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Microbiology > Cell structure and function > Flashcards

Cell structure and function Flashcards

1
Q

Process of life in all cells

A
  1. Growth (size)
  2. Reproduction (multiply sexually/asexually)
  3. Responsiveness
  4. Maintain homeostasis
  5. Metabolism: includes anabolic and catabolic reactions
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2
Q

anabolism

A

-chemical reaction where you start with a simple molecule and built upon that
-requires energy

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3
Q

catabolism

A

-chemical reaction where you break down larger molecules into smaller ones
-releases energy
-this controls rate of anabolism b/c it gives it energy

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4
Q

What are the three domain taxa?

A
  1. Bacteria
  2. Archaea
  3. Eukarya
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5
Q

Prokaryotes

A

-are organisms that lack a distinct nucleus (none there), has no membrane bound organelles
-can read their genetic code and make proteins simultaneously
-the domains are bacteria and archaea
-they are smaller than eukaryotes about 1-2 um
-ribosomes only in cytoplasm (smaller 70S)

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6
Q

Eukaryotes

A

-are organisms with a membrane bound nucleus and organelles
-domains under here are fungi, protozoa, small multicellular animals, plants, algae
-bigger in size about 10-100 um
-ribosomes found in cytoplasm, endoplasmic reticulum (larger 80S)

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7
Q

What do Prokaryotes and Eukaryotes have in common?

A

-both have ribosomes

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8
Q

Glycocalyx in Prokaryotes

A

-can also be called sweet cup
-a gelatinous sticky layer surrounding the outside of cells.
-Its function is to keep the cell from drying out, and can aid in causing diseases
-composed of polysaccharides, polypeptides or both usually in a slim layer or capsule

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9
Q

Capsule

A

-organized repeating units of organic chemicals firmly attached to cell surface, which may prevent bacteria from being recognized by the host immune system allowing it to cause disease

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10
Q

Slime layer

A

-loosely attached to the cell surface and is water soluble
-sticky layer allowing the cells to attach to surface as in the formation of the biofilm

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11
Q

Glycocalyx in Eukakryotes

A

-not as structured as in prokaryotes
-used to attach animals cells to each other and strengthen cell membrane surface
-surface needs to be strengthen of they were in hypertonic solutions
-provides protection against dehydration
-functions in cell-to-cell recognition and function
** cilia only in Eukaryotes while Flagella in both eukaryotes and prokaryotes

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12
Q

Flagella of prokaryotic cell

A

-long structures extending beyond cell surface to provide motility
-not all prokaryotes have flagella
-composed of a filament, basal body, rod, and hook
-flagellin protein forms the filament and is deposited in a helix at the lengthening top
-the base of the filament inserts into the hook and forms the rod
-basal body anchors filament and hook to cell wall by rod and a series of two gram + or four rings of gram -
-rotates 360

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13
Q

Monotrichous

A

bacteria with a single flagellum

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14
Q

Peritrichous

A

bacteria with multiple flagella all over

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15
Q

Lophotrichous

A

bacteria with multiple flagella in one spot

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16
Q

Amphitrichous

A

bacteria with single flagellum on both sides

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17
Q

Function of Bacterial flagella

A

-Their rotation propels bacterium through environment and it can be clockwise or counterclockwise
-bacteria move (taxis) in response to stimuli

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18
Q

Runs

A

movements in a single direction for some time due to counterclockwise rotation, increase with favorable stimuli

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19
Q

Tumbles

A

abrupt, random changes in direction due to clockwise rotation, increase with unfavorable stimuli

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20
Q

Chemotaxis

A

movement in response to chemicals

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21
Q

phototaxis

A

movement in response to light

22
Q

Positive/Negative taxis

A

-movement towards positive stimuli, while movement away from unfavorable stimuli

23
Q

Endoflagellate

A

-do not have a true flagella, it is within the body of the organism
-some bacteria and spirochetes are this

24
Q

Fimbriae

A

-sticky, proteinaceous, bristle like projections used by bacteria to adhere to one another, to host tissue, to substances in the environment, or allow the cell to slowly move across the surface
-maybe 100s per cell, shorter than flagella
-important in biofilms

25
Q

Biofilms

A

multiple bacteria species stick together and form this

26
Q

Pili

A

-long hollow tubes composed of pilin (protein)
-longer than fimbriae but shorter than flagella
-bacteria typically only have 1 pilus or 2 pili/cell if any
-join two bacterial cells and mediate the transfer of plasmid DNA from one cell to another (conjugation)
-also know as conjugation pili “sex pili”

27
Q

Prokaryotic cell wall

A

-cell walls provide structure and shape to prevent osmotic forces
-cell wall assist some cells in attaching to one another or eluding antimicrobial drugs
-animal cells lack cell wall so we can target bacterial cell walls with antibiotics
-bacteria and archaea cell wall chemistry differ

28
Q

Bacteria cell wall

A

-most bacteria cell wall are mainly composed of peptidoglycan, a few lack cell walls
-chains of NAM and NAG are attached to each other chains by tetrapeptide cross-bridges via NAM
-these bridges may be covalently bonded to one another or held by short connecting amino acids
-two types of cell walls (gram +) and (gram -)

29
Q

Gram + cell wall

A

-thick layer of peptidoglycan
-contains polyalcohol called teichoic acids
-some covalently linked to lipids, forming lipoteichoic acid that anchor peptidoglycan to the cell membrane
-retains crystal violet dye in gram staining, cells are purple

30
Q

Acid-fast bacteria

A

-contains up to 60% mycolic acid
-helps cells survive desiccation and resist normal gram staining b/c of hydrophobic interactions

31
Q

Gram - cell wall

A

-thin layer of peptidoglycan
-lacks teichoic acid
-has 2 lipid bilayers
-bilayer membrane outside the peptidoglycan contains phospholipids, proteins, and lipopolysaccharide (LPS) which may impede treatment of disease
-following gram stain the cells appear pink

32
Q

LPS (Lipopolysaccharide) endotoxin

A

-union of a lipid (Lip A) with a polysaccharide
-located outside
-dead cells release Lip A when the cell wall disintegrates which may trigger fever, shock, vasodilation, inflammation, blood clotting
-can be released when antimicrobial drugs kill bacteria

33
Q

Periplasmic space in gram - cells

A

-located between outer membrane and cell membrane
-contains thinner layer of peptidoglycan, and periplasm
-contains water, nutrients, and substances secreted by the cell, such as digestive enzymes, and proteins involved in transport

34
Q

Archaea cell wall

A

-have cell walls, fimbria, and glycocalyces as well as flagella, but the composition and characteristics do vary
-cell walls do not contain peptidoglycan but instead contain a variety of specialized polysaccharides and proteins
-gram + stain purple and gram stain pink (same as bacteria)
-they may also possess fimbriae-like structures called hami which are grappling hooks

35
Q

Eukaryotic cell wall

A

-fungi, algae, plants and a few protozoa have cell walls but no glycocalyx (if cell wall present)
-animal cells do not contain cell wall
-composed of various polyssacharides

36
Q

Plant cell walls contain?

A

cellulose

37
Q

Fungal cell walls are composed of?

A

chitin, cellulose, and or glucomannan

38
Q

Algal cell walls are composed of?

A

-either cellulose, proteins, agar, carrageenan, silicates, algin, calcium carbonate or combination of these

39
Q

Prokaryotic cytoplasmic membrane

A

-a phospholipid bilayer (fluid mosaic model) is composed of phospholipids and proteins
-integral proteins, peripheral proteins, and glycoproteins
-it controls the passage of substances into and out of the cell, therefor its selectively permeable
-their membrane also functions in energy storage/transfer and harvest light energy in photosynthesis

40
Q

Cytosol (Prokaryote)

A

-liquid portion of cytoplasm, like eukaryotes

40
Q

Inclusions (Prokaryote)

A

-may include reserve deposits of chemicals/molecules (lipids, starch, phosphate, PHB) and some are even gas vesicles

41
Q

Ribosomes (Prokaryotes)

A

-protein synthesis

42
Q

Cytoskeleton (prokaryotes)

A

-if present plays a role in forming cell’s basic shape

43
Q

Endospore

A

bacterial cells produce a dormant form called this and it happens in unfavorable conditions

44
Q

Endosporulation

A
  1. DNA is replicated
  2. DNA aligns along the cell’s long axis
  3. cytoplasmic membrane invaginates to form endospore
    4.cytoplasmic membrane grows and engulfs forespore within a second membrane. Vegetative cell’s DNA disintegrates
  4. a cortex of calcium and dispicolnic acid is deposited between the membranes
  5. Spore coat forms around endospore
    7.maturation of endospore completion of spore coat and increase in resistance to heat and chemicals by unknown process
  6. Endospore released from original cell
45
Q

Ribosomes in Eukaryotes

A
  • assembled ribosomes are 80S, and composed of smaller subunits 60S and 40S
    -in eukaryotes the ribosomes are on ER and in cytoplasm
46
Q

Ribosomes in Prokaryotes

A

-assembled ribosomes are 70S, and composed of smaller subunit 50S and 30S
-located in cytoplasm

47
Q

Mitochondria and chloroplast

A

-each have two membrane both composed of phospholipid bilayer
-mitochondria function to produce most of cell ATPs through cellular respiration
-chloroplast function to produce an organisms food via photosynthesis
-interior space of the matrix of the mitochondria and the stroma of chloroplast each contain 70S ribosomes and circular DNA
** these are prokaryotic ribosome characteristics

48
Q

Endosymbiotic theory

A

Eukaryotes may have formed from the union of small aerobic prokaryotic proteobacteria and cyanobacteria
-smaller prokaryotes may have been parasites but lost the ability to exist on their own but retained original portions of their DNA, ribosomes, and cytoplasmic membrane
-the larger anaerobic cell became dependent on the parasites on aerobic ATP production and food production
-the prokaryotes evolved into modern day mitochondria and chloroplast
-this provides an explanation for the origin of eukaryotic cells from prokaryotic cells
-first proposed by Konstantin Mereschowsky
-They formed a symbiotic relationship, and both cells benefited from each other mutually. The anaerobic bacteria procured food for the aerobic bacteria and provided it with a safe shelter.

49
Q

Support for the endosymiotic theory

A

-both mitochondria and chloroplast both have
* size of 1-2 um like prokaryotes
*2 phospholipid bilayer
*bacterial like ribosomes (70S)
* small prokaryotic like DNA (circular)

50
Q

Endosymbiotic theory (cyanobacterium role)

A

-anaerobic respiration –> chloroplast developed from this

51
Q

Endosymbiotic theory (proteobacterium role)

A

-aerobic respiration –> mitochondria developed from this

Microbiology (13 decks)

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