Chapter one Biology review 1. Describe and explain the contribution of Needham, Redi, Spallanzani, and Pasteur in the process of the cell theory. Needham: -he designed and experimented and supported abiogenesis’. He boiled meat broth for a short amount of time and poured into two flasks, covered and uncovered. Both became cloudy because of the growth of bacteria after several days. He believes that organisms came from water itself. BUT he didn’t boil the water long enough to kill the bacteria. Redi : - conducted one of the first controlled experiment that supported biogenesis He used meat in a jar half covered, with mesh and half open. After several days he found that the mesh covered meat had no maggots, while the open jar had maggots. o This showed people that maggots can’t become unless flies can land, people began to doubt spontaneous generation. Spallanzani: - He didn’t agree with Needham, so he repeated his experiment. (He was against spontaneous generation. He boiled the broth longer and put it into the two flasks, no life appeared in the sealed flask while the open flask had bacteria growth. o Boiling the broth killed the vital principle that made life arise from non living matter like water.
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Chapter one Biology review
1. Describe and explain the contribution of Needham, Redi, Spallanzani, and
Pasteur in the process of the cell theory.
Needham: -he designed and experimented and supported abiogenesis’.
He boiled meat broth for a short amount of time and poured into two
flasks, covered and uncovered. Both became cloudy because of the growth
of bacteria after several days.
He believes that organisms came from water itself.
BUT he didn’t boil the water long enough to kill the bacteria.
Redi : - conducted one of the first controlled experiment that supported
biogenesis
He used meat in a jar half covered, with mesh and half open. After several
days he found that the mesh covered meat had no maggots, while the open jar
had maggots.
o This showed people that maggots can’t become unless flies can land,
people began to doubt spontaneous generation.
Spallanzani: - He didn’t agree with Needham, so he repeated his experiment. (He
was against spontaneous generation.
He boiled the broth longer and put it into the two flasks, no life appeared in
the sealed flask while the open flask had bacteria growth.
o Boiling the broth killed the vital principle that made life arise from non
living matter like water.
Pasteur: -conducted experiments that disapproved abiogenesis, concluding that
organisms do not come from non living matter.
(Needham and
Spallanzani)
(Redi)
(Pasteur)
2. Explain the cell theory, biogenesis, and abiogenesis
Cell theory: -
All living organisms are made up of one or more cells
Cells are the basic unit of structure and functions in all organisms.
All cells are derived from pre-existing cells.
In multicellular organisms (plant/human) the activity of the entire organisms
depends on the activity of a single cell that makes up the organisms.
Biogenesis: the belief that living things come from other living things
Abiogenesis: erroneous idea that life can come and develop spontaneously from
lifeless matter.
3. Explain Hooke, Leeuwenhoek, Schleiden, Schwann, and Virchow
Hooke: Wrote a book in 1665 in which shows illustrations of tree barks as seen
under a microscope. The drawings showed compartments which he called “cells”
Leeuwenhoek: -Designed his own microscope in 1666/1667. They were tiny and
simple with a single lense and were much more powerful than the other
microscopes of the time.
In 1683 he marked the discovery of bacteria by observing plaque on teeth.
He called these bacteria “animalcules”
Schwann: He wrote that “all animals are made up of cells” then added that “cells
are organisms and plants are collectives of these organisms.
Virchow: he wrote that “cells are the last link in a great chain [that forms] tissues,
organs, systems and individuals... where cells exist there must have pre-existing
cells” in 1858.
4. Explain how the invention of the microscope permitted scientists to discover the
existence of cells, and how this discovery revised all scientific understanding.
Early users of microscopes tended to focus on their observations on known
objects and organisms. With the ability to enlarge 50x, this let scientists
view details they’ve never seen before.
Van Leeuwenhoek used a single lens system. He developed a technique for
grinding lenses that remained unsurpassed for 150 years. He achieved 500x
magnifications.
o He was the first person to observe microscopic organisms, he
introduced to the world and scientists in particular to the living
inhabitants of the micro-universe.
This helped scientists to start understanding organisms and cells more
Thorley.
5. Examine and compare images of cell structures generated by both light and
electron microscope.
Light microscopes: max magnification of 2000x
Can see most, but not all cells and cell structures.
Resolution limited to about 0.2 “um”
Resolving power is limiting so the lighting source must be changed to
accommodate this.
Electron microscope:
1. Transmission electron microscope (TEM)
-Magnifies up to 500,000 times
- Resolution as low as o.ooo2 “um”
-electrons are transmitted through the specimen
2. Scanning electron microscope (SEM)
o magnifies up to 300, 000 times
o resolution 0.005 “um” (lower then TEM)
o Specimen in sprayed with a gold coating and is scanned with a narrow
beam of electrons.
o electron detector creates a 3D image
6. Identify the parts of the compound light microscope and be able to determine
total magnification, field of view, and general microscope safety.
Identifying parts – PAGE 16 TEXT BOOK.
Total Magnification = Ocular x objective
Example: If your ocular is 10x and the low power objective is 20x then your total
magnification is 200x.
10 x 20 = 200x
Field of view: the area of the slide that you see when you look through microscope.
You use micro metres “um”. When going from millimetres to micro metres move the decimal
three places to the right or times by a 1000.
Examples of calculating F.O.V
1. Low power objective = 4x
High power objective = 40x
Eye piece lens = 10x
Low power field of view = 4.4 mm
What is the HIGH power field of view?
4.4mm x 4/10
4.4 x 0.10 = 0.44 mm
0.44x 1000 = 4400 um
The total F.O.V is 4400 um
2. Low power objective = 5x
Med power objective = 10x
Eyepiece lens = 5x
Low power FOV = 3.5mm
What is the medium power field of view?
3.5mm x 5/10
3.5 x 0.5 = 1.75mm
1.75mm x 1000 = 1750 um
The total F.O.V is 1750 um
Microscope Safety
o Make sure that your hands are dry when handling it.
o Handel the slides carefully and can break easily and cause cuts.
o When carrying the microscope always use one hand to hold the arm and the
other to support the bottom.
o Do not adjust any of the focussing knobs until ready for use
o Always focus using the coarse adjustment knob first, with the low power
objective lens in positions.
o Cover the microscope when not in use.
6. Compare and contrast prokaryotic cells and eukaryotic
Prokaryotic cells: Organisms with cells lacking a true nucleus and most other
types of organelles; Bacteria and Archaea. They are the smallest living cells.
Eukaryotic cells: organisms with cells containing nuclei and other types of
membrane-bound organelles; Protists, Fungi, Plants, and Animals
7. Describe the roll of the following structures:
Cell Membrane: a structure that separated the cell interior from the outside
world and controls the movement of materials into and out of the cell.
Endoplasmic reticulum: a membranous tubule system throughout a cell
Vacuole: membranous sacs that store nutrients, water and wastes.
Cilia: hair like structures extending from the cell membrane that beat in a
coordinated rhythm to produce movement. Helps enable protozoa such as the
paramecium to move about, and also helps to sweep food particles into their
gullets
Cytoplasm: a gel-like material consisting mostly of water that contains dissolved
materials and creates the chemical environment in which the other cell structures
work.
Ribosome: tiny two part structures found in the cells cytoplasm and attached to
the rough endoplasmic reticulum that helps put together proteins. They bring
together the mRNA strand, tRNA molecules carrying amino acids and the enzymes
involved in building polypeptides
Vesicle: small membrane sac for transport or storage of material within a cell.
Lysosome: membrane bound vesicles filled with digestive enzymes that can break
down worn out cell components or materials brought into the cell through
phagocytises
Nucleus: largest and most prominent structure within a cell, having double
membrane that contains the DNA instructions for making protein. Genetic
information is stored in the nucleus determines the cells structural characteristics
and how it functions.
Mitochondria: organelles with double membrane where organic molecules,
usually carbohydrates are broken down to release energy.
Golgi body: (golgi apparatus) a stack of flattened membrane bound sacs that
receive vesicles from the ER, contain enzymes for modifying proteins and lipids,
and package finished products into vesicles for transport to the cell membrane
and within the cell as lysosomes.
Flagella: long hair like projections extending from the cell membrane that
propelthe cell using whip-like motion.
Nucleolus: specialized area of chromatin inside the nucleus where ribosomal RNA
is produced to make ribosomes
Chloroplast: plastid that gives green plants their colour and transfers the energy
in sunlight into stored energy in carbohydrates during photosynthesis.
Microtubules/filament: rod like, hollow protein tubes that act like tracks along
which other organelles such a vesicles and mitochondria, can move.
Cell wall: rigid structure surrounding the cell membrane that protects and
supports the cell and allows materials to pass to and from the cell membrane
through pores.
9. Compare and contrast plant and animal cells in terms of the types of organelles
present.
Plant cells: - have outer cell walls made of cellulose (animals do not). Provides
rigidity and protecting
o Plants have one large central vacuole (animals have several small ones).