Chapter 3 - Principals of Biology

Cells

The smallest unit of life that displays all the properties of life; composed of cytoplasm surrounded by a plasma membrane.

Cell Theory

One of the major theories of biology, which states that all organisms are made up of cells; cells are capable of self-reproduction and come only from preexisting cells.

Surface-area-to-volume-ratio

Ratio of a cell's outside area to its internal volume; the relationship limits the maximum size of a cell.

Prokaryotic Cells

Cell that generally lacks a membrane-bound nucleus and organelles; the cell type within the domains Bacteria and Archaea.

Structures that are found in Archea

Cell wall is usually present, but no peptidoglycan, plasma membrane, ribosomes

Structures that are found in bacteria

Cell wall present usually with peptidoglycan, plasma membrane, ribosomes

Structures that are found in eularyotes

Cell wall sometimes present but not peptidoglycan, plasma membrane, nucleus, membrane-bound organelles, and ribosomes that are larger than prokaryotic ribosomes

plasma membrane

Membrane surrounding the cytoplasm that consists of a phospholipid bilayer with embedded proteins; functions to regulate the entrance and exit of molecules to and from the cell.

cell wall

Cellular structure that surrounds a plant, protistan, fungal, or bacterial cell and maintains the cell's shape and rigidity; composed of polysaccharides.

glycocalyx

Polysaccharide coating located on the exterior of the cell wall in some bacteria.

Capsule

A form of glycocalyx that consists of a gelatinous layer; found in blue-green algae and certain bacteria.

Cytoplasm

Region of a cell between the nucleus, or the nucleoid region of a bacterium, and the plasma membrane; contains the organelles of the cell.

nucleoid

Region of the cytoplasm in prokaryotic cells where DNA is located; it is not bound by a nuclear envelope.

Plasmids

Extrachromosomal ring of accessory DNA in the cytoplasm of prokaryotes.

Flagella

Long, slender extensions used for locomotion by some bacteria, protozoans, and sperm.

Fimbria

Small, bristlelike fiber on the surface of a bacterial cell that attaches bacteria to a surface; also fingerlike extension from the oviduct near the ovary.

Eukaryotic Cells

Type of cell that has a membrane-bound nucleus and membranous organelles; found in organisms within the domain Eukarya.

Organelle

Small, membranous structure in the cytoplasm having a specific structure and function.

Cell wall

Composition: Contains polysaccharides

Function: Support and protection

Plasma membrane

Composition: phospholipid bilayer

Function: defines cell boundary; regulates passage into and out of the cells

Nucleus

Composition: Nuclear envelope, nucleoplasm, chromatin, and nucleoli

Function: Storage of genetic information; synthesis of DNA and RNA

Nucleoli

Composition: Concentrated area of chromatin, RNA, and proteins

Function: RIbosomal subunit formation

Ribosomes

Composition: Protein and RNA in two subunits

Function: Protein Synthesis

Rough Endoplasmic Reticulum

Composition: Network of folded membranes studded with ribosomes

function: Folding, motification, and transport of proteins for export or associated with membranes

Smooth Endoplasmic Reticulum

Composition: Network of folded membranes having no ribosomes

Function: Lipid and carbohydrate synthesis in some cells; detoxification of chemicals

Golgi Apparatus

Composition: Stack of small membranous sacs

Function: Processing, packaging, and distribution of proteins and lipids

Lysosomes

Composition: Membranous vesicle containing digestive enzyme

Function: Intracellular digestion, recycling of cellular components

Vacuoles and Vesicles

Composition: membranous sacs of various sizes

function: Storage of substances

Peroxisomes

Composition: Membranous vesicle containing specific enzymes

Function: Breakdown of fatty acids and other metabolic tasks

Mitochondria

Composition: inner membrane (cristae) bound by an outer membrane

Function: Cellular Respiration

Chloroplasts

Composition: membranous grana bound by two membranes

Function: Photosynthesis

Cytoskeleton

Composition: microtubules, intermediate filaments, actin filaments

Function: Shape of cell and movement of its parts

Cilia and Flagella

Composition: Microtubules

Function: movement of cell

Centriole

Composition: Microtubules

Function: Cell division

Chromaitn

Network of DNA strands and associated proteins observed within a nucleus of a cell.

Chromosomes

The structure that transmits the genetic material from one generation to the next; composed of condensed chromatin; each species has a particular number of chromosomes that is passed on to the next generation.

Nucleoplasm

Semifluid medium of the nucleus, containing chromatin.

Nucleolus

Dark-staining, spherical body in the nucleus that produces ribosomal subunits.

Nuclear Envelope

Double membrane that surrounds the nucleus in eukaryotic cells and is connected to the endoplasmic reticulum; has pores that allow substances to pass between the nucleus and the cytoplasm.

Nuclear pore

Opening in the nuclear envelope that permits the passage of proteins into the nucleus and ribosomal subunits out of the nucleus.

Ribosomes

Site of protein synthesis in a cell; composed of proteins and ribosomal RNA (rRNA).

Polyribosomes

String of ribosomes simultaneously translating regions of the same mRNA strand during protein synthesis.

Vesicles

Small, membrane-bound sac that stores substances within a cell.

Cellular Respiration

A series of metabolic reactions that use the energy from carbohydrate, fatty acid, or amino acid breakdown to produce ATP molecules.

Photosynthesis

Process, usually occurring within chloroplasts, that uses solar energy to reduce carbon dioxide to carbohydrate.

Equation of photosynthesis

Solar energy + carbon dioxide + water --> Carbohydrate + oxygen

Equation of cellular respiration

Carbohydrate + oxygen --> Carbon dioxide + water + energy

stroma

Region within a chloroplast that surrounds the grana; contains enzymes involved in the synthesis of carbohydrates during the Calvin cycle of photosynthesis.

Thylakoids

Flattened sac within a granum of a chloroplast; membrane contains chlorophyll; location where the light reactions of photosynthesis occur.

Grana

Stack of chlorophyll-containing thylakoids in a chloroplast.

Matrix

Unstructured semifluid substance that fills the space between cells in connective tissues or inside organelles.

Cristae

Short, fingerlike projections formed by the folding of the inner membrane of mitochondria.

Actin Filament

Component of the cytoskeleton; plays a role in the movement of the cell and its organelles; a protein filament in a sarcomere of a muscle, its movement shortens the sarcomere, yielding muscle contraction.

Intermediate filament

Ropelike assemblies of fibrous polypeptides in the cytoskeleton that provide support and strength to cells; so called because they are intermediate in size between actin filaments and microtubules.

Microtubules

Small, cylindrical organelle composed of tubulin protein around an empty central core; present in the cytoplasm, centrioles, cilia, and flagella.

Centrosome

Central microtubule organizing center of cells. In animal cells, it contains two centrioles.

Endosymbiotic Theory

Explanation of the evolution of eukaryotic organelles by phagocytosis of prokaryotes.