Cell Biology: Prokaryotic & Eukaryotic Cells and Their Organelles

A comprehensive set of Q&A flashcards covering fundamental differences between prokaryotic and eukaryotic cells, their organelles, and key cellular processes.

What are the three basic structural components found in every cell?

Plasma membrane, cytoplasm, and genetic material (DNA/RNA).

Which cellular characteristic allows growth and tissue repair?

Reproduction (cell division).

Which cell type lacks a true nucleus?

Prokaryotic cells.

Give two structural differences between prokaryotic and eukaryotic DNA organization.

Prokaryotes possess a single circular chromosome in the cytoplasm (nucleoid) with no introns, whereas eukaryotes have multiple linear chromosomes inside a membrane-bound nucleus that contain introns and exons.

Name two energy-related processes that occur in mitochondria.

The Krebs (citric-acid) cycle and the electron-transport (respiratory) chain that produces ATP.

Which major metabolic process takes place inside chloroplasts?

Photosynthesis—conversion of solar energy into chemical energy (glucose).

What is the primary role of ribosomes?

Protein synthesis by translating mRNA into amino-acid sequences.

How does smooth endoplasmic reticulum contribute to cell function?

It synthesizes lipids (oils, phospholipids, steroids), detoxifies compounds, and forms transport vesicles.

State one similarity and one difference between plant and animal vacuoles.

Similarity: both store substances and aid in turgor/osmoregulation. Difference: plant cells usually have a single large central vacuole, while animal cells contain several small ones.

Which organelle is nicknamed “the cell’s packaging and shipping center”?

The Golgi apparatus.

Describe two functions of lysosomes.

Digest ingested particles (phagocytosis) and recycle worn-out organelles (autophagy); they can also trigger autolysis of the entire cell.

What cellular structure provides selective permeability for substance transport?

The plasma (cell) membrane.

Name the photosynthetic membrane sacs inside chloroplasts.

Thylakoids.

Which prokaryotic surface appendages facilitate attachment to surfaces and DNA transfer?

Pili (or fimbriae).

List three envelope layers that may surround a prokaryotic cell from outside inwards.

Capsule, cell wall (peptidoglycan), plasma membrane.

Which organelle contains catalase to break down hydrogen peroxide?

Peroxisome.

What term describes the programmed cell death in which mitochondria play a key role?

Apoptosis.

Which cytoskeletal network supports cell shape and organelle movement in both plant and animal cells?

The cytoskeleton (microtubules, microfilaments, intermediate filaments).

How do prokaryotes perform aerobic respiration without mitochondria?

Respiratory enzymes are embedded in the plasma membrane.

Define ‘nucleolus’.

A non-membranous structure inside the nucleus that assembles ribosomal subunits and contains rRNA and proteins.

What are introns?

Non-coding sections of eukaryotic DNA within genes that are removed from pre-mRNA during processing.

Name the two arms of a chromosome and specify which is shorter.

Short arm (p) and long arm (q); the p arm is shorter.

What is the telomere’s role?

Protects chromosome ends from degradation and fusion, contributing to genomic stability.

Which cell type is typically 1–10 µm in size and considered primitive?

Prokaryotic cells.

Which reproduction methods are used by eukaryotic cells for somatic and gamete formation?

Mitosis for somatic cells and meiosis for gametes.

What process enables cells to engulf large particles or microbes for digestion?

Phagocytosis.

Give one example of a plastid other than chloroplasts and state its function.

Amyloplast—stores starch in plant cells.

Why do muscle and liver cells contain numerous mitochondria?

They have high energy demands and require large amounts of ATP.

What is the primary function of the Golgi apparatus’s cisternae?

Modify, sort, and package proteins, lipids, and carbohydrates for delivery to specific destinations.

Which prokaryotic locomotor structure propels the cell through liquid?

Flagellum (whip-like appendage).

What cellular process replaces or removes defective proteins using proteolytic enzymes inside lysosomes?

Autophagy (self-eating).

Explain the significance of the central dogma referenced for ribosomes.

It describes information flow: DNA → RNA → Protein, wherein ribosomes translate mRNA into proteins.

Which plant-specific structure provides rigidity and protection outside the plasma membrane?

Cell wall composed mainly of cellulose.

Name two main categories of photosynthetic prokaryotes based on oxygen requirements.

Obligate anaerobes and microaerophiles; some are facultative or aerobic as well.

What are the specialized channels in the nuclear envelope that regulate molecular traffic?

Nuclear pores.

Which organelle forms hydrogen peroxide as a by-product while breaking down fatty acids?

Peroxisome (detoxifies the H₂O₂ using catalase).

Define ‘endocytosis’ and ‘exocytosis’.

Endocytosis: uptake of materials into the cell via vesicle formation; Exocytosis: export of materials when vesicles fuse with the plasma membrane.

Which plant organelle stores pigments giving flowers and fruits their color?

Chromoplast.

Identify the internal membrane system that is studded with ribosomes and continuous with the nuclear envelope.

Rough endoplasmic reticulum (RER).

What is the function of centrioles in animal cells?

Organize spindle fibers during cell division and form basal bodies of cilia/flagella.

How does the cell membrane maintain homeostasis?

By regulating active and passive transport of ions and molecules (selective permeability).

Which structures allow material exchange between separate compartments in eukaryotic cells?

Vesicles (formed by ER, Golgi, or plasma membrane).

State one reason why the Golgi apparatus is essential for immune defense.

It produces lysosomes containing hydrolytic enzymes that digest invading microbes.

What DNA location term arises from chromosome banding patterns and helps identify gene positions?

Chromosome bands (used in cytogenetic mapping).

How are peroxisomes different from lysosomes in their main enzymatic content?

Peroxisomes contain oxidative enzymes (e.g., catalase) for detox; lysosomes contain hydrolytic enzymes for digestion.

Which membrane system synthesizes most cellular phospholipids?

Smooth endoplasmic reticulum (SER).

Describe the nucleoid region in prokaryotes.

An area where the single circular chromosome is located, not bounded by a membrane.

What is binary fission?

Asexual reproduction in prokaryotes where the cell divides into two genetically identical daughter cells.

Why is compartmentalization advantageous to eukaryotic cells?

It increases efficiency by isolating incompatible reactions and concentrating enzymes and substrates.

Name two cell types or conditions classified by oxygen use in prokaryotes.

Obligate anaerobes (strictly no O₂) and facultative anaerobes (can use O₂ or not).

Which eukaryotic organelle builds lipid-derived hormones like steroid hormones?

Smooth ER (SER).

What is the kinetochore’s role on a chromosome?

It is the protein complex where spindle fibers attach during mitosis and meiosis for chromosome segregation.