Window on a New World

1.1

Window on a New World

Microscopes:

• Are anything that will magnify an object
• Make objects appear larger than they are
• Allow us to see objects that can’t be seen with our eyes
• The Inventor is Debatable:

15 95 - Jansson Brothers (Holland) produced a crude microscope (used a 2 lens system)

1610 - Galileo (Italy) built a crude compound microscope

1665 - Hooke (England) - built a compound microscope (3 lens system)

1673 - Van Leeuwenhook (Holland) was the first person to see unicellular movement

1939 - Hillier & Prebus (U of T. Canada) built first electron microscope

1965 - Stanford University (USA) built first scanning electron microscope

• there are 2 basic types:

1. Simple
2. Compound

1. Simple microscopes

• Are early microscopes
• Consist of a single lens
• contain more than one lens

2. Compound microscopes

• are parfocal :
• still focused when objectives are switched
• There are 2 types:
• Research
• Dissecting

A. Research

• Have one ocular
• Have a rotating nosepiece with 3 objectives
• Use transmitted light (passes through specimen)
• Create an inverted image (upside down & backwards)
• Are used to look at transparent specimens
• Can magnify up to 400 X

B. Dissecting

• Have 2 eyepieces ( biocular )
• Have 1 rotating objective
• has 2 light sources top & bottom
• Use incident light (light reflected off of specimen)
• Create a virtual image (same as it really is)
• Are used to look at solid objects
• Magnify specimens up to 30 X

Parts of a Microscope

Ocular (eyepiece)

• is the lens you look through
• it magnifies the object 10X

Objective Lenses

• Magnify the object;

-low 4x

-medium 10x

-high 40x

Revolving Nosepiece

• contains 2-4 objectives
• Rotates enabling different lenses to be used

Course Focusing Knob

• Is used to focus the object on LOW POWER
• It moves the stage up and down

Fine focusing Knob

• makes the image clearer

Iris diaphragm

• regulates the amount of light reaching the slide

Image Magnification

• Is the magnification you are using when viewing a specimen
• It is created by both the objective & ocular
• Note: Each objective lens has a different power:

Low 4x

Med 10x

High 40x

• Formula:

Image Magnification = ocular x objective

• Example 1:
• A student is viewing a specimen on low power. What is the image magnification?

Ocular = 10

Objective = 4

Image Magnification = Ocular x Objective

Image Magnification = 10 x 4 = 40

• Example 2:
• A student is viewing a specimen on high power. What is the image magnification?

Ocular = 10

Objective = 40

Image Magnification = Ocular x Objective

Image Magnification = 10 x 40 = 400

• Example 3:
• A student is viewing a specimen on medium power. What is the image magnification?

Ocular = 10

Objective = 10

Image Magnification = Ocular x Objective

Image Magnification = 10 x 10 = 100

Image

• It is what you see
• Is created using light (transmitted or incident)
• There are two types:

1. Virtual
2. Inverted

A. Virtual

• The image is the same as it really is
• Produced by a dissecting microscope
• Created using incident light;

reflects off the specimen

B. Inverted

• The image is upside down & backwards
• Produced by a research microscope
• Created using transmitted light;

passes through the specimen

Field of View

• Is the amount of the specimen you see
• It is less with higher magnifications
• It is measured in microns

Low Power Medium Power High Power

40001500 400 

Drawing Magnification

• Is how much bigger your drawing is then the actual specimen

• Formula:

D M = Drawing size

Estimated size

Drawing Size

Steps:

1. Draw the specimen
2. Measure the widest part in mm
3. Convert mm to microns (1000  = 1 mm)

45mm = 45000 

Estimating Size

Steps:

1. Estimate how many specimens fit across the field
2. Divide the field of view by that number

E.g. Low Power

1. About 4 will fit across

2. 4000  = 1000 

4

• Formula:

D M = Drawing size

Estimated size

D M = 45000

1000

DM = 45 It is 45 times larger

Example 1

• A student measures their drawing of a protozoa and it is 64 mm. The student is then asked to calculate her drawing magnification

Example 2

• A student measures their drawing of a protozoa and it is 24 mm. The student is then asked to calculate her drawing magnification

Example 3

• A student measures their drawing of a protozoa and it is 36 mm. The student is then asked to calculate her drawing magnification

Assignment

Workbook :

Label ‘Parts of a Light Microscope’

Comparing Compound and Dissecting Scopes

Text:

Assignment: Page 246 # 3, 4, 5, 6, 7, 8

1.2

Development of the Cell Theory

Spontaneous Generation

• Is the idea that life can emerge (spontaneously) from non-living matter
• It was an idea that continued to thrive from 1500s to the mid 1800s
• It was disproved by:

1. Francesco Redi
2. Louis Pasteur

1. Francesco Redi - 1668

• Questioned the idea that maggots could appear spontaneously from raw meat
• Conducted an experiment with flies & meat
• Redi’s Experiment:

Had 3 jars that contained raw meat:

1 open to the air

1 completely sealed

1 covered with gauze (contains tiny holes)

• Result = Only the closed one did not have flies

Needlham’s Experiment

• Belief: boiling destroyed microorganisms
• Needham’s Experiment: put boiled chicken broth into a sealed flask
• In theory, no microorganisms should exist
• But …microorganisms still appeared?!?
• Spontaneous generation remained popular… they ignored contact with air

Spallanzani’s Work

• Spallanzani’s belief: microbes in the air inside the flask got into the broth
• The test: remove the air from the flask and then seal in the boiled chicken broth
• Result: nothing grew in the chicken broth!
• Why is Spontaneous generation is still popular?!?

2. Louis Pasteur - 1864

• Expanded on the work of Needlham & Spallanzani
• Conducted experiment using broth and S shaped flasks
• Pasteur’s Experiment

He boiled the broth & put it in an s-shaped flask

After some time he removed the s-shaped flask

• Result = Swan neck let in no air & there was no mould growth but Removal of neck produced mould

Variables in Experiments

• Represent conditions that occur in an experiment
• There are 3:

1. Controlled variable
2. Manipulated variable
3. Responding variable

1. Controlled Variable

• Are the conditionsin an experiment that remain the same for each trial
• E.g. the temperature in the room

1. Manipulated Variable

• Are the condition(s)in the experiment that are changed
• E.g. amount of light

1. Responding Variable

• Is the response (what happens)
• E.g. the plant with no light dies

Cell Theory

• It applies to all living things (except prions & viruses)
• It is the corner stone of biology
• It has it’s beginning with:

1. Aristotle
2. Robert Hooke
3. Antoni van Leeuwenhoek

1. Aristotle 4th century B.C .

• Was a Greek philosopher who made careful observations & records of 500 animals species
• His scientific approach was the method used by later scientists

2. Robert Hooke 1665

• Looked at cork under a microscope
• He called the empty chambers he saw “cells”

3. Antoni van Leeuwenhoek

• Used a simple microscope (1 lens) to observe organisms
• He was the 1st to see the movement of bacteria, sperm, and protozoa
• He called them “ animalcules”
• It States:

1. All living things are made of 1 or more cells and materials made by these cells

2. All life functions take place in the cell, making them the smallest unit of life

3. All cells are produced from pre-existing cells through cell division

Assignment

Text: Pg 252 Questions: 2, 3, 4

1.3

Developments in Imaging Technology and Staining Techniques

Microscope Observation

• Is affected by 2 factors:

1. Contrast
2. Resolution

1. Contrast

• Is the ability to see differences between structures
• It is the result of a structures capacity to absorb light
• It is increased by using stains

Staining/ Fixation

• Kills the cell
• The stain attaches to internal structures in the cell
• E.g. Iodine (plants) or methylene blue (animals)

2. Resolution

• Is the clarity of the image
• Is the ability to distinguish between two structures that are close together (sharpness of the image)
• 0.2  is the standard for a light microscope
• High resolution = more clarity

Technology Advancements

• Have allowed for advancements in research & medicine
• Have allowed us to see organisms that we can’t see with our eyes
• Have enhanced our ability to see & study cell structures
• Examples are:

1. Florescence Microscopy
2. Confocal Technology
3. Electron Microscopes

1. Florescence Microscopy

• Was first used in the 1940’s
• It uses ultraviolet light to make cells fluoresce

2. Confocal Technology

• Was first used in the 1980s
• Uses laser beams & computers to produce 3D images

3. Electron Microscopes

• Use a beam of electrons to produce an image (micrograph)
• There are 2 types:

1. Transmission (TEM)
2. Scanning (SEM)

A. Transmission (TEM)

• Uses dead specimens
• Passes a beam of electrons through stained tissue imbedded inplastic
• Magnifies up to 100,000 times
• operates in a vacuum

B. Scanning (SEM)

• Electrons bounce off of gold covered specimens(gold reflects)
• It produces a 3D image
• It magnifies 300,000 times

Assignment

Workbook:

Complete Microscope Magnification Sheet

Microscopes –fill-in blank sheet (40 fill-ins)

1.4

Cell Research at the Molecular Level

Cell Research

• Is the result of new technology
• Has resulted in breakthroughs in medicine & industry
• Examples:

1. Scanning Tunnelling Microscope (STM) & Atomic Force Microscope (AFM)
2. Gene Mapping
3. Florescent Antibody technique
4. X-ray crystallography
5. GFP technology

1. STM & AFM

• Both have allowed scientist to produce images of molecules
• Improved understanding of the structure & function of molecules

2. Gene Mapping

• Geneticist showed the material in chromosomes was associated with inheritance
• Biochemists & microbiologists showed that the material in chromosomes is DNA
• DNA contains genes
• Genes direct all the activities that occur in the cell & code for your traits
• The Human Genome Project:

Created a map of human chromosomes

It involved finding:

1. The location of the genes
2. What those gene do

Benefits:

1. It could allows scientists to treat diseases
2. It could be used to make new varieties of plants E.g. a drought resistant plant

3. Florescent Antibody Technique

• Allowed diagnosis of diseases
• Showed that cell are open systems:

Interacting & exchanging materials with it’s environment E.g. O2

• Showed that messenger molecules target receptors & trigger reactions inside the cell

4. X-ray Crystallography

• Was used to determine the structure of DNA (that it was a double helix)

5. GFP Technology

• Is being used to study Alzheimer’s Disease
• Allows scientists to compare proteins in healthy tissue & unhealthy tissue

2.1

The Cell as an Efficient, Open System

Cells

• Are open systems;

Exchange matter and energywith the surroundings

Acquire nutrients & excrete waste

• Are the basic units of life
• Carry on all life processes within organelles:

Intake of nutrients

Movement

Growth

Response to stimuli

Exchange of gases

Waste removal

Reproduction

• There are two types of cells:

1. Prokaryotic
2. Eukaryotic

1. Prokaryotic

• Lack a nucleus
• DNA floats in the cytoplasm
• E.g. Bacteria

2. Eukaryotic

• Have a nucleus
• DNA is in the nucleus packaged as chromosomes
• E.g. Plant and Animals cells

Cell Structures

• There are 5 main structures:

1. Cell wall
2. Cell membrane
3. Nucleus
4. Cytoplasm
5. Organelles

1. Cell Wall

• Providesstrength and support
• Are found in plants, bacteria & protists
• Are made of cellulose

2. Cell Membrane

• It is a protective barrier
• It is semi-permeable

some particles can enter while others can’t

• It maintains balance (equilibrium) inside the cell

Allowing some substances in & keeping others out

• The structure is the Fluid Mosaic Model
• Mosaic refers to different substance held together by a common material

• It has 2 parts:
• A.) Phospholipids bilayer
• B.) Proteins
• Each part plays a role in maintaining equilibrium

A. Phospholipid bilayer

• Has a lipid bilayer that consists of:

a phospholipid head

a fatty acid tail

B. Proteins

• Float in the lipid bilayer
• Can be:

Receptors…(for hormones)

Channels or pumps …..(molecules travel through)

3. Nucleus

• Directs all cellular activities
• Is only found in Eukaryotes
• It contains:

DNA

a porous membrane

the nucleolus

• this stores RNA

4. Cytoplasm

• It is a gel-like substance (mostly water)
• contains nutrients needed for cellular activities
• It has organelles suspended in it

5. Organelles

• Are tiny organs
• Are the working units within the cell (like the working parts of a machine)
• Are not visible with a light microscope
• Examples:
• Mitochondria
• EndoplasmicReticulum
• Ribosome
• Golgi Apparatus
• Lysosomes
• Vacuoles & Vesicles
• Chloroplasts

a. Mitochondria

• Is the site of Cellular respiration
• Converts the chemical energy in glucose into ATP (energy)
• Muscles contain lots of these
• It is the “power house” of the cell (it generates energy)

1. EndoplasmicReticulum (ER)

• Is a series of tubes used to transport proteins
• There is two types:

1. Smooth
2. Rough

• Smooth ER

Is the site of fat/oil & steroid production

• Rough ER

Is the site of protein synthesis

1. Ribosomes

• Is the site of protein synthesis
• Take amino acids & make proteins

1. Golgi Apparatus

• Stores proteins which will be secreted for use outside the cell
• Glands contain a lot of these

1. Lysosomes

• Digest bacteria or damaged proteins
• Contain strong Enzymes
• Is called the suicide sac
• Are only found in animals
• White blood cells have lots of these

1. Vacuoles & Vesicles

• Are found in both plants & animals
• Both store nutrients & water
• Vesicles:

Transport substances throughout the cell

• Vacuoles:

Swell in plants when water enters (turgor pressure)

1. Chloroplasts

• Are found only in plant cells & some protists
• Contain a green pigment called chlorophyll (this captures light rays)
• Is the site of photosynthesis
• Converts carbon dioxide & water to sugar

Assignment

Draw a proper cell diagram

A. title

B. drawn in pencil

C. labels on the right

D. use straight edge for lines

Text – Page 273 # 2, 4, 7

Comparing Plant & Animal Cells

• Both are made up of:

Carbon

Hydrogen

Oxygen

Nitrogen

• In both element are combined to form organic compounds:

Lipids = (fats/ oils)

Carbohydrates = (sugar)

Protein = (muscle)

Nucleic acids = (DNA)

• In both water makes up 85 % of the cell (solvent for reactions)
• Both contain the following structures:

Membrane

Vacuoles

Vesicles

DNA

Mitochondria

Ribosomes

Nucleus

• What is different:

Only plant cells have chloroplasts & a cell wall

Only animal cells have centrioles & lysosomes

Structure / Plant / Animal
Vacuoles / large / small
Cell membrane & cytoskeleton / Same / Same
DNA structure / Same / Same
Centrioles (for cell division) / NONE / Has them
Cell wall / Has it / NONE
Chloroplast / Has it / NONE
Lysosome / NONE / Has it
Energy Storage / Starch / glycogen

Assignment

Label plant and animal cell diagrams in workbook

Label cell membrane diagram in WB

Cell Model Project

2.2

The Role of the Cell Membrane in Transport

The Cell Membrane

• Is selectively permeable
• controls the transport of particles into and out of the cell
• Is essential for the cell’s survival

Particle Model of Matter

• It is used to understand the types of transport in cells
• It states:

1. All matter is made of particlesbut the particles in different substances may be different in size and composition

1. The particles of matter are constantly moving or vibrating. They move the least in solids and the most in gases. Adding or removing energy will affect the movement of particles.

1. The particles of matter are attracted to one another or are bonded together.

1. Particles have spaces between them . The smallest are in solids and greatest in gases (exception - ice). The spaces may be occupied by particles of other substances.

Cell Transport

• Involves moving molecules into and out of the cell
• The type of transport that is used is determined by the molecules:

size

charge

whether or not they are soluble in lipids

• It occurs by:

1. Passive Transport
2. Active Transport
3. Endocytosis
4. Exocytosis
5. Phagocytosis

1.Passive Transport

• Does not require energy
• It is used by small molecules
• It continues until equilibrium is reached (same amount on both sides)
• There are 3 types:

1. Diffusion
2. Osmosis
3. Facilitated diffusion

A. Diffusion

•Is the movement of particles from an area of high concentration to an area of low concentration

•It is how plants get nutrients from the soil

• It is how DIALYSIS TUBING works

This is a synthetic semi-permeable cell membrane

It allows water, salt and sugar to diffuse through

it stops starch and protein from diffusing

• The rate (how fast it occurs) is affected by:

1. Size of molecules

(small = fast)

1. Temperature

(high = fast)

1. Concentration

(high = fast)

1. Medium through which it travels

(liquid or gas = fast) (solids = slow)

B.Osmosis

• Is the diffusion of water moleculesacross the cell membrane
• It is how plants take in water (in the roots)
• Three situations can arise depending if the cell’s environment is:

i) Hypertonic

ii) Hypotonic

iii) Isotonic

i)Hypertonic Environment

•There are more particles outside the cell

•Water diffuses out of the cell

•In animal cellscauses crenation

•In plant cellsit causes plasmolysis

ii)Hypotonic Environment

• There are less particles outside
• Water moves into the cell & causes it to swell
• E.g. over watering a plant… extra water can cause cells to explode!
• In animal cells it causes cytolysis
• In plant cells it causes deplasmolysis

iii)Isotonic Environment

• Has the same amount of solutes on either side
• There is no movement of solutes

C. Facilitated Diffusion

• Used by small substances that are not soluble in lipids ( they are water soluble & can’t pass through the membrane)
• Involves using:

i.)Channel proteins

ii.)Carrier proteins

i. ) Channel Proteins:

-Create pores through which particles can travel

ii.)Carrier Proteins:

Physically move the molecules across the membrane

Change shape when moving a molecule

2. Active Transport

• Requires energy (ATP)
• Particles move from an area of low concentration to high
• ‘pumps’ are used to move substances across

3. Endocytosis

• Use ATP & vesicles to move large molecules into the cell

4. Exocytosis

• Use ATP & vesicles to move large molecules out of the cell

5. Phagocytosis

• This is only done by certain types of cells & micro-organisms (E.g. Amoeba)
• A pseudopod:

(false foot) is formed

It wraps around the item

It then forms a vesicle …..Engulfing the food

Assignment

Predicting Solute Diffusion worksheet – WB

Text – Page 283 # 2, 3, 5, 6, 7

2.3

Applications of Cellular Transport in Industry and Medicine

Membrane Technology

• Is used to study:

1. Recognition proteins
2. Receptor proteins
3. Synthetic membranes (mimic real membranes)
4. In medicine

1. Recognition proteins

• Are embedded in membrane and some have a carbohydrate chain
• Are used by cells to recognize self from non -self

1. Receptor proteins

• Are proteins that hormones bind to…..initiating a response by the cell
• They are useful in the study of HIV and cancer
• Must recognize a virus in order to prevent it from entering the cell (focus of research)

1. Membrane Technology in Medicine

• Use for :

1. Creating liposomes
2. Dialysis

A. Liposomes