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Biology U1 > Cell Theory > Flashcards

Cell Theory Flashcards

1
Q

What are the 3 features of cells that cell theory states?

A
  1. all living things are composed of one or more cells
  2. the cell is the basic unit of life
  3. new cells arise from existing cells
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2
Q

What are the exceptions to the cell theory?

A
  1. Striated muscle fibers
    - enclosed inside one membrane, but are extremely long and contain multiple nuclei
  2. Aseptate fungi
    - consist of thread-like structures called hyphae which contain multiple nuclei
  3. Giant algae
    - certain species of unicellular algae may grow to very large sizes
    - example: Acetabularia
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3
Q

What are unicellular organisms?

A

Organisms consisting of only one cell

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4
Q

What are the 7 basic functions carried out by unicellular organisms (functions of life)?

A
  1. Nutrition
  2. Growth
  3. Response
  4. Excretion
  5. Metabolism
  6. Homeostasis
  7. Reproduction
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5
Q

How does Paramecium carry out the functions of life?

A
  1. Nutrition: feeds on smaller organisms by ingesting and digesting them in vesicles
  2. Growth: increases in size and dry mass by accumulating organic matter and minerals from its food
  3. Response: reacts to stimuli
    - example: reverses its direction when it reaches a solid object
  4. Excretion: expels waste products of metabolism
    - example: solid wastes are removed through an anal pore
  5. Metabolism: produces enzymes which catalyze many different chemical reactions in the cytoplasm
  6. Homeostasis: keeps internal conditions within limits
    - example: essential gases enter and exit the cell via diffusion
  7. Reproduction: reproduces asexually using mitosis or sexually using meiosis
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6
Q

How does Chlamydomonas carry out the functions of life?

A
  1. Nutrition: produces its own food using photosynthesis
  2. Growth: increases in size and dry mass due to photosynthesis and absorption of minerals
  3. Response: reacts to stimuli
    - example: senses where the brightest light is with its eye spot and swims towards it
  4. Excretion: expels waste products of metabolism
    - example: exchange gases and other essential materials via diffusion
  5. Metabolism: produces enzymes which catalyze many different chemical reactions in the cytoplasm
  6. Homeostasis: keeps internal conditions within limits
  7. Reproduction: reproduces asexually using mitosis or sexually using meiosis
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7
Q

Explain the significance of the Surface Area to Volume ratio

A
  • The rate at which materials are used or produced (i.e. metabolic rate) of the cell is proportional to the volume of the cell
  • The rate of material exchange is proportional to the surface area
  • As a cell grows larger its surface area to volume ratio becomes smaller
  • Therefore a cell that becomes too large may not be able to take in essential materials or excrete waste substances quick enough
  • Thus growing cells tend to divide and remain small to maintain a high SA:Vol ratio
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8
Q

What is the benefit that multicellular organisms have over unicellular organisms?

A
  • Multicellular organisms are capable of completing functions that unicellular cannot due to the collective actions of individual cells combining to create new synergistic effects (emergent properties)
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9
Q

What are examples of emergent properties?

A
  1. Cells may be grouped together to form tissues, which can carry out their roles more efficiently
  2. Organs are formed from the functional grouping of multiple tissues
  3. Organs that interact may form organ systems capable of carrying out specific body functions
  4. Organ systems collectively carry out life functions
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10
Q

What is the genome?

A

An organism’s entire set of genes

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11
Q

What is differentiation?

A
  • Differentiation is the process whereby newly formed cells become more specialized and distinct from one another
  • Differentiation involves the expression of some genes and not others in a cell’s genome
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12
Q

How are active genes packed?

A

Active genes are packed in an expanded form called euchromatin

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13
Q

How are inactive genes packed?

A

Inactive genes are packed in a more condensed form called heterochromatin

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14
Q

What are stem cells?

A

Stem cells are those that have the capacity to divide and to differentiate along different pathways

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15
Q

What are the 2 properties of stem cells?

A
  1. Self renewal
    - Stem cells can divide multiple times to produce abundant quantities of new cells
    - Useful for the growth or replacement of tissues
  2. Potency
    - stem cells are not fully differentiated and thus can produce different types of cells
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16
Q

What is stem cell therapy?

A

Stem cells can be used to replace damaged or diseased cells with healthy, functioning ones

17
Q

What is the process of stem cell therapy?

A
  1. The use of biological solutions to trigger the differentiation of stem cells into the desired type
  2. Surgical implantation of cells into the patient’s own tissue
  3. Suppression of host immune system to prevent rejection of cells
  4. Careful monitoring of new cells to ensure they do not become cancerous
18
Q

What are examples of stem cell therapy?

A
  1. Stargardt’s macular dystrophy
    - causes vision loss due to malfunctioning of membrane protein
    - no conclusive results so far
  2. Leukemia
    - production of abnormally large number of white blood cells
    - process: chemotherapy destroys cancer cells in the bone marrow => adult stem cells inserted into bone marrow => differentiate into blood cells
    - has cured leukemia completely many times
19
Q

What are 5 arguments FOR creating embryos for stem cell therapy?

A
  1. Health and quality of life of patients can be improved
  2. Early stage embryos are little more than balls of cells that have yet to develop the essential features of a human life
  3. If embryos lack a nervous system, they do not feel pain or suffer
  4. If embryos are produced deliberately, no individual is denied the chance of life
  5. Left over embryos from IVF go to waste otherwise

Biology U1 (6 decks)

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