Human Anatomy, Chapter 2: Foundations The Cell
The cell theory concepts
1) Cells are the building blocks of all plants and animals. 2) Cells are produced by the division of preexisting cells. 3) Cells are the smallest units that preform all vital functions.
Concentration gradient
A difference in the concentration of a substance across a distance.
Phospholipid bilayer
A double layer of phospholipids that makes up plasma and organelle membranes.
Nuclear envelope
A double membrane that surrounds the nucleus in the cell
Cytoplasm
A jellylike fluid inside the cell in which the organelles are suspended
Flagellum
A long, hairlike structure that grows out of a cell and enables the cell to move.
Cytoskeleton
A network of fibers that holds the cell together, helps the cell to keep its shape, and aids in movement
Rough ER
A network of interconnected membranous sacs in a eukaryotic cell's cytoplasm; covered with ribosomes that make membrane proteins and secretory proteins.
Gated channels
A protein channel in a cell membrane that opens or closes in response to a particular stimulus.
Golgi Apparatus
A system of membranes that modifies and packages proteins for export by the cell
Organelles
A tiny cell structure that carries out a specific function within the cell
Phagocytosis
A type of endocytosis in which a cell engulfs large particles or whole cells
Pinocytosis
A type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes.
Endoplasmic Reticulum (ER)
An extensive membranous network in eukaryotic cells, continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome-free (smooth) regions.
Lysosomes
An organelle containing digestive enzymes
Desmosomes
Anchoring junctions that prevent cells from being pulled apart
Centrioles
Cell organelle that aids in cell division in animal cells only
Peroxisomes
Contain oxidase enzymes that detoxify alcohol, hydrogen peroxide, and other harmful chemicals
Nucleus
Control center of the cell. Contains DNA.
Osmosis
Diffusion of water through a selectively permeable membrane
Cytokinesis
Division of the cytoplasm during cell division
Active transport
Energy-requiring process that moves material across a cell membrane against a concentration difference
Plasma membrane (Plasmalemma)
Envelops the entire cells and provides a selective barrier that regulates transport of substances into and out of the cell and contains receptors which bind with various substances that can regulate cell activity
Microvilli
Fingerlike extensions of plasma membrane of apical epithelial cells, increase surface area, aid in absorbtion, exist on every moist epithelia, but most dense in small intestine and kidney
Cytosol
Fluid portion of cytoplasm
Cilia
Hairlike projections that extend from the plasma membrane and are used for locomotion
Microfilaments
Long, thin fibers that function in the movement and support of the cell
Tight Junctions
Membranes of neighboring cells are pressed together, preventing leakage of extracellular fluid
Diffusion
Movement of molecules from an area of higher concentration to an area of lower concentration.
Mitochondria
Powerhouse of the cell
Cell Division
Process by which a cell divides into two new daughter cells
Exocytosis
Process by which a cell releases large amounts of material
Microtubules
Spiral strands of protein molecules that form a tubelike structure that make of cilia
Smooth ER
That portion of the endoplasmic reticulum that is free of ribosomes. Makes lipids
Receptor mediated endocytosis
The movement of specific molecules into a cell by the inward budding of membranous vesicles containing proteins with receptor sites specific to the molecules being taken in; enables a cell to acquire bulk quantities of specific substances.
Peripheral proteins
The proteins of a membrane that are not embedded in the lipid bilayer; they are appendages loosely bound to the surface of the membrane.
Intermediate filaments
Threadlike proteins in the cell's cytoskeleton that are roughly twice as thick as microfilaments
Carrier proteins
a protein that transports substances across a cell membrane
Somatic cells
all cells in the body, not including sex cells.
Hemidesmosomes
attach epithelial cells to the basement membrane
Fixed Ribosomes
attached to the endoplasmic reticulum
Exchange pumps
carrier proteins that move one solute in one direction and another solute in the opposite direction
Cell Junctions
contact points between the plasma membranes of tissue cells
Non-membraneous organelles
cytoskeleton, centrioles, ribosomes
Ion pumps
enzymes that use the energy released by the breakdown of ATP to transport certain ions across the membrane
Prophase
first and longest phase of mitosis, during which the chromosomes become visible and the centrioles separate and take up positions on the opposite sides of the nucleus
Extracellular fluid
fluid outside the cell
Sex cells
germ cells or reproductive cells
Nuclear pores
holes in the nuclear envelope that allow materials to pass in and out of the nucleus
Membraneous organelles
mitochondria, nucleus, endoplasmic reticulum, golgi apparatus, lysosomes, peroxisomes
Thick filaments
myosin
Basal body
organelle that develops from a centriole
Mitosis
part of eukaryotic cell division during which the cell nucleus divides
Integral proteins
penetrate the hydrophobic interior of the lipid bilayer (embedded in the membrane)
Interphase
period of the cell cycle between cell divisions
Endocytosis
process by which a cell takes material into the cell by infolding of the cell membrane
Apoptosis
programmed cell death
Selectively permeable
property of biological membranes that allows some substances to pass across it while others cannot; also called semipermeable membrane
Ribosomes
protein synthesis
Cell Adhesion Molecules (CAMs)
proteins found on the surface of most cells that aid in the binding of the cell to the extracellular matrix or other cells; integral membrane proteins; three major families: cadherins, integrins, selectins
Gap Junctions
provide cytoplasmic channels between adjacent animal cells
Mitotic rate
rate of cell division
Channels
regulate water flow and solutes through membrane
Metaphase
second phase of mitosis, during which the chromosomes line up across the center of the cell
Secretory vesicles
secrete substances outside the cell by exocytosis
Free Ribosomes
suspended in the cytosol
Membrane flow
the continuous movement and exchange of membrane segments
Telophase
the final phase of cell division, between anaphase and interphase, in which the chromatids or chromosomes move to opposite ends of the cell and two nuclei are formed.
Anaphase
the third phase of mitosis, during which the chromosome pairs separate and move toward opposite poles
Facilitated diffusion
the transport of substances through a cell membrane along a concentration gradient with the aid of carrier proteins through protein channels
Intercellular Attachments
there are three different types of cell junctions, by which cells attach to each other or to extracellular protein fibers
Chromosomes
threadlike structures made of DNA molecules that contain the genes
Spot Desmosomes
tie cells together allow bending and twisting
Stem cells
unspecialized cells that are able to renew themselves for long periods of time by cell division