER: lipid metabolism (making & breaking down lipids) Abundant in cells that make steroid hormones & in liver that detoxifies fat soluble drugs/toxins. Rough ER: makes proteins that are going to be secreted from the cell.

Figure 2.16b The Golgi Apparatus EXTRACELLULAR FLUID ode to Golgi Animated tutorial CYTOSOL Membrane renewal vesicles Lysosome Secretory vesicle Cisternae Maturing (trans) face This diagram shows the functional link between the ER and the Golgi apparatus. Golgi structure has been simplified to clarify the relationships between the membranes. Transport vesicles carry the secretory product from the endoplasmic reticulum to the Golgi apparatus, and transfer vesicles move membrane and materials between the Golgi cisternae. At the maturing face, three functional categories of vesicles develop. Secretory vesicles carry the secretion from the Golgi to the cell surface, where exocytosis releases the contents into the extracellular fluid. Other vesicles add surface area and integral proteins to the plasmalemma. Lysosomes, which remain in the cytoplasm, are vesicles filled with enzymes. Forming (cis) face Transport vesicle

Lysosomes See animation of cell taking In particles, digesting them & gettign rid of waste.

liver & muscle cells have as many as 300 mitochondria Figure 2.12 Mitochondria Inner membrane Cytoplasm of cell Cristae Matrix Organic molecules and O2 Outer CO2 ATP membrane Matrix Cristae Enzymes TEM  61,776 liver & muscle cells have as many as 300 mitochondria © 2012 Pearson Education, Inc.

Peroxisomes

Cytoskeleton Microvilli Microfilaments Plasmalemma Terminal web Mitochondrion Intermediate filaments Endoplasmic reticulum The cytoskeleton provides strength and structural support for the cell and its organelles. Interactions between cytoskeletal elements are also important in moving organelles and in changing the shape of the cell. Microtubule Secretory vesicle

Amoeba move due to rearranging their cytoskeleton Neutrophil motion

Centrioles & the Centrosome

Membrane proteins from adjacen t cells Gap ju nctions create gaps that connect animal cells. ••••••••••••.................. Gap----c ju nctions Membrane proteins from adjacen t cells line up to form a chan nel Figure 8-13b part 2 Biological Science,2/e © 2005 Pearson Prentice Hall,Inc.

A possible cause of Celiac disease

Three-dimensional view of tight junctions Plasma membranes of adjacent cells Figure 8-9b Biological Science, 2/e © 2005 Pearson Prentice Hall, Inc..

Inner Life of the Cell

1. Some integral membrane proteins form gated channels that open or close to: Regulate passage of materials in/out of cell Permit water movement in/out of cell Transport large proteins into cell Communicate with neighboring cells 2. Which organelle would be in abundance in immune cells that kill bacteria? a) SER c) lysosome b) b) RER d) centrosomes

3. Products made in the ER would travel to Nucleus b) Golgi peroxisome mitochondria

Functions of the plasma membrane include which of the following? regulation of exchange with the environment interaction with actin filaments to produce contractions production of proteins production of ATP

5. What are the benefits of having some organelles enclosed by a membrane?