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
Define diffusion
movement of a substance from an area of higher concentration to one of lower concentration
Define diploid
(of cell or nuclues) two complete sets of chromosomes, one from each parent
Define DNA polymerase
enzyme that functions in adding new nucelotides to a growing strand of DNA during DNA replication
Define DNA replication
process of duplicating a molecule of DNA
Define electrical gradient
difference in the electrical charge (potential) between two regions
Define endocytosis
import of material into the cell by formation of a membrane-bound vesicle
Define endoplasmic reticulum (ER)
cellular organelles that consists of interconnected membrane-bound vesicle
Define exocytosis
export of a substance out of a cell by formation of a membrane-bound vesicle
Define exon
one of the coding regions of an mRNA molecule that remain after splicing
Define extracellular fluid (ECF)
fluid exterior to cells: includes the interstital fluid, blood plasma, and fluid found in other reservoirs in the body
Define facilitated diffusion
diffusion of a substance with the aid of a membrane protein
Define flagellum
appendage on certain cells formed by microtubules and modified for movement
Define G(0) phase
phase of the cell cycle, usually entered from the G(1) phase; characterized by long or permanent periods where the cell does not move forward into the DNA synthesis phase
Define G(1)
first phase of the cell cycle, after a new cell is born
Define G(2)
third phase of the cell cycle, after the DNA synthesis phase
Define gene
functional length of DNA that provides the genetic information necessary to build a protein
Define gene expression
active interpretation of the information coded in a gene to produce a functional gene product
Define genome
organisms complete set of DNA
Define glycocalyx
coating of sugar molecules that surrounds the cell membrane
Define glycoprotein
protein that has one or more carbohydrates attached
Define Golgi apparatus
cellular organelle formed by a series of flattened, membrane-bound sacs that functions in protein modification, tagging, packaging, and transport
Define helicase
enzyme that functions to separate the two DNA strands of a double helix during DNA replication
Define histone
family of proteins that associate with DNA int he nucleus to form chromatin
Define homologous
describes two copies of the same chromosome (not identical), one inherited from each parent
Define hydrophilic
describe a substance or structure attracted to water
Define hydrophobic
describes a substance or structure repelled by water
Define hypertonic
describes a solution of concentration that is lower than a reference concentration
Define hypotonic
describes a solution concentration that is lower than a reference concentration
Define integral protein
membrane-associated protein that spans the entire width off the lipid bilayer
Define intermediate filament
type of cytoskeletal filament made of keratin, characterized by an intermediate thickness, and playing a role in resisting cellular tension
Define interphase
entire life cycle of a cell, excluding mitosis
Define interstitial fluid (ICF)
fluid in the cytosol of cells
Define intron
non-coding regions of a pre-mRNA transcript that may be removed during splicing
Define isotonic
describes a solution concentration that is the same as a reference concentration
Define kinetochore
region of a centromere where microtubules attach to a pair of sister chromatids
Define ligand
molecule the binds with specificity to a specific receptor molecule
Define lysosome
membrane-bound cellular organelle originating from the Golgi apparatus and containing digestive enzymes
Define messenger RNA (mRNA)
nucleotide molecule that serves as an intermediate in the genetic code between DNA and protein
Define metaphase
second stage of mitosis (and meiosis), characterized by the linear alignment of sister chromatids in the center of the cell
Define metaphase plate
linear alignment of sister chromatids in the center of the cell, which takes place during metaphase
Define microfilament
the thinnest of the cytoskeletal filaments; composed of actin subunits that function in muscle contraction and cellular structural support
Define microtuble
the thickest of the cytoskeletal filaments, composed off tubulin subunits that function in cellular movement and structural support
Define mictochondrion
one of the cellular organelles bound by a double lipid bilayer that function primarily in the production of cellular energy (ATP)
Define mitosis
division of genetic material , during which the cell nucleus breaks down and two new, fully functional, nuclei are formed
Define mitotic phase
phase of the cell cycle in which a cell undergoes mitosis
Define mutlipotent
stem cell that have the capacity to self-renew by dividing and to develop into multiple specialized cell types present in a specific tissue or organ
Define mutation
change in the nucleotide sequence in a gene within a cell’s DNA
Define mitotic spindle
network of microtubules, originating from centrioles that arranges and pulls apart chromosomes during mitosis
Define nuclear envelope
membrane that surrounds the nucleus; consisting of a double lipid-bilayer
Define nuclear pore
one of the small, protein-lined openings found scattered throughout the nuclear envelope
Define nucleolus
small region of the nucleus that functions in ribosome synthesis
Define nucleosome
unit of chromatin consisting of a DNA strand wrapped around histone proteins
Define nucleus
cell’s central organelle; contains the cell’s DNA
Define oligopotent
describes the condition of being more specialized than mulitpotency; have ability to transform into a limited number of several other types of cells
Define organelle
any of several different types of membrane-enclosed specialized structures in the cell that perform specific functions for the cell
Define osmosis
diffusion of water molecules down their concentration gradient across a selectively permeable membrane
Define passive transport
form of transport across the cell membrane that does not require input of cellular energy
Define peripheral protein
protein that does not span the width of the lipid bilayer, but is attached peripherally to integral proteins, membrane lipids or other components of the membrane
Define peroxisome
membrane-bound organelle that contains enzymes primarily responsible for detoxifying harmful substances
Define phagocytosis
endocyotsis of large particles
Define pinocytosis
endocytosis of fluid
Define pluripotent
describes the condition of being able to differentiate into a large variety of cell types except those that form a placenta or embryo
Define polypeptide
chain of amino acids linked by peptide bonds
Define polyribosome
group of ribosomes bound to an mRNA molecule like “beads” on a “thread”. Involved in peptide synthesis
Define promoter
region of DNA that signals transcription to begin as that site within the gene
Define prophase
first stage of mitosis (and meiosis), characterized by breakdown of the nuclear envelope and condensing of the chromatin to form chromosomes
Define proteome
entire set of proteins expressed by a cell, tissue, or organism
Define reactive oxygen species (ROS)
a group of extremely reactive peroxides and oxygen-containing radicals that may contribute to cellular damage
Define receptor
protein molecule that contains a binding a site for another specific molecule (called a ligand)
Define receptor-mediated endocytosis
endocytosis of ligands attached to membrane-bound receptors
Define ribosomal RNA (rRNA)
RNA that makes up the subunits of a ribosome
Define ribosome
cellular organelle that functions in protein synthesis
Define RNA polymerase
enzyme that unwinds DNA and then adds new nucelotides to a growing strand of RNA for the transcription phase of protein synthesis
Define S phase
stage of the cell-cycle during which DNA replication occurs
Define selective permeability
feature or any barrier that allows to certain substances to cross but excludes others
Define sister chromatid
one of a pair of identical chromosomes, formed during DNA replication
Define sodium-potassium pump
membrane-embedded protein pump that uses ATP to move Na+ out of a cell and K+ into the cell
Define somatic cell
all cells of the body excluding gamete cells
Define spliceosome
complex of the enzymes that serves to splice out the introns of a pre-mRNA transcript
Define splicing
the process of modifying a pre-mRNA transcript by removing certain, typically non-coding, regions
Define stem cell
cell that is oligo-, mutli-, or pleuripotent that has the ability to produce additional stem cells rather than becoming further specialized
Define telophase
final stage of mitosis (and meiosis), preceding cytokinesis, characterized by the formation of two new daughter nuclei
Define totipotent
embyronic cells that have the ability to differentiate into any type of cell and organ in the body
Define transcription
process of producing an mRNA molecule that is complementary to a particular gene of DNA
Define transcription factor
one of the proteins that regulate the transcription of genes
Define transfer RNA (tRNA)
molecules of RNA that serve to bring amino acids to a growing polypeptide strand and properly place them into the sequence
Define translation
process of producing a protein from the nucleotide sequence code of an mRNA transcript
Define triplet
consecutive sequence of three nucleotides on a DNA molecule that, when transcribed into an mRNA codon, corresponds to a particular amino acid
Define unipotent
describes the condition of being committed to a single specialized cell type
Define vesicle
membrane-bound structure that contains materials within or outside of the cell
