Chapter 3 Flashcards
What is glycocalyx
a slimy substance that adheres to the outside of the cell wall
What are the other two names for the same structure
capsule-thick layer
slime layer- thin layer
Name three possible functions of glycocalyx
- protect the cell from dehydration when the environment dries up.
- allows the bacteria to attach to tissue, which can then be invaded.
- protection against phagocytosis by white blood cells increasing the survival of the cell in the human body
What are the functions of the cell wall
- Its rigid structure maintains cell shape.
- Provides protection from the environment.
- also provides protection from osmotic pressure.
How do some antibiotics and lysozyme work on the cell wall
Bacteria produce enzymes to reseal breaks in the peptidoglycan cell wall that occurs during normal growth and division. Penicillin binds to enzymes, inactivating the enzymes
Lysozyme is an enzyme found in tears it digests peptidoglycan
Describe the structure of peptidoglycan
Is composed of two major subunits: alternating glycan molecules plus tetrapeptide chains
Glycan molecules
a simple sugar connected to an amino acid, there are two types: NAG, NAM
Gram Positive
a thick homogenous sheath of peptidoglycan ranging from 20-80nm and forms about 90% of the cell wall it also contains techoic acid
Gram Negative
more complex than gram positive, contains two layers: periplasm space and outer membrane
Periplasm space
region between the cell membrane and the outermembrane, composed of a layer of periplasm and peptidoglycan
Outer membrane
consists of bilayer structure: one layer is composed of phospholipids and other macromolecules, the outer layer is made of Lipopolysaccharide forms outer sheath of membrane
Porin proteins
allow specific molecules to pass and will shut off when the cell is threatened
Where is techoic acid found
gram positive cell wall which is a complex molecule that contains amino acids
Where is the outer membrane found and what does it do
in the gram negative cell wall and it acts as a barrier
Name the molecules that are found on the outer cell membrane
composed of phospholipid bilayer with proteins embedded in the bilayer
Integral proteins
Mainly involved in transport
Carrier protein
bind to specific substances and transport them across the cell membrane
Channel protein
opening which allows small, water soluble substances to go across the membrane
Function of cell membrane
serves as barrier to molecules using selectively permeable and enzymes embedded within the cell membrane help with anabolic chemical reactions including synthesis of the cell wall and appendages and catabolic pathway such as electron transport chain
Describe how mycoplasma has adapted without cell wall
it pumps ions (Na) out of the cell to keep turgor pressure equal inside and outside the cell…prevents lysis from occurring, cell membranes are strengthened by adding cholesterol, usually found in some eukaryotic cells
What is a flagella
long, thin, rigid hair-like appendages composed of protein
What does flagella do
it rotates 360* at nearly 2000rpm it causes the cell itself to slowly spin in the opposite direction it provides a way for bacteria to locomote
Composition of flagella
filament, hook, two rings
Filament
the long tube-like structure
Hook
the filament is inserted into hook
Two rings
hook inserted here, provides the anchor for the filament and the hook has one ring is attached to the cell membrane and the other ring is attached to the cell wall
Can bacteria have more than one flagella
yes bacteria can have one or more these can be arranged in many different ways
monotrichous
single flagellum at one end of the cell
amphitrichous
single flagellum at each end
lophotrichous
a tuft of many flagella at one end
peritrichous
flagella located on many sides of the bacterial cell
In what bacteria are flagella found
in all spirilla, half of the bacilli, and a few coccus
Fimbriae
short but numerous tubes composed of protein, have a tendency to stick to surfaces and to others
Function of fimbriae
adhere to epithelial cells, allowing the cells to invade the tissues
Pilus
long, less numerous hollow, tubular structures, found in gram negative bacteria and some gram positive bacteria, long pilus tube links the cytoplasm of one bacteria with the cytoplasm of another bacteria of the same species
functions of pilus
are used to exchange small amounts of circular DNA called plasmids between cells in a process called conjugation
where is fimbriae found
in E. coli it invades the intestine by clinging to epithelial cells lining the intestines
where is pilus found
in gram negative and some gram positive bacteria
How many chromosomes do bacteria have
a single, double stranded, circular piece of DNA
How many genes are found in a bacteria
3000 to 4000 genes
How many genes are found in a human cell
25000 to 32000
What are plasmids
very small circular pieces of DNA that are not essential for bacterial growth and cell maintenance
where are plasmids found
they are free floating and are not attached to the cell membrane they can however incorporate themselves into a bacterial chromosome on occasion
plasmid function
can provide information that can be helpful to survival, but not essential: resistance to drugs, production of toxins, and production of enzymes
70S ribosomes
the only true organelle found within a prokaryotic cell, 15,000 are found in the protoplasm of the cell
Macromolecule composition
ribosomal RNA-60% and proteins- 40%
Are prokaryotic cells and eukaryotic cells the same
no prokaryotic cells have 30s subunit, 50s subunit=70s and eukaryotic has 40s subunit, 60s subunit=80s
70s ribosome function
are used for protein synthesis
cytoplasmic inclusions
are small, membrane bound structures that will contain various substances they contain energy rich organic substances– produced in times of plenty and used when the environment is low in energy sources and contains gases used in buoyancy and floatation
Granules
areas within a cell that contains inorganic crystals, but are not membrane bound
granules function
stores important resources that are essential elements(sulfur, phosphorous) in building macromoleculs
Who produces endospores
only some gram-positive rods will produce, Bacillus and Clostridium
When are endospores produced
when conditions become unfavorable for further bacterial growth and the survival of the bacteria is in question
What is an endospore
is a small, protected, dormant bacteria that will germinate under favorable growth conditions into a new bacterial cell. It cannot divide or degrade compounds for energy or synthesize cell components until it has germinated into a new bacterial cell. It is genetically identical to the cell that produced it
Spore coat
this outer layer provides a nearly impervious barrier to many chemicals
cortex
this middle layer contains many calcium salts and dipicolinic acid this layer keeps the core very dry it prevents water from reaching core
core
this is the innermost layer contains the bacterial chromosome
