Cell Theory (mix)

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Questions and Answers

List the seven basic functions integral to the survival of living things.

Metabolism, Reproduction, Sensitivity, Homeostasis, Excretion, Nutrition, Growth/Movement.

What are the three core principles of the cell theory?

  1. The cell is the smallest unit of life. 2. All living things are composed of cells (or their cellular products). 3. Cells only arise from pre-existing cells.

What four basic features do all cells share?

They are enclosed by a membrane, contain cytosol, possess genetic material, and have ribosomes.

According to cell theory, spontaneous generation of life is currently possible on Earth.

<p>False (B)</p>
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Striated muscle fibres are considered typical eukaryotic cells.

<p>False (B)</p>
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Why are aseptate fungal hyphae considered atypical eukaryotic cells?

<p>They lack internal partitions (septa) between cells, resulting in a continuous cytoplasm with multiple nuclei.</p>
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What feature makes mature red blood cells atypical eukaryotic cells?

<p>They lack a nucleus and most other organelles, including the capacity to replicate.</p>
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What does the internal fluid of a cell, where biological processes occur, consist of?

<p>Cytosol</p>
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Which cellular components function to translate specific genetic instructions?

<p>Ribosomes</p>
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Most cells are measured in _____, while subcellular components may be measured in _____.

<p>micrometres (µm), nanometres (nm)</p>
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Which type of microscopy typically views dead specimens in monochrome and uses electromagnets?

<p>Electron Microscopy (C)</p>
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What type of image does a transmission electron microscope (TEM) generate?

<p>A cross-section image</p>
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What type of image does a scanning electron microscope (SEM) render?

<p>A 3D surface map</p>
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What technique uses antibodies conjugated to fluorescent probes to target specific cellular components for visualization under a light microscope?

<p>Immunofluorescence</p>
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What microscopy technique involves freezing biological specimens to determine molecular structures at near atomic resolution without crystallization?

<p>Cryogenic electron microscopy (Cryo-EM)</p>
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Using the mnemonic MIA, the formula for magnification is: Magnification = _____ _____ ÷ Actual size

<p>Image size</p>
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Using the mnemonic AIM, the formula for actual size is: Actual size = _____ _____ ÷ Magnification

<p>Image size</p>
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Match the unit prefix with its corresponding power of 10.

<p>centi- = $10^{-2}$ milli- = $10^{-3}$ micro- = $10^{-6}$ nano- = $10^{-9}$</p>
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Flashcards

Metabolism

Undertaking essential chemical reactions.

Reproduction

Producing offspring, either sexually or asexually.

Sensitivity

Being responsive to internal and external stimuli.

Homeostasis

Maintaining a stable internal environment.

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Excretion

Possessing the capacity to remove waste products.

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Nutrition

Exchanging materials/gases with the environment.

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Cell Theory

Cells are the smallest unit of life, all living things are composed of cells and cells arise from pre-existing cells.

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Cell Membrane

Separates internal contents from the external environment.

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Cytosol

Internal fluid where biological processes occur.

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Genetic Material

Functions as a set of instructions for cellular activity.

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Ribosomes

Translate specific genetic instructions within the cell.

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Multinucleated cells

Contain multiple nuclei due to cell fusion.

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Aseptate fungal hyphae

Lack internal partitions, having a continuous cytoplasm.

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Sieve tube elements

Connected by plasmodesmata forming supracellular assemblies.

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Red Blood Cells

Lack a nucleus and cannot replicate, produced by bone marrow.

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Microscope

Instrument to visualize something too small to view to the naked eye.

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Light Microscopy

Views living specimens in natural colour but has lower resolution.

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Electron Microscopy

Views dead specimens in monochrome with high resolution.

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Micrometer

Metric unit for cell measurement (10⁻⁶ metres)

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Nanometer

Metric unit for subcellular components (10⁻⁹ metres)

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Study Notes

  • Cell theory describes the structural organization of all living things.

Functions of Life

  • Metabolism: Living things undertake essential chemical reactions
  • Reproduction: Living things produce offspring, either sexually or asexually
  • Sensitivity: Living things respond to internal and external stimuli.
  • Homeostasis: Living things maintain a stable internal environment.
  • Excretion: Living things remove waste products.
  • Nutrition: Living things exchange materials and gases with the environment
  • Growth / Movement: Living things can move, and change shape or size

Cell Theory Principles

  • The cell is the smallest unit of life; unicellular organisms carry out all seven life functions
  • All living things consist of cells or their cellular products like hair and nails
  • Cells arise only from pre-existing cells, disproving spontaneous generation

Cell Features

  • Cells have a surrounding membrane that separates internal contents from the external environment
  • Cells contain cytosol, an internal fluid where biological processes occur
  • Cells contain genetic material, which is a blueprint for cellular activity
  • Cells contain ribosomes which translate the specific genetic instructions within the cell.

Atypical Cells

  • Striated muscle fibres are multinucleated because they form from fused individual muscle cells
  • Aseptate fungal hyphae lack internal partitions and have continuous cytoplasm
  • Sieve tube elements connect via plasmodesmata, supracellular assemblies along plant stems
  • Red blood cells lack a nucleus and cannot replicate, new cells are produced by bone marrow

Cell Size

  • Cells and their components are measured in micrometres (10⁻⁶ meters) or nanometres (10⁻⁹ meters)
  • Metric system prefixes for measurement from largest to smallest unit are: metre (m), centimetre (cm), millimetre (mm), micrometre (µm), and nanometre (nm)

Microscopes

  • Microscopes are used to view cells as most cells are too small to view with the naked eye.

Light Microscopy

  • Light microscopy views living specimens in natural colour, using lenses to bend light
  • Light microscopy has lower resolution and magnification (~100x)

Electron Microscopy

  • Electron microscopy views dead specimens in monochrome using electromagnets
  • Electron microscopy has higher resolution and magnification
    • Transmission electron microscopes generate a cross-section
    • Scanning electron microscopes render a 3D surface map

Microscope Developments

  • Immunofluorescence: Uses antibodies conjugated to fluorescent probes to target cell components
    • The fluorescent probe can be conjugated directly or indirectly via a secondary antibody, visualized under a light microscope with filters
  • Cryogenic electron microscopy: Freezing biological specimens for electron microscope visualization
    • Allows molecular structure determination at near-atomic resolution by freeze fracturing

Magnification Calculations

  • Magnification (MIA): Magnification = Image size ÷ Actual size
  • Actual Size (AIM): Actual size = Image size ÷ Magnification
  • All sizes must be in the same units for calculations

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