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Biology > Unit 2 Test > Flashcards

Unit 2 Test Flashcards

1
Q

prokaryotic cell

A

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

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2
Q

eukaryotic cell

A

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

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3
Q

cytosol (cytoplasm)

A

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

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4
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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5
Q

cell wall

A

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

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6
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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7
Q

nuclear envelope

A

In a 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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8
Q

chromosomes

A

A cellular structure consisting of one DNA molecule and associated protein molecules. A duplicated chromosome has two DNA 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 in the 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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9
Q

chromatin

A

The complex of DNA and proteins that makes up eukaryotic chromosomes. When the cell is not dividing, chromatin 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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10
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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11
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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12
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; includes the plasma membrane, the nuclear envelope, the smooth and rough endoplasmic reticulum, the Golgi apparatus, lysosomes, vesicles, and vacuoles

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13
Q

vesicles

A

A membrane-bound sac in or outside a cell

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14
Q

smooth endoplasmic reticulum

A

portion of the endoplasmic reticulum that is free of ribosomes; network
of membranous sacs and tubes; active in
membrane synthesis and other synthetic
and metabolic processes

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15
Q

rough endoplasmic reticulum

A

portion of the endoplasmic reticulum with ribosomes attached; network
of membranous sacs and tubes; active in
membrane synthesis and other synthetic
and metabolic processes

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16
Q

golgi apparatus

A

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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17
Q

lysosome

A

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

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18
Q

vacuoles

A

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

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19
Q

mitochondria

A

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

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20
Q

chloroplast

A

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

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21
Q

peroxisome

A

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

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22
Q

cytoskeleton

A

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

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23
Q

microtubules

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, rigid

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24
Q

centrosome

A

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

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25
Q

centrioles

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 centrioles

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26
Q

cilia

A

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

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27
Q

flagella

A

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

28
Q

microfilaments

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 contraction; also called an actin filament, movement

29
Q

extracellular matrix (ECM)

A

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

30
Q

plasmodesmata

A

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

31
Q

tight junctions

A

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

32
Q

desmosomes

A

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

33
Q

gap junctions

A

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

34
Q

selective permeability

A

property of biological membranes that allows them to regulate the passage of substances across them

35
Q

amphipathic

A

Having both a hydrophilic region and a hydrophobic region

36
Q

fluid mosaic model

A

The currently accepted model of cell membrane structure, which envisions the membrane as a mosaic of protein molecules drifting laterally in a fluid bilayer of phospholipids

37
Q

phospholipid

A

lipid made up of glycerol joined to two fatty acids and a phosphate group. The hydrocarbon chains of the fatty acids act as nonpolar, hydrophobic tails, while the rest of the molecule acts as a polar, hydrophilic head. Phospholipids form bilayers that function as biological membranes

38
Q

integral protein

A

transmembrane protein with hydrophobic regions that extend into and often completely span the hydrophobic interior of the membrane and with hydrophilic regions in contact with the aqueous solution on one or both sides of the membrane (or lining the channel in the case of a channel protein)

39
Q

peripheral protein

A

protein loosely bound to the surface of a membrane or to part of an integral protein and not embedded in the lipid bilayer

40
Q

aquaporins

A

channel protein in a cellular membrane that specifically facilitates osmosis, the diffusion of free water across the membrane

41
Q

passive transport

A

diffusion of a substance across a biological membrane with no expenditure of energy

42
Q

diffusion

A

random thermal motion of particles of liquids, gases, or solids. In the presence of a concentration or electrochemical gradient, diffusion results in the net movement of a substance from a region where it is more concentrated to a region where it is less concentrated

43
Q

concentration gradient

A

region along which the density of a chemical substance increases or decreases

44
Q

osmosis

A

diffusion of free water across a selectively permeable membrane

45
Q

isotonic

A

Referring to a solution that, when surrounding a cell, causes no net movement of water into or out of the cell

46
Q

osmoregulation

A

Regulation of solute concentrations and water balance by a cell or organism

47
Q

plasmolysis

A

phenomenon in walled cells in which the cytoplasm shrivels and the plasma membrane pulls away from the cell wall; occurs when the cell loses water to a hypertonic environment

48
Q

turgid

A

Swollen or distended, as in plant cells. (A walled cell becomes turgid if it has a lower water potential than its surroundings, resulting in entry of water.)

49
Q

flaccid

A

Limp. Lacking turgor (stiffness or firmness), as in a plant cell in surroundings where there is a tendency for water to leave the cell. (A walled cell becomes flaccid if it has a higher water potential than its surroundings, resulting in the loss of water.)

50
Q

facilitated diffusion

A

passage of molecules or ions down their electrochemical gradient across a biological membrane with the assistance of specific transmembrane transport proteins, requiring no energy expenditure

51
Q

ion gated channels

A

A gated channel for a specific ion. The opening or closing of such channels may alter a cell’s membrane potential

52
Q

exocytosis

A

cellular secretion of biological molecules by the fusion of vesicles containing them with the plasma membrane

53
Q

endocytosis

A

Cellular uptake of biological molecules and particulate matter via formation of vesicles from the plasma membrane

54
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)

55
Q

pinocytosis

A

A type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes

56
Q

receptor-mediated endocytosis

A

The movement of specific molecules into a cell by the infolding of vesicles containing proteins with receptor sites specific to the molecules being taken in; enables a cell to acquire bulk quantities of specific substances

57
Q

glycolipids

A

A lipid with one or more covalently attached carbohydrates

58
Q

glycoproteins

A

A protein with one or more covalently attached carbohydrates

59
Q

transport proteins

A

A transmembrane protein that helps a certain substance or class of closely related substances to cross the membrane

60
Q

hypotonic

A

Referring to a solution that, when surrounding a cell, will cause the cell to take up water

61
Q

hypertonic

A

Referring to a solution that, when surrounding a cell, will cause the cell to lose water

62
Q

water potential

A

The physical property predicting the direction in which water will flow, governed by solute concentration and applied pressure

63
Q

active transport

A

movement of a substance across a cell membrane against its concentration or electrochemical gradient, mediated by specific transport proteins and requiring an expenditure of energy

64
Q

ion pump

A

use ATP as an energy source to transport ions against their gradients

65
Q

bulk transport

A

moves large molecules by packing them in bulk in vesicles

Biology (6 decks)

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