Welcome to BIO201

1. Welcome to BIO201 Dr. Maura Parker mhparker@sccd.ctc.edu

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

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

4. 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

5. 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 e-mails and make appointments if you need to see me

6. Lecture #1 – Introduction to Cell Biology • Text – Chapter 6 – pages 94-101 • Note: tomorrow is Ch. 6 – pp 102-111

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

8. The size range of cells 10 m Human height 1 m Length of some nerve and muscle cells 0.1 m Unaided eye Chicken egg 1 cm Frog egg 1 mm 100 µm Light microscope Most plant and animal cells 10 µm Nucleus nucleus Most bacteria Most bacteria Mitochondrion 1 µm Electron microscope Smallest bacteria 100 nm Viruses Ribosomes 10 nm Proteins Lipids 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 1 nm Small molecules Atoms 0.1 nm

9. 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 mm resolution

10. (a) 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.] Brightfield (stained specimen). Staining with various dyes enhances contrast, but most staining procedures require that cells be fixed (preserved). (b) (c) Phase-contrast. Enhances contrast in unstained cells by amplifying variations in density within specimen; especially useful for examining living, unpigmented cells. 50 µm

11. (d) Differential-interference-contrast (Nomarski). Like phase-contrast microscopy, it uses optical modifications to exaggerate differences in density, making the image appear almost 3D. (e) 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. 50 µm (f) 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

12. Electron Microscopes - What is inside the cell? 1 µm (a) Cilia 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. Longitudinal section of cilium Cross section of cilium 1 µm (b) 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.

13. What do the parts inside the cell do? Cell Fractionation Homogenization Tissue cells 1000 g (1000 times the force of gravity) 10 min Homogenate Differential centrifugation Supernatant poured into next tube 20,000 g 20 min 80,000 g 60 min Pellet rich in nuclei and cellular debris 150,000 g 3 hr 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

14. 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

15. Pili: attachment structures on the surface of some prokaryotes Nucleoid: region wherethe 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 0.5 µm Flagella: locomotion organelles of some bacteria (a) A typical rod-shaped bacterium (b) A thin section through the bacterium Bacillus coagulans (TEM) A Typical Prokaryotic Cell

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

17. Outside of cell Carbohydrate side chain Hydrophilic region Inside of cell 0.1 µm Hydrophobic region (a) 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. Hydrophilic region Phospholipid Proteins (b) Structure of the plasma membrane The Plasma Membrane

18. Tomorrow….. • Chapter 6 – pp 102-111 • Cellular Anatomy – nucleus, ribosomes, ER, Golgi, lysomsomes, peroxisomes, mitochondria and chloroplasts