Unit 1: Cell Structure and Function - Tour of the Cell

Flashcards testing concepts of cell organization, microscopic resolution, cell theory, domain classification, and organelle functions.

What are the nine levels of organization in the human body listed in order from simplest to most complex?

Atom, Molecule, Macromolecule, Organelle, Cell, Tissue, Organ, Organ System, Organism.

What are the diameter size ranges of prokaryotic and eukaryotic cells?

Prokaryotic cells are $0.1$ to 5.0\,̱m in diameter, whereas eukaryotic cells range from $10$ to 100\,̱m in diameter.

How do total surface area and surface area to volume ratio change when a $4\text{-cm}$ cube is divided into sixty-four $1\text{-cm}$ cubes?

Total surface area increases from $96\,cm^2$ to $384\,cm^2$, and the surface area to volume ratio increases from $1.5:1$ to $6:1$, while total volume remains $64\,cm^3$.

Which three scientists articulated the cell theory in the mid-1800s?

Matthias Schleiden, Theodor Schwann, and Rudolf Virchow.

What are the three core principles of the original Cell Theory, and what key concept was added later?

Original principles: 1. All organisms are composed of one or more cells. 2. The cell is the structural unit of life. 3. Cells arise only by division from a pre-existing cell. Added later: Cells contain genetic information (DNA) passed to the next cell generation.

What magnification and resolution limits characterize conventional light microscopy?

It allows magnification up to 1000 times and can resolve details as small as 0.2\,̱m ($200\,nm$), a limitation imposed by the wavelength of light.

What components and light path are shown in this diagram of conventional light microscopy?

A bright light from a light source is focused onto the specimen on a glass slide by a condenser lens, and light passes through the specimen to objective, tube, and eyepiece lenses to focus an image on the retina.

How do the two sets of filters in a fluorescence microscope operate?

The first filter passes only wavelengths that excite the particular fluorescent dye before light reaches the specimen. The second filter blocks out excitation light and passes only wavelengths emitted when the dye fluoresces.

How does confocal fluorescence microscopy create sharp 3D images of specimens?

It scans the specimen with a laser beam focused on a single point at a specific depth, using a pinhole aperture in the detector to block out-of-focus light and capture optical sections that combine into a 3D image.

How low can the resolution of superresolution fluorescence microscopy reach?

It breaks the conventional $200\,nm$ limit, achieving a resolution as low as $20\,nm$.

What specimen preparation and imaging mechanisms are used in Transmission Electron Microscopy (TEM)?

Specimens are chemically fixed, embedded in plastic, cut into very thin sections, stained with salts of uranium and lead, and placed in a vacuum; magnetic coils focus a beam of electrons through the specimen to achieve up to 1,000,000-fold magnification and details as small as about $1\,nm$.

How does Scanning Electron Microscopy (SEM) construct an image, and what is its resolution range?

A specimen coated with a thin heavy metal film is scanned by a focused electron beam; scattered or emitted electrons measured by a detector form 3D images on a video screen with resolution between $3\,nm$ and $20\,nm$.

In differential cell fractionation, which cell components sediment in the pellets at medium, high, and very high speeds?

Medium speed pellets mitochondria; high speed pellets microsomes and small vesicles; very high speed pellets ribosomes, viruses, and large macromolecules.

What are the three major divisions of the Tree of Life?

Bacteria, Archaea (extremophiles), and Eukarya (protists, fungi, plants, animals).

What four structures are shared by all cells?

Outer cell (plasma) membrane, chromosomes containing DNA, ribosomes for protein production, and cytoskeletal elements.

Where is the chromosome located within a prokaryotic cell?

It exists as a supercoiled chromosome located in a region called the nucleoid.

What distinguishes cytoplasm from cytosol?

Cytoplasm includes all contents found inside a cell excluding the nucleus, whereas cytosol is specifically the liquid or aqueous portion of the cytoplasm.

What is the function of the nucleolus in eukaryotic cells?

It is the site inside the nucleus where components of ribosomes are synthesized and processed.

What organelles make up the endomembrane system?

Nuclear envelope, endoplasmic reticulum, Golgi apparatus, transport vesicles, vacuoles, and lysosomes.

How do free ribosomes differ in function from ribosomes attached to the rough endoplasmic reticulum?

Free ribosomes produce proteins that remain within the cytosol, while attached ribosomes produce proteins intended for secretion, packaging, or insertion into the plasma membrane.

What are the key functions of the smooth endoplasmic reticulum?

Synthesizing lipids and modifying toxic molecules (detoxification).

What is the function of the Golgi apparatus?

It receives products from the endoplasmic reticulum, modifies them as they move through its cisternae, and ships them out in vesicles.

What are lysosomes and what conditions do they require to function?

Organelles unique to animal cells formed from Golgi vesicles containing digestive enzymes; they operate at a low pH to digest materials and recycle worn-out structures and organelles.

What enzyme in peroxisomes detoxifies hydrogen peroxide?

Catalase.

What does the Endosymbiotic Theory explain?

The origin of mitochondria and chloroplasts, proposing that an ancestral cell engulfed a bacterial cell and retained it in a symbiotic relationship rather than digesting it.