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Plasma membrane

def: a fatty film so thin and transparent that it can not be seen directly in the light of a microscope.

personal info: it is made up of a two-ply sheet of lipid molecules that are 5nm thick. It serves as a barrier to prevent the contents of the cell escaping (sort of like skin). Nutrients are passed in through it, and waste is passed out. (so it's also like a mouth and butt, heh). When a cell grows or changes shape, so does the membrane. It can deform without tearing, and if poked it will not explode or pop like a balloon but seal immediatly.

Bacteria have only one membrane, the plasma membrane.
Eukaryotic cells however have other internal membranes surrounding things like the E.R. golgi apparatus and mitochondria.


  • Channels and pumps to let waste and nutrients in or out.
  • It has proteins that act as sensors to enable the cell to receive information about changes in the environment so it can respond to them.


def: the most abundant lipids in the cell membrane in which the tail is linked to the head via a phosphate group. (ugh, chemistry)


def: the most common type of phospholipid in most cell membranes.


  • the smaaaaall molucule choline attached to a phosphate group as it's hydrophilic head and two long (compisating for the small head?) hydrocarbon chains as the hydrophobic tails.

Peripheral membrane proteins

def: proteins that can be released from the membrane by more gentle extraction procedures that interfere with protein-protein interactions but leave the lipid bilayer intact.


def: the macromolucules that perform most of the cell's functions

job qualifications:

*They can serve as building blocks for cell structures
*They form enzymes that catalyze the cell's chemical reactions
*they regulate gene expression
*They enable cells to move
*They enable cells to comunnicate with each other

Proofreading (chapter 6)

def: The process by which DNA polymerase corrects its own errors as it moves along DNA.

Peroxisome (chapter 15)

def: Small membrane-enclosed organelle that uses molecular oxygen to oxidize organic molecules. Contains some enzymes that produce hydrogen peroxide (H2O2) and others that degrade it.

Phagocytotic Cell (chapter 15)

def: A cell such as a macrophage or neutrophil that is specialized to take up particles and microorganisms by phagocytosis.

Phagocytosis (chapter 15)

def: The process by which particulate material is engulfed ("eaten". ie om,nom,nom) by a cell. Prominent in predatory cells, such as Amoeba proteus and in cells of the vertebrate immune system such as macrophages.

Pinocytosis (chapter 15)

def: Type of endocytosis in which soluble materials are taken up from the environment and incorporated into vesicles for digestion (literally "cell drinking")

Phosphoinositide-3-Kinase (chapter 16)

def: Enzyme that phosphorylates inositol phospholipids in the plasma membrane in response to signals received by a cell. The phosphorylated lipids become docking sites for intracellular signaling proteins.

Protein Kinase (chapter 16)

def: One of a very large number of enzymes that transfers the terminal phosphate group of ATP to a specific amino acid chain on a target protein.

Protein Kinase C (PKC) (chapter 16)

def: Enzyme that phosphorylates target proteins in response to a rise in diacylglycerol and Ca2+ ions.

Protein Phosphatase (chapter 16)

def: Enzyme that removes, by hydrolysis, a phosphate group from a protein, often with high specificity for the phosphorylated site.

Promoter (chapter 7)

def: Nucleotide sequence in DNA in which RNA polymerase binds to begin transcription.

Protease (proteinase, proteolytic enzyme) (chapter 7)

def: Enzyme such as trypsin that degrades proteins by hydrolyzing some of their peptide bonds.

Proteasome (chapter 7)

def: Large protein complex in the cytosol that is responsible for degrading cytosolic proteins that have been marked for destruction by ubiquitulation or by some other means.

Positive Feedback Loop (chapter 8)

def: Situation in which the end product of a reaction stimulates its own production.

Post-transcriptional Control (chapter 8)

def: Regulation of gene expression that occurs after transcription of the gene has begun; examples are regulation of RNA splicing and other RNA processing events, and regulation of translation by microRNA.

Phenotype (chapter 10)

def: The observable character of a cell or an organism.

Plasmid (chapter 10)

def: Small circular DNA molecule that replicates independently of the genome. Used extensively as a vector for DNA cloning.

Polymerase Chain Reaction (PCR) (chapter 10)

def: Technique for amplifying specific regions of DNA by multiple cycles of DNA synthesis, each followed by a brief heat treatment to separate complementary DNA strands.

p53 (chapter 18)

def: Regulatory protein that responds to the presence of DNA damage, preventing the cell from entering S phase until the damage has been repaired.

Phragmoplast (chapter 18)

def: Structure made of microtubles and membrane vesicles that forms in the equitorial region of a dividing plant cell and from which the membrane that divides the daughter cells will be made. (fuck you. makes no sense. ><)

Programmed Cell Death (chapter 18)

see apoptosis

Prometaphase (chapter 18)

def: Stage of mitosis that precedes metaphase.

Prophase (chapter 18)

def: First stage of mitosis during which the chromosomes are condensed but not yet attached to a mitotic spindle. Also a superficially similar stage in meiosis.

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