AP chap 3: cellular organization

active transport

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

amphipathic

third stage of mitosis (and meiosis), during which sister chromatids separate into two nuclear regions

anticodon

consecutive sequence of three nucleotides on a tRNA molecule that is complementary to a specific codon on an MRNA molecule

autolysis

breakdown of cells by their own enzymatic action

autophagy

lysosomal breakdown of a cell’s own components

call cycle

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

cell membrane aka plasma membrane

membrane surrounding all animal cells, composed of a lipid bilayer interspersed with various molecules

centriole

small, self-replicating organelle that provides the origin of microtubule 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 subsequence phase

chromatin

substance consisting of DNA and associated protein

chromosome

condensed version of chromatin

cillia

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

codone

consecutive sequence of three nucleotides on an mRNA molecule that corresponds to a specific amno acid

concentration gradient

difference in the concentration of a substance between two regions

cyclin

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

cyclin-dependent kinase (CDK)

one 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 water-based fluid called cytosol within which are all the other organelles and cellular solute and suspended

cytoskeleton

“skeleton” of a cell

cytosol

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

diffusion

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

DNA polymerase

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

DNA replication

process of duplicating a molecule of DNA

electrical gradient

difference in the electrical charge (potential) between two regions

endocytosis

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

endoplasmic reticulum

cellular organelle that consists of interconnected membrane-bound tubules

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 remain after splicing

extracellular fluid (ECF)

fluid exterior to cells

facilitated diffusion

diffusion of a substance with the aid of a membrane protein

G1 phase

first phase after a cell is born

G2

third phase after dna synthesis

gene

functional length of DNA hat 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

glycoprotein

protein that has one or more carbohydrates attached

golgi apparatus

cellular organelle formed by a series of flattened, membrane-bound sacs that function to separate the two strands of double helix during DNA replication

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 reference concentration

integral protein

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

intermediate filament

type of cytoskeleton filament made of keratin

interphase

entire life cycle of a cell, excluding mitosis

interstitial fluid (IF)

fluid in the cytosol of cells

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 reference concentration

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 RNA (mRNA)

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

metaphase

second stage of mitosis (and meiosis)

metaphase plate

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

microfilament

the thinnest of the cytoskeletal filaments

microtubule

the thickest of the cytoskeletal filaments