Prokaryotes, Eukaryotes & Eukaryotic Cell Organisation

31 question-and-answer flashcards covering distinctions between prokaryotic and eukaryotic cells, organelle structure and function, cytoskeleton, plasma membrane, mitochondria, and mitochondrial DNA.

What key structural feature distinguishes prokaryotic cells from eukaryotic cells?

Prokaryotic cells lack a nucleus surrounded by a complex nuclear membrane.

Where is the genetic material located in prokaryotic cells?

In a nucleoid that contains a single circular chromosome.

Give two domains that consist of prokaryotic organisms.

Bacteria and Archaea.

How are the chromosomes of eukaryotic cells arranged?

They are multiple, linear chromosomes enclosed within a membrane-bound nucleus.

Name four groups of organisms that are eukaryotic.

Protozoa, Fungi, Plants and Animals.

Compare the approximate size ranges of prokaryotic vs eukaryotic cells.

Prokaryotes: 0.5–5 µm; Eukaryotes: 5–100 µm.

Do prokaryotic cells possess membrane-bound organelles?

No; they lack specific membrane-bound organelles.

What is the primary function of ribosomes?

Protein synthesis.

Where can ribosomes be found inside a eukaryotic cell?

Free in the cytoplasm or bound to the rough endoplasmic reticulum (ER).

What key steps occur inside the nucleus?

DNA transcription to mRNA, ribosome assembly in the nucleolus, and regulation of nuclear import/export through nuclear pores.

Which organelle performs protein processing and quality control?

The rough endoplasmic reticulum (RER).

List two major functions of the smooth endoplasmic reticulum (SER).

(1) Synthesis of lipids, steroid hormones and carbohydrates; (2) Detoxification of drugs/poisons and storage of calcium ions.

What is the main role of the Golgi apparatus?

Modifying, sorting, labelling and packaging proteins into vesicles for transport.

Which organelle contains proteases, nucleases, carbohydrases and lipases for macromolecule degradation?

The lysosome.

Name the three major types of cytoskeletal filaments.

Microfilaments (actin), intermediate filaments and microtubules.

What cellular functions are supported by the cytoskeleton?

Maintaining cell shape, positioning organelles, vesicle transport and cell motility.

Identify three molecular motor proteins and the filaments they move along.

Myosin (actin filaments), kinesin (microtubules) and dynein (microtubules).

Approximately how thick is the plasma membrane?

About 5 nm.

What property of the plasma membrane allows lipids and many membrane proteins to move within the bilayer?

Lateral diffusion (membrane fluidity).

How is selective exchange across the plasma membrane achieved?

Through pumps and carrier proteins embedded in the membrane.

What is the primary energy molecule produced by mitochondria?

ATP.

Besides energy production, give two other roles of mitochondria.

Cell signalling and regulation of apoptosis (programmed cell death).

Describe the four structural regions of a mitochondrion.

Outer membrane, intermembrane space, inner membrane with cristae, and the matrix.

What is the role of cristae in mitochondria?

They increase the inner membrane surface area for oxidative phosphorylation enzymes.

Where is mitochondrial DNA located and what does it encode?

In the matrix; it encodes 13 polypeptides for oxidative phosphorylation plus tRNAs and rRNAs.

How is mitochondrial DNA inherited?

Maternally.

How many genes are found in human mitochondrial DNA?

37 genes.

Where are most mitochondrial proteins encoded?

By nuclear DNA; they are synthesised in the cytoplasm and imported into mitochondria.

Which organelles work together to route a newly synthesised secretory protein to the plasma membrane?

Rough ER, transport vesicles, Golgi apparatus, and additional vesicles to the plasma membrane.

What is the function of nuclear pores?

They control the import and export of materials between the nucleus and cytoplasm.

Which cellular structure acts as the cell’s “post office” for protein labelling and shipping?

The Golgi apparatus.