Cell Biology Lecture – Plasma Membrane, Cytoplasm, Nucleus & Specialized Organelles

Vocabulary flashcards covering major structures, components and functions of the plasma membrane, cytoplasm, nucleus, and specialized organelles from the lecture notes.

Plasma Membrane (Cell Membrane)

Outer boundary of the cell; phospholipid bilayer that regulates substance exchange and maintains homeostasis.

Selectively Permeable

Property of allowing some molecules to cross the membrane while restricting others.

Fluid Mosaic Model

Concept describing the membrane as a flexible, moving lipid sea with floating proteins and carbohydrates.

Phospholipid Bilayer

Dual layer of phospholipids with hydrophilic heads outward and hydrophobic tails inward, forming the membrane’s core.

Integral Protein

Membrane protein that spans the bilayer and functions in transport or signaling.

Peripheral Protein

Protein loosely attached to membrane surface; often involved in cell signaling.

Cholesterol (Membrane)

Steroid lipid inserted in animal membranes to stabilize and adjust fluidity.

Glycoprotein

Protein with carbohydrate chains; important for cell recognition and communication.

Glycolipid

Lipid with attached carbohydrate; aids in cell-cell interactions and recognition.

Endocytosis

Process of engulfing external material into the cell via vesicle formation.

Exocytosis

Vesicular process that releases materials from the cell to the exterior.

Cytoplasm

Entire cell interior excluding nucleus; comprises cytosol, organelles and cytoskeleton.

Cytosol

Semi-fluid portion of cytoplasm composed of water, ions, proteins and solutes.

Organelle

Membrane-bound or specialized cellular structure performing a specific function.

Cytoskeleton

Dynamic network of protein filaments providing support, shape and intracellular transport.

Microfilament (Actin Filament)

Thinnest cytoskeletal fiber composed of actin; enables muscle contraction, cell movement and cytokinesis.

Intermediate Filament

Rope-like cytoskeletal fiber providing tensile strength and anchoring organelles.

Microtubule

Hollow tubulin cylinder forming tracks for transport, spindle fibers and cilia/flagella cores.

Dynein

Motor protein that moves cargo toward the cell center along microtubules.

Kinesin

Motor protein that transports cargo toward the cell periphery along microtubules.

Cytoplasmic Streaming

Movement of cytoplasm that distributes materials within the cell.

Cytokinesis

Division of the cytoplasm; actin contractile ring separates daughter cells after mitosis.

Diapedesis

Actin-mediated process allowing white blood cells to squeeze through capillary walls.

Phagocytosis

Actin-driven engulfment of particles or pathogens by a cell forming a phagosome.

Nucleus

Membrane-bound organelle housing DNA and controlling gene expression and cell activities.

Nuclear Envelope

Double membrane surrounding the nucleus, continuous with rough ER.

Nuclear Pore

Protein-lined channel in nuclear envelope permitting selective nucleus–cytoplasm exchange.

Nucleoplasm

Gel-like fluid inside the nucleus containing chromatin and nucleotides.

Chromatin

DNA-protein complex that condenses into chromosomes during cell division.

Nucleolus

Dense nuclear region where rRNA synthesis and ribosome assembly occur.

Lysosome

Membrane-bound vesicle containing hydrolytic enzymes for intracellular digestion.

Autophagy

Lysosomal recycling of damaged organelles or proteins to maintain cellular health.

Autolysis

Self-destruction of a cell via lysosomal enzyme release when severely damaged.

Peroxisome

Enzyme-filled organelle that breaks down fatty acids and detoxifies hydrogen peroxide.

Catalase

Peroxisomal enzyme that converts hydrogen peroxide into water and oxygen.

Alpha Oxidation

Peroxisomal pathway degrading branched-chain fatty acids.

Beta Oxidation

Stepwise removal of two-carbon units from very long-chain fatty acids in peroxisomes.

Plasmalogen

Ether phospholipid synthesized in peroxisomes; abundant in myelin of brain white matter.

Mitochondrion

Double-membrane organelle generating ATP; contains its own maternal DNA.

Cristae

Inner mitochondrial membrane folds that increase surface area for ATP production.

Oxidative Phosphorylation

Mitochondrial process where electron transport chain drives ATP synthesis.

Krebs Cycle (Citric Acid Cycle)

Mitochondrial matrix pathway oxidizing acetyl-CoA to CO₂ and reducing cofactors.

Heme Synthesis

Mitochondrial and cytosolic pathway producing heme for hemoglobin and cytochromes.

Urea Cycle

Mitochondrial-cytosolic sequence converting toxic ammonia into excretable urea.

Gluconeogenesis

Formation of glucose from non-carbohydrate substrates, partly occurring in mitochondria.

Ketogenesis

Mitochondrial conversion of acetyl-CoA into ketone bodies during fasting.

Ribosome

rRNA-protein complex that translates mRNA into polypeptides.

Free Ribosome

Cytosolic ribosome synthesizing proteins that remain in the cytoplasm.

Membrane-Bound Ribosome

Ribosome attached to rough ER that produces proteins for secretion, membranes or lysosomes.

Cilia

Short, microtubule-based projections that beat rhythmically to move fluid or particles.

Flagella

Long, whip-like structure driven by microtubules and dynein for cell motility (e.g., sperm).

Plasma Membrane (Cell Membrane)

Outer boundary of the cell; phospholipid bilayer that regulates substance exchange and maintains homeostasis.

Selectively Permeable

Property of allowing some molecules to cross the membrane while restricting others.

Fluid Mosaic Model

Concept describing the membrane as a flexible, moving lipid sea with floating proteins and carbohydrates.

Phospholipid Bilayer

Dual layer of phospholipids with hydrophilic heads outward and hydrophobic tails inward, forming the membrane’s core.

Integral Protein

Membrane protein that spans the bilayer and functions in transport or signaling.

Peripheral Protein

Protein loosely attached to membrane surface; often involved in cell signaling.

Cholesterol (Membrane)

Steroid lipid inserted in animal membranes to stabilize and adjust fluidity.

Glycoprotein

Protein with carbohydrate chains; important for cell recognition and communication.

Glycolipid

Lipid with attached carbohydrate; aids in cell-cell interactions and recognition.

Endocytosis

Process of engulfing external material into the cell via vesicle formation.

Exocytosis

Vesicular process that releases materials from the cell to the exterior.

Cytoplasm

Entire cell interior excluding nucleus; comprises cytosol, organelles and cytoskeleton.

Cytosol

Semi-fluid portion of cytoplasm composed of water, ions, proteins and solutes.

Organelle

Membrane-bound or specialized cellular structure performing a specific function.

Cytoskeleton

Dynamic network of protein filaments providing support, shape and intracellular transport.

Microfilament (Actin Filament)

Thinnest cytoskeletal fiber composed of actin; enables muscle contraction, cell movement and cytokinesis.

Intermediate Filament

Rope-like cytoskeletal fiber providing tensile strength and anchoring organelles.

Microtubule

Hollow tubulin cylinder forming tracks for transport, spindle fibers and cilia/flagella cores.

Dynein

Motor protein that moves cargo toward the cell center along microtubules.

Kinesin

Motor protein that transports cargo toward the cell periphery along microtubules.

Cytoplasmic Streaming

Movement of cytoplasm that distributes materials within the cell.

Cytokinesis

Division of the cytoplasm; actin contractile ring separates daughter cells after mitosis.

Diapedesis

Actin-mediated process allowing white blood cells to squeeze through capillary walls.

Phagocytosis

Actin-driven engulfment of particles or pathogens by a cell forming a phagosome.

Nucleus

Membrane-bound organelle housing DNA and controlling gene expression and cell activities.

Nuclear Envelope

Double membrane surrounding the nucleus, continuous with rough ER.

Nuclear Pore

Protein-lined channel in nuclear envelope permitting selective nucleus–cytoplasm exchange.

Nucleoplasm

Gel-like fluid inside the nucleus containing chromatin and nucleotides.

Chromatin

DNA-protein complex that condenses into chromosomes during cell division.

Nucleolus

Dense nuclear region where rRNA synthesis and ribosome assembly occur.

Lysosome

Membrane-bound vesicle containing hydrolytic enzymes for intracellular digestion.

Autophagy

Lysosomal recycling of damaged organelles or proteins to maintain cellular health.

Autolysis

Self-destruction of a cell via lysosomal enzyme release when severely damaged.

Peroxisome

Enzyme-filled organelle that breaks down fatty acids and detoxifies hydrogen peroxide.

Catalase

Peroxisomal enzyme that converts hydrogen peroxide into water and oxygen.

Alpha Oxidation

Peroxisomal pathway degrading branched-chain fatty acids.

Beta Oxidation

Stepwise removal of two-carbon units from very long-chain fatty acids in peroxisomes.

Plasmalogen

Ether phospholipid synthesized in peroxisomes; abundant in myelin of brain white matter.

Mitochondrion

Double-membrane organelle generating ATP; contains its own maternal DNA.

Cristae

Inner mitochondrial membrane folds that increase surface area for ATP production.

Oxidative Phosphorylation

Mitochondrial process where electron transport chain drives ATP synthesis.

Krebs Cycle (Citric Acid Cycle)

Mitochondrial matrix pathway oxidizing acetyl-CoA to CO₂ and reducing cofactors.

Heme Synthesis

Mitochondrial and cytosolic pathway producing heme for hemoglobin and cytochromes.

Urea Cycle

Mitochondrial-cytosolic sequence converting toxic ammonia into excretable urea.

Gluconeogenesis

Formation of glucose from non-carbohydrate substrates, partly occurring in mitochondria.

Ketogenesis

Mitochondrial conversion of acetyl-CoA into ketone bodies during fasting.

Ribosome

rRNA-protein complex that translates mRNA into polypeptides.

Free Ribosome

Cytosolic ribosome synthesizing proteins that remain in the cytoplasm.

Membrane-Bound Ribosome

Ribosome attached to rough ER that produces proteins for secretion, membranes or lysosomes.