Chapter 2 - Cell Structure

Front 1

filament

Back 1

chain of cells

Front 2

Cellular differentiation

Back 2

ability of a cell to exist in different morphological and functional forms depending on what genes are expressed in the cell

Front 3

Chains

Back 3

cell divides in one plane eg. Streptococcus

Front 4

Packets

Back 4

Cell divides in two or more planes perpendicular to one another

Front 5

Clusters

Back 5

Cell divides in several planes at random eg. Staphylococcus

Front 6

Why are most cells small?

Back 6

Diffusion issues, dilution issues (2x increase -> # mlcls increase by 8x to maintain concentration), and surface area to volume issues

Front 7

How do Eukaryotic cells deal with the size issue?

Back 7

Active protein-mediated movement and mixing of the cytoplasm, compartmentalization of reactions into smaller organelles, long thin shapes to increase surface area

Front 8

How do large prokaryotic cells deal with the size issue?

Back 8

Thiomargarita namibiensus: reduces the volume of its metabolically active cytoplasm by forming a large metabolically-inactive membrane-bound vacuole

Epulopiscium fishelsoni: increases the SA by synthesizing an invaginated (folded) membrane

Front 9

2 types of capsules

Back 9

1) polysaccharide capsules- chains of a single type of sugar

2) Polypeptide capsules - chains of a single type of amino acid

Front 10

capsule

Back 10

usually the outermost layer, covering a S-layer, if present

perhaps protects organisms from drying or viruses won't be able to inject their DNA or immune cells aren't able to recognize or engulf or may be an adherence mechanism (although still largely unknown)

Front 11

periplasm

Back 11

a water-filled cellular compartment

Gm +ive: the region between the cytoplasmic membrane and the peptidoglycan layer(s)

Gm -ive: region between the outer membrane and cytoplasmic membrane, includes the thin peptidoglycan layer(s)

Front 12

Mycoplasma

Back 12

parasitic bacteria

members of Gm+ive group

don't need a cell wall: live in an osmotically compatible host

Front 13

Surface stress

Back 13

=PR/2

Front 14

Surface (S)-layers

Back 14

a single kind of protein repeated over and over in a regular geometric pattern completely enveloping the cell

Each S-layer protein is shaped like a pin-wheel and is made from 6 identical amino acid chains

Front 15

Function of S-layer

Back 15

potentially a protective layer from viruses (largely obscure)

Front 16

Slime

Back 16

material similar to capsule material excreted by bacteria

Front 17

Monotrichous

Back 17

possess a single flagellum

in rod shaped bacteria, this flagellum may be located at the ends of the cell(polar) or at another location (non-polar)

Front 18

Peritrichous

Back 18

bacteria possess many flagella scattered over the cell surface

Front 19

Lopotrichous

Back 19

bacteria have many flagella present in a single location on the cell surface

Front 20

flagella

Back 20

long filamentous appendages

one way bacteria moves is by swimming using flagella

Front 21

Proteins that compose flagella

Back 21

flagellin is attached via a hook protein to a rod protein embedded in the membrane and wall by several protein rings (the basal structure)

motor protein at the base of flagellum requires energy from the transport of H+

Front 22

Main difference in flagellum between Gm+ive and Gm-ive bacteria

Back 22

number of protein rings

Front 23

endoflagella

Back 23

flagella anchored in the cytoplasmic membrane at the poles of the cell and spiral outside the peptidoglycan but inside the outer membrane, overlapping at the midpoint

located in the periplasm

Front 24

function of endoflagella

Back 24

rotates inside the periplasm, causes the entire spiral cell to rotate and exhibit "corkscrew" motion

Front 25

Advantage of endoflagella

Back 25

exposed flagella fail to operate in highly viscous environments

corkscrew motion enables spirochetes to drill through highly viscous gel-like environments

Front 26

Pili

Back 26

protein projections from cell surface

different structural types of pili with different functions

Front 27

Functions of pili (Type IV)

Back 27

Attachment to surfaces

HGT by transformation

Twitchingmotility

conduct (transfer) electrons to an external terminal electron acceptor during synthesis of ATP by oxidative phophorylation (nanowires)

Front 28

Twitching motility

Back 28

the jerky movement of bacteria along a surface mediated by extension and retraction of pili which pulls bacteria forward

requires ATP consumption

Front 29

Stalks

Back 29

Used for attachment to submerged surfacesusing a polysaccharide “glue” called “holdfast” at the end of the stalk

Some stalks are an extension of cellenvelope and cytoplasm

Increases SA for phosphorus absorptionwhile minimizing increase in V

Front 30

Function of stalks

Back 30

When starved for phosphorus, shortstalked cells can differentiate into long stalked cells

Increases SA for phosphorus absorptionwhile minimizing increase in V

Front 31

symmetric binary fission

Back 31

resulting cells are the same

Front 32

asymmetric binary fission

Back 32

resulting cells are not the same

Front 33

2 kinds of gliding exhibited by motile species

Back 33

centipede-like gliding- gliding using protein appendages

inch worm-like gliding using extension and retraction of a terminal organelle

Front 34

bud

Back 34

in protuberance, a bud is synthesized at a location on the surface of a "mother" cell

Front 35

gliding motility

Back 35

a form of locomotion in which bacteria move over a surface not in a jerky manner but in smooth continuous, motion without the aid of flagella or pili

Front 36

nucleoid

Back 36

supercoiled DNA

some Archaea: DNA wound around (+)velycharged histone proteinsforming nucleosomes: similar to Eukarya(BIOL 112)

Front 37

hami/ hamus

Back 37

The hamus is along, barbed, grappling hook probably used for attachment to surfaces and other Archaea

Front 38

differences between flagella in bacteria and archaea

Back 38

Archaealflagella...

1) and bacterial flagella are not evolutionarily-related

2) rotate like bacterial flagella but no envelope rings.

4) uses energy supplied by ATP consumption, not by H+transport.

Front 39

cannula

Back 39

In the white balls, individual cells are connected by hollow protein tubes about 25 nm in diameter and up to 150 nm inlength

The tubules are called “cannulae”.

Front 40

Function of cannula

Back 40

The function of the cannula network is still unclear. It might act to anchor cells to each other or as a means of communication for the exchange of either nutrients or even genetic material.

Front 41

Function of peptidoglycan

Back 41

prevent osmotic lysis of cell in hypotonic environment

Front 42

Which two amino acids form peptidoglycan?

Back 42

N-acetylglucosamine (NAG or G)

N-acetylmuramic acid (NAM or M)

Front 43

What is the difference in Gm+ive and Gm-ive PG?

Back 43

In Gm-ive: tetrapeptides are directly X-linked to each other (<50% linked)

Gm+ive: X-linking involves additional amino acids (1-5) and there is also a higher density of X-linking (up to 80%)

Front 44

ABC transporters

Back 44

ATP-Binding Cassette transporters

Front 45

planctomycetes

Back 45

bacteria that have a nuclear body or exhibits Eukarya-like membrane-bound intracellular compartmentalization

Front 46

Which colour does Gram-stain stain positive and negative bacteria?

Back 46

Gram-positive = purple

Gram-negative = red

Front 47

protoplast

Back 47

a spherical membrane bound structure that forms when a bacteria cell is treated with lysozyme in an isotonic environment

Front 48

plasmolysis

Back 48

when under hypertonic conditions, the volume of the cytoplasm decreases and the membrane collapses, may lead to cell death

Front 49

teichoic acids

Back 49

polymers of phosphorylated sugar alcohols found in Gm+ive cell walls, called teichoic acid if anchored to NAM

Front 50

lipoteichoic acid (LTA)

Back 50

if a teichoic acid is anchored to a sugar in the headgroup of a cell membrane phosph- or glycolipid

Front 51

What is beyond PG in Gm+ive and Gm-ive bacteria?

Back 51

Gm+ive: Gm+ive cell wall

Gm-ive: outer membrane (OM)

Front 52

outer membrane

Back 52

found in Gm-ive cell walls beyond the PG< is composed of phospholipid, lipopolysaccharide and a variety of proteins, unlike SM, contains phospholipids but usually only in the inner leaflet

Front 53

lipopolysaccharide (LPS)

Back 53

dominates the outer leaflet of the outer membrane, is divided into 3 regions: Lipid A (several hydrocarbon tails anchored to a sugar derivative) , the R-core (sugars), and the O-polysaccharide (uncharged sugars that extends from the cell surface)

Front 54

lipoprotein

Back 54

a protein that functions to anchor the PG to the OM (a protein with hydrocarbon tails)

Front 55

porins

Back 55

small, water filled channels used for transporting small hydrophilic molecules to pass through the outer membrane

Front 56

What makes the OM even less permeable than the CM?

Back 56

stronger lateral interactions between LPS molecules as opposed to phospholipids

1) R-core of LPS possesses a high density of negative charge (charge repulsion prevented bc Ca+2 and Mg+2 ions present in the environment bind to the mlcls)

2) LPS has more than 2 hydrocarbon tails per molecule