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LAB 1: LIFE UNDER THE MICROSCOPE
DATE: January 12, 2022
What are the two types of microscopes (used in this lab)? What is common between the two? What is different about the two?
1. dissecting microscopes
2. compound microscopes
same: both use regular light to illuminate the specimen
different: the type of specimens you view on these microscopes are very different
What is the dissecting microscope used for?
to view larger, opaque, 3D objects
commonly used to search for specimens or for magnifying a dissection
typically have a lower maximum magnification than a compound microscope
the one in the lab has a max magnification of 40X
Where is the focus knob and what is its purpose?
a dial on the side of the stem
moves the lenses closer to or further away from the stage to give a clearer view
Where is the ocular lenses and what is its purpose?
the eyepiece
lenses through which you view the specimen
magnify 10X
Where is the objective lenses and what is its purpose?
lens and dial between the focus knob and ocular lenses
magnifies the specimen by 2X (low power) or 4X (high power)
Where is the stage and what is its purpose?
BIOL 1218 Lab Notes 1 1
, at the base of the microscope
the platform to place the specimen
What is the compound microscope used for? What other features does it have?
typically for smaller, see-through (or colourless) specimens (bacteria, sing-celled organisms, cell, or tissue samples)
has 4 objective lenses that magnify the specimen
How many ocular lenses does a compound microscope have?
two (for the ones at langara)
How many focus knobs does a compound microscope have?
two
1. coarse focus
2. fine focus
What is the magnification of objective lenses on a compound microscope?
4X (low)
10X (medium)
40X (high)
What is a condenser and iris diaphragm? Where are they located?
condenser contains lenses that focus the light rays from the light source onto the specimen
the iris diaphragm is within the condenser which opens and closes to control the amount of light going through the specimen
What are the 3 broad categories of Domains? What defines them?
1. Archaea
2. Bacteria
3. Eukarya
based on their evolutionary relationships which is reflected in fundamental similarities and differences in their cells
What are prokaryotic cells? What domain do they fall under?
cells that do not have a nucleus or other membrane-bound organelles
domains Archaea and Bacteria
What are eukaryotic cells? What domain do they fall under?
cell that have both nucleus and membrane-bound organelles
domains Eukarya
What are Archaea?
commonly found in extreme environments such as highly saline lakes or in high-temperature hydrothermal vents
look the same as bacteria, and can only be differentiated using molecular methods
What are Bacteria?
single-celled prokaryotic organisms
includes bacteria and cyanobacteria
ecologically function in a variety of ways
some bacteria form a mutualistic relationship with plants
What is a bacterial colony?
the result of a single bacterial cell dividing and producing many more identical bacterial cells
results in a cluster of cells that may be visible without a microscope
Since there are limited physical differences between bacterial species, how do we identify bacterium?
relies on biochemical and molecular methods
first step is to identify the basic shape of the cells
BIOL 1218 Lab Notes 1 2
, Why do cocci, bacilli, and spirilla bacterial cells have different colours from one another?
they’re either pink or purple
relates to the structure of their cell walls
What is cyanobateria?
photosynthetic bacteria that are typically larger than regular bacteria
they have photosynthetic pigments, but do not have chloroplasts (the organelle of photosynthesis found in plants)
What are eukarya?
encompasses all eukaryotic organisms
have a true nucleus and membrane-bound organelles
What are the two basic forms of eukarya?
1. plant cells
2. animal cells
What is monophyletic?
a group that contains the ancestral form and ALL of its descendants
the term “protists” is still used informally as monophyletic
What are diatoms?
single-celled aquatic organisms found primarily in marine environments
usually planktonic — they drift in aquatic environments
What are phytoplankton?
diatoms and other photosynthetic members of plankton
they are primary producers — use photosynthesis to produce ~80% of the oxygen we breathe and form the basis for marine
food webs
live in shells made of silica (glass)
What are dinoflagellates?
a planktonic single-celled organism
some dinoflagellates are photosynthetic (photoautotrophic) and therefore phytoplankton
others consume other organisms for their energy (heterotrophic)
some can create light (bioluminescence — chemical reaction)
What are egulena?
single-celled organism that can perform photosynthesis and consume other creatures for energy
they move using a single flagellum at their terminal end
results in their corkscrew movement through the water
What are Paramecium?
protists that are strictly heterotrophic
the cilia that cover the surface of the cell allows rapid movement of the entire cell
also propels their prey of bacteria
they engulf their prey by the cell membrane and are digested inside the cell
move very quickly
What are the defining characteristics of plants?
differentiation of cells into distinct tissues
the ability to perform photosynthesis
except for a few species that digest decaying material directly or are parasitic
Why do plants perform photosynthesis?
BIOL 1218 Lab Notes 1 3
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