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Microbiology Exam 3 Exam > Eukaryotes: Endodymbiotic Theory > Flashcards

Eukaryotes: Endodymbiotic Theory Flashcards

1
Q

Nucleus

A

Defining organelle of eukaryotic cells

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2
Q

What does the nucleus contain?

A

Genomic DNA

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3
Q

What is the role of the Nucleus?

A

Storage and expression of genetic information

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4
Q

What does the Nucleus do?

A

Forces spatial and temporal separation of transcription and translation

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5
Q

What are the features of the Nucleus?

A

Nucleolus
Nuclear Pores
Double membrane
Nucleosomes
Nuclear lamina

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6
Q

Nucleolus

A
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7
Q

What are the nuclear pores

A

Entry/exit tightly controlled by nuclear pore complex

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8
Q

What is the double membrane of the nucleus

A

Membranes are continuous with each other
Membrane is also continuous with the rough ER

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9
Q

What is the Nucleosome of the Nucleus

A

Histine octamers (2X: H2a, H2b, H3, H4)
160 bases of DNA
HIstone H1
Leads tp packing ratio of approximately 8000X

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10
Q

What is the nuclear Lamina of the nucleus

A

Mesh of protein filaments that lines the inside of the inner membrane for structural support

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11
Q

What does the Mitochondria do?

A

Specialize in energy production (ATP) via ETC

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12
Q

Where goes glycolysis take place in the mitochondria?

A

Cytosol

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13
Q

Where does the Krebs Cycle take place in the Mitochondria?

A

Mitochondrial Matrix

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14
Q

Where is the ETS located in the mitochondria?

A

Mitochondria INNER membrane

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15
Q

What are the features of the mitochondria?

A

Double membrane
Possesses its own chromosome (circular)
Replicated autonomously within the cell to meet cellular energy demands

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16
Q

What is chloroplast?

A

Specialise in converting solar energy into cellular energy (ATP) and reducing power (NADPH) that can drove the fixation of carbon dioxide into organic molecules)

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17
Q

Why is ATP needed for Carbon fixation in Chloroplast?

A

ATP provides the driving force that promotes reaction

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18
Q

Why is NADPH needed for carbon fixation in Chloroplasts?

A

NADPH provides the reducing power (electrons + hydrogens) needed for reaction

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19
Q

What are the features of chloroplasts?

A

Three membranes
Stroma
Contains its own chromosome
Replicates autonomously within the cell

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20
Q

What are the three membranes in the chloroplast?

A

Double membrane (outer and inner)
Thylakoid membrane system
contains the chloroplasts chromosome (circular)
contains photosystems/ETS

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21
Q

What is the stroma in chloroplasts?

A

the fluid-filled internal space of the chloroplasts which encircle the grana and the thylakoids. It contains chloroplast DNA, starch and ribosomes along with enzymes needed for the Calvin cycle.

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22
Q

Where is the chromosome in the chloroplast?

A

Contained within the thylakoids

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23
Q

When does the Endosymbiotic Theory say bacteria first appear?

A

3.5 billion years ago

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24
Q

According to Endosymbiotic Theory when did eukaryotes emerge?

A

1.8 billion years ago, with the development of the mitochondria

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25
Q

Endoplasmic theory suggests that the two endoplasmic events (appearance of bacteria and eukaryotes) occurred when?

A

Free-living bacteria were engulfed by another cell

26
Q

What had to happen for the mitochondria to arise?

A

A symbiotic relationship was established with an alpha-proteobacteria

27
Q

What cells were involved in the creation of the mitochondria?

A

Host cell: provides a safe environment, nutrients, etc.
Symbiote: provides ATP to the host

28
Q

What is the step that had to take place in order for chloroplast to arise?

A

A symbiotic relationship was established with cyanobacteria

29
Q

What cells are required to give rise to chloroplast?

A

Host cell: provides a safe environment
Symbiote: allows the cell to take advantage of sunlight for photosynthesis

30
Q

What are some suggestive clues of the Endosymbiotic theory?

A

Mitochondria and Chloroplasts
-resemble bacteria in size (0.5-5 um)
- generate their own energy
- contain their own DNA
- contain circular DNA like bacteria unlike their linear genomes common to eukaryotes
- are bound by double membranes, as bacteria would that have been brought into a cell via endocytosis
-replicate independently of the cell
-divide by binary fission-like do bacteria and unlike the mitotic processes of eukaryotes
-ribosomes are sensitive to the same antibiotics as are bacteria, unlike eukaryotic ribosomes (e.g. streptomycin, chloramphenicol, neomycin)
- proteins begin with N-formylmethionine, as do bacteria

31
Q

What are the evidentiary clues to the Endosymbiotic Theory?

A

-The composition of mitochondrial and chloroplast inner membranes more closely resembles those of bacterial membranes than typical eukaryotic membranes
-Mitochondrial DNA resembles alpha-protobacteria in sequence and organization; Chloroplast DNA resembles alpha-protobacteria in sequence and organization; Chloroplast DNA resembles cyanobacteria in sequence and organization

32
Q

What is the Rough Endoplasmic Reticulum?

A

Extension of the nuclear membrane

33
Q

What are the roles of the Rough ER?

A

-Part of the protein secretory pathway
-Protein folding
-Protein modification
-Transfer of Golgi apparatus
-ER system increases in response to cellular needs

34
Q

What part of the protein secretory pathway is in the Rough ER?

A

-Newly created polypeptides may carry nested signal sequences
-First signal guides ribosome to dock with translocon on ER membrane
-Polypeptide chain imported into lumen of ER

35
Q

What is the role of the smooth ER?

A

-Lipid synthesis and transport (phospholipids and Steroids)
-Detoxification
-Carbohydrate metabolism

36
Q

What is the Golgi Apparatus?

A

Part of the protein secretion pathway
-cis-face receives proteins from rough ER
-Trans-face ships proteins to final destination

37
Q

What is the purpose of Lysosomes?

A

-Involved in intracellular digestion
-Contain enzymes for digestion (hydrolases)
-Function best under acidic conditions
-Achieved by proton pumps in membrane
-Activated to digest bacteria, etc.

38
Q

What is the role of flagella and cilia?

A

Cell movement

39
Q

What is the structure of flagella and cilia?

A

-Distinctly different than bacteria
-Located within the plasma membrane
-Components (axoneme, space for intraflagellar transport, basal body)

40
Q

What are the different components of Axoneme in flagella and cilia?

A

Microtubules
Dyein motors
-Hydrolyze ATP
-Pull against microtubules
-Create whipping motion
Nexin (connective protein)
Inner sheath

41
Q

What are the different components of flagella and cilia?

A

Axoneme
Space for intraflagellar transport
Basal body

42
Q

What is the Cell Wall?

A

Semi-rigid structure at the cell periphery that provides support and structure

43
Q

What does the cell wall do?

A

Holds the cell in a certain shape

44
Q

What does the cell wall protect the cell from?

A

Chemicals
Physical stresses
Osmotic stress

45
Q

Not all Eukaryotic microbes have a cell wall

A

Some do not have any cell wall
Some only have a cell wall in certain life stages

46
Q

What are the different types of cell walls?

A

Cellulose
Silicon dioxide
Chitin
Carbohydrate-modified proteins

47
Q

What are the components of a cellulose cell wall?

A

-Linear polysaccharide chains of glucose linked via Beta-1,4 glycosidic bonds
-Chains are crosslinked by hydrogen binds for increased tensile strength
-Most algae have cell walls of cellulose
-Water molds and slime molds

48
Q

What are the components of a Silicon dioxide cell wall?

A

Diatoms (specialized group of algae)
-Frusule (Epithecae & Hypothecae)

49
Q

What are the components of a Chitin cell wall?

A

The linear polysaccharide of N-aceytl-glucosamine linked via Beta-1,4 glycosidic bonds
-Chains are cross-linked by hydrogen bonds for increased tensile strength
-The acetylamino group permits more HB than does a hydroxyl group
-Accordingly, chitin tends to be stronger than cellulose
(Chitin is the same compound found in exoskeletons of insects)
(Most fungi have cell walls of chitin except water molds and slime molds)

50
Q

What organisms have Carbohydrate-modified protein cell walls?

A

Protozoan parasites
(most protozoa do not have cel walls)
(exceptions are Giardia, Cryptosporidium, and Entamoeba)

51
Q

What are the two life cycles of the organisms that have Carbohydrate-modifies protein cell walls? (Giardia, Cryptosporidium, and Entamoeba)

A

Trophozoite stage
Cyst Stage

52
Q

What is the purpose of the Trophozite stage in Carbohydrate-modified proteins?

A

Causes disease within the intestinal tract of hosts
Cells do NOT possess cell walls
-permits parasite motility
-enhances interaction with the host intestine

53
Q

What is the purpose of the Cyst (transmission) stage in Carbohydrate-modified proteins?

A

Required for transmission between hosts
Possess cell walls made of carbohydrate-modified proteins
Promotes survival in freshwater that would otherwise destroy the cells due to osmotic pressure differences
Not only promotes survival in an acidic stomach, but acids actually start the process of excystation so the infectious parasites can emerge in time to become established in the intestinal tract

54
Q

What is the cytoskeleton?

A

Network of protein filaments, tubules, and molecular motors that provide shape, internal organization, and the means to move and divide

55
Q

What are the three major types of cytoskeletal elements?

A

Microtubules, microfilaments, Intermediate filaments

56
Q

What is the composition of Microtubules?

A

Polymers of alpha-tubulin and beta-tubulin dimers
Subunits assemble into 24 nm fibers

57
Q

What is the role of microtubules?

A

-Form an intracellular organization network
-Movement of vesicles, granules, organelles, and chromosomes within the cell
-Direct vesicles to intended locations
-Hold organelles in proper positions
-Separate chromosomes during cell division
-Form the axoneme of cilia and flagells

58
Q

What is the composition of Microfilaments?

A

Polymers of actin monomers
Assemble into two intertwined protofilaments
Diameter 7 nm helix

59
Q

What is the role of microfilaments?

A

-Typically found at the periphery of the cell where they help maintain cell shape
-Cell movement (pseudopods)

60
Q

What is the composition of intermediate filaments?

A

Polymers of various proteins (Examples: Keratins, Lamins, Vimentin, etc.)
-Proteins rich in alpha-helices
-Helical regions of monomers form dimer
-Dimers assemble to form tetramers
-Tetramers assemble both lengthwise and side by side to form long, bundled, filaments
(Diameter: 8 to 11 nm)

61
Q

What are the roles of intermediate filaments?

A

Structure and support
-Keratins: various structure/support roles
-Lamins: nuclear lamina

Microbiology Exam 3 Exam (3 decks)

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