Welcome to BIO201 Dr. Maura Parker

The Course…. Cell Biology – Cell Anatomy and Function Cell Biology – Energy and Metabolism Genetics – DNA, Chromosomes and Inheritance Genetics – Gene Expression and Technology

Grading 4 exams – 52% Quizzes – 14% Lab Reports – 24% (8 labs x 3% each) Independent Research – 10%

Student Expectations Read before class - quizzes are not announced Be prepared with questions – every question is a good question – especially during Review sessions Prepare for lab sessions – you have lots to do and 3 hours is not a lot of time! DO NOT COPY OTHER STUDENTS’ LAB REPORTS

Expectations for me To provide you with the materials to learn Be at class prepared Be at lab sessions prepared Answer questions Note: Please send me s and make appointments if you need to see me

Lecture #1 – Introduction to Cell Biology Text – Chapter 6 – pages Note: tomorrow is Ch. 6 – pp

The Cell is the Fundamental Unit of Life all living things are composed of cells multicellular and unicellular organisms prokaryotes and eukaryotes

The size range of cells Nucleus Most bacteria Measurements 1 centimeter (cm) = 10  2 meter (m) = 0.4 inch 1 millimeter (mm) = 10 –3 m 1 micrometer (µm) = 10 –3 mm = 10  6 m 1 nanometer (nm) = 10 –3 µm = 10  9 m 10 m 1 m 0.1 m 1 cm 1 mm 100 µm 10 µm 1 µm 100 nm 10 nm 1 nm 0.1 nm Human height Length of some nerve and muscle cells Chicken egg Frog egg Most plant and animal cells Mitochondrion Smallest bacteria Viruses Ribosomes Proteins Lipids Small molecules Atoms Unaided eye Light microscope Electron microscope nucleus Most bacteria

Light Microscopes – Cells can be Seen! magnification: image size/object size resolution: the minimum distance 2 points can be separated and still distinguished as 2 points typically 1000x magnification and 0.2  m resolution

Brightfield (unstained specimen). Passes light directly through specimen. Unless cell is naturally pigmented or artificially stained, image has little contrast. [Parts (a)–(d) show a human cheek epithelial cell.] (a) Brightfield (stained specimen). Staining with various dyes enhances contrast, but most staining procedures require that cells be fixed (preserved). (b) Phase-contrast. Enhances contrast in unstained cells by amplifying variations in density within specimen; especially useful for examining living, unpigmented cells. (c) 50 µm

Differential-interference-contrast (Nomarski). Like phase-contrast microscopy, it uses optical modifications to exaggerate differences in density, making the image appear almost 3D. Fluorescence. Shows the locations of specific molecules in the cell by tagging the molecules with fluorescent dyes or antibodies. These fluorescent substances absorb ultraviolet radiation and emit visible light, as shown here in a cell from an artery. Confocal. Uses lasers and special optics for “optical sectioning” of fluorescently-stained specimens. Only a single plane of focus is illuminated; out-of-focus fluorescence above and below the plane is subtracted by a computer. A sharp image results, as seen in stained nervous tissue (top), where nerve cells are green, support cells are red, and regions of overlap are yellow. A standard fluorescence micrograph (bottom) of this relatively thick tissue is blurry. 50 µm (d) (e) (f)

Electron Microscopes - What is inside the cell? Scanning electron micro- scopy (SEM). Micrographs taken with a scanning electron micro- scope show a 3D image of the surface of a specimen. This SEM shows the surface of a cell from a rabbit trachea (windpipe) covered with motile organelles called cilia. Beating of the cilia helps move inhaled debris upward toward the throat. (a) Transmission electron micro- scopy (TEM). A transmission electron microscope profiles a thin section of a specimen. Here we see a section through a tracheal cell, revealing its ultrastructure. In preparing the TEM, some cilia were cut along their lengths, creating longitudinal sections, while other cilia were cut straight across, creating cross sections. (b) Cilia 1 µm Longitudinal section of cilium Cross section of cilium 1 µm

What do the parts inside the cell do? Tissue cells Homogenization Homogenate 1000 g (1000 times the force of gravity) 10 min Differential centrifugation Supernatant poured into next tube 20,000 g 20 min Pellet rich in nuclei and cellular debris Pellet rich in mitochondria (and chloro- plasts if cells are from a plant) Pellet rich in “microsomes” (pieces of plasma mem- branes and cells’ internal membranes) Pellet rich in ribosomes 150,000 g 3 hr 80,000 g 60 min Cell Fractionation

Prokaryotes vs. Eukaryotes bacteria and archaea – prokaryotes both have plasma membrane, cytoplasm, chromosomes and ribosomes eukaryotes have a membrane-enclosed nucleus prokaryotic DNA is in the nucleoid region

Pili: attachment structures on the surface of some prokaryotes Nucleoid: region where the cell’s DNA is located (not enclosed by a membrane) Ribosomes: organelles that synthesize proteins Plasma membrane: membrane enclosing the cytoplasm Cell wall: rigid structure outside the plasma membrane Capsule: jelly-like outer coating of many prokaryotes Flagella: locomotion organelles of some bacteria (a) A typical rod-shaped bacterium (b) A thin section through the bacterium Bacillus coagulans (TEM) 0.5 µm A Typical Prokaryotic Cell

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

Carbohydrate side chain Outside of cell Inside of cell Hydrophilic region Hydrophobic region Hydrophilic region (b) Structure of the plasma membrane Phospholipid Proteins TEM of a plasma membrane. The plasma membrane, here in a red blood cell, appears as a pair of dark bands separated by a light band. (a) 0.1 µm The Plasma Membrane

Tomorrow….. Chapter 6 – pp Cellular Anatomy – nucleus, ribosomes, ER, Golgi, lysomsomes, peroxisomes, mitochondria and chloroplasts