Chapter 4: Cell Structure and Function - Practice Flashcards

Comprehensive practice flashcards covering Chapter 4: Cell Structure and Function from Biology (14th Edition) by Sylvia S. Mader and Michael Windelspecht.

What three scientists contributed to the formulation of the Cell Theory, and what were their specific contributions?

Matthias Schleiden (1838) determined that all plants are composed of cells, Theodor Schwann (1839) determined that all animals are composed of cells, and Rudolph Virchow (1855) established that cells come only from preexisting cells because cells are self-reproducing.

What are the three core tenets of the Cell Theory?

1. All organisms are composed of cells.
2. Cells are the basic units of structure and function in organisms.
3. Cells come only from preexisting cells because cells are self-reproducing.

What is the typical size range of biological cells?

Cells range in size from $1\,\text{millimeter}\ (\text{mm})$ down to $1\,\text{micrometer}\ (\mu\text{m})$ in diameter.

Why is a high surface-area-to-volume ratio advantageous for cells?

A higher surface-area-to-volume ratio allows smaller cells to adequately and efficiently exchange materials across the plasma membrane compared to larger cells.

According to the surface-area-to-volume relationship model, how do total surface area and surface-area-to-volume ratio change when one $4\text{-cm}$ cube is divided into sixty-four $1\text{-cm}$ cubes?

While total volume remains unchanged at $64\,\text{cm}^3$, total surface area increases from $96\,\text{cm}^2$ to $384\,\text{cm}^2$, increasing the surface-area-to-volume ratio from $1.5:1$ to $6:1$.

What is the maximum magnification and resolving power of a compound light microscope?

It has a maximum magnification of about $1000\times$ and resolves objects separated by $0.2\,\mu\text{m}$, which is $500\times$ better than the human eye.

How does a Transmission Electron Microscope (TEM) compare to a compound light microscope in resolving power?

A TEM resolves objects separated by $0.0002\,\mu\text{m}$, which is $500,000\times$ better than the human eye.

How does a Scanning Electron Microscope (SEM) form three-dimensional images of specimens?

The specimen is coated with a thin layer of metal, and an electron beam scans across its surface. Emitted secondary electrons are detected and focused by magnetic lenses to construct a 3D image on a screen.

What are the definitions of magnification, resolution, and contrast in microscopy?

Magnification is the ratio between image size and actual object size; resolution is the minimum distance between two objects allowing them to be distinguished as separate; contrast is the difference in shading of an object compared to its background.

How does confocal microscopy create three-dimensional images of a cell?

A narrow laser beam scans across a transparent specimen focused on a single thin plane at a time, performing optical sectioning at different depths that a computer compiles into a rotatable 3D electronic image.

What are the two taxonomic domains of prokaryotes, and how do they differ?

Bacteria and Archaea. Bacteria act as decomposers, cause diseases, and aid in manufacturing products/drugs; Archaea live in extreme habitats. Both are structurally similar but biochemically distinct.

What three basic shapes do prokaryotic cells exhibit?

Spherical coccus, rod-shaped bacillus, and spiral spirillum (if rigid) or spirochete (if flexible).

What structural layers make up the cell envelope of a bacterium shown in this diagram?

The plasma membrane (a lipid bilayer regulating substance passage that can form internal pouches called mesosomes), the cell wall (strengthened by peptidoglycan to support shape), and the glycocalyx (a polysaccharide outer layer that forms a capsule when well-organized).

What are plasmids in prokaryotic cells?

Plasmids are small, extrachromosomal accessory rings of DNA found in the bacterial cytoplasm.

What are the specific functions of bacterial flagella, fimbriae, and conjugation pili?

Flagella provide cell motility; fimbriae are small, bristlelike fibers used for surface adhesion; conjugation pili are rigid, tubular structures used to transfer DNA between bacterial cells.

What four evolutionary stages describe the origin of eukaryotic organelles according to the endosymbiotic theory model?

1. Invagination of the plasma membrane forms a double-membraned nucleus.
2. Membrane proliferation generates the endomembrane system.
3. Engulfment of an aerobic bacterium gives rise to mitochondria.
4. Engulfment of a photosynthetic bacterium gives rise to chloroplasts.

What are the two major classes of eukaryotic organelles?

1. The Endomembrane System (organelles that communicate via membrane channels or transport vesicles).
2. Energy-Related Organelles (mitochondria and chloroplasts, which are independent and self-sufficient).

How do liver cells and nerve cells demonstrate structural adaptation through organelle abundance?

Liver cells contain abundant smooth endoplasmic reticulum to detoxify drugs, while nerve cells have extensive plasma membrane surface area to transmit electrical impulses.

What structural components make up the eukaryotic nucleus, and what are their functions?

The nuclear envelope (a double membrane with nuclear pores for exchange), nucleoplasm containing chromatin (diffuse DNA and proteins that condense into chromosomes during cell division), and the dark nucleolus (site of ribosomal subunit production).

What sequence of events targets a ribosome synthesizing a polypeptide to the endoplasmic reticulum?

1. Ribosome translates mRNA to produce a signal peptide.
2. Signal recognition particle (SRP) binds the signal peptide, halting translation.
3. SRP binds an ER receptor channel, opens the pore, and releases the ribosome.
4. Translation resumes and polypeptide is fed into the ER lumen.
5. An enzyme cleaves the signal peptide.

What are the primary functional differences between rough ER and smooth ER?

Rough ER is studded with ribosomes and synthesizes, modifies, and processes proteins (including glycoproteins); Smooth ER lacks ribosomes and synthesizes lipids, detoxifies drugs in the liver, and stores molecules.

What is the structural organization and function of the Golgi apparatus?

It consists of flattened saccules (sac-like structures) with a cis (inner) face that receives transport vesicles from the ER and a trans (outer) face that packages modified proteins and lipids into vesicles for intracellular destination or secretion.

What are lysosomes, and what is their role in cellular digestive processes?

Lysosomes are acidic, membrane-bound vesicles produced by the Golgi apparatus containing hydrolytic enzymes that break down large molecules, recycle cellular parts, and digest pathogens engulfed by white blood cells.

How do organelles work together within the endomembrane system during protein synthesis and secretion?

Rough ER synthesizes proteins and packages them into transport vesicles that travel to the Golgi apparatus cis face. The Golgi modifies, sorts, and packages proteins into secretory vesicles at its trans face, which fuse with the plasma membrane for exocytosis.

What metabolic reaction takes place in peroxisomes, and how is the toxic product neutralized?

Peroxisomal enzymes catalyze reactions that generate hydrogen peroxide ($H_2O_2$), which is immediately converted into water ($H_2O$) and oxygen ($O_2$) by the enzyme catalase.

What genetic condition is caused by a defect in a peroxisomal membrane protein?

Adrenoleukodystrophy (ALD), which leads to neurological damage due to impaired lipid metabolism.

What functions does the central vacuole perform in plant cells?

Taking up to $90\%$ of cell volume, it stores water, nutrients, pigments, and wastes, maintains turgor pressure, stores toxic defensive compounds against herbivores, and breaks down aged organelles.

How do chloroplasts and mitochondria complement each other in cellular energy transformations?

Chloroplasts capture solar energy to convert $\text{CO}_2$ and $\text{H}_2\text{O}$ into energy-rich carbohydrates and $\text{O}_2$. Mitochondria break down these carbohydrates using $\text{O}_2$ to produce ATP during cellular respiration, releasing $\text{CO}_2$ and $\text{H}_2\text{O}$.

What are the structural features of a chloroplast, and where are its components located?

It features a double membrane enclosing a fluid stroma and stacks of disc-like thylakoids called grana. Chlorophyll pigment is embedded in thylakoid membranes, while carbohydrate-synthesizing enzymes reside in the stroma.

What internal structures make up a mitochondrion?

A mitochondrion has a double membrane whose inner membrane is convoluted into folds called cristae, surrounding an inner semifluid matrix containing carbohydrate-cleaving respiratory enzymes, mitochondrial DNA, and ribosomes.

What three types of protein fibers form the eukaryotic cytoskeleton?

Actin filaments, intermediate filaments, and microtubules.

What is the structure of actin filaments, and how do they interact with motor proteins?

Actin filaments are thin, flexible fibers composed of actin subunits resembling a twisted pearl necklace. They interact with the motor protein myosin using ATP hydrolysis to drive muscle contraction, cytoplasmic streaming, and pseudopod movement.

What functions do intermediate filaments perform in animal cells?

They form a ropelike assembly of fibrous polypeptides that support the nuclear envelope, form cell-cell junctions, and contain keratin to provide mechanical strength to skin cells.

How are microtubules constructed, and what organizing structure controls their assembly?

Microtubules are hollow cylinders made of $13$ tubular spirals of $\alpha$ and $\beta$ tubulin dimers. Their assembly is controlled by the microtubule-organizing center (MTOC), primarily the centrosome.

Which motor proteins move along microtubules to transport membrane-bound vesicles?

Kinesin and dynein.

What is the microtubule arrangement in animal cell centrioles?

Centrioles are short cylinders composed of $27$ microtubules arranged into $9$ overlapping triplets ($9 \times 3$ pattern) surrounding an empty center.

What is the microtubule structure of eukaryotic cilia and flagella, and how do they produce movement?

They contain a $9 + 2$ pattern consisting of an outer ring of $9$ microtubule doublets surrounding $2$ central single microtubules. Dynein side arms reach to adjacent doublets using ATP, causing the shaft to bend.

How does the basal body of a eukaryotic flagellum differ structurally from its shaft?

The basal body contains $9$ microtubule triplets with no central microtubules ($9 \times 3$ pattern), whereas the shaft contains $9$ microtubule doublets anchored to a central pair ($9 + 2$ pattern).