Labs
Make sure to understand the purpose of each lab that we did and be able to answer questions about procedure, the data you collected, techniques used and data you got.
● Lab # 3 Anatomy of the microscope
● Lab # 4 Plant Cells
Make sure to Review:
● Discovery and Early Study of Cells
○ Leeuwenhoek (1632­1723)
■ Dutch biologist who invented the microscope
○ Hooke (1635­1703)
■ Looked in a cork, and saw tiny room­like structure ­ called them cells (latin for “tiny rooms”)
● Cell Theory
○ Schleiden (1838)
■ Discovered that plants are made of cells
○ Schwann (1839)
■ Discovered that animals are made of cells
○ Virchow
■ All cells come from preexisting cells
○ Three statements of the cell theory and their meaning
■ 1. All living things are made of cells
● Exception: Some people consider viruses to be alive, and they ae not made of cells
■ 2. The cell is a structural and functional unit of all living things
● Exception: Endosymbiotic Theory ­ Mitochondria and Chloroplasts were once in prokaryotes (lacking a nucleus) that were swallowed by eukaryotes (have a nucleus). This theory can be proved because these organelles have their own DNA.
● Structural:
○ Many different shapes and sizes
○ All have nuclei and membrane
○ Many different functions
● Functional:
○ Need food and energy
○ Each cell performs a different task that contribute to the body as a whole
○ Each cell can function on its own (heart muscles can beat on their own)
■ 3. All cells come from preexisting cells
● The first cell could not have come from a pre­existing cell
● Abiogenesis vs.Biogenesis (the Spontaneous Generation Controversy)
○ Biogenesist
■ Life is only created from other life
○ Abiogenesist
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■ Life can be created without other life (spontaneous generation)
○ Works of Spallanzani and Pasteur in disproving Abiogenesis
■ Spallanzani
● Boiled two flasks: one with a cork on, one without a cork on. The one without the cork on produced “beasties,” or bacteria
● Spallanzani thought this would disprove abiogenesis, or spontaneous generation, because this experiment shows that the bacteria came from elsewhere (a previous life source), and not from the non­living flask
○ BUT, this was disputed. Abiogenesist said that oxygen couldn’t get through the corked flask, and this was the reason the “beasties” only appeared in the open flask.
■ Pasteur (1822­1895)
● The French Academy of science held a competition for the best experiment either proving or disproving spontaneous generation. Pasteur, a biogenesist needed air to be able to enter his flask, yet not bacteria, in order to disprove spontaneous generation. So he went up to the French Alps, where the air was clean, and lo and behold, no bacteria grew. This showed that even with a flask that allots oxygen in, contaminated air must be in place to grow bacteria (contaminated air hold previous life). In spontaneous generation were true, bacteria would have grown in the flask in the alps.
● Invented a flask: bent at the top so air could enter, yet microorganisms couldn’t. This helped keep bacteria out.
■ Germ Theory of Disease
● Theory of the “beasties” ­ bacteria is in the air. Proved by Pasteur (see above)
■ Pasteurization ­ Ways to keep bacteria out
● Boil liquid
● Use flask Pasteur invented (see above)
Work of Semmelweis on Childbed Fever and how his work was later understood with the development of Pasteur’s Theory of Disease
○ Semmelweiss’s childbirth patients were dying, and the women who gave birth at home weren’t. Semmelweis wanted to know why. His friend was pricked with a scalpel and became sick days later, showing symptoms of childbed fever. Semmelweis then made everyone wash their hands. The people of his time thought he was crazy and put him in a mental institution. This connects to Pasteur’s theory of disease because Semmelweis thought that since bacteria was in the air, the dying patients affected, similarly to Pasteur’s proof that bacteria is in the air (see above).
Instruments and Techniques used to study cells (know the advantages and disadvantages of each)
○ Compound (Light) Microscope
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Advantage: magnification is 1500­2000x, easy to focus
Disadvantage: upside down, have to stain, dead cells, only magnifies 1500­2000, thin
○ Microtome (how tissues are prepared: preserver, embedded in wax, sliced…)
■ Slippery so must imbed in something
■ Make little paper boats, melt wax, and pour into boat
■ While wax is liquid you take preserved tissue and put piece of tissue inside
■ Put boat in cold water ­ immerse it quickly, take it out, unwrap it, stick it to a wooden block and cup on microtome, stain
○ Staining
■ Kill cell
■ Fix to prevent cell decay
■ Slice it
■ Stain it
○ Phase Contrast Microscope
■ Advantage: cells alive, don’t need to stain
■ Disadvantage: need to be thin cells, not ideal for thick
○ Electron Microscope (TEM and SEM)
■ TEM
● Advantage: Image displayed on TV
● Disadvantage: Dry, embedded with plastic, sliced and thin
■ SEM
● Advantage: Can use 3D
● Disadvantage: Only hits surface
○ Microdissecting instruments
■ Microknives
■ Microneedles
■ Micropipettes
○ Ultracentrifuge
■ Separates cell part according to size and density
Cell Organelles ­ know structure and function of each and be able to recognize them in a drawing of an animal and/ or plant cell)
○ Cell Membrane ­ security
■ Protects the cells
■ Bilayer barrier
● Lipid (fat) bilayer made of hydrophilic (pro water) and hydrophobic (anti­water) phospholipids
○ Head­to­tail arrangements so each hydro gets what they want (water or not)
● Proteins (in the lipids) ­ float in the lipids
○ Receptors ­ ID signposts identify the cell ­ address where things have to go
○ Cell to cell recognition
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○ Gatekeepers ­ allow certain things in/out
■ Made of oil (oil and water don’t mix)
Nucleus (DNA à RNA à Protein) ­ control center or intelligence division
■ Filled with nucleoplasm
■ Contains DNA
● DNA = original genetic material
● RNA = copy
■ Chromatin ­ unraveled DNA and protein
■ Usually easiest organelle to see under a microscope
■ Contains informative for everything in the cell
■ Crucial in cell division
■ Nucleolus, center, produces ribosomes
Ribosomes ­ Machines
■ Little dots found on the rough ER or free in the cytoplasm
● When floating it means they are needed right away in the cell
■ Produced in nucleolus
■ Produce the proteins and are the site of protein synthesis
Endoplasmic Reticulum (ER) ­ conveyor belts
■ Connected to nuclear membrane
■ “Highway of the cell” ­ transports
■ Rough ER has ribosomes and makes proteins, and smooth ER makes lipids
Lysosomes
■ Type of vesicle (waste sack)
■ Have digestive enzymes that break down waste
■ Digest harmful waste
■ “Suicide Sac” ­ can release stuff that destroys the cell
● Autodigestion ­ old cells that you need to get rid of (webbing between fingers, tail of a tadpole)
■ Tay Sach’s disease ­ genetic disease cause by not enough enzymes in lysosome
Golgi Apparatus ­ shipping
■ Stores, modifies, and packages proteins
■ Synthesis of polycharrides
■ Stuff transported to and from golgis with vesicles ­ sacks
Vacuole ­ storage
■ Stores stuff ­ water, dissolved materials, sometimes waste
■ Large central vacuole ­ usually found in plant cells
■ Many smaller vacuoles ­ usually found in animal cells
Mitochondria ­ Power/Energy
■ “Powerhouse of the Cell”
■ Looks like a hotdog with mustard
■ Has its own DNA
■ Cellular respiration is here (releasing of energy for the cell to use)
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Centrioles
■ Aid in cell division
■ Only found in animal cells
Chloroplast
■ Only in plant cells
■ Used for photosynthesis ­ using light energy and water to make energy for the cell
■ Contain chlorophyll ­ green pigment
Cell Wall
■ Rigid layer outside cell membrane
■ Only in plant cells
■ contains cellulose
Differences between tissues, cell and organs­ look at hierarchy sheet
○ Atom ­> Molecule ­> Organelle ­> Cell ­> Tissue ­> Organ ­> Organ system ­> Organism
Types of Cells
○ Plant vs. Animal Cells
■ Plant ­ cell wall, chloroplasts, one large vacuole
■ Animal ­ centriole
○ Prokaryote vs. Eukaryote
■ Prokaryote ­ lacks a nucleus
■ Eukaryote ­ has a nucleus
○ Endosymbiotic Theory­ Maybe chloroplasts and mitochondria were once prokaryotic cells
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Exceptions to the Cell Theory: 1st cell, mitochondria and chloroplast (they are units and function), Viruses ­ see above
II.Cell Division
○ Structures Involved in Cell Division
■ Spindle ‐ strings that attach to the chromosome during cell division
■ Asters, Centrioles (animal cell division) ‐ centrioles produce spindle fibers, and asters are star shaped
■ Cell plate ‐ kind of like the cleavage furrow for a plant cell ‐ when dividing, since plants cells have a rigid outer layers, they cannot bend to make a cleavage furrow, so instead they have a solid line in between the two dividing cells which is the cell plate
■ Chromosomes ‐ 2 identical halves of rod shaped things that contain DNA and protein
■ Chromotids ‐ each rod when the chromosomes are paired up in chromosome form
■ Centromere ‐ the thing that holds the two chromosome rods together
○ Cell Cycle
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Interphase
● G1 ‐ GROWTH ‐ the cell grows and matures
● S ‐ SYNTHESIS ‐ the DNA is copied (synthesized)
● G2 ‐ PREPARATION ‐ cell prepares for cell division
Mitosis (know the major events and how to identify each stage)
● Prophase ‐ nuclear envelope and nucleus disappear, chromosome become rod like and attached by centromeres, centrioles move and project spindle fibers
● Metaphase ‐ chromosomes line up and the spindle fibers attach themselves to the centromeres
● Anaphase ‐ the chromotids separate
● Telophase ‐ two nuclei are formed, spindle fibers disintegrate, chromosomes begin to untangle again
● Cytokinesis ‐ division of the cytoplasm, and eventually two separate cells
○ Animal ‐ cleavage furrow (membrane pulled inwards)
○ Plant ‐ cell plate (divider between the becoming two new cells that eventually becomes the cell membrane), cell wall surrounds the membrane
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