Chapter 3 Flashcards
Define active transport
form of transport across the cell membrane that requires input of cellular energy
Define amphipathic
describes a molecule that exhibits a difference in polarity between its two ends, resulting in a difference in water solubility
Define anaphase
third stage of mitosis (and meiosis) during which sister chromatids separate into two new nuclear regions of a dividing cell
Define anticodon
consecutive sequence of three nucleotides on a tRNA molecule that is complementary to a specific codon on an mRNA molecule
Define autolysis
breakdown of cells by their own enzymatic action
Define autophagy
lysosomal breakdown of a cell’s own components
Define cell cycle
life cycle of a single cell, from its birth until its division into two new daughter cells
Define cell membrane
membrane surrounding all animal cells, composed of a lipid bilayer interspersed with various molecules; also known as plasma membrane
Define centriole
small, self-replicating organelle that provides the origin for microtubule growth and moves DNA during cell division
Define centromere
region of attachment for two sister chromatids
Define centrosome
cellular structure that organizes microtubules during cell division
Define channel protein
membrane-spanning protein that has an inner pore which allows the passage of one or more substances
Define checkpoint
progress point in the cell cycle during which certain conditions must be met in order for the cell to proceed to a subsequence phase
Define chromatin
substance consisting of DNA and associated proteins
Define chromosome
condensed version of chromatin
Define cilia
small appendage on certain cells formed by microtubules and modified for movement of materials across the cellular surface
Define cleavage furrow
contractile ring that forms around a cell during cytokinesis that pinches the cell into two halves
Define codon
consecutive sequence of three nucleotides on an mRNA molecule that corresponds to a specific amino acid
Define concentration gradient
difference in the concentration of a substance between two regions
Define cyclin
one of a group of proteins that function in the progression of the cell cycle
Define cyclin-dependent kinase (CDK)
one of a group of enzymes associated with cyclins that help them perform their functions
Define cytokinesis
final stage in cell division, where the cytoplasm divides to form two separate daughter cells
Define cytoplasm
internal material between the cell membrane and nucleus of a cell, mainly consisting of a water-based fluid called cytosol, within which are all the other organelles and cellular solute and suspended materials
Define cytoskeleton
“skeleton” of a cell: formed by rod-like proteins that support that cell’s shape and provide, among other functions, locomotive abilities