Human Physiology - Chapter 03: Cell Structure and Genetic Control

Flashcards covering cell components, membrane transport, organelle function, genetic expression, and cell division based on the Chapter 3 Human Physiology lecture notes.

Plasma (cell) membrane

A selectively permeable membrane composed of a double layer of phospholipids with embedded proteins that gives form to the cell and controls the passage of materials.

Cytoplasm

The fluid, jellylike substance (cytosol) located between the plasma membrane and the nucleus in which organelles are suspended and chemical reactions occur.

Nucleus

The largest organelle, enclosed by a double-layered nuclear envelope, which contains DNA and directs all cellular activities.

Smooth Endoplasmic Reticulum

A system of interconnected membrane-forming canals and tubules that metabolizes nonpolar compounds and stores $Ca^{2+}$ in striated muscle cells.

Rough Endoplasmic Reticulum

A part of the endoplasmic reticulum with ribosomes embedded on its outer surface that assists in protein synthesis for secretion or delivery to the Golgi complex.

Ribosomes

Granular particles composed of protein and RNA that synthesize proteins and may act as enzymes called ribozymes.

Golgi complex

A cluster of flattened membranous sacs (cisternae) that synthesizes carbohydrates and packages molecules for secretion or delivery to lysosomes.

Mitochondria

Membranous sacs with folded inner partitions called cristae that release energy from food molecules and transform it into usable ATP.

Lysosomes

Membranous sacs filled with more than 60 types of digestive enzymes that digest foreign molecules and worn or damaged organelles.

Peroxisomes

Spherical membranous vesicles containing enzymes (oxidases) that detoxify harmful molecules and catalase to break down hydrogen peroxide.

Centrosome

A nonmembranous mass of two rodlike centrioles located near the nucleus that helps organize spindle fibers during mitosis.

Microfilaments and Microtubules

Thin, hollow tubes that support the cytoplasm, organize the intracellular environment, and transport materials within the cell.

Cilia

Minute cytoplasmic projections that move particles along the cell surface (motile types with "9+2" structure) or sense fluid movement (primary type with "9+0" structure).

Flagellum

A single whip-like structure composed of microtubules in a "9+2" arrangement that propels a cell; the sperm is the only example in the human body.

Microvilli

Folds in the plasma membrane that increase the surface area for chemical reactions and rapid diffusion.

Fluid Mosaic Model

The theory that proteins and phospholipids are not trapped in a fixed position but constantly move laterally within the plasma membrane.

Integral proteins

Membrane proteins that span the entire thickness of the plasma membrane.

Peripheral proteins

Membrane proteins that are embedded on just one side of the plasma membrane.

Glycocalyx

A system of glycoproteins, glycolipids, and polysaccharides attached to the outer plasma membrane that serves as protection and cell markers.

Phagocytosis

A bulk transport process (cell eating) where pseudopods engulf large extracellular substances to form a food vacuole.

Endocytosis

A process where the plasma membrane furrows inward to bring large materials into the cell as a vesicle; includes pinocytosis and receptor-mediated forms.

Exocytosis

The process by which large cellular products are moved out of the cell as vesicles fuse with the plasma membrane.

Autophagy

The lysosomal process of digesting viruses, worn-out organelles, and toxic proteins within a vacuole called an autophagosome.

Apoptosis

Programmed cell death involving the release of lysosomal contents or the activation of enzymes called caspases.

Genome

The complete set of all the genes in a particular individual or species.

Proteome

The full set of all the proteins that are produced from the genome.

Chromatin

The combination of DNA and positively charged proteins called histones that form nucleosomes within the nucleus.

Euchromatin

The active, extended form of chromatin where genes are available for genetic transcription.

Heterochromatin

Inactive regions of chromatin that are highly condensed.

Genetic Transcription

The process where DNA-directed RNA synthesis occurs using the enzyme RNA polymerase.

Genetic Translation

The process of protein synthesis where mRNA is used at the ribosome to assemble a specific amino acid sequence.

Introns

Portions of a gene that do not code for proteins and are spliced out of the precursor messenger RNA.

Exons

The coding portions of a gene that are kept and joined together to form the final messenger RNA.

Alternative Splicing

The process of cutting and splicing precursor mRNA in different ways to allow one gene to code for multiple proteins.

Codon

A sequence of three bases in mRNA that specifies a particular amino acid.

Anticodon

A sequence of three nucleotides on transfer RNA (tRNA) that is complementary to a specific codon on mRNA.

Ubiquitin

A molecule that tags short-lived or damaged proteins to mark them for degradation by a proteasome.

Semiconservative replication

The method of DNA replication where each new DNA molecule consists of one original parental strand and one new daughter strand.

Mitosis

The division of the cell nucleus consisting of four stages: prophase, metaphase, anaphase, and telophase.

Cytokinesis

The division of the cytoplasm into two separate daughter cells.

Necrosis

Pathological cell death caused by deprivation of blood supply leading to tissue death.

Hyperplasia

Growth due to an increase in the number of cells.

Hypertrophy

Growth due to an increase in the size of individual cells.

Meiosis

A two-step cell division process that occurs in the gonads to produce gametes with half the number of chromosomes.

Crossing-over

The swapping of genetic material between homologous chromosomes during Prophase I of meiosis, resulting in genetic recombination.

Epigenetic Inheritance

The transmission of silenced genes to daughter cells via modifications like acetylation or methylation without changing the DNA base sequence.