Biology Chapter 4 Flashcards
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. Enclose and support plant cells.
Central Vacuole
In a plant cell, a large membranous sac with diverse roles in growth and the storage of chemicals and wastes.
Chlorophyl
- A green pigment located within the chloroplasts of plants and algae and in the membranes of certain prokaryotes. Chlorophyll a participates directly in the light reactions, which convert solar energy to chemical energy.
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.
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.
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. A chromosome consists of one very long DNA molecule and associated proteins.
Cilia
The short, numerous appendages that propel Paramecium.
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.
Cytoskeleton
- A network of protein fibers in the cytoplasm of a eukaryotic cell; includes microfilaments, intermediate filaments, and microtubules.
Cytosol
The semifluid portion of the cytoplasm.
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.
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. See also rough ER; smooth ER.
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 eukaryotic cells.
Extracellular Matrix
layer that helps hold cells together in tissues and protects and supports the plasma membrane made of collagen, enzymes, and glycoproteins, that provide structural and biochemical support of surrounding cells. Can even influence the activity of genes through
the signals it relays.
Golgi Apparatus
An organelle in eukaryotic cells consisting of stacks of membranous sacs that modify, store, and ship products of the endoplasmic reticulum.
Lyosome
A digestive organelle in eukaryotic cells; contains hydrolytic enzymes that digest engulfed food or damaged organelles.
Mitochondria
An organelle in eukaryotic cells where cellular respiration occurs. Enclosed by two membranes, it is where most of the cell’s ATP is made.
Nuclear Envelope
A double membrane that encloses the nucleus, perforated with pores that regulate traffic with the cytoplasm.
Nucleus
(1) An atom’s central core, containing protons and neutrons. (2) The organelle of a eukaryotic cell that contains the genetic material in the form of chromosomes, made of chromatin.
Nucleoid
A non–membrane-bounded region in a prokaryotic cell where the DNA is concentrated.
Organelle
A membrane-enclosed structure with a specialized function within a cell.
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.
Plasmodesmata
An open channel in a plant cell wall that connects the cytoplasm of adjacent cells.
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 ribosomal subunits are constructed in the nucleolus.
