Cell Introduction and Plasma Membrane

Comprehensive vocabulary flashcards covering cell structure, plasma membrane dynamics, eukaryotic organelles, and the cytoskeleton based on Chapter 10 lecture notes.

Cell

The basic unit of a living organism, with approximately $50 \times 10^{12}$ to $75 \times 10^{12}$ cells in the human body.

Plasma Membrane

A continuous and sealed "Fluid Mosaic" composed of lipids, cholesterol, proteins, and carbohydrates that separates intracellular compartments from the external environment.

Fluid Mosaic Model

A model where the chemical and physical properties of lipids allow the membrane to be dynamic, influenced by composition like cholesterol and cis-unsaturated fatty acids.

Phosphatidylcholine

A phospholipid found in the plasma membrane consisting of a polar head and a hydrophobic tail.

Cis "on the same side"

A configuration of unsaturated fatty acids, such as cis-Oleic acid, where hydrogen atoms are on the same side of the double bond, contributing to membrane fluidity.

Trans "on the other side"

A configuration of fatty acids, such as trans-Oleic acid, where hydrogen atoms are on opposite sides of the double bond.

Ethanol ($CH_3CH_2OH$)

A molecule that can alter neuronal function in the central nervous system by interacting with membrane lipids and affecting membrane fluidity and protein function.

Spur Cell Anemia

A conditions found in end-stage alcoholic liver disease characterized by excess membrane cholesterol.

Integral proteins

Proteins that span the membrane and serve as channels, transporters, receptors, or structural proteins.

Peripheral proteins

Proteins attached to the membrane through weak electrostatic interactions that function as enzymes, structural proteins, or electron carriers.

Glycocalyx

A "sugar coat" network of polysaccharides projecting from cellular surfaces used for protection, recognition, and cell adhesion.

Oligosaccharide

Carbohydrate chains that attach to proteins in the plasma membrane through N- or O-glycosidic bonds.

Prokaryotic Cells

Cells typically $0.2 - 2.0 \times 10^{-6}\text{m}$ in size, lacking a nucleus and membrane-surrounded organelles, containing a single circular DNA chromosome.

Eukaryotic Cells

Cells typically $10 - 100 \times 10^{-6}\text{m}$ in size that contain a nucleus, organelles (e.g., mitochondria, lysosomes), and many chromosomes.

Central Dogma of Molecular Biology

The pathway of genetic information flow: Replication (DNA) $\rightarrow$ Transcription (RNA) $\rightarrow$ Translation (Protein).

Nucleus

The largest subcellular organelle in animal cells, containing most of the genetic material and serving as the site for DNA replication and transcription.

Nucleolus

The major site within the nucleus for ribosome synthesis and processing.

Nuclear envelope

A double-membrane that separates the nucleus from the cytoplasm, with an outer membrane continuous with the rough ER.

Mitochondria

The site of energy production ($ATP$) containing an outer membrane, an inner membrane (cristae) for the electron-transport chain, and a matrix for the Krebs cycle.

Lysosomes

Organelles of digestion and recycling that eliminate unwanted material using enzymes with highest activity near a pH of $5.5$.

Rough Endoplasmic Reticulum (Rough ER)

A network of membranous tubules involved in the synthesis and post-translational modifications of proteins.

Smooth Endoplasmic Reticulum (Smooth ER)

A network involved in drug metabolism (via Cytochrome P450 enzymes) and the synthesis of hydrophobic molecules like lipids and steroid hormones.

Ribosomes

Organelles whose main function is to perform translation ($mRNA \rightarrow \text{proteins}$).

Golgi Complex

An organelle that modifies proteins from the rough ER via carbohydrate addition, sulfation, or phosphorylation, and sorts them for distribution.

Peroxisomes

Cytoplasmic organelles that use molecular oxygen ($O_2$) for oxidative reactions, such as detoxifying $H_2O_2$ and oxidizing very-long-chain fatty acids.

Cytoskeleton

A system of three major components (microtubules, actin filaments, and intermediate filaments) that maintains cell shape and enables organelle movement.

Microtubules

Dynamic polymers in the cytoskeleton that move/position organelles, transport vesicles, and assist in cell division; inhibited by Colchicine.

Actin filaments

Dynamic polymers also called microfilaments that manage the shape and movement of the cell surface and cell division; inhibited by Cytochalasin.

Intermediate filaments

Stable and slow-moving components of the cytoskeleton that provide structural support and a scaffolding for attachment.