Anton van Leeuwenhoek, a Dutch scientist in the mid-1600s, was the first to record looking at water under a microscope. He found that water was full of living things.
Italian physician Redi disproved spontaneous generation. Others observed maggots crawling out of meat and assumed the dead cow meat gave rise to baby flies. By performing this experiment, Redi disproved that theory and sought another explanation: that flies lay eggs on the meat, which only provides the food maggots need to survive. The source of the baby fly larvae is, therefore, not the dead meat, but the living fly parents. Experiment 1: Meat was placed in an unsealed jar. Observation: Flies laid eggs on the meat and maggots emerged. Experiment 2: Meat was placed in a sealed jar. Observation: Flies could not enter the sealed jar and therefore, maggots did not form on the raw meat. Experiment 3: Meat was placed in a jar covered with gauze. Observation: The gauze prevented flies from entering the jar, and therefore, maggots did not form on the raw meat. Conclusion: Maggots arise from the eggs laid by flies, not by spontaneous generation. This supported the theory of biogenesis, which states that "all life arises from other life."
Some of Pasteur's flasks, still free of microorganisms, are at the Pasteur Institute in Paris.
What benefits could there be to having distinct organelles separated by membranes? Chemical reactions which interfere with each other can occur at the same time.
This is an actual microscopic image. Colors are added digitally to enhance the different parts.
Animal (liver) cell
Personal experience - U of P, mice stress-immune response - Good Sam, sleep lab/EKG - OHSU, melatonin research
Cells: StructureThe Building Blocks of Life Heartlife 2012-2013 Teacher: Julie Pen Science is Organized Knowledge
The Discovery of Cells• Robert Hooke (mid-1600s) – Observed a sliver of cork with a hand-made microscope – Saw a “row of empty boxes” – Coined the term cell
Cell TheoryThe Cell Theory states:1. Cells are the basic units of life.2. All living organisms are made up of one or more cells.3. New cells can only come from already existing cells. – no spontaneous generation• Francisco Redis experiment:
Louis Pasteur• Biogenesis: the theory that life can only arise from another living thing
Cell Size & Shape • All cells have: – a membrane – cytoplasm – DNA
Cell Types• All living organisms are made up of cells. – There are two major cell types:PROKARYOTIC Cells – All bacteria and archaebacteria – Lack a nucleus – Lack membrane-bound organellesEUKARYOTIC Cells – Plants, animals, fungi and Protists – Have an enclosed nucleus – Have membrane-bound organelles
Prokaryotic CellBacteria often have a rigid cell wall and capsule around the plasma membrane for extra protection.
Cell Organelles• Organelle = “little tool”• Organelles found only inside eukaryotic cells• Watery stuff between the organelles is cytosol• Area inside a cell is the cytoplasm – includes the organelles but NOT the nucleus
Cell MembraneCell Membrane• Boundary of the cell – a.k.a plasma membrane• Holds cell contents together • Semi-permeable: acts like a filter or screen – some things pass while others cannot
Cell Membrane• Made of a phospholipid bilayerSemi-permeable:A few moleculesmove freely acrossthe membrane(in and out of the cell) • water • carbon dioxide • ammonia • oxygenOther molecules need the help oftransport proteins to get across
Nucleus• Easiest cell structure to see under a microscope• Contains chromatin – genetic material including DNA, RNA and proteins – form chromosomes• “Control center of the cell”
Nucleus• Surrounded by a double membrane• Nuclear Pores – holes in membrane allow material to enter and leave the nucleus• Nucleolus is an area of concentrated RNA
Endoplasmic Reticulum• Abbreviated “ER”• Connected to nuclear membrane• “Highway of the cell”• Smooth ER – makes lipids • hormones, steroids, some vitamins, etc.• Rough ER – studded with ribosomes – makes proteins
Golgi Apparatus• Looks like a stack of pancakes• Stores, sorts, modifies and packages proteins• Molecules transported to and from the Golgi by means of vesicles
Lysosomes• "Garbage disposal of the cell"• Contain hydrolytic enzymes that break down food & wastes• Destroy old cell parts as well as invaders• Formed from the Golgi apparatus
Mitochondria• “Powerhouse of the cell”• Cellular respiration occurs here to convert and release energy for the cell to use• Has its own DNA and ribosomes• Folded parts called cristae increase surface area
Vacuoles• Storage containers for water, food, enzymes, wastes, pigments, etc.
VacuolesAnimal cells havemultiple, smaller vacuoles Plant cells have one large central vacuole
Cell Wall• Found in plant and bacterial cells• Rigid, protective barrier composed of cellulose fibers• Located outside the cell membrane
Chloroplast• Found only in plant cells• Contains the green pigment chlorophyll• Site of food (glucose) production known as photosynthesis• Contains own DNA and replicates independently
The green bubbles are the chloroplasts filled with Chlorophyll
Week 5 Lab Review Intro to MicroscopyLaboratory Science as a Career
Cytoskeleton• Microfilaments and microtubules provide a scaffolding on which organelles can anchor or move themselves – contracting muscles cells – dividing cells pinch in half – waving cilia and rotating flagella
Cilia & Flagella• Hair or tail-like structures that provide motility (movement)• Formed from microtubules that arrange themselves into centrioles• Generally occur only in animal and bacteria cells
Peroxisomes• Small sacks enclosed in a single membrane• Contains enzymes that break down fatty acids & toxic peroxides (found in alcohol, formaldehyde, and other poisons)• Found mostly in kidney and liver cells• Formed from budding off the ER
Quick Review• Which organelle is the "control center" of the cell? nucleus (containing DNA, the blueprints)• Which organelle holds the cell together? plasma membrane (made of a phospholipid bilayer)• Which organelles are NOT found in animal cells? cell wall (and capsule), chloroplasts, large/central vacuole• Which organelle helps plant cells make food? chloroplasts (via photosynthesis, using chlorophyll)• What does E.R. stand for? endoplasmic reticulum
This cell has no clear nucleus, but it does have a CELL WALL. Is it prokaryotic or eukaryotic?
Careers in Laboratory Science• Researcher – PhD or MD/PhD – Design experiments, publish conclusions – Apply for grants, hire staff• Research Assistant – Manages experiments – Assists with data collection, data entry, and statistical analysis• Medical Lab Tech – Run lab tests and reports data • research or medical treatment • Forensic science • genetic counseling• Pharmaceutical Production & Sales – Requires business skills & knowledge of chemistry and human physiology