Download Chapter 4 Prokaryotic Cell

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts

Cytoplasmic streaming wikipedia, lookup

Cell culture wikipedia, lookup

Cell encapsulation wikipedia, lookup

Amitosis wikipedia, lookup

Cellular differentiation wikipedia, lookup

Extracellular matrix wikipedia, lookup

Cell cycle wikipedia, lookup

Cell growth wikipedia, lookup

Cell nucleus wikipedia, lookup

Mitosis wikipedia, lookup

Organ-on-a-chip wikipedia, lookup

Flagellum wikipedia, lookup

JADE1 wikipedia, lookup

Cell wall wikipedia, lookup

Cytosol wikipedia, lookup

Signal transduction wikipedia, lookup

Cytokinesis wikipedia, lookup

Chemotaxis wikipedia, lookup

Cell membrane wikipedia, lookup

Endomembrane system wikipedia, lookup

List of types of proteins wikipedia, lookup

Transcript
Chapter 4
Prokaryotic cell
• Bacteria are prokaryotic organisms
• DNA is not enclosed within a membrane
• DNA is not associated with histone
proteins ( no nucleosomes)
• No membrane bound organelles.
• Cell walls – peptidoglycan
• Divide by binary fission
Curved rod
Bent rod
Loose spiral
Tight spiral
Glycocalyx
• Capsule – gelatinous substance – outside
the cell wall.
• Polysaccharides
• Contribute to the virulence
• Protect bacteria from phagocytosis
• Capsulated Streptococcus pneumoniae –
pneumonia
• Uncapsulated – destroyed by WBCs
•
•
•
•
•
•
•
•
•
Streptococcs mutans – surface of teeth
Tooth decay
Flagella
long filamentous
Movement – motile
Rotate their flagella to swim
Exhibit chemotaxis
Positive chemotaxis – towards substances
Negative chemotaxis - move away
Spirochetes
Treponema pallidum
syphilis
Fimbriae
• Gram - bacteria have hair like structures.
• Shorter thinner than flagella
• Numerous
• Attachment – virulence
• Neisseria gonorrhoeae – fimbriae –
Mucous membrane – colonize the area
• No fimbriae – cannot colonize
Pili
•
•
•
•
One or two pili
Longer than fimbriae
Used for conjugation
Join two bacterial cells together for DNA
transfer
Cell wall
• Protects internal structures and plasma
membrane
• Made up of peptidoglycan
• Glycan – sugar – repeating units of disaccharide
• N-acetylmuramic acid
• N-acetylglucosamine
• Peptido-peptide-amino acids
• Rows are sugars are cross linked by amino acid
chains.
Lipoprotein
Phospholipid
lipopolysaccharide
Lipid A
Endotoxin
Septic shock
•
•
•
•
•
•
•
•
Mycoplasma has no cell walls
Cell wall can be damaged
Antibiotic penicillin
Stops the formation of peptide cross
bridges in peptidoglycan
Lysozyme-enzyme-tears, saliva, mucus
Breaks the bond between sugar
molecules.
Gram- more resistant – outer membrane
Gram+ more sensitive – peptidoglycan is
exposed to the environment
Plasma membrane
•
•
•
•
•
•
Encloses the cytoplasm
Phospholipids and proteins
No sterols – exception is mycoplasma
Phospholipids are arranged in a bilayer
Proteins are inserted
Structure – fluid mosaic
• Plasma membrane – selectively
permeable (semipermeable)
• Damaged by alcohol, polymyxin
• Molecules constantly cross the membrane
• Nutrients get into the cell
• Waste products move out of the cell
• Active process and passive process
• Passive process – molecules move from
an area of high concentration to low
concentration. Energy is not used.
• Active process – molecules move from an
area of low concentration to high
concentration Energy is used.
• Passive process
• Simple diffusion, facilitated diffusion,
osmosis
• Simple diffusion – molecules move from
an area of high concentration to low
concentration.
• CO2 and O2 cross the membrane by
means of simple diffusion.
• Facilitated diffusion – molecules move
from an area of high concentration to low
concentration. Energy is not used.
• Transport proteins are used.
• Osmosis – movement of water molecules
from an area of high concentration of
water to an area of low concentration of
water through a selectively permeable
membrane.
• hypotonic – solute concentration lower
outside the cell. Water moves into the cell.
• Cell swells up and breaks down. Osmotic
lysis.
• Cell walls are damaged – bacteria
undergo osmotic lysis.
• Hypertonic – solute concentration is higher
outside the cell.
• water moves out of the cell. Plasma
membrane shrinks away from the cell wall.
• Plasmolysis
• Most bacteria cannot survive in a
hypertonic environment
Active process
• Active transport - molecules move from an area
low concentration to high concentration. Energy
is used. Transport proteins are involved. Ribose,
histidine
• Group translocation – molecules move from an
are low concentration to high concentration.
Energy is used. Transport proteins are involved.
While the molecule is being transported, it is
chemically altered.
• Glucose transported across the membrane,
phosphate is added.
• Cytoplasm – carbohydrates, proteins,
lipids, ribosomes, DNA, inclusions
• Nuclear area (nucleoid) – long circular,
double stranded DNA – chromosome
• Genetic information needed for the
structure and function of the cell.
• Some bacterial cells – small circular DNA
– plasmid
• Plasmids make the bacterium resistant to
antibiotics.
• Ribosomes – two subunits
• Each subunit is made up of proteins and
ribosomal RNA.
• 70S ribosomes – smaller, less dense than
80S ribosomes
• Protein synthesis
• Inclusions – organic or inorganic
• Metachromatic granules – phosphate –
used by the cell to make ATP.
• Corynebacterium diphtheriae
• Polysaccharide granules – glycogen or
starch
• Lipid inclusions – hydroxybutyric acid
• Bacillus, Mycobacterium
• Sulfur granules – Thiobacillus – uses
sulfur for energy.
• Carboxysomes – enzyme – ribulose
diphosphate carboxylase.
• Needed for photosynthesis
• Cyanobacteria – photosynthetic bacteria
• Gas vacuoles – hollow cylinders covered
by protein.
• Float at a certain depth in water - light
Endospores
• Clostridium and Bacillus
• Dormant stage of the cell
• Resistant to hostile environmental
conditions
• Heat, UV light, disinfectant, desiccation
• Nutrient depletion
• sporulation
• Endospores – dehydrated
• DNA, RNA, ribosomes, enzymes, dipicolinic
acid, calcium ions.
• Stay dormant for thousands of years.
• When conditions are favorable, spores
germinate into vegetative cells.
• Sporulation is not reproduction.
• One cell – one spore – germinates into a single
cell.
• No increase in the number of cells