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Biology 1113 > Chapter 6 - A Tour of the Cell > Flashcards

Chapter 6 - A Tour of the Cell Flashcards

1
Q

what is found in all cells?

A

ribosomes

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2
Q

what is found in eukaryotic but not prokaryotic cells?

A

endomembrane system

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3
Q

what is a structure is found only in prokaryotic cells?

A

nucleoid

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4
Q

what are the 3 domains of life?

A

1) bacteria
2) archaea
3) eukarya

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5
Q

what falls under the domain of prokaryotes?

A

domain of bacteria and archaea

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6
Q

what falls under the domain of eukarya?

A

literally everything else

plants, animals, fungi, protists

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7
Q

what features do ALL cells share?

A

1) plasma membrane (selective barrier)
2) cytosol (fluid in plasma membrane)
3) chromosomes (carry genes in form of DNA)
4) ribosomes (make proteins)

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8
Q

where is the DNA in a eukaryotic cell?

A

the nucleus - bound by a double membrane called the nuclear envelope

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9
Q

where is the DNA in a prokaryotic cell?

A

nucleoid - a region that is not membrane-enclosed

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10
Q

what are the components of a prokaryotic cell?

A

1) fimbriae (attachment structures on the surface)
2) nucleoid
3) ribosomes
4) ribosomes)
5) plasma membrane (encloses cytoplasm)
6) capsule (outer coating)
7) flagella

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11
Q

what is the cytoplasm?

A

refers to the interior of either type of cell

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12
Q

what is the cytoplasm in a eukaryotic cell?

A

the region between the nucleus and the plasma membrane - does not include the nucleus!

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13
Q

what is the cytosol?

A

a component of eukaryotic cells inside the cytoplasm that suspends organelles

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14
Q

do prokaryotic cells have membrane bound organelles?

A

no

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15
Q

what is the plasma membrane?

A

a selective membrane that function as a selective barrier that allows passage of enough oxygen, nutrients, and wastes

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16
Q

surface area and volume relationship?

A

for each square micrometer of plasma membrane, only a limited amount of a particular substance can cross per second so the ratio of surface area to volume is critical

as a cell increases in size its SA grow proportionately less than its volume –> smaller objects have a greater ratio of SA:volume

microvilli increase SA without really increasing volume

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17
Q

what is the cytoplasm in a prokaryotic cell?

A

cytoplasm is everything found inside the plasma membrane (including nucleoid)

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18
Q

are prokaryotic or eukaryotic cells bigger?

A

eukaryotic cells are generally much larger than prokaryotic cells

eukaryotic cells: 10-100 micrometers
prokaryotic: 1-5 micrometers/.1-1

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19
Q

how do we study cells?

A

light microscopy, electron microscopy, unaided eye

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20
Q

what is magnification?

A

size relative to actual specimen

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21
Q

what is resolution?

A

measure of the clarity, minimum distance of two distinguishable points

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22
Q

what is cell fractionation?

A

it takes apart and separates major organelles and other sub cellular structure from one another

does this by size and density with a centrifuge

enables scientists to determine the functions of organelles through further biochemistry and cytology

you can correlate cell function with structure - by separating one organelle from another, you can do biochemical analysis to test what these components of the cell are doing and allows you to correlate cell function with structure

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23
Q

what is the plasma membrane of a eukaryotic cell made of?

A

made of double layer of phospholipids and proteins

proteins are embedded in the lipid bilayer - proteins are important because they help with membrane transport (channel protein needed so hydrophilic molecules can cross hydrophobic lipid bilayer)

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24
Q

which organelle functions in cellular respiration?

A

mitochondria

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25
Q

structure of animal vs. plan cells?

A

check out pg. 100 in the book, it’s awesome

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26
Q

what is the nuclear envelope?

A

it encloses the nucleus and separates its contents from the cytoplasm = it’s a double membrane of two lipid bilayers

perforated by pore structure

nucleus | nuclear envelope | cytoplasm

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27
Q

what is the nuclear pore complex?

A

a protein* structure called a pore complex lines each pore and regulates the entry and exit of proteins and RNA

at the lip of each pore in the nuclear envelope, the inner and outer membranes of the nuclear envelope are continuous

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28
Q

what is the nuclear lamina?

A

the inner side of the envelope is lined by the nuclear lamina which is an array of protein* filaments that maintains the shape of the nucleus by supporting the nuclear envelope - supports cytoskeleton

the nuclear lamina is thought to help organize the DNA within the nucleus

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29
Q

what are chromosomes

A

structures that carry genetic information of DNA

structure consisting of one, tightly coiled DNA molecule and associated proteins. Formed when cell is ready to divide

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30
Q

what is chromatin?

A

The complex of DNA and proteins that makes up chromosomes

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31
Q

how many chromosomes does a human cell have?

A

46

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32
Q

what are the components of a eukaryotic cell? what do they do?

A

1) plasma membrane
2) cytoskeleton: the structural frame work of the cell and tracks for transporting cargo
3) mitochondria: makes ATP molecules
4) nucleus and ribosomes: DNA is structurally arranged in nucleus

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33
Q

what is used to make mRNA?

A

DNA

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34
Q

what is the nucleolus? (nucleoli)

A

distinct structure where rRNA (ribosomal RNA) is transcribed and ribosomes are assembled

ribosomal proteins imported from the cytoplasm are assembled with rRNA into large and small subunits of ribosomes –> subunits exit nucleus through nuclear pores into the cytoplasm where a large and small subunit can assemble into a ribosome

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35
Q

what is rRNA?

A

ribosomal RNA

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36
Q

what is the nucleus?

A

contains most of the cell’s genes

mitochondria and chloroplast also house genes

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37
Q

where else can DNA be found in the cell?

A

mitochondria and chloroplasts

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38
Q

what is a nucleosome

A

1 unit of chromatin consisting of histones and coiled DNA

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39
Q

what are ribosomes?

A

complexes made of rRNA and ribosomal proteins than carry out the synthesis of proteins

not membrane bound = not organelles

they are free in the cytosol or bound to the rough ER/nuclear envelope

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40
Q

are ribosomes organelles?

A

no! because they are not membrane bound

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41
Q

general structure of a cell

A

nucleus | cytoplasm (cytosol) | plasma membrane

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42
Q

what is in the nucleus?

A

chromatin, nucleuolus, nuclear lamina

nuclear pores, nuclear envelope envelope the nucleus

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43
Q

ribosomes build proteins in two cytoplasmic locales. what are they?

A

free ribosomes are suspended in the cytosol, nucleus, mitochondria

membrane bound ribosomes are attached to the rough ER or nuclear envelope

bound and free ribosomes are structurally identical and cal alternate between the two roles

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44
Q

what kinds of proteins do free ribosomes usually make?

A

the proteins usually function within the cytosol

ex. like the enzymes that catalyze sugar break down
ex. nuclear histome

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45
Q

what kind of proteins do membrane bound ribosomes usually make?

A

1) proteins that are destined for insertion into membranes
2) proteins for packing within certain organelles such as lysosomes
3) secretion (insulin)

ex. digestive enzymes released into the gut, insulin receptor protein (on membrane), antibodies in the blood, collagen (found in extra-cellular matrix)

46
Q

what are the parts of the endomembrane system?

A

1) nuclear envelope
2) endoplasmic reticulum
3) golgi apparatus
4) lysosomes
5) vesicles/vacuoles
6) plasma membrane

Please Never Eat Gross Lettuce Vallory

47
Q

what does endomembrane system do?

A
  • synthesis, modification, and transport of proteins going to the membranes, organelles, or out of the cell
  • metabolism and movement of lipids
  • detoxification of poisons
48
Q

what are vesicles?

A

sacs made of membrane

the membranes of the endomembrane system are related either through direct continuity or by the transfer of the membrane segments as tiny vesicles

the various membranes are not identical in structure and function!

characteristics of a given membrane can be modified during the membrane’s life (thickness, compositions, types of chemical rxn)

49
Q

What is the ER?

A

extensive network of membranes that counts for more than half the total membrane in many eukaryotic cells

consists of a network of membranous tables/sacs called cisternae

ER membrane is continuous with the nuclear envelope so the space between the two membranes of the envelope is continuous with the lumen of the ER

50
Q

what are the function of the smooth ER?

A
  • synthesis of lipids (steroids)
  • metabolism of carbohydrates
  • detoxification of drugs and poisons
  • storage of calcium ions (in ER lumen)

not studded with ribosomes, translation doesn’t occur here

51
Q

what is the ER lumen?

A

the internal compartment of the ER - a cavity/space

52
Q

what are glycoproteins?

A

most secretory proteins from the rough ER are glycoproteins: proteins with carbohydrates covalently bonded to them

the carbohydrates are attached to the proteins in the ER lumen by enzymes built into the ER membrane

53
Q

what are transport vesicles?

A

vesicles in transit from one part of the cell to another

secretory proteins depart from the rough ER in the membranes of vesicles from the transitional ER

54
Q

what are the functions of the rough ER?

A
  • makes secretory proteins
  • helps with protein folding
  • glycosylation
  • source of new membrane

it’s a membrane factory: grows in place by adding membrane proteins and phospholipids to its own membrane then it expands are portions of it are transferred in the form of transport vesicles to other components of the endomembrane system

  • makes membrane phospholipids
55
Q

what is the golgi apparatus?

A

a warehouse for receiving, sorting, shipping, and manufacturing

products of the ER (like proteins) are modified and stored then sent to other destinations

located close to ER but not connected membrane wise

56
Q

what are the two distinct sides of the golgi apparatus?

A

cis: receiving side
trans: shipping side

cis is usually located near the ER so transport vesicles move material from the ER to the golgi membrane

57
Q

what does the golgi modify?

A

products of the ER are usually modified during their transit from cis to trans region of golgi

modifies: carbohydrates by changing sugar substitutes, membrane phospholipids

58
Q

how does the golgi sort it’s products before sending from the trans side?

A

1) molecular identification tags such as phosphate groups are kind of like zip codes
2) transport vesicles budded from the golgi may have external molecules on their membrane that recognize “docking sites” on the surface of specific organelles or on the plasma membrane

59
Q

what are the function of the golgi?

A

1) modification of proteins (further glycosylation)
2) modification of phospholipids by carbohydrates
3) polysaccharide synthesis
4) sorting and release of products into vesicles

golgi pinches off transport vesicles that give rise to lysosomes, other types of specialized vesicles, and vacuoles

60
Q

What is a likely function of a cell with an extensive Golgi apparatus?

A

High levels of protein secretion

61
Q

what is a lysosome? what does it do?

A

vesicles that have digestive enzymes in them - enzymes used to break down macromolecules

62
Q

when do lysosomal enzymes work best?

A

in the acidic environment - which just so happens to be found in lysozomes

63
Q

where are hydrolytic enzymes and the lysosomal membrane made?

A

made by the rough ER and are then transferred to the golgi for more processing

64
Q

what is phagocytosis?

A

the engulfing of smaller organism/food particles

the food vacuole is formed then fuses with the lysosome whose enzymes digest the food

65
Q

what are some of the products that are digested by the lysosome? what happens to them?

A

simple sugars, amino acids, other monomers

they pass into the cytosol and become nutrients for the cell

66
Q

what are macrophages?

A

a type of white blood cell that helps defend the body by engulfing and destroying bacteria through phagocytosis and lysosomes

67
Q

what is autophagy?

A

when lysosomes use their hydrolytic enzymes to recycle the cell’s own organic material

damaged organelle or small amounts of cytosol become surrounded by a double membrane and a lysosome fuses with the outer membrane of this vesicle while the inner membrane is degraded along with the damaged organelles –> resulting compound releasing into cytosol

cell renews itself!

68
Q

what are vacuoles?

A

large vesicles formed from the ER and golgi

vacuole membrane is selective so the solution inside a vacuole differs in composition from the cytosol

69
Q

what are contractile vacuoles?

A

pump excess water out of the cell = maintain suitable concentration of ions and molecules inside the cell

70
Q

what is the function of vacuoles?

A

1) cell growth

2) protection (by storing compounds that are poisonous) 3) storage (proteins in seeds)

71
Q

what is a central vacuole?

A

plant cells have a central vacuole which helps with cell growth and allows cell to be bigger without having to use up a lot of expensive nutrients

72
Q

what is the pathway of proteins that are going to be secreted?

A

rough ER —> golgi apparatus —> plasma membrane (fuses and secretes)

73
Q

what are the two structure in eukaryotic cells that convert energy to forms that a cell can use for work?

A

1) mitochondria

2) chloroplasts (plants/algae)

74
Q

what are mitochondria?

A

sites of cellular respiration

the metabolic process that uses oxygen to drive the generation of ATP by extracting energy from sugars, fats, etc

75
Q

what is cellular respiration?

A

the metabolic process that uses oxygen to drive the generation of ATP by extracting energy from sugars, fats, etc

76
Q

what are cholorplasts?

A

sites of photosynthesis:
process that converts solar energy into chemical energy

mitochondria then uses this energy to make ATP

77
Q

what is the endosymbiont theory?

A

the theory that an early eukaryotic cell engulfed an Roxy-gen using non-photsynthetic cell –> they formed a relationship and eventually merged into a single organism = a eukaryotic cell with a mitochondrion –> then this cell also took up a photosynthetic prokaryote = has chloroplasts

makes sense because it explains many structural features of mitochondria and chloroplasts:

  • double membranes (organelles of endomembrane system have single membrane)
  • contain ribosomes and circular DNA associated w/ their inner membrane
  • autonomous organelles (able to grow in size and reproduce within cell)
78
Q

how many mitochondria does a cell have?

A

based on activity

more active = 100’s, 1000’s (muscles)
less active = 1, 2 etc

79
Q

how many layers enclose the mitochondria and what are they?

A

2 phospholipid bilayers w/ embedded proteins

outer membrane is smooth
inner membrane is convoluted with infolding called cristae = gives inner membrane large SA

80
Q

what does the inner membrane of the mitochondria do?

A

it divides the mitochondrion into two internal compartments

1) inter membrane space (region between inner and outer membranes)
2) mitochondrial matrix (it’s enclosed by the inner membrane)

81
Q

why are cristae important?

A

extensive foldings = it increases surface area which is important because electron transport chains (carries out production of ATP) –> high surface to volume ratio means lots of oxidative phosphorylation can happen

82
Q

what happens in the mitochondrial matrix? where is it located?

A

inside/enclosed by the inner membrane

where Krebb’s cycle occurs
contains ribosomes
contains mtDNA

83
Q

what is the thylakoid?

A

flat, interconnected sacs. membrane contains chlorophyll in the chloroplast

84
Q

what are plastids?

A

family of specialized organelles. includes chloroplasts, amyloplasts (starch storage), elaioplasts (lipid storage) - not all sites have different kinds of plastids

85
Q

the membranes of the chloroplast dive the chloroplast space into 3 compartments. what are they?

A

1) inter membrane space
2) storma
3) thylakoid

86
Q

what is a geranum?

A

stack of thylakoid

87
Q

what is the stroma?

A

fluid outside of thylakoids, contains DNA, ribosomes, enzymes; (Calvin cycle: ATP —> sugars)

88
Q

what is a peroxisome?

A

a specialized metabolic compartment bound by a single membrane

contain enzymes that remove hydrogen atoms from various substrates and transfer them to O2 producing H2O2

89
Q

what is the cytoskeleton?

A

a network of fibers extending through the cytoplasm

plays a major role in organizing the structures and activities of the cell

90
Q

what are the three molecular structures in the cytoskeleton?

A

1) microtubules
2) microfilaments
3) intermediate filaments

91
Q

what are the functions of the cytoskeleton?

A

1) give support to the cell and maintain its shape
(important for plants that lack cell walls)
very dynamic - can be dismantled in one part of the
cell and reassembled in a new location = changes
shape of cell

2)cell motility
requires interaction of the cytoskeleton with motor
proteins

3) manipulated plasma membrane
bends it inward to form food vacuoles

92
Q

what are the thickest and thinest components of the cytoskeleton?

A

microtubules are the thickest

microfilaments are the thinnest (aka actin filaments)

intermediate filaments are middle range

93
Q

what are microtubules?

A

components of the cytoskeleton - hollow rods constructed from a globular protein called tubulin*

94
Q

tubulin

A

forms microtubules

each tubulin protein is a dimer: a molecule made up of two subunits - each dimer consists of two slightly different polypeptides: alpha and beta tubulin

95
Q

what is the function of microtubules?

A
  • shape and support the cell
  • serve as tracks along which organelles w/ motor proteins can move
  • guide vesicles from the ER to the golgi and from the golgi to the plasma membrane
  • involved in separation of chromosomes during cell division
  • cell motility: cilia and flagella
96
Q

what is a centrosome?

A

in animal cells, microtubules grow out from a centrosome - often located near nucleus

97
Q

what are centrioles?

A

within the centrosome is a pair of centrioles, each composed to nine sets of triplet microtubules arranged in a ring

centrome is like the pack of straws
centriole is a set of triplet straw in a star ring
the microtubule is the straw

98
Q

what are flagella and cilia?

A

in eukaryokes, a specialized arrangement of microtubules is responsible for flagella and cilia

cilia: rowing movement, large numbers
flagella: swimming movement, 1 or a few/cell

99
Q

what are microfilaments?

A

thin solid rods that are part of the cytoskeleton

built from molecules of actin (globular polymer protein)

twisted double chain of actin* subunits

structural role is to bear tension (pulling forces)

well known for their role in cell motility: actin and myosin cause contractions of muscle cells

100
Q

which parts of the cytoskeleton are found in all eukaryotic cells?

A

microtubles and microfilaments

intermediate filaments are only found in the cells of some animals including vertebrates

101
Q

what are intermediate filaments?

A

fibrous proteins coiled into cables

diverse in shape and size

keratin*

inside of nuclear envelope is made of intermediate filaments

102
Q

what are the function is microfilaments?

A
  • maintenance of cell shape (tension bearing)
  • changes in cell shape
  • muscle contraction (actin/myosin)
  • cytoplasmic streaming in plant cells
103
Q

what are the functions of intermediate filaments?

A
  • maintenance of cell shape
  • anchorage of nucleus/other organelles
  • formation of nuclear lamina
104
Q

what is the cell wall?

A
  • component of cell that only exists in some cells

ex. plants, fungi, unicellular eukaryotes, most bacteria

105
Q

what is the cell wall made of in plants?

A

cellulose fibers and other polysaccharides and proteins

106
Q

what is the cell wall made of in bacteria?

A

peptidoglycan (polymers of sugars and amino acids)

107
Q

what are plasmodesmata?

A

channels that exists between adjacent plant cells that let water and small solutes (proteins, RNA) pass from cell to cell

108
Q

what is the extra cellular matrix?

A

matrix outside and between animal cells
made up of glycoprotein (protein modified with sugar/carbohydrate)
ex. most abundant glycoprotein: collagen

109
Q

what does the extra cellular matrix do?

A

ECM is important for cell adhesion and communication: anything that happens on the outside of the cell will be transmitted to change gene expression

cell differentiation, proliferation, are determined by cell communication through ECM

changes in the ECM affect the cytoskeleton and thus affect signaling inside and eventually genes in the nucleus

110
Q

what are the three types of cell junctions in animals?

A

1) tight junctions: membranes of neighboring cells are pressed together, preventing leakage of extracellular fluid
2) desmosomes: anchoring junctions, fasten cells together into strong sheets
3) gap junctions: communicating junctions, provide cytoplasmic channels between adjacent cells

Biology 1113 (12 decks)

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