Cell Organization: Nucleus, Cytoplasm, and Organelles

A comprehensive set of Q&A flashcards covering the nucleus, cytoplasm, organelles, and plasma membrane concepts from the notes.

What are the three regions of the nucleus?

Nuclear envelope, nucleolus, and chromatin.

What is the function of the nuclear envelope?

A double membrane barrier with nuclear pores that encloses the nucleoplasm.

What are nuclear pores?

Openings in the nuclear envelope where the two layers fuse to regulate exchange with the cytoplasm.

What is nucleoplasm?

The jellylike fluid inside the nucleus in which nuclear elements are suspended.

What is the nucleolus?

Sites where ribosomes are assembled.

What is chromatin?

DNA wound around histone proteins forming beads-on-a-string; becomes chromosomes during cell division.

What happens to chromatin during cell division?

It coils and condenses to form chromosomes.

What is the cytoplasm?

The cellular material outside the nucleus but inside the plasma membrane; site of most cellular activities.

What are the three major components of the cytoplasm?

Cytosol, inclusions, and organelles.

What is cytosol?

Semitransparent fluid that suspends the other elements; largely water with nutrients and solutes.

What are inclusions?

Chemical substances such as lipid droplets, glycogen granules, pigments, etc., stored in the cytosol.

What is the mitochondrion and its function?

A double-membrane organelle with cristae that produces ATP; the powerhouse of the cell.

What are ribosomes and where are they located?

Tiny particles of protein and rRNA; sites of protein synthesis; free in cytoplasm or attached to rough ER.

What is the rough endoplasmic reticulum?

ER studded with ribosomes; synthesizes membrane and secreted proteins; proteins are moved into transport vesicles.

What is the function of the smooth endoplasmic reticulum?

Lipid metabolism and detoxification; lacks ribosomes and connects with rough ER.

What is the Golgi apparatus role?

Modifies, packages, and ships proteins received from the rough ER; forms secretory vesicles.

What are lysosomes?

Membranous sacs with digestive enzymes; digest worn-out or foreign substances; abundant in phagocytes.

What are peroxisomes?

Membranous sacs with oxidase enzymes that detoxify harmful substances; contain catalase.

What does catalase do in peroxisomes?

Converts hydrogen peroxide into water and oxygen.

What is the cytoskeleton and its function?

An elaborate network of protein filaments that provides an internal framework, shape, and movement.

What are microfilaments and their role?

Actin filaments involved in cell motility and changes in cell shape.

What are intermediate filaments?

Strong, rope-like filaments that provide structural stability.

What are microtubules?

Hollow tubes of tubulin that form tracks for movement and the mitotic spindle.

What are centrioles and where are they located?

Rod-shaped bodies near the nucleus important for organizing spindle during cell division.

What are cilia and when do they form?

Whiplike extensions that move substances along the cell surface; longer projections form flagella (e.g., sperm).

What are microvilli?

Tiny finger-like projections increasing surface area; core is actin; found in absorptive cells.

What is the plasma membrane?

A fragile barrier enclosing the cell, described by the fluid mosaic model.

Describe the phospholipid bilayer.

Two layers with hydrophilic heads facing water and hydrophobic tails inward; cholesterol within; proteins scattered in the membrane.

What is cholesterol's role in the membrane?

Stabilizes and keeps the membrane flexible.

What is glycocalyx?

A sugar-coated cell surface formed by glycoproteins and glycolipids; helps with blood type determination and cell recognition.

What are glycoproteins and their significance?

Proteins with attached sugar groups that act as receptors and cell-adhesion molecules; part of glycocalyx.

What are tight junctions?

Impermeable junctions that encircle cells and form leakproof sheets.

What are desmosomes?

Anchoring junctions that rivet cells together for mechanical strength.

What are gap junctions?

Communicating junctions formed by connexons that allow passage between cells.

What is the nucleus' role in the cell?

Control center that houses DNA, the blueprint for building proteins and for cell reproduction.

What is DNA?

Deoxyribonucleic acid; genetic material containing genes that guide protein synthesis.

What is chromatin vs chromosomes?

Chromatin is loose DNA with histones in non-dividing cells; condenses into chromosomes during division.

What is the cell theory?

Cell is the basic structural/functional unit; organismal activity depends on cells; structure and function are complementary; life arises from cells.

What are the three main regions of all cells?

Plasma membrane, nucleus, and cytoplasm.

What is the fluid mosaic model?

Plasma membrane structure described as a dynamic mosaic of lipids and proteins in a fluid bilayer.

What are transport proteins in the plasma membrane?

Proteins that form channels or act as carriers to move substances across the membrane.