Fundamentals of Anatomy & Physiology - Chapter 3: The Cellular Level of Organization

Flashcards covering key concepts from the lecture presentation on cellular organization, including cell structure, organelles, membrane transport, protein synthesis, and cell life cycle.

Cell

The smallest living unit in the human body.

Cell theory

Cells are the building blocks of all organisms; All cells come from the division of preexisting cells; Cells are the smallest units that carry out life’s essential physiological functions; Each cell maintains homeostasis at the cellular level.

Sex cells (germ cells)

Male sperm and female oocyte cells that allow for reproduction.

Somatic cells

All body cells except sex cells.

Plasma membrane (cell membrane)

Forms the outer boundary of the cell and allows for selective transport of substances.

Physical isolation (function of plasma membrane)

Separates the inside of the cell from the surrounding extracellular fluid.

Regulation of exchange with the environment (function of plasma membrane)

Controls the entry of ions and nutrients, the elimination of wastes, and the release of secretions.

Sensitivity to the environment (function of plasma membrane)

Sensitive to changes in the environment and contains receptors that allow the cell to respond to chemical signals.

Structural support (function of plasma membrane)

Anchors cells to each other and to extracellular materials and provides stability to tissues.

Hydrophilic heads (of phospholipids)

Face outward to the watery environments of the extracellular fluid and the intracellular fluid (cytosol).

Hydrophobic tails (of phospholipids)

Form the inside core of the membrane and act as a barrier to ions and water-soluble compounds.

Cholesterol (in plasma membrane)

Makes the plasma membrane less fluid and less permeable.

Integral proteins

Proteins within the membrane.

Transmembrane proteins

Integral proteins that span the entire width of the membrane.

Peripheral proteins

Proteins bound to the inner or outer surface of the membrane.

Anchoring proteins

Attach to inside or outside structures and stabilize membrane position.

Recognition proteins (identifiers)

Label cells as normal or abnormal.

Enzymes (membrane proteins)

Catalyze reactions.

Receptor proteins

Bind and respond to ligands (ions, hormones).

Carrier proteins

Bind and transport specific solutes through the membrane.

Channels (membrane proteins)

Integral proteins with a central pore which permits water and small solutes to flow through.

Gated channels

Open or close to regulate the passage of substances through a channel.

Glycocalyx

Extend beyond the outer surface of the membrane and form sticky “sugar coat”.

Cytoplasm

All materials between the plasma membrane and the membrane of the nucleus.

Cytosol (intracellular fluid)

A colloid which contains water and dissolved nutrients, ions, proteins, and waste products.

Organelles

Internal structures with specific functions within a cell.

Inclusions

Masses of insoluble materials inside cells.

Nonmembranous organelles

Organelles not completely enclosed by a membrane.

Membranous organelles

Organelles isolated from the cytosol by a membrane.

Cytoskeleton

Framework of proteins in the cytoplasm for shape, strength, and flexibility.

Microfilaments

Smallest filaments composed of the protein actin; provide mechanical strength and attach the plasma membrane to the cytoplasm.

Intermediate filaments

Mid-sized insoluble filaments that strengthen the cell and maintain its shape; stabilize position of organelles and cell position with respect to surrounding cells.

Microtubules

Large, hollow tubes of tubulin proteins that strengthen cell and anchor organelles; change cell shape and assist in cell movement.

Microvilli

Small finger-shaped projections of the plasma membrane on the exposed surface of a cell that increase the surface area for absorption.

Centrioles

A pair of cylindrical structures that form spindle apparatus during cell division.

Centrosome

Region of the cytoplasm next to the nucleus that serves as a microtubule-organizing center; location of centrioles.

Cilia

Long, slender extensions of the plasma membrane.

Flagellum

A long, whip-like extension of the plasma membrane that beats in a wavelike motion and allows sperm cells to move.

Ribosomes

Organelles that synthesize proteins; composed of small and large ribosomal subunits.

Proteasomes

Organelles that contain enzymes (proteases) which break down proteins for recycling.

Endoplasmic reticulum (ER)

A network of interconnected intracellular membranes continuous with the nuclear envelope; Site of synthesis, storage, transport and detoxification.

Smooth endoplasmic reticulum (SER)

Endoplasmic reticulum with no attached ribosomes; functions = Synthesis of phospholipids and cholesterol, steroid hormones, glycerides and glycogen

Rough endoplasmic reticulum (RER)

Endoplasmic reticulum with ribosomes attached to the surface; synthesizes proteins and glycoproteins, modifies them, and packages them in transport vesicles for export to the Golgi apparatus.

Golgi apparatus (Golgi complex)

Stacks of flattened membranous discs called cisternae that modify and packages secretions, proteins and renews the plasma membrane. Also packages Lysosomes.

Lysosomes

Vesicles containing enzymes which serve as digestive organelles.

Autolysis

Self-destruction of damaged cells when lysosomes disintegrate and release digestive enzymes which destroy the cell.

Peroxisomes

Small vesicles which contain enzymes that break down organic compounds such as fatty acids

Mitochondria

Organelles that take chemical energy from food and produce energy in the form of ATP.

Cellular respiration

Energy production by aerobic metabolism.

Glycolysis

Breaks down glucose into 2 pyruvates and takes place in the cytosol.

Citric acid cycle

Breaks down pyruvate into carbon dioxide and occurs in the mitochondrial matrix.

Membrane flow (membrane trafficking)

A continuous exchange of membrane segments by vesicles.

Nucleus

Largest organelle which serves as the control center for cellular operations controlling metabolism, information storage, and protein synthesis.

Nuclear envelope

Double membrane around the nucleus connected to the endoplasmic reticulum.

Nuclear pores

Opening in the nuclear envelope which allow for chemical communication.

Nucleoplasm

The fluid portion inside the nucleus.

Nucleosomes

Complexes made of D N A coiled around histones.

Genetic code

Chemical language of DNA instructions of how to build proteins.

Gene

Functional unit of heredity, a D N A sequence that carries the instructions for one protein.

Protein synthesis

The assembling of functional polypeptides in the cytoplasm with involved uncoiling DNA and temporarily removing histones.

Transcription

Synthesis of R N A from a D N A template; all R N A is formed through this process

Messenger R N A (m R N A)

Carries the transcribed information for the sequence of amino acids in a protein.

Introns

Noncoding sequences removed from m R N A during R N A processing.

Exons

Coding segments attached (spliced) together during R N A processing.

Translation

Synthesis of a polypeptide based on the instructions in m R N A.

Transfer R N A (t R N A)

Delivers amino acids during translation; contains anticodons.

Mutations

Permanent changes in a cell’s D N A that affect the nucleotide sequence of one or more genes.

Selectively permeable

The plasma membrane allowing certain substances to pass but not others based on size, electrical charge, molecular shape, lipid solubility.

Passive transport

Transport through the plasma membrane that requires no energy.

Active transport

Transport through the plasma membrane that requires energy.

Diffusion

The net movement of a substance from an area of higher concentration to an area of lower concentration.

Concentration gradient

The difference between the high and low concentrations of a substance.

Simple diffusion

Allows substances to cross the lipid portion of the membrane.

Channel-mediated diffusion

Allows substances to pass through a membrane channel (protein).

Osmosis

Net diffusion of water across a membrane that is permeable to water.

Osmotic pressure

The force with which pure water moves into a solution as a result of its solute concentration.

Osmolarity (osmotic concentration)

The total solute concentration in an aqueous solution.

Tonicity

Describes how the concentration of solutes in a solution affects cells.

Isotonic solution

Solution that has equal concentration of solute as the cell; does not cause osmosis.

Hypotonic solution

Solution that has a lower solute concentration than the cell; causes water to enter the cell by osmosis and the cell may rupture (hemolysis).

Hypertonic solution

Solution that has a higher solute concentration than the cell; causes water to leave the cell by osmosis and the cell shrinks (crenation).

Carrier-mediated transport

Transport across specialized integral membrane proteins; can be passive or active

Symport (cotransport)

Two substances move in the same direction at the same time during the carrier-mediated protein.

Antiport (countertransport)

Two substances move in opposite directions during the carrier-mediated protein.

Facilitated diffusion

Diffusion through specialized carrier proteins; for molecules too large to fit through channel proteins or insoluble in lipid.

Active transport

Uses energy to move substrates against their concentration gradients.

Primary active transport

Pumping solutes against a concentration gradient using A T P.

Secondary active transport

Uses a previously established concentration gradient to move solutes, so does not use A T P directly.

Vesicular transport (bulk transport)

Materials move into or out of a cell in vesicles.

Endocytosis

Imports extracellular materials packaged into vesicles.

Receptor-mediated endocytosis

Vesicles contain a specific target molecule.

Pinocytosis

Endocytosis of extracellular fluid.

Phagocytosis

Endocytosis of solid particles.

Exocytosis

Exports intracellular materials packaged into vesicles which fuse with the plasma membrane.

Transcytosis

Endocytosis on one side of the cell and exocytosis on the opposite side allows substances to pass though the cell.

Membrane potential

Results from unequal distribution of positive and negative charges across the plasma membrane.

Cell division

A form of cellular reproduction where a single cell divides to produce two identical daughter cells.

Apoptosis

A genetically controlled death.

Interphase

The period between two cell divisions in which somatic cells spend most of their lives.

G0 phase

The nondividing state.