Campbell Biology Concepts & Connections Chapter 4

cell theory

The theory that all living things are composed of cells and that all cells come from other cells.

electron microscope

A microscope that uses magnets to focus an electron beam through, or onto the surface of, a specimen. Achieves a hundredfold greater resolution than a light microscope.

prokaryotic cell

A type of cell lacking a membrane-enclosed nucleus and other membrane-enclosed organelles; found only in the domains Bacteria and Archaea.

eukaryotic cell

A type of cell that has a membrane-enclosed nucleus and membrane-enclosed organelles. All organisms except bacteria and archaea are composed of these types of cells.

cytosol

The semifluid portion of the cytoplasm.

chromosome

A gene-carrying structure found in the nucleus of a eukaryotic cell and most visible during mitosis and meiosis; also, the main gene-carrying structure of a prokaryotic cell. Consists of one very long DNA molecule and associated proteins.

ribosome

A cell structure consisting of RNA and protein organized into two subunits and functioning as the site of protein synthesis in the cytoplasm. In eukaryotic cells, the subunits are assembled in the nucleolus.

cytoplasm

The contents of a eukaryotic cell between the plasma membrane and the nucleus; consists of a semifluid medium and organelles; can also refer to the interior of a prokaryotic cell.

nucleoid

A non-membrane-bounded region in a prokaryotic cell where the DNA is concentrated.

flagellum

A long cellular appendage specialized for locomotion.

capsule

Jellylike outer coating of many prokaryotes.

cell wall

A protective layer external to the plasma membrane in plant cells, bacteria, fungi, and some protists; protects the cell and helps maintain its shape.

plasma membrane

The membrane at the boundary of every cell that acts as a selective barrier to the passage of ions and molecules into and out of the cell; consists of a phospholipid bilayer with embedded proteins.

fimbriae

Attachment structures on the surface of some prokaryotes.

organelle

A membrane-enclosed structure with a specialized function within a cell.

cellular metabolism

All the chemical activities of a cell.

nucleus

The organelle of a eukaryotic cell that contains the genetic material in the form of chromosomes, made of chromatin.

chromatin

The complex of DNA and proteins that makes up eukaryotic chromosomes; often used to refer to the diffuse, very extended form taken by chromosomes when a cell is not dividing.

nuclear envelope

A double membrane that enclosed the nucleus, perforated with pores that regulate traffic with the cytoplasm.

nucleolus

A structure within the nucleus where ribosomal RNA is made and assembled with proteins imported from the cytoplasm to make ribosomal subunits.

endomembrane system

A network of membranes inside and surrounding a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles.

vesicle

A sac made of membrane in the cytoplasm of a eukaryotic cell.

endoplasmic reticulum

An extensive membranous network in a eukaryotic cell, continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome-free )smooth) regions.

smooth endoplasmic reticulum

That portion of the endoplasmic reticulum that lacks ribosomes.

rough endoplasmic reticulum

That portion of the endoplasmic reticulum with ribosomes attached that make membrane proteins and secretory proteins.

golgi apparatus

An organelle in eukaryotic cells consisting of stacks of membranous sacs that modify, store, and ship products of the endoplasmic reticulum.

lysosome

A digestive organelle in eukaryotic cells; contains hydrolytic enzymes that digest engulfed food or damaged organelles.

vacuole

A membrane-enclosed sac that is part of the endomembrane system of a eukaryotic cell and has diverse functions in different kinds of cells.

central vacuole

In a plant cell, a large membranous sac with diverse roles in growth and the storage of chemicals and wastes.

mitochondrion

An organelle in eukaryotic cells where cellular respiration occurs. Enclosed by two membranes, it is where most of the cell's ATP is made.

mitochondrial matrix

The compartment of the mitochondrion enclosed by the inner membrane and containing enzymes and substrate for the citric acid cycle.

cristae

An infolding of the inner mitochondrial membrane.

chloroplast

An organelle found in plants and algae that absorbs sunlight and uses it to drive the synthesis of organic compounds(sugars) from carbon dioxide and water.

stroma

The dense fluid within the chloroplast that surrounds the thylakoid membrane and is involved in the synthesis of organic molecules from carbon dioxide and water. Sugars are made here by the enzymes of the Calvin cycle.

thylakoid

A flattened membranous sac inside a chloroplast. Their membranes contain chlorophyll and the molecular complexes of the light reactions of photosynthesis.

granum

A stack of membrane-bounded thylakoids in a chloroplast. The sites where light energy is trapped by chlorophyll and converted to chemical energy during the light reactions of photosynthesis.

endosymbiont theory

The theory that mitochondria and chloroplasts originated as prokaryotic cells engulfed by an ancestral eukaryotic cell. The engulfed cell and its host cell then evolved into a single organism.

phospholipid bilayer

A double layer of phospholipids that makes up plasma and organelle membranes.

organelles

A tiny cell structure that carries out a specific function within the cell.

cell size

ratio between surface area vs volume

why cells are small?

cells depend on diffusion through the cell membrane for nutrients, waste disposal, oxygen. the bigger the cell the smaller the surface area to volume ratio.

origin theory

that these organelles evolved from free living prokaryotes

plants

cellulose

fungi

chitin

bacteria

peptidoglycan

animal and most protozoan

no walls