Chapters 4-6 Vocab

cell wall

rigid cell covering comprised of various molecules that protects the cell, provides structural support, and gives shape to the cell

central vacuole

large plant cell organelle that regulates the cell’s storage compartment, holds water, and plays a significant role in cell growth as the site of macromolecule degradation

centrosome

region in animal cells made of two centrioles that serves as an organizing center for microtubules

chlorophyll

green pigment that captures the light energy that drives the light reactions of photosynthesis

chloroplast

plant cell organelle that carries out photosynthesis

chromatin

protein-DNA complex that serves as the chromosomes' building material

chromosome

structure within the nucleus that comprises chromatin that contains DNA, the hereditary material

cilium

(plural = cilia) short, hair-like structure that extends from the plasma membrane in large numbers and functions to move an entire cell or move substances along the cell's outer surface

cytoplasm

entire region between the plasma membrane and the nuclear envelope, consisting of organelles suspended in the gel-like cytosol, the cytoskeleton, and various chemicals

cytoskeleton

protein fiber network that collectively maintains the cell's shape, secures some organelles in specific positions, allows cytoplasm and vesicles to move within the cell, and enables unicellular organisms to move independently

cytosol

the cytoplasm's gel-like material in which cell structures are suspended

desmosome

linkages between adjacent epithelial cells that form when cadherins in the plasma membrane attach to intermediate filaments

electron microscope

an instrument that magnifies an object using an electron beam that passes and bends through a lens system to visualize a specimen

endomembrane system

group of organelles and membranes in eukaryotic cells that work together modifying, packaging, and transporting lipids and proteins

endoplasmic reticulum (ER)

series of interconnected membranous structures within eukaryotic cells that collectively modify proteins and synthesize lipids

eukaryotic cell

cell that has a membrane-bound nucleus and several other membrane-bound compartments or sacs

extracellular matrix

material secreted from animal or fungal cells that provides mechanical protection and anchoring for the cells in the tissue

flagellum

(plural = flagella) long, hair-like structure that extends from the plasma membrane and moves the cell

gap junction

channel between two adjacent animal cells that allows ions, nutrients, and low molecular weight substances to pass between cells, enabling the cells to communicate

Golgi apparatus

eukaryotic organelle comprised of a series of stacked membranes that sorts, tags, and packages lipids and proteins for distribution

intermediate filament

cytoskeletal component, comprised of several fibrous protein intertwined strands, that bears tension, supports cell-cell junctions, and anchors cells to extracellular structures

light microscope

an instrument that magnifies an object using a beam of visible light that passes and bends through a lens system to visualize a specimen

lysosome

organelle in an animal cell that functions as the cell’s digestive component; it breaks down proteins, polysaccharides, lipids, nucleic acids, and even worn-out organelles

microfilament

the cytoskeleton system's narrowest element; it provides rigidity and shape to the cell and enables cellular movements

microscope

an instrument that magnifies an object

microtubule

the cytoskeleton system's widest element; it helps the cell resist compression, provides a track along which vesicles move through the cell, pulls replicated chromosomes to opposite ends of a dividing cell, and is the structural element of centrioles, flagella, and cilia

mitochondria

(singular = mitochondrion) cellular organelles responsible for carrying out cellular respiration, resulting in producing ATP, the cell’s main energy-carrying molecule

nuclear envelope

double-membrane structure that constitutes the nucleus' outermost portion

nucleoid

central part of a prokaryotic cell's central part where the chromosome is located

nucleolus

darkly staining body within the nucleus that is responsible for assembling ribosome subunits

nucleoplasm

semi-solid fluid inside the nucleus that contains the chromatin and nucleolus

nucleus

cell organelle that houses the cell’s DNA and directs ribosome and protein synthesis

organelle

compartment or sac within a cell

peroxisome

small, round organelle that contains hydrogen peroxide, oxidizes fatty acids and amino acids, and detoxifies many poisons

plasma membrane

phospholipid bilayer with embedded (integral) or attached (peripheral) proteins, and separates the cell's internal content from its surrounding environment

plasmodesma

(plural = plasmodesmata) channel that passes between adjacent plant cells' cell walls, connects their cytoplasm, and allows transporting of materials from cell to cell

prokaryote

unicellular organism that lacks a nucleus or any other membrane-bound organelle

ribosome

cellular structure that carries out protein synthesis

rough endoplasmic reticulum (RER)

region of the endoplasmic reticulum that is studded with ribosomes and engages in protein modification and phospholipid synthesis

smooth endoplasmic reticulum (SER)

region of the endoplasmic reticulum that has few or no ribosomes on its cytoplasmic surface and synthesizes carbohydrates, lipids, and steroid hormones; detoxifies certain chemicals (like pesticides, preservatives, medications, and environmental pollutants), and stores calcium ions

tight junction

protein adherence that creates a firm seal between two adjacent animal cells

unified cell theory

a biological concept that states that one or more cells comprise all organisms; the cell is the basic unit of life; and new cells arise from existing cells

vacuole

membrane-bound sac, somewhat larger than a vesicle, which functions in cellular storage and transport

vesicle

small, membrane-bound sac that functions in cellular storage and transport; its membrane is capable of fusing with the plasma membrane and the membranes of the endoplasmic reticulum and Golgi apparatus

active transport

method of transporting material that requires energy

amphiphilic

molecule possessing a polar or charged area and a nonpolar or uncharged area capable of interacting with both hydrophilic and hydrophobic environments

antiporter

transporter that carries two ions or small molecules in different directions

aquaporin

channel protein that allows water through the membrane at a very high rate

carrier protein

membrane protein that moves a substance across the plasma membrane by changing its own shape

caveolin

protein that coats the plasma membrane's cytoplasmic side and participates in the liquid uptake process by potocytosis

channel protein

membrane protein that allows a substance to pass through its hollow core across the plasma membrane

clathrin

protein that coats the plasma membrane's inward-facing surface and assists in forming specialized structures

concentration gradient

area of high concentration adjacent to an area of low concentration

diffusion

passive transport process of low-molecular weight material according to its concentration gradient

electrochemical gradient

a combined electrical and chemical force that produces a gradient

electrogenic pump

pump that creates a charge imbalance

endocytosis

type of active transport that moves substances

exocytosis

process of passing bulk material out of a cell

facilitated transport

process by which material moves down a concentration gradient (from high to low concentration) using integral membrane proteins

fluid mosaic model

describes the plasma membrane's structure as a mosaic of components including phospholipids

glycolipid

combination of carbohydrates and lipids

glycoprotein

combination of carbohydrates and proteins

hydrophilic

molecule with the ability to bond with water; “water-loving”

hydrophobic

molecule that does not have the ability to bond with water; “water-hating”

hypertonic

situation in which extracellular fluid has a higher osmolarity than the fluid inside the cell

hypotonic

situation in which extracellular fluid has a lower osmolarity than the fluid inside the cell

integral protein

protein integrated into the membrane structure that interacts extensively with the membrane lipids' hydrocarbon chains and often spans the membrane

isotonic

situation in which the extracellular fluid has the same osmolarity as the fluid inside the cell

osmolarity

total amount of solutes dissolved in a specific amount of solution

osmosis

transport of water through a semipermeable membrane according to the water's concentration gradient across the membrane that results from the presence of solute that cannot pass through the membrane

passive transport

method of transporting material through a membrane that does not require energy

peripheral protein

protein at the plasma membrane's surface either on its exterior or interior side

pinocytosis

a variation of endocytosis that imports macromolecules that the cell needs from the extracellular fluid

plasmolysis

detaching the cell membrane from the cell wall and constricting the cell membrane when a plant cell is in a hypertonic solution

potocytosis

variation of pinocytosis that uses a different coating protein (caveolin) on the plasma membrane's cytoplasmic side

primary active transport

active transport that moves ions or small molecules across a membrane and may create a difference in charge across that membrane

pump

active transport mechanism that works against electrochemical gradients

receptor-mediated endocytosis

variation of endocytosis that involves using specific binding proteins in the plasma membrane for specific molecules or particles

secondary active transport

movement of material that results from primary active transport to the electrochemical gradient

selectively permeable

membrane characteristic that allows some substances through (also known as semipermeable)

solute

substance dissolved in a liquid to form a solution

symporter

transporter that carries two different ions or small molecules

tonicity

amount of solute in a solution

transport protein

membrane protein that facilitates a substance's passage across a membrane by binding it

transporter

specific carrier proteins or pumps that facilitate movement

uniporter

transporter that carries one specific ion or molecule

activation energy

energy necessary for reactions to occur

active site

enzyme's specific region to which the substrate binds

allosteric inhibition

inhibition by a binding event at a site different from the active site, which induces a conformational change and reduces the enzyme's affinity for its substrate

Anabolic

(also, anabolism) pathways that require an energy input to synthesize complex molecules from simpler ones

ATP

adenosine triphosphate, the cell’s energy currency

Bioenergetics

study of energy flowing through living systems

Catabolic

(also, catabolism) pathways in which complex molecules break down into simpler ones

chemical energy

potential energy in chemical bonds that releases when those bonds are broken

Coenzyme

small organic molecule, such as a vitamin or its derivative, which is required to enhance an enzyme's activity

Cofactor

inorganic ion, such as iron and magnesium ions, required for optimal enzyme activity regulation

competitive inhibition

type of inhibition in which the inhibitor competes with the substrate molecule by binding to the enzyme's active site

Denature

process that changes a substance's natural properties

Endergonic

describes chemical reactions that require energy input

energy coupling

process during which energy released by one reaction is used to drive another reaction