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23 Cards in this Set
- Front
- Back
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What does the cell theory state? |
The cell theory states that living organisms are composed of cells, that cells are the smallest unit of life, and that cells come from pre-existing cells. |
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What is the purpose of scale bars or stated magnification? |
Scale bars or stated magnifications enable you to determine the actual size of specimens. |
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What is the significance of surface area to volume ratio? |
It is essential that a high surface area to volume ratio exists for a cell. As a cell increases in size, the volume increases much faster than the surface area, thus decreasing the surface area to volume ratio. This decreases the chances of the successful existence of the cell. |
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What is meant by emergent properties? |
Cells show emergent properties. This means that the interaction of the parts of the cell results in the whole being greater than the sum of its parts. |
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How does cell specialization occur? |
In multicellular organisms, cells differentiate to carry out specialized functions. This specialization occurs as a result of differential expression of genes in a multicellular organism. |
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What is the main characteristic of stem cells? |
Stem cells have yet to go through the differentiation process. Thus they maintain the ability to differentiate along different pathways. There appear to be stem cells in most major types of tissues. |
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Where are stem cells currently being used the most in Medicine? And in the future? |
Stem cells have many therapeutic uses, including the replacement of damaged bone marrow cells in leukemia patients. In the future, it may be possible to treat conditions such as Alzheimer’s disease and Parkinson’s disease with stem cells. |
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What characterizes prokaryotic cells? Name the main constituents. |
Prokaryotic cells have ribosomes, a cell wall, a cell membrane, a nucleoid region, and, in most cases, plasmids. These simple cells divide by binary fission. |
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Describe the main features of DNA in prokaryotic cells (in distinction to eukaryotic cells). |
DNA exists in the nucleoid region of prokaryotic cells. It is circular in form and is not associated with proteins. |
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In which types of cells do membrane-bound organelles occur? |
Membrane-bound organelles, including a nucleus, are associated with eukaryotic cells. |
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How is compartmentalization in eukaryotic cells accomplished? What subcellular components illustrate this principle? |
Eukaryotic cells exhibit much more compartmentalization than prokaryotic cells. This allows certain areas to carry out specialized and highly efficient functions. Organelles best demonstrate this compartmentalization, and include mitochondria, chloroplasts, nuclei, vacuoles, Golgi apparatus, endoplasmic reticulum, and lysosomes. |
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List major differences between eukaryotic cells of plants and animals (4 items required). |
The eukaryotic cells of animals contain centrioles, while the eukaryotic cells of plants do not. Plant cells contain chloroplasts, animal cells do not. Plant cells have cell walls, animal cells do not. Plant cells have larger vacuoles than animal cells. |
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What do cell membranes contain? What is classified as central or peripheral? |
Cell membranes include phospholipids and proteins. These proteins may be classified as integral or peripheral, depending on their location. |
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What causes the main properties of the cell membrane, what are they called? |
The hydrophobic and hydrophilic properties of the cell membrane are the result of the chemical nature of the phospholipid bilayer. |
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Give examples for active and passive transport.
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Examples of passive transport, which does not require any cellular energy, include diffusion, facilitated diffusion, and osmosis. Examples of active transport,which does require the expenditure of cellular energy, include endocytosis, exocytosis, and the sodium–potassium pump. |
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Why does the plasma membrane have a degree of fluidity?
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It is essential that the plasma membrane has a degree of fluidity so that shape changes can occur to allow endocytosis and exocytosis. |
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What are some potential problems with cell theory?
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‘Concerns’ of the cell theory include the multinucleated cells of muscle cells, fungal hyphae, and some green algae. Also, the characteristics of viruses raise some questions concerning cell theory. The ‘first’ cell always presents a problem for the cell theory. |
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What does the endosymbiotic theory state? If true, when did this happen? |
At present,the endosymbiotic theory is the most accepted explanation for the development of eukaryotic cells from prokaryotic cells. This theory states that, about 2 billion years ago, a bacterium took up residence inside a very simple eukaryotic cell. The theory goes on to say that this was the first step in thedevelopment of the organelles we see today in eukaryotic cells. |
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What are the processes involved in cell division?
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Cell division allows the production of two identical daughter cells. Cell division involves both mitosis, a nuclear division, and cytokinesis, a cytoplasmic division. |
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What is cancer? Name some associated terms.
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Cancer involves cells whose cell cycles are out of control. Mutagens, oncogenes, and metastasis are all terms commonly associated with cancer.
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What are cyclins? How can interphase be further subdivided?
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Cyclins are a group of proteins that control a cell’s progression through the cell cycle. The cell cycle involves interphase, in which the cell is busy carrying out the functions for which it is designated through differentiation. Metabolic activities such as protein synthesis, DNA replication, and organelle reproduction occur in this phase. Interphase includes the smaller phases known as G1,S, and G2.Ñn@ |
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What are the phases of mitosis? What is a chromatid?
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The four stages of mitosis are prophase, metaphase, anaphase, and telophase. During prophase and metaphase the chromosome is actually two molecules of DNA attached together at the centromere. Each molecule of DNA is called a chromatid.
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Describe supercoiling, where does it occur and what happens?
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The DNA in the nucleus of eukaryotic cells goes through a process called supercoiling to form the chromosomes that enter into mitosis. This supercoiling involves DNA wrapping around spherical proteins called histones to form nucleosomes. |
