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Biology > Cell Structure > Flashcards

Cell Structure Flashcards

Biologists use microscopes and the tools of biochemistry to study cells. Eukaryotic cells have internal membranes that compartmentalize their functions. The eukaryotic cell's genetic instructions are housed in the nucleus and carried out by the ribosomes. The endomembrane system regulates protein traffic and performs metabolic functions in the cell. Mitochondria and chloroplasts change energy from one form to another.

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1
Q

Light Microscope (LM)

A

An optical instrument with lenses that refract (bend) visible light to magnify images of specimens

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2
Q

Organelle

A

Any of several membrane-enclosed structures with specialized functions, suspended in the cytosol of eukaryotic cells

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3
Q

Electron Microscope (EM)

A

A microscope that uses magnets to focus an electron beam on or through a specimen, resulting in a practical resolution that is 100-fold greater than that of a light microscope using standard techniques. A transmission electron microscope is used to study the internal structure of thin sections of cells. A scanning electron microscope is used to study the fine detail of cell surfaces

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4
Q

Scanning Electron Microscope (SEM)

A

A microscope that uses an electron beam to scan the surface of a sample, coated with metal atoms, to study the details of its topography

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5
Q

Transmission Electron Microscope (TEM)

A

A microscope that passes an electron beam through very thin sections stained with metal atoms and is primarily used to study the internal ultrastructure of cells

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6
Q

Cell Fractionation

A

The disruption of a cell and separation of its parts by centrifugation at successively higher speeds

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7
Q

Cytosol

A

The semifluid portion of the cytoplasm

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8
Q

Eukaryotic Cell

A

A type of cell with a membrane-enclosed nucleus and membrane-enclosed organelles. Organisms with these cells (protists, plants, fungi, and animals) are called eukaryotes

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9
Q

Prokaryotic Cell

A

A type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles. Organisms with these cells (bacteria and archaea) are called prokaryotes

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10
Q

Nucleoid

A

A non-membrane-enclosed region in a prokaryotic cell where its chromosome is located

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11
Q

Cytoplasm

A

The contents of the cell bounded by the plasma membrane; in eukaryotes, the portion exclusive of the nucleus

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12
Q

Plasma Membrane

A

The membrane at the boundary of every cell that acts as a selective barrier, regulating the cell’s chemical composition

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13
Q

Nucleus

A

The organelle of a eukaryotic cell that contains the genetic material in the form of chromosomes, made up of chromatin

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14
Q

Nuclear Envelope

A

In eukaryotic cell, the double membrane that surrounds the nucleus, perforated with pores that regulate traffic with the cytoplasm. The outer membrane is continuous with the endoplasmic reticulum

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15
Q

Nuclear Lamina

A

A netlike array of protein filaments that lines the inner surface of the nuclear envelope and helps maintain the shape of the nucleus

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16
Q

Chromosome

A

A cellular structure consisting of one DNA molecule and associated protein molecules. (In some contexts, such as genome sequencing, the term may refer to the DNA alone). A eukaryotic cell typically has multiple, linear chromosomes, which are located int he nucleus. A prokaryotic cell often has a single, circular chromosome, which is found in the nucleoid, a region that is not enclosed by a membrane

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17
Q

Chromatin

A

The complex of DNA and proteins that make up eukaryotic chromosomes. When the cell is not dividing, this exists in its dispersed form, as a mass of very long, thin fibers that are not visible with a light microscope

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18
Q

Nucleolus

A

A specialized structure in the nucleus, consisting of chromosomal regions containing ribosomal RNA (rRNA) genes along with ribosomal proteins imported from the cytoplasm; site of rRNA synthesis and ribosomal subunit assembly

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19
Q

Ribosome

A

A complex of rRNA and protein molecules that functions as a site of protein synthesis in the cytoplasm; consists of a large and a small subunit. In eukaryotic cells, each subunit is assembled in the nucleolus

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20
Q

Endomembrane System

A

The collection of membranes inside and surrounding a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles; including the plasma membrane, the nuclear envelope, the smooth and rough endoplasmic reticulum, the Golgi apparatus, lysosomes, vesicles, and vacuoles

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21
Q

Vesicle

A

A membranous sac in the cytoplasm of a eukaryotic cell

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22
Q

Endoplasmic Reticulum (ER)

A

An extensive membranous network in eukaryotic cells, continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome-free (smooth) regions

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23
Q

Smooth ER

A

The portion of the endoplasmic reticulum that is free of ribosomes

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24
Q

Rough ER

A

That portion of the endoplasmic reticulum with ribosomes attached

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25
Q

Glycoproteins

A

A protein with one or more covalently attached carbohydrates

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26
Q

Transport Vesicles

A

A small membranous sac in a eukaryotic cell’s cytoplasm carrying molecules produced by the cell

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27
Q

Golgi Apparatus

A

An organelle in eukaryotic cells consisting of stacks of flat membranous sacs that modify, store, and route products of the endoplasmic reticulum and synthesize some products, notably noncellulose carbohydrates

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28
Q

Lysosome

A

A membrane-enclosed sac of hydrolytic enzymes found in the cytoplasm of animal cells and some protists

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29
Q

Phagocytosis

A

A type of endocytosis in which large particulate substances or small organisms are taken up by a cell. It is carried out by some protists and by certain immune cells of animals (in mammals, mainly macrophages, neutrophils, and dendritic cells)

30
Q

Vacuole

A

A membrane-bounded vesicle whose specialized function varies in different kinds of cells

31
Q

Food Vacuole

A

A membranous sac formed by phagocytosis of microorganisms or particles to be used as food by the cell

32
Q

Contractile Vacuole

A

A membranous sac that helps move excess water out of certain fresh-water protists

33
Q

Central Vacuole

A

In a mature plant cell, a large membranous sac with diverse roles in growth, storage, and sequestration of toxic substances

34
Q

Mitochondrion

A

An organelle in eukaryotic cells that serves as the site of cellular respiration; uses oxygen to break down organic molecules and synthesize ATP

35
Q

Chloroplasts

A

An organelle found in plants and photosynthetic protists that absorbs sunlight and uses it to drive the synthesis of organic compounds from carbon dioxide and water

36
Q

Endosymbiont Theory

A

The theory that mitochondria and plastids, including chloroplasts, originated as prokaryotic cells engulfed by a host cell. The engulfed cell and its host cell then evolved into a single organism

37
Q

Crista

A

An infolding of the inner membrane of a mitochondrion. The inner membrane houses electron transport chains and molecules of the enzyme catalyzing the synthesis of ATP (ATP synthase)

38
Q

Mitochondrial Matrix

A

The compartment of the mitochondrion enclosed by the inner membrane and containing enzymes and substrates for the citric acid cycle, as well as ribosomes and DNA

39
Q

Thylakoid

A

A flattened, membranous sac inside a chloroplast. They often exist in stacks called grana that are interconnected; their membranes contain molecular “machinery” used to convert light energy to chemical energy

40
Q

Granum

A

A stack of membrane-bounded thylakoids in the chloroplast. They function in the light reactions of photosynthesis

41
Q

Stroma

A

The dense fluid within the chloroplast surrounding the thylakoid membrane and containing ribosomes and DNA; involved in the synthesis of organic molecules from carbon dioxide to water

42
Q

Plastid

A

One of a family of closely related organelles that includes chloroplasts, chromoplasts, and amyloplasts. They are found in cells of photosynthetic eukaryotes

43
Q

Peroxisome

A

An organelle containing enzymes that transfer hydrogen atoms from various substrates to oxygen (O2), producing and then degrading hydrogen peroxide (H2O2)

44
Q

Cytoskeleton

A

A network of microtubules, microfilaments, and intermediate filaments that extend throughout the cytoplasm and serve a variety of mechanical, transport, and signaling functions

45
Q

Motor Protein

A

A protein that interacts with cytoskeletal elements and other cell components, producing movement of the whole cell or parts of the cell

46
Q

Microtubule

A

A hollow rod composed of tubulin proteins that makes up part of the cytoskeleton in all eukaryotic cells and is found in cilia and flagella

47
Q

Centrosome

A

A structure present in the cytoplasm of animal cells that functions as a microtubule-organizing center and is important during cell division. It has two centrioles

48
Q

Centriole

A

A structure in the centrosome of an animal cell composed of a cylinder of microtubule triplets arranged in a “9+0” pattern. A centrosome has a pair of these

49
Q

Flagellum

A

A long cellular appendage specialized for locomotion. Like motile cilia, eukaryotic ones have a core with nine outer doublet microtubules (the “9+2” arrangement) ensheathed in an extension of the plasma membrane. Prokaryotic ones have a different structure

50
Q

Cilium

A

A short appendage containing microtubules in eukaryotic cells. A motile one is specialized for locomotion or moving fluid past the cell; it is formed from a core of nine outer doublet microtubules (the “9+2” arrangement) ensheathed in an extension of the plasma membrane. A primary one is usually nonmotile and plays a sensory and signaling role; it lacks the two inner microtubules (the “9+0” arrangement)

51
Q

Basal Body

A

A eukaryotic cell structure consisting of a “9+0” arrangement of microtubule triplets. This may organize the microtubule assembly of a cilium or flagellum and is structurally very similar to a centriole

52
Q

Dyneins

A

In cilia and flagella, a large motor protein extending from one microtubule doublet to the adjacent doublet. ATP hydrolysis drives changes in its shape that lead to bending of cilia and flagella

53
Q

Microfilament

A

A cable composed of actin proteins in the cytoplasm of almost every eukaryotic cell, making up part of the cytoskeleton and acting alone or with myosin to cause cell contractions; also called an actin filament

54
Q

Actin

A

A globular protein that links into chains, two of which twist helically about each other, forming microfilaments (actin filaments) in muscles and other kinds of cells

55
Q

Cortex

A

The outer region of cytoplasm in a eukaryotic cell, lying just under the plasma membrane, that has a more gel-like consistency than the inner regions due to the presence of multiple microfilaments

56
Q

Myosin

A

A type of motor protein that associates into filaments that interact with actin filaments to cause cell contractions

57
Q

Pseudopodium

A

A cellular extension of amoeboid cells used in moving and feeding

58
Q

Cytoplasmic Streaming

A

A circular flow of cytoplasm, involving interactions of myosin and actin filaments, that speeds the distribution of materials within cells

59
Q

Intermediate Filament

A

A component of the cytoskeleton that includes filaments intermediate size between microtubules and microfilaments

60
Q

Cell Wall

A

A protective layer external to the plasma membrane in the cells of plants, prokaryotes, fungi, and som protists. Polysaccharides such as cellulose (in plants and some protists), chitin (in fungi), and peptidoglycan (in bacteria) are important structural components of these

61
Q

Primary Cell Wall

A

In plants, a relatively thin and flexible layer that surrounds the plasma membrane of a young cell

62
Q

Middle Lamella

A

In plants, a thin layer of adhesive extracellular material, primarily pectins, found between the primary walls of adjacent young cells

63
Q

Secondary Cell Wall

A

In plant cells, a strong and durable matrix that is often deposited in several laminated layers around the plasma membrane and provides protection and support

64
Q

Extracellular Matrix (ECM)

A

The meshwork surrounding animal cells, consisting of glycoproteins, polysaccharides, and proteoglycans synthesized and secreted by cells

65
Q

Collagen

A

A glycoprotein in the extracellular matrix of animal cells that forms strong fibers found extensively in connective tissue and bone; the most abundant protein in the animal kingdom

66
Q

Proteoglycan

A

A large molecule consisting of a small core protein with many carbohydrate chains attached, found in the extracellular matrix of animal cells. It may consist of up to 95% carbohydrate

67
Q

Fibronectin

A

An extracellular glycoprotein secreted by animal cells that helps them attach to the extracellular membrane

68
Q

Integrin

A

In animal cells, a transmembrane receptor protein with two subunits that interconnects the extracellular matrix and the cytoskeleton

69
Q

Plasmodesma

A

An open channel through the cell wall that connects the cytoplasm of adjacent plant cells, allowing water, small solutes, and some larger molecules to pass between the cells

70
Q

Tight Junction

A

A type of intercellular junction between animal cells that prevents the leakage of material through the space between cells

71
Q

Desmosome

A

A type of intercellular junction in animal cells that functions as a rivet, fastening cells together

72
Q

Gap Junction

A

A type of intercellular junction in animal cells, consisting of proteins surrounding a pore that allows the passage of materials between cells

Biology (12 decks)

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