Unit 3 – Biology and Environment Science 10 - Leinweber

Cycling of Matter in Living Systems 1.1 A Window on a New World Cycling of Matter in Living Systems

Early Microscopes and Microscopists Hans and Zacharias Janssen, Dutch lens-makers, invented the compound microscope in 1595. Compound microscopes use more than one lens to magnify the object Robert Hooke, in 1665, used a three lens microscope to view cork cells Around the same time, Antoni van Leeuwenhoek, using only a single lens microscope was the first to see the movement of single cells that we now know as bacteria.

The Microscope

Skill and Practice: Calculating Magnification p. 244 To use a compound microscope to estimate the size of an object you need to be able to calculate the magnification of certain combinations of lenses When using a compound microscope the magnification can be calculated: Magnification = (power of objective lens)(power of eyepiece lens)

Magnification of Objects M = is magnification ratio hi = height or length of the image ho = height or length of the object * any units can be used for the measurement as long as they are consistant M = hi ho

Example A 1.5um bacterium appears to have a length of 52.0um through the microscope lens. Calculate the magnification power of the microscope.

Homework Read pg 242-246 in text Section 1.1 Pg 244 Skill Practice “Calculating Magnification” WB pg 155-157 Q 1-13 The Compound Light Microscope WS (in notes)

1.2 Development of Cell Theory Cycling of Matter in Living Systems

Spontaneous Generation Abiogenesis is a theory that states that nonliving things can be transformed into living things. Proposed by Greek philosopher, Aristotle Implied that fish and frogs came from mud, and flies came from rotten meat Scientists accepted this theory for nearly 2000 years At times referred to as "spontaneous generation"

Francesco Redi, an Italian physician in 1668 set out to prove flies do not come from meat, by conducting an experiment Pieces of meat were placed in 4 different jars not covered (experimental) Pieces of meat were placed in 4 different jars sealed (control) Experimental group -> attracted flies -> laid eggs -> maggot -> fed on meat -> turned to flies Control group ->no fly attraction -> no flies produced Redi concluded flies did not come from rotting meat But...Air was claimed to be the active ingredient to the rotting meat to produce flies So... Redi used an experimental test, this time covering the container with a very fine mesh, allowing for air flow, but no fly contact Conclusion... Meat cannot be transformed into flies.

Major Contribution – Scientific Methods Variables – Controlled Manipulated Responding

Pasteur’s Experiments Louis Pasteur (1822-1895) Boiled broth for a long time -> clear broth ->swan-necked flask -> microbes trapped in curve of the flask Conclusion: microbes could not be created from non-living broth

The Cell Theory No one scientist developed the cell theory. Robert Hooke First described cells in 1665, while looking at a piece of cork under a primitive microscope. He saw honeycomb shaped structures and described them as cells. Anton van Leeuwenhoek Observed living blood cells, bacteria, and single-cell organisms

Robert Brown 1820, described the tiny sphere in the plant cell as the nucleus Theodor Schwann (zoologist) and Mathias Schleiden (botanist) concluded plant and animal tissues are composed of cells prepared the foundations of the modern cell theory

The modern Cell Theory states: All living things are made up of one or more cells and the materials produced by these cells. All life functions take place in cells, making them the smallest unit of life All cells are produced from pre-existing cells through the process of cell division

Homework: Read pg 247-252 in text Section 1.2 WB pg 150-152 Q 1-14

1.3 Developments in Imaging Technology and Staining Techniques Cycling of Matter in Living Systems

Contrast Scientist discovered that they could manipulate the light source to alter the contrast between structures in the cell and improve the image. Experiments with stains and coloring agents showed that particular stains could attach to particular parts of the cell, improving the contrast between internal structures and producing better images A disadvantage to staining is that it kills the cells making it impossible to view living cells.

Microscopes We are going to be looking at 4 types of microscopes: Light Microscopes Electron Microscopes TEM SEM Confocal Laser Scanning Microscope Scanning Tunneling Microscope

Light Microscope Think of the compound microscope as a good friend It is relatively inexpensive, reliable, but it has its limitations. Maximum magnification ~2000X

Electron Microscopes The “go to” reliable microscope with lots of power, and just a hint of mystery Engineered in the 1930s. Specimens are illuminated with a beam of electrons instead of light. Makes electron micrograph.

Transmission Electron Microscope Works like a slide projector. Electrons go through a thin sample to give the micrograph Magnifies 10 000 000X

Scanning Electron Microscope Sweeps a beam of electrons over object to get a 3D image. Magnification of up to 300,000x

Confocal Laser Scanning Microscope Has very powerful observation abilities Invented in the 1960s. Can study thick specimens, measures 2D slices in order to form a 3D image.

Scanning Tunneling Microscope Very technologically advanced. It seems like it can do ANYTHING. Developed in the 1980s, can obtain an image of atoms on an object’s surface. Can produce images of DNA. Uses an electron probe to make a 3D image

Homework: Read Section 1.3 pg 253-260 Complete pg 260 1.3 Check & Reflect, #1-6 WB pg 160-161 Q 1-6