Bio U1 - 1.1 Flashcards
State the three parts of the cell theory.
- The cell is a basic unit of life
- All living things are composed by cells
- Cells come from preexisting cells
Outline evidence that supports the cell theory.
Observation and experimentation
- Subcellular components have not performed functions of life
- Spontaneous generation has never been observed
- Tissues from animals, plants, eukariots, bacteria, and fungi have all been shown to have cells
Compare the use of the word “theory” in daily language and scientific language
- daily language: doubtful, uncertain
- scientific language: it has been proven through numerous observation and experimentation. There currently no doubt. Well-substantiated.
Outline the 7 functional characteristics of life
henrrg m
homeostasis
excretion
nutrition
reproduction
response to stimuli
growth
metabolism
Outline the activities occurring in the volume and at the surface of the cell.
Volume means in the citoplasm and in it many metabolic reactions occur. Metabolic reactions always need reactants (oxygen and nutrients) and produce waste (urea and CO2)
Cell surface refers to the entering and leaving of reactants.
Calculate the surface area, volume and SA:V ratio of a cube.
- SA: l^2
- V: l^3
- SA:V = l^2:l^3 = 1/l
Explain the benefits and limitations of using cubes to model the surface area and volume of a cell
- Benefits: easier to visualize, manipulate, and measure. The relationship of SA and V between cubes and cells is equal.
- Limitations: cubes and cells are not the same and one should be warry of that
Describe the relationship between cell size and the SA:V ratio of the cell.
- As the cell increases the ration becomes smaller
- Larger Cells have less surface area relative to the amount of volume
Explain why cells are often limited in size by the SA:V ratio.
Larger cells have a larger metabolism, thus there is a greater need for reactants and a greater production of waste. This then becomes unsustainable as the surface area is too small for such a large metabolism.
List three adaptations of cells that maximize SA:V ratios
- Long Extensions (neurons)
- Thin, flattened shape (red blood cells)
- Microvilli (small intestine epithelial cells)
Define and provide an example of a unicellular organism.
An organism that consists of only one cell
- Bacteria
- Amoeba
- Paramecium
Define and provide an example of a multicellular organism.
Organisms that consists of more than one cell
- Frogs
- Humans
- Plants
Define “emergent property.”
- A property that arises only with many individuals
Provide an example of emergent properties at different hierarchical levels of life.
- Cardiac cells contract in synchrony and together become cardiac tissue, which can pump blood and through that perform numerous functions of life
Describe features of striated muscle fibers that make them a discrepancy from a typical cell.
- Striated muscle fibers have multiple nuclei and are long. A eukaryotic cell with more than one nuclei.
Describe features of red blood cells that make them a discrepancy from a typical cell.
- Red blood cells do not have a nuclei
Describe features of aseptate fungal hyphae that make them a discrepancy from a typical cell.
- Aseptate hyphae are not made of clearly defined individual cells. They have a continuous cytoplasm along the length of the hyphae.
Describe features of giant algae that make them a discrepancy from a typical cell.
- A huge single celled organism with a single celled nucleus
Define magnification.
How much larger an object appears compared to its real size
Given the magnification of the ocular and objective lenses, calculate the total microscope magnification.
- Multiply the ocular and objective lens
Define “field of view.”
- The diameter of the area visible through the microscope
Outline how to determine the diameter of a field of view using low power magnification.
- Use a transparent metric ruler and focus on the scale of the ruler
Calculate the field of view diameter of a microscope under medium or high power.
- High power = Smaller field of view
- Diameter (LP) x Magnification Objective (LP) / Magnification Objective (HP) = Diameter (HP)
Outline how to estimate the size of a sample in the microscope field of view.
- Estimate the fraction of the field of view the object occupies
- Multiply the field of view size by that estimated fraction
- For example: if an object occupies 3/4 of the FOV and the FOV is 5mm, then multiply 3/4 by 5 and you will know the size of the object
Define micrograph.
- It is a picture taken through a microscope to show what has been magnified with detail and precision
State why the magnification of a drawing or micrograph is not the same as the magnification of the microscope.
- Drawings distort the form and size of a picture, as we cannot draw such small objects with their precise size
Use a formula to calculate the magnification of a micrograph or drawing.
Drawing Magnification = Measured size of drawing /
Size of specimen
- Answers should be rounded to one sig fig
Define tissue.
- A group of cells that specialize in the way and perform the same function
- They are only present in multicellular organisms
Define differentiation.
It is the specialization of cells in functions and structures
Outline the benefits of cell specialization in a multicellular organism.
They become better, more efficient, and more economic on performing a task, making the being more complex and having multiple metabolisms.
Describe the relationship between cell differentiation and gene expression.
Differentiation is due to different genes from a common genome expressing themselves
Define totipotent.
Can become an cell (including placenta in placental mammals)
ex: zygotes
Define Pluripotent
Can become any cell excluding the placenta
ex: inner cell mass of a blastocyst
Define multipotent
Partially differentiated but can still become multiple different cells that are related
ex: umbilical cord stem cells
Define zygote
The cell that results from a sperm fertilizing an egg
Define embryo
Ear;y stages of develepment after the zygote divides
List two key properties of stem cells that have made them on the active areas of research in biology and medicine today.
- They can differentiate into any cell
- They have unlimited division capability
Explain why stem cells are most prevalent in the early embryonic development of a multicellular organism.
- Because it is during this period that the stem less are less differentiated or not differentiated at all, thus the prevalence of them in this early developmental stage. As the body develops, those cells will begin to differentiated and perform specific functions in the body.
Contrast the characteristics of embryonic, umbilical cord and adult somatic stem cells.
- Embryonic stem cells: pluripotent, inner mass of the blastocyst
- Umbilical Cord stem cells: multipotent, they can only differentiated into blood cells
- Adult somatic stem cells: they are found in the liver, skin, and bone marrow, and they have limited differentiation
Describe characteristics of Paramecium that enable it to perform the functions of life.
H - Homeostasis: Material move across cell membrane
E - Excretion: Anal pore for solids and Contractile Vacuole for liquids (CO2)
N - Nutrition: Heterotrophic (eat through the oral groove, englobes other unicellular beings)
R - Reproduction: Asexual and Sexual
R - Response to stimuli: Cilia (allows them to move and interact with environment)
G - Growth: They grow until their SA:V is unsustainable and then they divide
M - Metabolism: Enzymes in cytoplasm
Describe characteristics of Chlamydomonas that enable it to perform the functions of life.
H - Homeostasis: Contractile Vacuoles to move water out of the cell membrane to maintain stable water levels
E - Excretion: Difusion to the cell membrane that then excretes to the environment (O2)
N - Nutrition: Autotrophic (Chloroplasts)
R - Reproduction: Asexual reproduction after the cell is big or though sexual reproduction when the nuclei fuse
R - Response to stimuli: Eyespot and Flagella that are sensitive
G - Growth: They absorb minerals from the environment and through photosynthesis
M - Metabolism: Enzymes in Chloroplast and Cytoplasm
Outline the cause and symptoms of Stargardt’s disease.
Cause: Recessively inherited gene that causes the photoreceptors in the center of the retina, the macula, eventually making the person go blind.
Symptoms: Central blindness, while peripheral vision remains intact
Explain how stem cells are used in the treatment of Stargardt’s disease.
Coaxing stem cells into growing into retinal pigment epithelium (RPE) would help nourish and support other cells in the eye, effectively curing the blindness.
Outline the cause of leukemia
Leukemia is a cancer and it is caused by the mutation of cells in the bone marrow and lymphatic system, the body’s blood-forming tissues
Explain how stem cells are used in the treatment of leukemia.
- Chemotherapy is done to kill the cells with the cancerous gene in the bone marrow
- A bone marrow (containing adult blood stem cells) transplant occurs
- If successful, the adult stem cells establish themselves, divide, and then form new healthy blood cells for the patients
Discuss the benefits and drawbacks in using embryonic stem cells.
- Benefits: they divide indefinitely and can differentiate into any cell and they will not have genetic mutations that have accumulated with age. The usage of IVF embryos that would have been thrown away is a greater re-purposing.
- Draw-backs: The destruction of a human embryo is ceasing the life of a potential human being and if the division is not controlled, those cells can become tumorous
Discuss the benefits and drawbacks in using cord blood stem cells.
- Benefit: as these cells are harvested from the being, they will not be rejected by it later in life, if the need to use them arises. Easy to obtain and store as well.
- Drawback: they are only multipotent, therefore they can only divide into a specific type of cell, and they must be frozen
Discuss the benefits and drawbacks in using adult stem cells.
Benefits: will not be rejected from the body, no major ethical concerns are raised with their use. They can be used to regenerate tissue cell and only need the consent of the adult.
Drawbacks: they are only multipotent, therefore cannot differentiate into any cell and they are hard to obtain and not present in all parts of the body.
What is iPSC
It is the reprogramming of human somatic cells into an embryonic-like state in which they obtain the ability to differentiate into any body cell, hence they become pluripotent once again.
