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AP Biology (Bob) > Cell Structure (Chapter 4) > Flashcards

Cell Structure (Chapter 4) Flashcards

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1
Q

Robert Hooke

A

first scientist to see cell walls with microscope in 1665

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2
Q

light microscope

A

visible light is passed through the specimen and then glass lens

lenses refact the light to magnify the image

maximum magnification is ~1000x

maximum resolution is about 0.2 micrometer

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3
Q

electron microscope

A

developed in the 1950s

focuses beam of electrons through specimen or on its surface

100x better than light microscope

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4
Q

transmission electron microscope (TEM)

A

aims electron beam through thin section of a specimen

specimen is stained with atoms of a heavy metals

electrons passing through are scattered more in dense areas

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5
Q

scanning electron microscope (SEM)

A

electron beam scans the surface of the sample

beam excites the electrons on the surface

secondary electrons are detected by a device

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6
Q

cell fractionalization

A

process of placing broken up cells in centrifuge

largest cell components settle to the bottom

enables researchers to use biochemical tests on specific cell parts and organelles

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7
Q

features common to all cells

A

plasma membrane: selective barrier

cytosol: semifluid, jellylike substance
chromosomes: carry genes in the form of DNA
ribosomes: tiny complexes that make proteins

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8
Q

eukaryotic cell characteristics

A

DNA in a nucleus with a double membrane

cytoplasm is the only region between nucleus and membrane

variety of organelles

tend to be larger

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9
Q

prokaryotic cell characteristics

A

DNA concentrated in nucleoid not bounded by membrane

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10
Q

factors affecting cell size

A

requirement for cellular metabolism sets lower bound on cell size

ratio of surface area to volume of cell sets upper bound on cell

volume grows proportionally bigger than surface area

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11
Q

composition of membranes

A

double layer of phospholipids and other lipids

proteins are embedded in lipid bilayer

lipids and proteins are suited to membrane functions

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12
Q

plasma membrane

A

membrane enclosing the cell

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13
Q

cytoskeleton

A

reinforces cell’s shape

functions in cell movement

components are made of protein

types are microfilaments, intermediate filaments, microtubules

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14
Q

flagellum

A

motility structure present in some animal cells

composed of a cluster of microtubules within an extension of the plasma membrane

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15
Q

nuclear envelope

A

double membrane enclosing the nucleus

each membrane is a lipid bilayer with associated proteins

seperated by a space of 20-40 nm

perforated by pores that are 100 nm in diameter

continuous with the ER

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16
Q

nucleolus

A

non-membranous structure involved in production of ribosomes

ribosomal RNA (rRNA) is synthesized

proteins from cytoplasm assembed with rRNA into ribosomes

nucleus has one or more nucleoli

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17
Q

chromatin

A

material consisting of DNA and proteins

appears as diffuse mass

visible in a dividing cell as individual condensed chromosomes

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18
Q

ribosomes

A

complexes that synthesize proteins

free in cytosol or bound to rough ER or nuclear envelope

bound ribosomes make proteins for:

insertion in membranes

packaging within certain organelles such as lysosomes

export from the cell (secretion)

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19
Q

golgi apparatus

A

organelle active in synthesis, modification, sorting, and secretion of cell products

consists of flattened membranous sacs called cisternae

golgi stack has distinct structural directionality: cis face receives, trans face ships

manufactures some macromolecules

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20
Q

lysosome

A

digestive organelle where macromolecules are hydrolyzed

acidic environment that is not ctive in cytosol

only in animal cells

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21
Q

mitochondrion

A

organelle where cellular respiration occurs and most ATP is generated

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22
Q

peroxisome

A

organelle with various specialized metabolic functions

produces hydrogen peroxide as a by-product then converts it to water

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23
Q

microvilli

A

projections that increase the cell’s surface area

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24
Q

centrosome

A

region where the cell’s microtubules are initiated

contains a pair of centrioles

only in animal cells

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25
Q

endoplasmic reticulum

A

network of membranous sacs and tubes

active in membrane synthesis and other synthetic and metabolic processes

has rough (ribosome studded) and smooth regions (lacks ribosomes)

26
Q

centrole vacuole

A

prominent organelle only in older plant cells

functions include storage, breakdown of waste products, hydrolysis of macromolecules

enlargement of vacuole is a major mechanism of plant growth

only in plant cells

27
Q

chloroplast

A

photosynthetic organelle

converts energy of sunlight to chemical energy stored in sugar molecules

only in plant cells

28
Q

plasmodesmata

A

channels through cell walls that connect the cytoplasms of adjacent cells

only in plant cells

29
Q

cell wall

A

outer layer that maintains cell’s shape and protects the cell from mechanical damage

made of cellulose, other polysaccharides, and protein

primary cell wall and secondary cell wall

only in plant cells

30
Q

nucleus

A

contains most of the genes in the eukaryotic cell

most conspicuous cell; averages 5 µm in diameter

includes nuclear envelope, pore complex, nuclear lamina, chromosomes, chromatin, nucleolus

31
Q

pore complex

A

protein structure that lines each pore

regulates entry and exit of proteins and RNAs

32
Q

nuclear lamina

A

lines nuclear side of nuclear envelope

netlike array of protein filaments that maintain shape of nucleus

33
Q

chromosomes

A

discrete unit of DNA in the nucleus

carry genetic information

each contains one long DNA molecule associated with proteins

34
Q

messenger RNA (mRNA)

A

sythesized by the nucleus

transported to cytoplasm

translated by ribosomes into specific polypeptides

35
Q

functions of smooth ER

A

synthesis of lipids including oils, phospholipids, steroids

detoxify drugs and poisons especially in liver cells

detoxification involves adding hydroxyl groups to drugs

stores calcium ions

36
Q

functions of rough ER

A

secretes proteins (glycoproteins) produced by ribosomes attached to rough ER

polypeptide chain grows from a bound ribosome

chain is threaded into the ER lumen through a pore

polypeptide folds into its functional share

37
Q

phagocytosis

A

process of surrounding smaller organism

38
Q

autophagy

A

recycle cell’s own organic mateiral

39
Q

contractile vacuole

A

pump excess water out of the cell

maintain suitable conditions for ions and molecules

common in freshwater protists

40
Q

endosymbiont theory

A

early ancestor of eukaryotic cells

engulfed energy using non-photocynthetic prokaryotic cell

eventually becomingendosymbiont (cell within another cell)

consistent with characteristics: two membrans, contain ribosomes and DNA

41
Q

mitrochondrial matrix

A

enclosed by inner membrane of mitochondria

contains many different enzymes and mitochondrial DNA

catalyze some of the steps of cellular respiration

large surface area of inner membrane increases productivity

42
Q

thylakoids

A

membrane system inside the chloroplast

flattened, interconnected sacs

granum: stacks of thylakoids
stroma: fluid outside the thylakoid containing chloroplast DNA

43
Q

types of plastids

A

chloroplast

amyloplast: colorless organelle that stores starch
chromoplast: pigments in fruits and flowers

44
Q

peroxisomes

A

specialized metabolic compartment bounded by a single membrane

45
Q

microtubules

A

hollow rods constructed from globular portein called tubulin

tubulin protein is a dimer – molecule made of two subunits

serves as track for organelles with motor proteins

grow out from centrosomes and centrioles

46
Q

cilia and flagella

A

microtubule-containing extensions of some cells

flagella drive the cell through liquid

cilia can drive the cell or move objects along surface of cell

47
Q

9+2 pattern

A

nine doublets of microtubules are arranged in a ring

two single microtubules in the center

48
Q

9+0 pattern

A

nine doublets of microtubules are arranged in ring

no microtubules in center

non-motile primary cilia

49
Q

basal body

A

anchors the cilium or flagellum in the cell

50
Q

dyneins

A

large motor proteins that cause bending

two feet walk along the microtubule

one foot maintains contact while the other moves

51
Q

microfilaments

A

thin solid rods built from actin moelcules, granular protein

bear tension and support muscle contraction

52
Q

intermediate filaments

A

larger than microfilaments, smaller than microtubules

maintain cell shape

anchor nucleus and othe organelles

formation of nuclear lamina

53
Q

extracellular matrix (ECM)

A

made of glycoproteins and other carbohydrate containing molecules

collegen is one of most abundant glycogens

forms strong fibers outside the cell

54
Q

integrins

A

membrane proteins with two subunits

bind to the ECM on one side and to associated proteins attached to microfilaments

55
Q

fibronectin

A

attaches the ECM to integrins embedded in the plasma membrane

56
Q

collagen

A

fibers are embedded in a web of proteoglycan complexes

57
Q

plasmodesmata

A

type of cell junction in plant cells

perforates cell walls

membrane lined channel filled with cytosol

joins adjacent cells and unifies plant into single organism

water and small solutes can pass freely

58
Q

tight junction

A

plasma membrane of neighboring cells are very tightly pressed together

bound together by specific proteins and forming a continuous seal

59
Q

desmosomes

A

funtion like rivets to fasten cells together in strong sheets

intermediate filaments made of strudy keratin proteins anchor desmosomes

attach muscle cells to each other muscle

60
Q

gap junction

A

provide cytoplasmic channels from one cell to an adjacent cell

consist of membrane proteins that surround a pore

ions, sugars, amino acids and other small molecules can pass

AP Biology (Bob) (3 decks)

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