CYTOGENETICS LESSON 3: THE CELL AND CELL CYCLE

Flashcards covering key concepts from the cell and cell cycle lecture notes, including cell types, organelles, and cytoskeletal components.

What is the basic functional unit of living organisms, and can an organism be unicellular or multicellular?

The cell; yes, organisms can be unicellular or multicellular.

Approximately how many variations of cells exist?

About 260.

Name examples of cell types based on tissues.

Osteocytes, chondrocytes, nerve cells, epithelial cells, muscle cells, secretory cells, adipose cells, blood cells.

Name examples of cell types based on function.

Conductive cells, connective cells, glandular cells, storage cells.

What is the difference between somatic and gametic cells?

Somatic cells are body cells; gametic cells are sex cells.

What does differentiation mean in cells?

The process by which cells acquire specialized structure and function.

What is the plasma membrane and its main functions?

The cell boundary (plasmalemma) that regulates exchange with the environment, attaches to adjacent cells and extracellular matrix, and enables communication.

What is the structure of the phospholipid bilayer?

Polar, hydrophilic head and nonpolar, hydrophobic tail; phospholipids are amphipathic.

How can membrane fluidity be increased?

Fluidity is increased by the presence of unsaturated fatty acids that prevent tight packing.

What role does cholesterol play in the plasma membrane?

Cholesterol is an amphipathic molecule with a kinked conformation that prevents overly dense packing of phospholipid tails.

What is the glycocalyx and its functions?

A coating of glycoproteins and glycolipids on the cell surface that mediates cell recognition, adhesion, adsorption of molecules, provides protection, and helps define biochemical identity.

What is the cell wall and how does it differ among organisms?

A rigid layer of polysaccharides; bacteria have peptidoglycan; fungi have chitin.

What is the nucleus and what does it contain?

The largest organelle; the control center containing DNA, proteins, and RNA (including mRNA, tRNA, rRNA).

What are heterochromatin and euchromatin?

Heterochromatin is dense, inactive chromatin; euchromatin is lighter and active in RNA synthesis; together they are chromatin.

What is the nucleolus?

Sites of ribosomal RNA synthesis and ribosome assembly; ribosomal subunits are assembled in the nucleus and exported to the cytoplasm.

What is the cytoplasm’s cytosolic component and its role?

Cytosol; it’s the fluid medium in which cytoplasmic organelles suspend and metabolic reactions occur.

What is the cytoskeleton and its main roles?

A network that provides structural support, organizes organelles, facilitates material transfer, and enables cell movement.

What are microfilaments and their characteristics?

Actin filaments (~7 nm) forming a double helix; form linear bundles or networks and serve as tracks for myosin in movement.

What are intermediate filaments and give an example?

Filaments 8–10 nm in diameter made of various proteins; keratin is a common example, found in hair, nails, and skin.

What are microtubules and their key features?

Largest cytoskeletal fibers (~25 nm) made of tubulin (α- and β-tubulin) in hollow tubes; dynamic with growth/shrinkage and polarity.

What is the centrosome and centriole?

The centrosome is the microtubule-organizing center near the nucleus; it contains a pair of centrioles (nine triplets of microtubules); plants lack centrioles but have MTOCs.

What are flagella and cilia?

Flagella are long, whip-like structures that move the cell; cilia are shorter, usually numerous; motile cilia beat, primary cilia are non-motile.

What is the endoplasmic reticulum and its two forms?

An extensive network of flattened membrane-bound tubules and sacs; Rough ER bears ribosomes and synthesizes proteins and phospholipids; Smooth ER synthesizes lipids, detoxifies, and stores calcium.

What is the rough endoplasmic reticulum’s primary function?

Ribosomes on the rough ER synthesize polypeptides and feed them into the ER lumen; it also contributes to membrane phospholipid synthesis.

What is the smooth endoplasmic reticulum’s primary role?

Produces lipids (phospholipids, cholesterol, steroids, glycolipids) and detoxifies substances; stores calcium ions.

What are mitochondria and why are they called the powerhouse of the cell?

Organelles where cellular respiration occurs to produce ATP; they have two membranes with inner membrane infoldings called cristae.

What are chloroplasts and their function?

Organelles in plants and some algae where photosynthesis occurs; convert light energy to chemical energy and release oxygen.

What are ribosomes and what do they do?

Ribosomal RNA and proteins forming two subunit complexes; align mRNA and translate it into a polypeptide chain.