52 Questions
What is the function of the endomembrane system in eukaryotic cells?
Regulates protein traffic and performs metabolic functions
Where are the genetic instructions of eukaryotic cells housed?
Nucleus
What is the main function of the cytoskeleton in a cell?
Organizes structures and activities in the cell
How do mitochondria and chloroplasts contribute to eukaryotic cells?
Change energy from one form to another
What is the function of the plasma membrane in a cell?
It controls what enters and exits the cell
What is the role of chloroplasts in a cell?
Convert light energy to chemical energy
Where is genetic information stored in a cell?
In the DNA in the nucleus
What is the function of mitochondria in a cell?
Break down molecules and generate ATP
What is the theoretical resolution of modern electron microscopes?
About 0.002 nm
What are the three important parameters in microscopy?
Magnification, resolution, and contrast
What is the role of ribosomes in a cell?
Sites of protein synthesis
What prevented cell biologists from using standard light microscopy when studying organelles?
The resolution barrier
What is the function of the cell wall in plant cells?
Provide protection
What is the primary function of the scanning electron microscope (SEM)?
Detailed study of the topography of a specimen
What is the size range of cells in terms of diameter?
Between 1 and 100 µm
What is the measure of the clarity of an image in microscopy?
Resolution
Which microscopy technique uses optical modifications to exaggerate differences in density, creating an almost 3-D image?
Differential interference contrast microscopy
Which microscopy technique digitally removes out-of-focus light, creating a sharper 3-D image?
Deconvolution microscopy
Which microscopy technique uses UV light to record individual fluorescent molecules' positions, breaking the resolution limit?
Super-resolution microscopy
Which microscopy technique reveals specific molecule locations by labeling them with fluorescent dyes or antibodies?
Fluorescence microscopy
Which microscopy technique amplifies variations in density in unstained cells, useful for examining living cells?
Phase-contrast microscopy
Which microscopy technique aims an electron beam through a thin section of the specimen, revealing internal cell structure?
Transmission electron microscopy
Which microscopy technique provides 3-D images of specimen surfaces by detecting secondary electrons?
Scanning electron microscopy
Which microscopy technique offers high resolution but kills cells and can introduce structural artifacts?
Electron microscopy
Which microscopy technique rapidly freezes specimens at low temperatures, allowing visualization of molecules in a rigid state?
Cryo-electron microscopy
Which microscopy technique uses stains to enhance contrast in images, but most stains require cells to be preserved, killing them?
Not mentioned
Which type of microscopy has revitalized the study of living cells with advances like fluorescent markers and techniques like confocal and deconvolution microscopy?
Light microscopy
Which microscopy technique preserves specimens at extremely low temperatures, allowing for detailed visualization?
Cryo-electron microscopy
What technique visualizes cellular structures without the use of preservatives, complementing X-ray crystallography?
Cryo-EM
What was the Nobel Prize for Chemistry in 2017 awarded for?
Developers of Cryo-EM
What is a major difference between prokaryotic and eukaryotic cells?
Location of DNA
What technique is used to study cell structure and function by separating cell components based on size and density?
Cell fractionation
What do prokaryotic cells lack compared to eukaryotic cells?
True nucleus and membrane-enclosed organelles
What do cell fractionation and intact cell studies complement?
Preparation and identification of specific cell components and their functions
What is a technique that can reveal protein complexes, subcellular structures like ribosomes, and even individual proteins?
Cryo-EM
What is the study of cell structure that integrates cytology and biochemistry?
Cytology
What do eukaryotic cells have that compartmentalize their functions?
Internal membranes
What is a technique that helps correlate cell function with structure, such as identifying mitochondria as sites of cellular respiration?
Biochemical tests and electron microscopy
What are essential features shared by prokaryotic and eukaryotic cells?
Plasma membrane, cytosol, chromosomes, and ribosomes
What is a technique that involves homogenizing cells and centrifuging the homogenate at increasing speeds?
Cell fractionation
What is the relationship between the surface area and volume of a cell as it increases in size?
The surface area grows proportionately less than its volume
What is the typical diameter range of eukaryotic cells?
10-100 µm
What is a key difference in the composition of the plasma membrane in cells?
Consists of a double layer of phospholipids with various proteins attached or embedded
What is the function of the plasma membrane in a cell?
Functions as a selective barrier for the exchange of substances
What is the size range of the smallest bacteria, mycoplasmas?
0.1-1.0 µm
What is the interior of both eukaryotic and prokaryotic cells called?
Cytoplasm
What is the role of the organelles within the cytosol of eukaryotic cells?
Specialized functions within the cell
What is the need for a surface area large enough to accommodate the volume of a cell?
To facilitate material exchange between the cell and its environment
What type of cells may have many long, thin projections from their surface to increase the surface area?
Cells with high material exchange, like intestinal cells
What does a Scientific Skills Exercise allow calculation of for actual cells?
Volumes and surface areas
What do larger organisms have more of, rather than larger cells compared to smaller organisms?
More cells
What is the geometric relationship between surface area and volume critical for?
Facilitating material exchange between a cell and its environment
Study Notes
Cell Structure and Function: Key Techniques and Eukaryotic Cells
- Cryo-EM is a technique that visualizes cellular structures without the use of preservatives, complementing X-ray crystallography.
- Cryo-EM can reveal protein complexes, subcellular structures like ribosomes, and even individual proteins.
- The Nobel Prize for Chemistry in 2017 was awarded to the developers of Cryo-EM.
- Microscopes are essential tools in cytology, the study of cell structure, integrating cytology and biochemistry.
- Cell fractionation is a technique used to study cell structure and function, separating cell components based on size and density.
- Cell fractionation involves homogenizing cells, centrifuging the homogenate at increasing speeds, resulting in a series of pellets containing different cell components.
- Biochemical tests and electron microscopy help correlate cell function with structure, such as identifying mitochondria as sites of cellular respiration.
- Cell fractionation enables the preparation and identification of specific cell components and their functions, complementing intact cell studies.
- Prokaryotic and eukaryotic cells share basic features, including the plasma membrane, cytosol, chromosomes, and ribosomes.
- A major difference between prokaryotic and eukaryotic cells is the location of their DNA, with eukaryotic DNA mostly in the nucleus.
- Prokaryotic cells lack a true nucleus and other membrane-enclosed organelles, appearing simpler in internal structure.
- Eukaryotic cells, found in protists, fungi, animals, and plants, have internal membranes that compartmentalize their functions.
Cell Structure and Function
- Eukaryotic cells have a true nucleus, while prokaryotic cells lack a true nucleus, reflecting their earlier evolution.
- The interior of both cell types is called the cytoplasm, but eukaryotic cells have specialized organelles within the cytosol, absent in most prokaryotic cells.
- Eukaryotic cells are generally larger than prokaryotic cells, with typical diameters of 10-100 µm, while mycoplasmas, the smallest bacteria, have diameters between 0.1 and 1.0 µm.
- The plasma membrane of a cell functions as a selective barrier, with the surface area to volume ratio being critical for the exchange of substances.
- As a cell increases in size, its surface area grows proportionately less than its volume, emphasizing the importance of the surface area to volume ratio.
- Larger organisms do not have larger cells than smaller organisms, but they have more cells, as illustrated in Figure 6.7.
- The plasma membrane consists of a double layer of phospholipids with various proteins attached or embedded, and carbohydrate side chains may be attached to proteins or lipids on the outer surface.
- The geometric relationships between surface area and volume are critical for facilitating material exchange between a cell and its environment.
- The need for a surface area large enough to accommodate the volume helps explain the microscopic size of most cells and the elongated shapes of some cells, such as nerve cells.
- Cells with high material exchange, like intestinal cells, may have many long, thin projections from their surface to increase the surface area.
- A Scientific Skills Exercise allows calculation of volumes and surface areas of actual cells, providing insight into the maximization of surface area in various organisms.
- The exercise also explores the synthesis of new cytoplasm and plasma membrane by a growing yeast cell, using a scale bar to determine sizes.
Explore the key techniques in studying cell structure and function, from cryo-electron microscopy to cell fractionation. Learn about the differences between prokaryotic and eukaryotic cells, including their internal structures and specialized organelles. Understand the critical role of surface area to volume ratio in material exchange and cell size.
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