Term
Cell Theory:
Outline the three components of the cell theory |
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Definition
1. Cells are the smallest unit of life
2. All organisms are made of one or more cells
3. Cells arise from pre-existing cells
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Term
Describe the features of the following cell types that challenge the concepts of the cell theory
-Striated Muscle Fibres
-Giant Algae
-Aseptate Fungal Hyphae |
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Definition
Striated muscle cells make up the muscle tissue that we use to move. They are formed by smaller cells fusing together.
As a result:
- Their cells are very large (~30 mm long).
- They have many nuclei (sometimes several hundred)
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Fungi consist of long structures called hyphae. In aseptate fungi,
the hyphae are long tube-like structures with many nuclei.
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Algae are photosynthetic organisms that are simple in structure and internal organization. They form the base of most marine food chains.
Giant algae are single cells that can grow to be up to 100 mm long. Despite their size, they still only have a single nucleus |
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Term
List the functions of life
Hint: Mr. Sheng |
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Definition
M - Metabolism: Chemical reactions inside the cell including photosynthesis and cell respiration
R - Response: Ability to react to changes in the environment
S - Reproduction: Producing offspring and passing on genes
H - Homeostasis: Keeping internal conditions within tolerable and predetermined limits
E - Excretion: Getting rid of waste products of metabolism
N - Nutrition: Organisms must obtain food to provide energy for metabolism and growth
G - Growth: Gradual increase in size over lifetime
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Term
Compare the metabolic functions of Paramecium and Chlorella |
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Definition
Chlorella
Chlorella is unicellular green algae found in marine environments.
•Nutrition – photosynthesis inside chloroplasts
•Metabolism – occur in the cytoplasm
•Excretion – diffusion controlled by a cell membrane
•Reproduction – cells divide through mitosis
•Response – cilia (small hairs) move cell towards the light
•Growth – cells assimilate biomass and become larger until cell division happens.
•Homeostasis – vacuoles excrete water through exocytosis to manage water content
Paramecium
Paramecia are unicellular organisms that are found in freshwater and other marine environments.
•Homeostasis – contractile vacuoles fill up and expel water to maintain internal balance
•Metabolism – occurs in the cytoplasm
•Response – cilia used to propel through the water towards food
•Reproduction – asexual reproduction through mitosis
•Nutrition – food inside vacuoles is digested and carbon compounds used for cell respiration
•Growth – assimilated biomass is used to increase cell size before division
•Excretion – movement of substances controlled by a cell membrane
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Term
| Cell Size: Explain the importance of the surface area to volume ratio as a factor limiting cell size |
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Definition
| The importance of the surface area is because the volume of a cell determines the number of chemical reactions that can take place in its cytoplasm. These reactants require the import of reactants and the export of waste so the higher the volume, the faster resources are consumed. |
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Term
| List three adaptations of cells that may function to maximize the surface area to volume ratio |
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Definition
1. The higher the volume, the faster the resources are consumed.
2. That if more surface area is available, more reactants and products can diffuse in/out of the environment.
3. The surface area determines the rate at which molecules can pass through the membrane.
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Term
| Magnification: Compare the advantages and disadvantages of using light microscopes and electron microscopes |
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Definition
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a light microscope is a useful way to study tissues and living cells as it allows observation of living organisms in color.
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Electron microscopes have a much higher resolution than light microscopes.
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they will not be well-defined, and their positions will be unclear when viewed using a light microscope
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Electron microscopes cannot be viewed in color just black and white
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Term
| Identify the difference between a transmission electron micrograph and a scanning electron micrograph |
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Definition
| SEM creates an image by detecting reflected or knocked-off electrons, while TEM creates an image using transmitted electrons. |
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Term
| Cell Specialization: Outline, with an example, the organization of cells in a multicellular organism |
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Definition
| The body of a multicellular organism, such as a tree or cat, demonstrates multi-level organization: tissues, organs, and organ systems. Similar cells are grouped into tissues, tissue groups form organs, and similarly, formed organs are grouped into an organ system. |
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Term
Define emergent properties in relation to multicellular organisms |
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Definition
| The functions and properties that individual cells are not capable of, this happens when cells fuse and organize. |
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Term
| Explain how cells differentiate through selective gene expression |
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Definition
| Cell differentiation occurs as a result of changes in gene expressions. This involves some parts of the Genome being used while others not. All cells in the body have identical genes. |
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Term
| Describe how genes may be packaged within eukaryotic cells |
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Definition
| However, the genetic material in eukaryotes is stored in the nucleus and packaged tightly into linear chromosomes. |
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Term
Stem Cells: State the two key qualities of stem cells |
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Definition
1. Stem cells have great potential for use in medical therapies. For example, stem cells can be differentiated into tissues for implantation.
2. Stems cells are specialized cells that have the ability to divide and differentiate into different cell types.
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Term
| Differentiate between pluripotent, multipotent, and unipotent stem cells (with examples) |
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Definition
Totipotent: can become any cell type
Pluripotent: can become most cell types
Multipotent: can only differentiate into a class of cell
Unipotent: can differentiate along only one lineage.
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Term
Outline the therapeutic use of stem cells |
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Definition
- Stem cells may be extracted from embryos or from the mother's placenta / umbilical cord; certain adult tissue can also produce small amounts
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Stem cells may be used to substitute healthy, working cells for damaged or diseased cells
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Term
Describe the use of stem cells to treat Stargardt’s disease |
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Definition
| Retinal epithelial cells are grown from embryonic stem cells and then implanted. |
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Term
| List three other therapeutic examples of stem cells |
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Definition
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Term
| Compare the implications of stem cell therapy using cells derived from different sources |
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Definition
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They have almost unlimited potential
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There is more risk of the cells becoming or turning into a tumor.
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Almost unlimited differentiation potential.
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Less chance of genetic damage via mutations.
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More risk of cells becoming a tumor
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Removing cells from the embryo kills it.
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These cells are pluripotent and can be frozen for storage until needed later in life.
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There is no major risk of cells turning into a tumor.
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Cells come from the patient and so are genetically compatible
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Limited quantity in the umbilical cord
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Limited capacity to differentiate compared to embryonic stem cells
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They are harder to obtain and have less growth potential than other types.
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There is less chance of tumor development
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Less chance of tumor development
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Fully compatible with patients’ tissues
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Removal of cells does not kill the adult.
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Difficult to obtain from deep in tissues
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