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MBIO1010 > Lecture Set 2 : Part 3 > Flashcards

Lecture Set 2 : Part 3 Flashcards

1
Q

what is the cytoplasm?

A

-material bounded by the cytoplasmic membrane

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2
Q

what is the protoplast?

A

-cytoplasmic membrane + cytoplasm + everything within
-everything within = macromolecules, nucleotides, soluble proteins, DNA + RNA, ribosomes, and inclusions
-the living content of a cell

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3
Q

what is the nucleoid?

A

-region that contains the cell’s genome

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4
Q

what is contained within the cell’s typical genome?

A

-single circular double stranded DNA chromosome (essential genes)
-one or more plasmids (non-essential genes)
-smaller pieces of circular double stranded DNA (replicate independent of the chromosome)

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5
Q

why is the prokaryotes chromosome not arranged into a typical linear chromosome?

A

-circular is more compact and can allow for faster replication/division

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5
Q

why do prokaryotes contain a low number of plasmids?

A

-kept to a minimum to preserve energy
-can be energetically expensive to hold many plasmids (increases the fitness cost of the cell)

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6
Q

what is a cell’s fitness cost?

A

-referring to a cell’s ability to stay alive and reproduce and its “cost” to stay alive
-costs can come metabolically, genetically, size-wise, or adaptively
-ex: acquiring a beneficial trait that may affect the efficiency of another trait (the cost is in how the cell must compensate now for the lack of efficiency despite the benefit in another area)

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7
Q

how can the genes on plasmids become essential?

A

-the cell manipulates the environment they are in for the gene to become essential
-ex: gene for antibiotic resistance (becomes essential in the presence of antibiotics

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8
Q

what is the role of a ribosme?

A

-protein synthesis
-going from RNA > protein (translation)

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9
Q

what ribosomes are contained within bacteria?

A

-70S ribosomes
-made from 2 subunits (large subunit and small subunit)

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10
Q

what is significant about the bacteria having the 70S ribosome?

A

-good target for antibiotics because eukarya have the 80S ribosome

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11
Q

what are the components of the bacteria’s 70S ribosome?

A

-30S subunit (small subunit) containing 16S rRNA
-50S subunit (large subunit) containing both 23S and 5S rRNA

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12
Q

what are the numbers for the eukarya subunits?

A

-10 units higher than the bacteria
-40S small subunit
-60S large subunit

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13
Q

what proteins are made by cytoplasmic ribosomes?

A

-cytoplasmic proteins

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14
Q

what proteins are made by membrane associated ribosomes?

A

-membrane proteins
-proteins to be exported from the cell

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15
Q

what are the functions of proteins?

A

-can act as enzymes (catalyze chemical reactions)
-can act as transport proteins (move molecules across membranes)
-have a structural purpose

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16
Q

what is the purpose of structural proteins?

A

-help determine the shape of the cell
-involved in cell division (spindle apparatus)

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17
Q

what are proteins made of?

A

-polypeptides (long polymer of amino acids joined by peptide bonds)

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18
Q

what are capsules and slime layers in bacterial cells?

A

-polysaccharide/protein layers that assist in cell attachment to surfaces (biofilm formation)
-can provide a selective advantage for cell growth in nature (ex: in a human as a pathogen)
-protects cells against phagocytosis
-allows cells to resist desiccation
-not necessarily essential for lab growth

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19
Q

what are the characteristics of capsules and slime layers?

A

-can be thick or thing
-can be rigid or flexible
-capsules are more tightly attached
-slime layers are more loosely attached

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20
Q

how do capsules and slime layers protect cells from phagocytosis?

A

-acts as a “cloak of invisibility”
-makes it harder for them to be detected by immune cells

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21
Q

what is desiccation?

A

-drying (can cause cell death)
-ex: dried yeast

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22
Q

what is a biofilm?

A

-community of bacteria that is surface associated

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23
Q

what are the advantages of bacterial cells forming a biofilm?

A

-innermost cells are more protected (layers of cells surrounding them as a defence)
-innermost cells have a lack of oxygen and nutrients due to less diffusion (slower growing cells)
-less cell division in these cells provides resistance against antibiotics that only target actively dividing cells
-biofilms are very difficult to eradicate

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24
where can biofilms form?
-drains -test tubes itself -top of a liquid in a test tube (pelicle, air-liquid interface)
25
what will all cells have?
-nucleiod (DNA) -ribosomes (Proteins)
26
what will some cells have but others may not?
-capsules/slime layers -fimbriae -pili -cell inclusions -gas vesicles -endospores
27
what are fimbriae?
-hair-like protein appendages that are anchored to the cytoplasmic membrane and extend through the cell wall -shorter than pili typically -usually more fimbriae per cell in comparison to pili
28
what is the function of fimbriae? what is an example of this?
-allow for adhesion to solid surfaces (helps with biofilms) -ex: neisseria gonorrhoeae (stick to epithelial cells on mucous membranes)
29
what are pili?
-hair-like protein appendages that assist in surface attachment as well as facilitating genetic exchange between cells -longer than fimbriae typically -usually less pili per cell in comparison to fimbriae
30
how does the pili facilitate genetic exchange between cells?
-does so through horizontal gene transfer (specifically conjugation) -transfers genes through the extension of a specific pili that comes from a plasmid within the gene donor -the recipient will receive the ability to form the specific pili in the process of gene transferring -does not occur from parent to offspring (vertical gene transfer) -occurs from 2 cells within a generation
31
what pili is involved in a twitching motility?
-Type IV (4) pili -attaches its pilus and pulls itself (slinky)
32
what are cell inclusions?
-visible aggregates in the cytoplasm (internal) -used for energy and nutrient storage
33
what are examples of the storage of carbon polymers?
-poly-B-hydroxyalkanoate (PHA = umbrella term) (lipid storage) -glycogen (polymer of glucose)
34
what are polyphosphate granules (volutin)?
-accumulations of inorganic phosphate
35
what are sulfur globules?
-storage of elemental sulfur
36
what is an important type of PHA produced in many bacteria and archaea?
-polyhydroxybutyrate (PHB) -can be harvested and used to produce plastics that are biodegradable by other bacteria, archaea, and fungi
37
what are magnetosomes?
-intracellular granules of Fe3O4 (magnetite) or Fe3S4 (oxides and sulphides of iron)
38
what is the purpose of magnetosomes?
-give the cell magnetic properties -allows it to orient itself in a magnetic field?
39
what is magnetotaxis?
-bacteria that migrate along Earth's magnetic field (direction of movement)
40
what is significant about magnetosomes?
-bacteria require different amounts of oxygen to survive -microaerofiles are a bacteria that only need a small amount of oxygen -by aligning themselves to a magnetic field, they are in the optimal environment for oxygen (live in freshwater)
41
what are different bacterias oxygen needs?
-aerobic (lots of oxygen) -anaerobic (no oxygen) -faculative anerobes (live with or without) -microaerofiles (small amount)
42
what are gas vesicles?
-spindle shaped gas-filed structures made of protein -protein is impermeable to gas (once trapped it cannot leave)
43
what is the function of gas vesicles?
-provides buoyancy to planktonic prokaryotes -planktonic = free floating in water bodies -ex: photosynthetic cyanobacteria
44
how does photosynthetic cyanobacteria use gas vesicles?
-use them to adjust their vertical position in the water where light intensity is optimal for photosynthesis (energy generation) -allows them to form blooms within water bodies
45
what are endospores?
-dormant cells that form inside a mother cell -metabolically inactive -formation is trigged by a lack of nutrients/harsh conditions that cannot be withstood by the bacteria -strongest and most resistant type of spore
46
what cells can produce endospores?
-only some gram positive bacteria (only one gram negative found that can form them) -ex: bacillus species (aerobic rod bacteria) -ex: clostridium species (anaerobic rod bacteria) -not formed by archaea or eukaryotes (bacteria specific)
47
what is a vegetative cell?
-any normal cell that is capable of growth and is metabolically active -used to create endospores (becomes the mother cell)
48
what are the 7 stages of endospore formation?
-asymmetric cell division (NOT binary fission) -septation -mother cell engulfs the forespore -formation of the cortex -coat synthesis -endospore matures -mother cell is lysed
49
what occurs in the stage of asymmetric cell division? how does it differ from binary fission?
-DNA is replicated and indentical chromosomes are pulled to opposite ends -when the septum is formed, the mother cell is much larger than the prespore
50
what occurs in the stage of septation?
-a septum is formed that divides the cell into 2 unequal compartments -two compartments are the mother cell (larger) and the prespore/forespore (smaller)
51
what occurs in the stage of the mother cell engulfing the forespore?
-the forespore gets surrounded by 2 membranes (both its own and the mother cells)
52
what occurs in the stage of forming the cortex?
-thick layers of peptidoglycan form between the two membranes -2 different layers -a highly cross-linked layer (core wall) (outer) -a loosely cross-linked layer (cortex) (inner = 1/2 spores volume)
53
what occurs in the stage of coat synthesis?
-protein layers begin to surround the core wall -spore coat + exosporium -these protect the spore from chemicals and enzymes -accumulation within the core (center)
54
what accumulates within the core during coat synthesis? what is their purpose?
-calcium -dipicolinic acid -small acid soluble proteins (SASPs) -help stabilize DNA (protect it against damage and radiation)
55
what occurs in the stage of the endospore maturing?
-the core is dehydrated -10-30% of the vegatative cells water content is removed (1/5)
56
what occurs in the stage where the mother cell is lysed?
-mother cell disintegrates and releases the mature spore
57
what can occur in some cases after endospore formation?
-the endospore can germinate to form the vegetative cell again if conditions become favourable
58
what is the purpose of the spore coat and cortex?
-protects the endospore against chemicals, enzymes, physical damage, and heat
59
what is the purpose of the 2 membranes around the endospore?
-act as permeability barriers to protect against chemicals
60
why would a cell want to create an endospore?
-endospores have high resistance (can preserve the cell's DNA for when conditions improve)
61
what can endospores resist?
-boiling for hours -UV and gamma radiation -chemical disinfectants -desiccation (drying) -age (can survive for a long time)

MBIO1010 (28 decks)

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