Biological Science, Chapter 7 Inside The Cell

Front 1

Morphology

Back 1

The shape and appearance of an organism's body and its component parts.

Front 2

Chromosome

Back 2

Gene-carrying structure consisting of a single long molecule of DNA and associated proteins (e.g., histones). Most prokaryotic cells contain a single, circular chromosome; eukaryotic cells contain multiple noncircular (linear) chromosomes located in the nucleus.

Front 3

Gene

Back 3

A section of DNA (or RNA, for some viruses) that encodes information for building one or more related polypeptides or functional RNA molecules along with the regulatory sequences required for its transcription.

Front 4

Nucleoid

Back 4

In prokaryotic cells, a dense, centrally located region that contains DNA but is not surrounded by a membrane.

Front 5

Plasmid

Back 5

A small, usually circular, supercoiled DNA molecule independent of the cell's main chromosome(s) in prokaryotes and some eukaryotes.

Front 6

Ribosome

Back 6

A large complex structure that synthesizes proteins by using the genetic information encoded in messenger RNA strands. Consists of two subunits, each composed of ribosomal RNA and proteins.

Front 7

Organelle

Back 7

Any discrete, membrane-bound structure within a cell (e.g., mitochondrion) that has a characteristic structure and functions.

Front 8

Cytoskeleton

Back 8

In eukaryotic cells, a network of protein fibers in the cytoplasm that are involved in cell shape, support, locomotion, and transport of materials within the cell. Prokaryotic cells have a similar but much less extensive network of fibers.

Front 9

Cytoplasm

Back 9

All of the contents of a cell, excluding the nucleus, and bounded by the plasma membrane.

Front 10

Flagellum

Back 10

A long, cellular projection that undulates (in eukaryotes) or rotates (in prokaryotes) to move the cell through an aqueous environment.

Front 11

Glycolipid

Back 11

Any lipid molecule that is covalently bonded to a carbohydrate group.

Front 12

Nucleus

Back 12

The large, membrane-bounded organelle that contains the genetic material, in the form of multiple linear DNA molecules organized into structures called chromosomes.

Front 13

Nuclear Envelope

Back 13

The doubled-layered membrane enclosing the nucleus of a eukaryotic cell.

Front 14

Nuclear Lamina

Back 14

The double-layered membrane enclosing the nucleus of a eukaryotic cell.

Front 15

Nucleolus

Back 15

In eukaryotic cells, specialized structure in the nucleus where ribosomal RNA processing occurs and ribosomal subunits are assembled.

Front 16

Endoplasmic Reticulum (ER)

Back 16

A network of interconnected membranous sacs and tubules found inside eukaryotic cells

Front 17

Rough ER

Back 17

The portion of the endoplasmic reticulum that is dotted with ribosomes. Involved in synthesis of plasma membrane proteins, secreted proteins, and proteins localized to the ER, Golgi apparatus, and lysosomes.

Front 18

Lumen

Back 18

The interior space of any hollow structure (e.g., the rough ER) or organ (e.g., the stomach).

Front 19

Smooth ER

Back 19

The portion of the endoplasmic reticulum that does not have ribosomes attached to it. Involved in synthesis and secretion of lipids.

Front 20

Golgi Apparatus

Back 20

A eukaryotic organelle, consisting of stacks of flattened membranous sacs (cisternae), that functions in processing and sorting proteins and lipids destined to be secreted or directed to other organelles.

Front 21

Cisterna

Back 21

A space containing fluid, such as those occurring between the membranes of flattened sacs of the Golgi apparatus and the endoplasmic reticulum, also between the two membranes of the nuclear envelope.

Front 22

Cytosol

Back 22

The fluid portion of the cytoplasm.

Front 23

Perixosome

Back 23

A cell organellecontaining catalase, peroxidase, and other oxidative enzymes and performingessential metabolic functions, as the decomposition of fatty acids and hydrogenperoxide.

Front 24

Glyoxysome

Back 24

Specialized type of peroxisome found in plant cells and packed with enzymes for processing the products of photosynthesis.

Front 25

Lysosome

Back 25

A small organelle in an animal cell containing acids and enzymes that catalyze hydrolysis reactions and can digest large molecules.

Front 26

Autophagy

Back 26

The process by which damaged organelles are surrounded by a membrane and delivered to a lysosome to be destroyed.

Front 27

Phagocytosis

Back 27

Uptake by a cell of small particles or cells by pinching off the plasma membrane to form small membrane-bound vesicles; one type of endocytosis.

Front 28

Receptor Mediated Endocytosis

Back 28

Uptake by a cell of certain extracellular macromolecules, bound to specific receptors in the plasma membrane, by pinching off the membrane to form small membrane-bound vesicles.

Front 29

Early Endosome

Back 29

A small membrane-bound vesicle, formed by endocytosis, that is an early stage in the formation of a lysosome.

Front 30

Late Endosome

Back 30

A membrane-bound vesicle that arises from an early endosome and develops into a lysosome.

Front 31

Endocytosis

Back 31

General term for any pinching off of the plasma membrane that results in the uptake of material from outside the cell. Includes phagocytosis, pinocytosis, and receptor-mediated endocytosis.

Front 32

Pinocytosis

Back 32

Uptake by a cell of extracellular fluid by pinching off the plasma membrane to form small membrane-bound vesicles; one type of endocytosis.

Front 33

Endomembrane System

Back 33

A system of organelles in eukaryotic cells that performs most protein and lipid synthesis. Includes the endoplasmic reticulum (ER), Golgi apparatus, and lysosomes.

Front 34

Vacuole

Back 34

A large organelle in plant and fungal cells that usually is used for bulk storage of water, pigments, oils, or other substances. Some vacuoles contain enzymes and have a digestive function similar to lysosomes in animal cells.

Front 35

Mitochondria

Back 35

A eukaryotic organelle that is bounded by a double membrane and is the site of aerobic respiration.

Front 36

Cristae

Back 36

Sac-like invaginations of the inner membrane of a mitochondrion. Location of the electron transport chain and ATP synthase.

Front 37

Mitochondrial Matrix

Back 37

Central compartment of a mitochondrion, which is lined by the inner membrane; contains the enzymes and substrates of the Krebs cycle and mitochondrial DNA.

Front 38

Plastids

Back 38

A double membrane bound organelle involved in the synthesis and storage of food, and is commonly found within the cells of photosynthetic organisms, like plants.

Front 39

Chloroplasts

Back 39

A chlorophyll-containing organelle that is bounded by a double membrane and in which photosynthesis occurs; found in most plant and algal cells. Also the location of amino acid, fatty acid, purine, and pyrimidine synthesis.

Front 40

Thylakoids

Back 40

A flattened, membrane-bound vesicle inside a plant chloroplast that functions in converting light energy to chemical energy. A stack of thylakoids is a granum.

Front 41

Grana

Back 41

In chloroplasts, a stack of flattened, membrane-bound vesicles (thylakoids) where the light reactions of photosynthesis occur.

Front 42

Stroma

Back 42

The fluid matrix of a chloroplast in which the thylakoids are embedded. Site where the Calvin cycle reactions occur.

Front 43

Differential Centrifugation

Back 43

Procedure for separating cellular components according to their size and density by spinning a cell homogenate in a series of centrifuge runs. After each run, the supernatant is removed from the deposited material (pellet) and spun again at progressively higher speeds.

Front 44

Nuclear Pores

Back 44

An opening in the nuclear envelope that connects the inside of the nucleus with the cytoplasm and through which molecules such as mRNA and some proteins can pass.

Front 45

Nuclear Pore Complex

Back 45

A large complex of dozens of proteins lining a nuclear pore, defining its shape and transporting substances through the pore.

Front 46

Ribosomal RNA (rRNA)

Back 46

The RNA component of the ribosome, and is essential for protein synthesis in all living organisms.

Front 47

Messenger RNA (mRNA)

Back 47

An RNA molecule that carries encoded information, transcribed from DNA, that specifies the amino acid sequence of a polypeptide.

Front 48

Virus

Back 48

Anyof various submicroscopic agents that infect living organisms, often causingdisease, and that consist of a single or double strand of RNA or DNA surroundedby a protein coat. Unable to replicate without a host cell, viruses aretypically not considered living organisms.

Front 49

Nuclear Localization Signal

Back 49

A short amino acid sequence that marks a protein for delivery to the nucleus.

Front 50

Pulse Chase Experiment

Back 50

A type of experiment in which a population of cells or molecules at a particular moment in time is marked by means of a labeled molecule and then their fate is followed over time.

Front 51

ER Signal Sequence

Back 51

A short amino acid sequence that marks a polypeptide for transport to the endoplasmic reticulum where synthesis of the polypeptide chain is completed and the signal sequence removed.

Front 52

Signal Recognition Particle

Back 52

A RNA-protein complex that binds to the ER signal sequence in a polypeptide as it emerges from a ribosome and transports the ribosome-polypeptide complex to the ER membrane where synthesis of the polypeptide is completed.

Front 53

Glycosylation

Back 53

Addition of a carbohydrate group to a molecule.

Front 54

Actin Filament

Back 54

A long fiber, about 7 nm in diameter, composed of two intertwined strands of polymerized actin protein; one of the three types of cytoskeletal fibers. Involved in cell movement. Also called a microfilament.

Front 55

Actin

Back 55

A globular protein that can be polymerized to form filaments. Actin filaments are part of the cytoskeleton and constitute the thin filaments in skeletal muscle cells.

Front 56

Motor Protein

Back 56

A class of proteins whose major function is to convert the chemical energy of ATP into motion. Includes dynein, kinesin, and myosin.

Front 57

Cytokenesis

Back 57

Division of the cytoplasm to form two daughter cells. Typically occurs immediately after division of the nucleus by mitosis or meiosis.

Front 58

Cytoplasmic Streaming

Back 58

The directed flow of cytosol and organelles that facilitates distribution of materials within some large plant and fungal cells. Occurs along actin filaments and is powered by myosin.

Front 59

Intermediate Filament

Back 59

A long fiber, about 10 nm in diameter, composed of one of various proteins (e.g., keratins, lamins); one of the three types of cytoskeletal fibers. Form networks that help maintain cell shape and hold the nucleus in place.

Front 60

Nuclear Lamins

Back 60

Intermediate filaments that make up the nuclear lamina layer-a lattice?like layer inside the nuclear envelope that stiffens the structure.

Front 61

Microtubule

Back 61

A long, tubular fiber, about 25 nm in diameter, formed by polymerization of tubulin protein dimers; one of the three types of cytoskeletal fibers. Involved in cell movement and transport of materials within the cell.

Front 62

Dimers

Back 62

An association of two molecules, which may be identical (homodimer) or different (heterodimer).

Front 63

Microtubule Organizing Center

Back 63

General term for any structure (e.g., centrosome and basal body) that organizes microtubules in cells.

Front 64

Centrosome

Back 64

Structure in animal and fungal cells, containing two centrioles, that serves as a microtubule-organizing center for the cell's cytoskeleton and for the mitotic spindle during cell division.

Front 65

Centriole

Back 65

One of two small cylindrical structures, structurally similar to a basal body, found together within the centrosome near the nucleus of a eukaryotic cell.

Front 66

Kinesin

Back 66

Any one of a class of motor proteins that use the chemical energy of ATP to transport vesicles, particles, or chromosomes along microtubules.

Front 67

Cilia

Back 67

One of many short, filamentous projections of some eukaryotic cells containing a core of microtubules. Used to move the cell and/or to move fluid or particles along a stationary cell.

Front 68

Axoneme

Back 68

A structure found in eukaryotic cilia and flagella and responsible for their motion; composed of two central microtubules surrounded by nine doublet microtubules (9 + 2 arrangement).

Front 69

Basal Body

Back 69

A structure of nine pairs of microtubules arranged in a circle at the base of eukaryotic cilia and flagella where they attach to the cell. Structurally similar to a centriole.

Front 70

Dynein

Back 70

A class of motor proteins that use the chemical energy of ATP to “walk” along an adjacent microtubule. Dyneins are responsible for bending of cilia and flagella, play a role in chromosome movement during mitosis, and can transport certain organelles.