Prokaryotic Cells

Classification and Structure

Genetic and Growth

Prokaryotic Domains

Aerobes and anaerobes

Prokaryotic cell structure

Archaea

Bacteria

Cell wall

Flagella

Other organelles

D - Simple organism, include all bacteria

No membrane bound organelles

single circular molecule of DNA located in a region of the cell called nucleoid region

Cause infections and important to understand the structure of the bacteria to treat the infection

All life can be categorized into three domains - arcahea, bacteria and eukarya

D: single cell organism similar in structure to bacteria

D: contain genes and metabolic pathway that makes it more similar to eukaryotes

Historically known as extremophiles - does not exist in extreme condition - recent research has shifted that perspective

Use alternative source of energy

some are photosynthetic, others are chemosynthetic and can generate energy from inorganic compounds such as sulfur and nitroged based components such as ammonia

Hypothesized they have the same origin as eurokarytes, they both start with translation with methionine, contain RNA polymerases and associate DNA with histones

Archaea contains a single circular choromosome, divide by by binary fission or budding, and overall share a similar structure to bacteria

Resistant to many antibiotics

contain cell membrane and cytoplasm, some have flagella or fimbriae (similar to cilia)

bacteria and eurokaryates have similar structure - so it is difficult to develop medicine that targets only one

there are enough biochemical difference that antibacterial vaccines can be developed to target bacteria

antibiotic aim for the bacterial ribosome which is significantly smmaler than the eukaryotic ribosome

More bacteria than animals and plants combined

Mutualistic symbiotics - co-exist with cells and good for us

Pathogens or parasites - provide no advantage and are harmful - ex. Chlamydia trachomatis - sexually transmited infection or clostirdium tentani - cause tetanus

Classification of bacteria by shape

Spirilli - spiral shaped bacteria - ex. treponema pallidum

Bacilli - rod-shaped bacteria - ex. escherichia coli

Cocci - spherical bacteria - ex. streptococcus pyogenes

Aerobes -

require oxygen for metabolism

Anaerobes

Obligate

Aerotolerant

Facultative

cannot survice in an environment that does not have any oxygen

using oxygen when present but switching when it is not present

unable to use oxygen but do not die when oxygen is present

Does not use oxygen - use fermentation or other forms of cellular metabolism

Cell wall is the outer barrier to the cell, cell membrane (plasma membrane) is the next layer and composed of phospholipids - together they are called envelope

F: provide structure

F: control the movement of solutes in and out of the baterium

Two types of cell wall

Gram positive

Gram negative

D.Thin walls, contain peptodoglycan bu in very low doses

Detection method - stain using crystal violet stain and counter stain with safranin

if the envolope absorbs the crystal violet stain - gram positive

if it does not absorb the stain - then pink-red - gram neg

adjacent to cell membranne and separated by periplasmic space

they also have outer membrane - contains phospholipids and lipopolysacccarides (this trigers an immure response in human beings)

The inflammatory response to lipopolysaccharides is much stronger thant the response to lipoteichoic acid

D: thick layer of peptidoglycan (polymeric substance made from amino acids and sugars)

F: cell wall provides structure and may aid a pathogen by providing protection from a host organism's immune system

Cell wall also contains lipteichoic acid - the human immane system might be activated by exposure to this

D: whiplike structures used for propulsion

F: to move toward food or away from toxins or immune cells

Chemotaxis - ability of the cell to detec chemical stiumli and move toward or away from them

Structure

Filament

hollow, helical structure composed of flagellin

basal body

complex structure that anchors the flagellum to the cytoplasmic membrane, motor of flagellum, rotates upto 300Hz

Hook

contains the filament and the basal body - as basal body rotate, it exerts torque on the filament, which creates spin and propel bacterium forward

overall structure similar in gram positive and negative - some different physical structure and chem composition

Some of the DNA in prokaryotic cel is carried on plasmids - can make it more resistant to antibiotics

do not have mitochondria - ATP production is done in the cell membrane

have a mild version of cytoskeleton

Contain ribosomes but they are different size from the eukaryotes - pro ribo- 30S to 50S subunits, vs. euk ribo - 40S to 60S subunits

Genetic recombination

Transformation

Conjugation

Transduction

Transposons

Foreign genetic material integrates to host genomes - they come from bacteria after lysing

The mating for bacteria - the donor male with pilus transfers genetic material to recipient femalel. The female becomes a male. The conjugation bridge is formed using the pilus.

When a vector (virus that is carrying genetic material) is used to transfer gene from one bacterium to other one

Genetic elements capable of inserting and removing themselves from the genome

Growth phases

Lag phase - adapting to environment

Exponential/log -growing

Stationary - growth slows down

Death - the environment cannot support