4.1 Cell Envelope and its Modifications Flashcards
Most prokaryotic cells, particularly bacterial cells, have a chemically complex ______.
Cell envelope
Tightly bound three-layered structure of Cell envelop consists of:
Outermost-glycocalyx
Middle-cell wall
Inner-plasma membrane
Each layer of the envelope performs ____ (same/distinct) function. They act together as a _____.
Distinct function; Single protective unit
On the Basis of differences in the cell envelopes and Gram staining, bacteria are classified as
Gram-positive and Gram-negative
Bacteria taking up gram stain are _____, and the others that do not are _____ bacteria.
Gram-positive; Gram-negative
______ layer is responsible for providing a sticky character to the bacteria.
Glycocalyx
Among different bacteria, ______ differs in composition and thickness.
Glycocalyx
In some bacteria, Glycocalyx is a loose sheath called ______.
In other, Glycocalyx is tough and hard, called ______.
Slime Layer;
Capsule
Cell Wall determines ______ and provides a strong ______ to prevent the bacterium from ______.
shape of cell; structural support; bursting or collapsing.
Selectively permeable that interacts with the outside world is ______.
plasma membrane
The membrane, which is structurally similar to prokaryotes and eukaryotes, is
Plasma membrane
A special membraneous structure that is formed by the extensions of plasma membrane into the cell is ______.
Mesosome
Mesosomes are in the form of _____.
Vesicles, tubules, and lamellae
Mesosomes help in:
Helps in
i) Cell wall formation
ii) DNA replication & DNA distribution to daughter cells
iii) Respiration
iv) Secretion processes
v) Increase surface area of plasma membrane and enzymatic content
In some prokaryotes like ____, there are other membranous extensions into the cytoplasm called ____, which contain ____.
Cyanobacteria; Chromatophores; pigments
Chromatophores are internal membrane system which becomes extensive and complex in ______ bacteria.
Photosynthetic bacteria
Bacterial cells may be ____ (motile/non-motile/both).
Both (motile or non-motile)
Motile bacteria have thin filamentous extensions from their cell wall, known as ______.
Flagella
All Bacteria show ____ (same/different) number and arrangement of flagella.
different
The three main parts of the bacterial flagellum are __
Filament, hook and basal body
The longest portion of the bacterial flagellum is ____ that extends from cell surface to ____ (inside/outside).
Filament; outside
Besides flagella, the two surface structures of Bacteria which do not play a role in motility (locomotion) are ______.
Pili and Fimbriae
The elongated tubular structures composed of a special protein in bacteria are _____
Pili
Small bristle-like fibers sprouting out of the bacterial cell are ____ to help attach bacteria to ______.
Fimbriae; Host tissues and rocks in streams
