Lab Exam 1 Flashcards
Hardy-Weinberg Principle
A population’s allele and genotype frequencies are constant, UNLESS there is some type of force acting upon them.
For equilibrium to exist, five conditions must be met:
- No natural selection
- No mutation
- No migration
- Large population
- Random mating
Genetic Drift
Changes in allelic frequencies of a gene that are due solely to chance
Bottleneck Effect
An extreme example of genetic drift that happens when the size of a population is severely reduced
The Founder Effect
The reduction of genomic variability that occurs when a small group of individuals become separated from a larger population
Natural Selection
The process by which members of a population become adapted to their environment
Ocular (eyepiece)
Magnifies the image produced by the microscope’s objective
Draw Tube
Connects the ocular to the body tube
Body
Hold the nosepiece at on end and includes the draw tube
Arm
Serves as a handle
Nosepiece
Holds the objective lenses & attaches them to the microscope head
Objectives
Directly observe the object under the microscope that the user is examining
Scanning Objective
4x
Used for viewing larger specimens or searching for a specimen; the shortest objective; magnifies the object 4x
Low-Power Objective
Used for coarse and preliminary focusing; magnifies the object 10x
High-Power Objective
Used for final and fine focusing; magnifies the object 40x
Oil-Immersion Objective
Uses the optical properties of oil immersion to magnify a specimen; magnifies the object 100x
Stage
platform on which slides are placed
To control the movement of slides, stage clips secure the slides
Light Source (Illuminator)
Serves as the source of illumination for the microscope
Iris Diaphragm
Regulates light entering the micropscope; usually is controlled by mechanical lever or rotating disk
Condenser
A lens system found beneath the stage; used to focus the light on the specimen
Coarse-focus adjustment knob
Used to adjust the microscope on scanning and low-power ONLY
Fine-Focus Adjustment Knob
Used to adjust the specimen into final focus
Base
The supportive portion of the microscope, which rests on the laboratory table
Total Magnification
A multiplication of the power of the objective and ocular (eyepiece)
E.g. Scanning objective is 4x and eyepiece is 10x; total magnification = 40x
Resolving Power
The ability to resolve objects (distinguish between two closely saved, minute objects and separate entities)
Stereomicroscope
Also known as dissecting microscope. Has two oculars and capable of 4x to 50x magnification
Provide a greater field of view and depth to field than compound microscopes so more advantageous when viewing larger objects and dissecting
Working Distance
The distance between the objective lends and the specimen.
As the working distance decreases, the magnification increases.
More light is needed when the working distance decreases
Field of View
the circular field you see when you through the ocular.
the size of a specimen can be estimated if one knows the field of view at each magnification
Depth of Field
The thickness of the specimen in focus at any one time
