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Flashcards in Cell Biology Deck (72)
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Define: Prokaryotes

Any of the group of organisms primarily characterized by the lack of true nucleus and other membrane-bound cell compartments: such as mitochondria and chloroplasts, and by the possession of a single loop of stable chromosomal DNA in the nucleiod region and cytoplasmic structures, such as plasma membrane, vacuoles, primitive cytoskeleton, and ribosomes.


Define: Eukaryotes

cells are organized into compartmentalized structures called organelles, the nucleus in particular. The presence of a distinct nucleus encased within membranes differentiates the eukaryotes from the prokaryotes. The eukaryotes are also known for having cytoplasmic organelles apart from nucleus, such as mitochondria, chloroplasts and Golgi bodies


Define: TEM

TEM --> transmission electron microscopy
Those forms of electron microscopy in which electrons are transmitted through the object to be imaged, suffering energy loss by diffraction and to a small extent by absorption.


Define: SEM

Scanning electron microscope (SEM)

a type of electron microscope capable of producing high resolution images of a sample surface.


Define: Plasma membrane

The cell’s outer membrane made up of a two layers of phospholipids with embedded proteins, and separates the contents of the cell from its outside environment, as well as regulates what enters and exits the cell


Define: Organelles

Plural form of organelle, i.e. a membrane-bound compartment or structure in a cell that performs a special function


Define: Cell wall

A membrane of the cell that forms external to the cell membrane whose main role is to give cells rigidity, strength and protection against mechanical stress


Define: Cell envelope

The cell envelope comprises the inner cell membrane and the cell wall of a bacterium. In gram-negative bacteria an outer membrane is also included. This envelope is not present in the Mollicutes where the cell wall is absent.


Define: Cytoplasm

The contents of a cell surrounded by the cell membrane, except for the nucleus in the eukaryotic cell


Define: Nucleus

The large, membrane-bounded organelle that contains the genetic material, in the form of multiple linear DNA molecules organized into structures called chromosomes


Define: Nuclear envelope

The two layered membrane that encases the nucleus of a eukaryotic cell, which separates the nucleus from other cell organelles


Define: Ribosome

A minute, sphere-shaped particle composed of protein and ribonucleic acid (RNA) that serves as the site of protein synthesis


Define: DNA

Deoxyribonucleic acid

A nucleic acid that generally is double-stranded and helical, and a crucial biomolecule for containing the genetic information for cell growth, division, and function


Define: RNA

Ribonucleic acid

A nucleic acid that is frequently single-stranded and folded onto itself, and composed of repeating nucleotide units of ribose sugar, phosphate group, and nitrogenous base


Define: Amino acids

The building block of protein in which each is coded for by a codon and linked together through peptide bonds.


Define: Endoplasmic reticulum

A membrane-bound organelle that occurs as labyrinthine, interconnected flattened sacs or tubules connected to the nuclear membrane, running through the cytoplasm, and may well extend into the cell membrane


Define: Golgi apparatus

An organelle that is comprised of membrane-bound stacks and is involved in glycosylation, packaging of molecules for secretion, transporting of lipids within the cell, and giving rise to lysosomes


Define: Lysosomes

Organelle containing a large range of digestive enzymes used primarily for digestion and removal of excess or worn-out organelles, food particles, and engulfed viruses or bacteria


Define: Peroxisomes

Peroxisome, membrane-bound organelle occurring in the cytoplasm of eukaryotic cells. Peroxisomes play a key role in the oxidation of specific biomolecules. ... Specialized types of peroxisomes have been identified in plants, among them the glyoxysome, which functions in the conversion of fatty acids to carbohydrates.


Define: Mitochondria

A spherical or rod-shaped organelle with its own genome, and is responsible for the generation of most of the cell's supply of adenosine triphosphate through the process of cellular respiration


Define: Chloroplasts

Chlorophyll-containing plastid found within the cells of plants and other photosynthetic eukaryotes


Define: Vacuoles

A membrane-bound vesicle found in the cytoplasm of a cell whose function includes intracellular secretion, excretion, storage, and digestion


Define: Cytoskeleton

The lattice or internal framework of a cell composed of protein filaments and microtubules in the cytoplasm, and has a role in controlling cell shape, maintaining intracellular organization, and in cell movement


Define: Centrosomes

The organelle located near the nucleus in the cytoplasm that divides and migrates to opposite poles of the cell during mitosis, and is involved in the formation of mitotic spindle, assembly of microtubules, and regulation of cell cycle progression; the region pertaining to the organelle.


Define: Fluid Mosaic Model

The fluid mosaic model explains various observations regarding the structure of functional cell membranes. According to this biological model, there is a lipid bilayer in which protein molecules are embedded. The lipid bilayer gives fluidity and elasticity to the membrane


Define: Membrane proteins

A type of protein that is attached to, or associated with, a biological membrane (i.e. of a cell or of an organelle)
Proteins are one of the most essential biomolecules. They serve as structural material, as enzymes, as transporters, as antibodies, or as gene expression regulators. They are made up of polymers comprised of amino acids.


Define: Plasma membrane

The cell’s outer membrane made up of a two layers of phospholipids with embedded proteins, and separates the contents of the cell from its outside environment, as well as regulates what enters and exits the cell


Define: Cytoplasmic membrane

The plasma membrane, also called the cytoplasmic membrane, is the most dynamic structure of a procaryotic cell. Its main function is a s a selective permeability barrier that regulates the passage of substances into and out of the cell.


Define: Phospholipids

Phospholipids are a subgroup of lipids. Other major types of lipids are fatty acids, sphingolipids, sterol lipids, and prenol lipids. Lipids are organic compounds that are readily soluble in nonpolar solvent (e.g. ether) but not in polar solvent (e.g. water).


Define: Osmotic pressure

A hydrostatic pressure caused by a difference in the amounts of solutes between solutions that are separated by a semi-permeable membrane.