Examining a Variety of Prokaryote and Eukaryote Cells
Living organisms that contain eukaryotic cells are known as eukaryotes.
These organisms can either be unicellular (e.g. amoeba) or multicellular (e.g. plants, animals, fungi)
Eukaryotic cells have multiple chromosomes, comprised of DNA and protein.
These chromosomes are protected within the nucleus.
Eukaryote= Eu- true karyote- kernel
What is the cell nucleus? The cell nucleus is the control panel of the cell, it controls everything.
What is the main difference between prokaryotic and eukaryotic cells? The main difference is that eukaryotic is a membrane bound structure, prokaryotic cells do not have a nucleus.
Give an example of a prokaryotic cell? Bacteria is an example of a prokaryotic cell.
Define organelle? An organelle is a membrane bound structure. These are little “organs” inside the cell that have different features.
What is the advantage of having organelles? The advantage of having organelles is that it provides a barrier between the inside of the cell and the outside of the cell.
Organisms with prokaryotic cells are called prokaryotes.
They were the first type of organisms to evolve and are still the most common organism today.
Prokaryotic cells are usually smaller and simpler than eukaryotic cells.
They do not have a nucleus or other membrane-bound organelles.
The DNA in prokaryotic cells is n the cytoplasm rather than enclosed within a nuclear membrane.
Prokaryotic cells are found in single-celled organisms such as bacteria.
All cells have a plasma
Comparing eukaryotes and prokaryotes
Nucleus No Yes
DNA Single circular piece of DNA Multiple chromosomes
Membrane-bound organelles No Yes
Examples Bacteria Plants, Animals, Fungi
All cells have a plasma membrane, ribosomes, cytoplasm and DNA.
Prokaryotic cells exist as single cells. They all lack a nucleus and membrane-bound structures.
Eukaryotic cells have a nucleus and membrane-bound structures called organelles.
1. Describe three features distinguishing cells from eukaryotic cells:
The cell wall of a prokaryotic cell is an important feature of prokaryotic cells. Cell walls are a multi-structural. In bacteria, the cell wall contributes to virulence (disease-causing ability)
Unlike eukaryotes, prokaryotes lack membrane bound organelles such as a mitochondrion and nucleus.
Prokaryotes contain a single circular main chromosome
2a. The function of the flagellum is to provide locomotion. There may be a single polar flagellum or multiple flagella at each end of the cell, the flagella may even be distributed over the entire cell.
4a. The way prokaryotes reproduce is through bacterial conjugation which is when there is a one-way exchange of genetic information from a donor cell to a recipient cell.
Before the 16th century it was believed that living creatures arose by spontaneous generation.
In 1590 the first compound microscope was made by two Dutch lens makers, Hans and Zacharias Janssen.
It consisted quite simply of two convex lenses placed at either end of a wooden tube.
This had a magnification of 9x
Magnification and Resolution
Microscopes enhance our sense of sight.
They function by making things appear bigger (magnifying them)
At the same time, they increase the amount of detail we can see. (Increasing our ability to distinguish between two objects or resolve them)
Magnification: Is the process of enlarging an object by using an optical instrument.
Resolution: The ability to tell that two objects that are very close together are distinct objects rather than just one.
2. A situation where phase contrast microscopy would improve image quality is when you are trying to examine fine detail
a. In animal cells you can see the nucleus with the light microscope.
b. With the light microscopes, you can see cell wall in plant cells.
4. Ribosomes are not generally seen with a light microscope due to how small they are.
a. Blood cells- Leichman’s stain in red-pink
b. Starch- Schlutz’s solution in blue
c. DNA- Faulgen’s stain in red/purple
d. Fungal spores- Anfine blue stain
e. Nuclei- Haematoxlin in blue
f. Cellulose- Eosin in pink/red
6. Generally the highest magnification you can get is 400 x
8. Magnification refers to how large an organism is while resolution refers to how much detail you can see.
Type of Microscope Magnification Resolution Method to produce image Image type
Light Microscope 1.5cm-100nm Light source passes through the convex objective lens 2D
Fluorescence microscope The sample viewed is labelled with a fluorescent substance that will attach to the substance the scientist wants to examine. 2D
Transmission electron microscope 10-5m – 0.1nm The interaction between the substance and the electrons reveal extra details. 2D
Scanning electron microscope 10-5m – 0.1nm Secondary electrons are picked up by a collector, amplified and transmitted onto a viewing screen. 3D
1. The electron microscope produces more detail because electrons pass through though the specimen and are scattered.
a. The transmission electron microscope would be suited for seeing detailed images of cells.
b. The scanning electron microscope would be suited for seeing small organisms such as bacteria and viruses.
c. The bright field microscope with the thin section would be good for seeing hair strands.
d. The dissecting microscope would be good for crossections.
1. Magnification refers to how large the object appears in the microscope while resolution refers to how detailed the specimen is in the microscope.
2. A light microscope works by a light travelling though the microscope and onto the specimen, allowing us to see details of the specimen.
3. Light microscopes do not allow you too see fine detail of cells
4. The process of fluorescence microscopy involves a fluorescent substance attaching to the specimen, allowing the scientist to see the specimen in detail.
5. In an electron microscope, electrons are shot through the electron gun and onto the specimen, this allows us to see the specimen in full detail.
7. Electron microscopes allow you too see more details in a specimen
8. The process of a confocal laser scanning microscope is
2. Plant cells, human red blood cell are eukaryotes while E.coli, tobacco mosaic, HIV, Trypanosoma, bacteriophage and green alga are prokaryotes.
3. The statement “not drawn to scale” means that the specimen drawn is not the size that the person drew it.
4. The typical plant cell is