A+P CH 3

active transport

form of transport across the cell membrane that requires input of cellular energy

amphipathic

describes a molecule that exhibits a difference in polarity between its two ends, resulting in a difference in water solubility

anaphase

third stage of mitosis, during which sister chromatids separate into two new nuclear regions of a dividing cell

anticodon

consecutive sequence of three nucleotides on a tRNA molecule that it complementary to a specific codon on an mRNA molecule

autolysis

breakdown of cells by their own enzymatic actiona

autophagy

lysosomal breakdown of a cell’s own components

cell cycle

life cycle of a single cell, from its birth until its division into two new daughter cells

cell membrane

membrane surrounding all animal cells, composed of a lipid bilayer intersperse with various molecules; also known as plasma membrane

centriole

small, self-replicating organells that provides the origin for microtubules growth and moves DNA during cell division

centromere

region of attachment for two sister chromatids

centrosome

cellular structure that organizes microtubules during cell division

channel protein

membrane-spanning protein that has an inner pore which allows the passage of one or more substances

checkpoint

progress point in the cell cycle during which certain conditions must be met in order for the cell to proceed to a subsequent phase

chromatin

substance consisting of DNA and associated proteins

chromosome

condensed version of chromatin

cilia

small appendage on certain cells formed by microtubules and modified for movement of materials across the cellular surface

cleavage furrow

contractile ring that forms around a cell during cytokinesis that pinches the cell into two halves

codon

consdecutive sequence of three nucleotides on an mRNA molecule that corresponds to a specific amino acid

concentration gradient

difference in the concentration of a substance between two regions

cyclin

one of a group of proteins that function in the progression of the cell cycle

cyclin-dependent kinase

one of a group of enzymes associated with cyclins that help them perform their functions

cytokinesis

final stage in cell division, where the cytoplasm divides to form two separate daughter cells

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 other organelles and cellular solute and suspended materials

cytoskeleton

skeleton of a cell; formed by rod-like proteins that support the cell’s shape and provide, among other functions, locomotive abilities

cytosol

clear, semi-fluid medium of the cytoplasm, made up mostly of water

diffusion

movement of a substance from an area of higher concentration to one of lower concentration

diploid

condition marked by the presence of a double complement of genetic material (two sets of chromosomes, one set inherited from each of two parents)

DNA polymerase

enzyme that functions in adding new nucleotides to a growing strand of DNA during DNA replication

DNA replication

process of duplication a molecule of DNA

electrical gradient

difference in the elctrical charge (potential) between two regions

endocytosis

import of material into the cell by formation of a membrane-bound vesicle

endoplasmic reticulum (ER)

cellular organelle that consists of interconnected membrane-bound tubules, which may or may not be associated with ribosomes (rough type or smooth type)

exocytosis

export of a substance out of a cell by formation of a membrane-bound vesicle

exon

one of the coding regions of an mRNA molecule that remian after splicinge

extracellular fluid (ECF)

fluid exterior to cells; includes the interstitial fluid, blood plasma, and fluid found in other reservoirs in the body

facilitated diffusion

diffusion of a substance with the aid of a membrane protein

flagellum

appendage on certain cells formed by microtubules and modified for movement

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

G-1 phase

first phase of the cell cycle, after a new cell is born

G-2 phase

third phases of the cell cycle, after the DNA synthesis phase

gene

functional length of DNA that provides the genetic information necessary to build a protein

gene expression

active interpretation of the information coded in a gene to produce a functional gene product

genome

entire complement of an organism’s DNA; found within virtually every cell

glycocalyx

coating of sugar molecules that surrounds the cell membrane

glycoprotein

protein that has one or more carbohydrates attached

golgi apparatus

cellular organelle formed by a series of flattened, membrane-bound sacs that functions in protein modification, tagging, packaging, and transport

helicase

enzyme that functions to separate the two DNA strands of a double helix during DNA replication

histone

family of proteins that associate with DNA in the nucleus to form chromatin

homologous

describes two copies of the same chromosome (not identical), one inherited from each parent

hydrophilic

describes a substance or structure attracted to water

hydrophobic

describes a substance or structure repelled by water

hypertonic

describes a solution concentration that is higher than a reference concentration

hypotonic

describes a solution concentration that is lower than a refernece concentrationi

integral protein

membrane-associated protein that spans the entire width of the lipid bilayer

intermediate filament

type of cytoskeletal filament made of keratin, characterized by an intermediate thickness, plays role in resisting cellular tension

interphase

entire life cycle of a cell, excluding mitosis

interstitial fluid (IF)

fluid in the small spaces between cells not contained with blood vessels

intracellular fluid (ICF)

fluid in the cytosol of cells

intron

non-coding regions of a pre-mRNA transcript that may be removed during splicing

isotonic

describes a solution concentration that is the same as a reference concentrationki

kinetochore

region of a centromere where microtubules attach to a pair of sister chromatids

ligand

molecule that binds with specificity to a specific receptor molecule

lysosome

membrane-bound cellular organelle originating from the Golgi apparatus and containing digestive enzymes

messenger (mRNA)

nucleotide molecule that serves as an intermediate in the genetic code between DNA and proteinm

metaphase

second stage of mitosis, characterized by the linear alignment of sister chromatids in the center of the cell

metaphase plate

linear alignment of sister chromatids in the center of the cell, takes place during metaphase

microfiliament

thinnest of the cytoskeletal filaments; composed of actin subunits that function in muscle concentration and cellular structural support

microtubules

thickest of the cytoskeletal filaments, composed of tubulin subunits that function in cellular movement and structural support

mitochondrion

one of the cellular organelles bound by a double lipid bilayer that function primarily in the production of cellular energy (ATP)

oligopotent

describes the condition of being more specialized than multipotency; condition of being able to differentiate into one of a few possible cell types

organelle

any of several different types of membrane-enclosed specialized structures in the cell that perform specific functions for the cell

osmosis

diffusion of water molecules down their concentration gradient across a selectively permeable membrane

passive transport

form of transport across the cell membrane that does not require input of cellular energy

peripheral protein

membrane-associated protein that does not span the width of the lipid bilayer, but it attahced peripherally to integral proteins, membrane lipids, or other components of the membrane

peroxisome

membrane-bound organelles that contains enzymes primarily responsible for detoxifying harmful substances

phagocytosis

endocytosis of large particles

pinocytosis

endocytosis of fluid

pluripotent

describes the condition of being able to differentiate into a large variety of cell types

polypeptide

chain of amino acids linked by peptide bonds

polyribosome

simultaneous translation of a single mRNA transcript by multiple ribosomes

promoter

region of DNA that signals transcription to begin at that site within the gene

prophase

first stage of mitosis, characterized by breakdown of the nuclear envelope and condensing of chromatin to form chromosomes

proteome

full complement of proteins produced by a cell (determined by the cell’s specific gene expression)

reactive oxygen species

group of extremely reactive peroxides and oxygen-containing radicals that may contribute to cellular damage

receptor

protein molecule that contains a binding site for another specific molecule (ligand)

receptor-mediated endocytosis

endocytosis of ligands attahced to membrane-bound receptors

ribosomal RNA (rRNA)

RNA that makes up the subunits of a ribosome

ribosome

cellular organelle that functions in protein synthesis

RNA polymerase

enzyme that unwinds DNA and then adds new nucleotides to a growing strand of RNA for the transcription phase of protein synthesis

S phase

stage of the cell cycle when DNA replication occurs