Cellular Evolution and Cell Types Flashcards
When were the first compound (double lens) microscopes made?
The end of the sixteenth century.
Who is credited with the discovery of cells?
Robert Hooke
Describe the question Robert Hooke attempted to answer and his results.
Hooke wanted to understand why cork stoppers were so well suited to holding air in a bottle. After examining cork under a microscope, Hooke found small pores within the material, which he called cells (inspired by the cells inhabited by monks).
Describe Anton van Leeuwenhoek’s work.
Leeuwenhoek was a Dutchman who constructed simple microscopes and ground lens. When he examined a drop of pond water under the microscope, he discovered small “animalcules” that moved under the lens. He also viewed bacteria taken from pepper and scrapings of his teeth.
Who determined that plants were made of cells and that the plant embryo arose from a single cell?
A German lawyer turned botanist named Matthias Schleiden.
What are the two points of Schwan’s cell theory?
- All organisms are composed of one or more cells.
- The cell is the structural unit of life.
Where did Schleiden’s and Schwann’s theories fall short of knowledge accepted today?
Their theories on the origin of cells proved to be less insightful since they agreed that cells could arise from noncellular materials (inorganic materials).
What is the third point of cell theory, and who proposed it?
- Cells can arise only by division from a preexisting cell.
- This was proposed by German pathologist Rudolf Virchow.
(This idea lies in contradiction to the theories of cell origin made by Schwann and Schleiden)
What is the smallest unit to exhibit life?
The cell
Who began the first culture of human cells, and how was it accomplished?
George and Martha Gey of Johns Hopkins University in 1951. The cells were taken from a malignant tumor of a lady named Henrietta Lacks (thus the name HeLa for the cells).
What does in vitro mean?
In vitro refers to the conditions–in culture, outside the body–in which cells are grown in a lab.
How do biologists examine complexity in reference to cells?
They think in terms of order and consistency. The more complex a structure, the more parts it has, the less tolerance for errors it has, and the more regulation is necessary to maintain it.
What is the error rate of DNA replication?
There is less than one mistake every ten million nucleotides incorporated.
Describe the hierarchy of life in terms of materials and their size.
- Atoms.
- Molecules
- Polymers
- Complexes
- Subcellular organelles
- Cells
Give some examples of cellular consistency in structure across species.
- Each cell has a consistent appearance when viewed under a microscope (meaning the organelles each have a particular size and location).
- Each type of organelle has a specific composition of macromolecules which are arranged in a predictable pattern.
Describe the structure of epithelial cells.
These cells have two important sides: the apical and basal sides. The apical side faces the intestinal channel and have long processes called microvilli. At the basal end are large numbers of mitochondria to produce the energy required to fuel various membrane transport processes.
Describe the structure and function of the microvilli of the intestinal epithelial cells.
Because of their internal skeleton of filaments, microvilli are able to project outward from the apical cell surface. This skeleton is composed of protein (actin) monomers polymerized in a characteristic array.
Describe the structure and function of the intestinal mitochondria.
Each mitochondrion has a defined pattern of membranes. Each of these in turn contains a consistent array of proteins, including an electrically powered ATP-synthesizing machine projecting from the inner membrane.
Describe the discrepancy in the way in which evolution has progressed in the levels of biological organization.
On the macro scale (such as a human or cat), there are major differences in anatomy. However, on the micro scale (cells and their organelles) structures are very similar.
Name some examples of processes or structures that are similar between diverse species.
The actin filament of the intestinal epithelial cells, the ATP-synthesizing enzyme, the synthesis of proteins, the conservation of chemical energy, and the construction of a membrane.
What role do genes play in the body?
Genes, while they act as a type of “storage locker” for information (DNA), also play a role in facilitating processes. Examples include making the blueprints for constructing cellular structures, the directions for running activities, and the program for making more of them.
Name one case in which cellular reproduction leads to a case of unequal cytoplasmic division.
The division of a human oocyte.
Where does virtually all of the energy used by life on earth come from?
The electromagnetic radiation of the sun.
Describe the process by which electromagnetic radiation from the sun becomes energy for living creatures.
The light is trapped in the pigments of plants, where it is photosynthesized. There, it is converted into chemical energy that is stored in energy-rich carbohydrates (examples: sucrose or starch). An animal or human can then consume this energy (usually in the form of glucose).
How is glucose broken down in the body?
Glucose is released by the liver into the blood where it circulates, delivering chemical energy to the cells. Once in the cell, the energy is broken down into a form that the cell can use as energy (usually ATP).
Define enzymes
Molecules that greatly increase the rate at which chemical processes occur.
Define metabolism.
The sum total of the chemical reactions in a cell.
What initiates dynamic, mechanical changes within the cell? (such as material transport, structure assembly, disassembly, and movement of the cell)
Changes in the shape of “motor” proteins initiate this.
Describe the receptors of the cell.
Receptors interact with substances in the environment in a highly specific way. Cells have receptors to hormones, growth factors, and extracellular material. Receptors also provide pathways through which external stimuli can evoke specific responses in target cells. Cells respond to stimuli by altering their activities, moving, or even committing suicide.
What does robustness mean in reference to a cell?
Cells are durable because they are protected from dangerous fluctuations in composition and behavior by regulatory systems.
