Chapter 4 Evolutionary Origin of Cells and Their General Features – Video Notes (Practice Flashcards)

A comprehensive set of Q&A flashcards covering cell theory, prokaryotic/eukaryotic differences, cell structures, organelles (including ER, Golgi, lysosomes, vacuoles, chloroplasts, mitochondria), the cytoskeleton, motor proteins, cilia/flagella, endomembrane system, protein sorting, and endosymbiosis as presented in the lecture notes.

What are the two major categories of life and a defining feature of each?

Prokaryotes: simple cell structure, no nucleus. Eukaryotes: more complex cells with a membrane‑bound nucleus and internal membranes that form organelles.

What are the four basic attributes shared by all cells?

Plasma membrane, cytoplasm, genetic material, and ribosomes.

As a cell grows, what happens to the surface area‑to‑volume ratio and why is this important?

SA:V decreases; a high SA:V is needed for adequate nutrient uptake and waste export.

According to the original cell theory, what are its three core ideas?

All organisms are made of one or more cells; the cell is the fundamental unit of life; all cells come from preexisting cells.

What are the modern additions to cell theory listed in the notes?

All cells have the same basic chemical composition; all cells use energy; all cells contain DNA that is duplicated and passed on as cells divide.

Where is DNA located in prokaryotic cells?

In the nucleoid region.

What are the two main categories of prokaryotes and a note about their prevalence?

Bacteria (very abundant in environment and our bodies) and Archaea (less common; often in extreme environments).

What internal components are typically found inside the bacterial plasma membrane?

Cytoplasm, nucleoid region, and ribosomes.

What is glycocalyx and what function does the capsule provide?

Glycocalyx traps water, provides protection, and helps evading the immune system (capsule).

What prokaryotic appendages are present and what are their roles?

Pili (attachment) and flagella (movement).

What are the main components of the nucleus as listed in the notes?

Nuclear envelope, nuclear pore, chromatin, nucleolus.

Which plant cell organelle is responsible for photosynthesis?

Chloroplasts.

What distinguishes Rough ER from Smooth ER?

Rough ER has bound ribosomes and synthesizes secretory proteins; Smooth ER lacks ribosomes and synthesizes lipids, metabolizes carbohydrates, detoxifies poisons, and stores calcium.

What are the main functions of the Rough Endoplasmic Reticulum?

Secretes glycoproteins, distributes transport vesicles, and acts as a membrane factory.

What are the main functions of the Smooth Endoplasmic Reticulum?

Synthesis of lipids; carbohydrate metabolism; detoxification; calcium storage.

What is the Golgi apparatus responsible for, and what are its two sides called?

Modifies, sorts, and ships proteins; cis side near the nucleus and trans side near the plasma membrane.

What are lysosomes and what is notable about their environment?

Digestive enzymes (acid hydrolases) that function best at acidic pH (~5); proton pumps maintain the low pH.

What is the central vacuole and its role in plants?

A large storage organelle that helps maintain turgor pressure in plant cells.

Name a plant-specific feature of plant cells related to walls and connections.

Cell walls surround plant cells; plasmodesmata connect adjacent plant cells; plastids are plant organelles.

What organelles are semiautonomous and why are they considered semiautonomous?

Mitochondria and chloroplasts; they grow and divide but depend on the cell for some internal components.

What is the primary role of mitochondria?

Make ATP (energy production) and participate in other metabolic processes.

What is endosymbiosis, and which organisms were the ancestors of mitochondria and chloroplasts?

Endosymbiosis: a smaller species lives inside a larger one; mitochondria derived from purple bacteria (α‑proteobacteria) and chloroplasts from cyanobacteria.

What is protein sorting in eukaryotic cells and what signals direct targeting?

Proteins are sorted to their destinations using sorting signals—short amino acid sequences that direct targeting.

What is cotranslational sorting and which destinations use it?

Sorting for ER, Golgi, lysosomes, vacuoles, plasma membrane, and secretion; ER signal sequence binds SRP and targets the ribosome‑ER channel.

What is post‑translational sorting and which destinations use it?

Sorting for nucleus, mitochondria, chloroplasts, and peroxisomes; proteins made in the cytosol are targeted to these organelles.

What is SRP and what is its role in cotranslational sorting?

Signal recognition particle; binds the ER signal sequence and directs ribosomes to the ER channel.

What are the key components of the nucleus listed in the notes?

Nuclear envelope, nuclear pore, chromatin, nucleolus.

What are the main functions of the cytoskeleton?

Structural support, aids in cell division, organelle transport, and cell movement.

What are microtubules composed of and what are their ends called?

Proteins (α- and β-tubulin); plus end and minus end; exhibit dynamic instability.

What is the MTOC and how does it differ in animal vs. plant cells?

MT organizing center; animals have a centrosome containing centrioles; plants lack centrosomes and centrioles.

What are intermediate filaments and provide examples?

Tension‑bearing fibers that help maintain cell shape; examples include keratins and nuclear lamins.

What are actin filaments (microfilaments) and their role?

Dynamic filaments with plus and minus ends; support the plasma membrane and contribute to cell shape and strength.

What is a motor protein and how does it move cargo?

Motor proteins move along cytoskeletal filaments; the head binds to the filament, the tail binds to cargo, and ATP hydrolysis drives movement.

Which motor protein drives the sliding of microtubules in cilia and flagella to cause bending?

Dynein.

What are cilia and flagella made of and what causes their bending?

Microtubules; dynein motors cause adjacent microtubules to slide, bending the structure.

What are vesicles and which processes involve them?

Membranous sacs that transport molecules; involved in exocytosis and endocytosis.

What are the major components of the endomembrane system?

Nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, plasma membrane, vesicles.

What is the primary function of the plasma membrane?

Boundary between cell and environment; handles selective transport, cell signaling via receptors, and cell adhesion.

What is the role of the plasma membrane in cell signaling and adhesion?

Receptors receive extracellular signals; adhesion proteins help cells stick together; transport proteins move substances across the membrane.

What is the difference between cytosol and cytoplasm?

Cytosol is the fluid inside the cell; cytoplasm includes cytosol plus organelles.

What is the role of ribosomes and where can they be found?

Synthesize proteins; can be free in cytoplasm or bound to rough ER.

What is the nucleolus responsible for?

Ribosome synthesis.

What organelle contains ribosomes and is involved in protein synthesis for membranes and secretion?

Rough endoplasmic reticulum.