Categorias: Todos - ribosomes - prokaryotic

por Balqis Mustazim 8 anos atrás

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Prokaryotes

Prokaryotic cells are characterized by their smaller size and lack of membrane-bound organelles. They reproduce through binary fission and exhibit various types of motility, such as running, swimming, and tumbling.

Prokaryotes

NUR BALQIS BINTI MUSTAZIM 190154

Prokaryotic Cell


Prokaryotic CellCharacteristicsSmaller in sizeNo membrane bound organellesCell division by binary fissionTypes of motilityRun or swimTumblesSwarmStructures internal to the cell wallPlasma membraneMechanical boundary of cell, nutrientand waste transportLocation for metabolic processesDetection of environmental cuesfor chemotaxisCytoplasmsubstance of the cell within plasma membraneconsist of 80% water and primarily contain protein, carbohydrates and lipidsNuclear area or nucleoidcontain genetic informationRibosomessites for protein synthesisInclusionsStorage of carbon, phosphate and other substanceExternal structures to the cell wallGlycocalyxAttachment to surfaceProtect against dehydrationInhibit movement of nutrients out of cellsSource of nutrientsFlagellaLong filamentous appendages for motilityAxial filamentsPresent in spirochetesKnown as endoflagellaFor corkscrew movementFimbriaeOccur at poles or distributed over the entire surfaceFunction as attachmentCell WallResponsible for the shape of cellPrevent bacterial cells from rupturing due to changes in pressureThe point of anchorage for flagellaMay contain antigen if bacteria is infectiousTypes of cell wallGram +veGram -veAtypica

External structures to the cell wall

Fimbriae
Function as attachment
Occur at poles or distributed over the entire surface
Axial filaments
For corkscrew movement
Known as endoflagella
Present in spirochetes
Flagella
Long filamentous appendages for motility
Glycocalyx
Source of nutrients
Inhibit movement of nutrients out of cells
Protect against dehydration
Attachment to surface

Types of motility

Swarm
Tumbles
Run or swim

Cell wall

Types of cell wall
Gram -ve
Gram +ve
May contain antigen if the bacteria is infectious
The point of anchorage flagella
Prevent bacterial cells from rupturing due to the change in pressure
Responsible for the shape of the cell

Structures internal to the cell wall

Endospore
Inclusions
Types of inclusions

Gas vesicles

Magnetosomes

Iron oxide (Fe3O4) that act like magnet

Carboxysomes

Used for co2 fixation during photosynthesis

Contain the enzyme ribulose 1,5-diphosphate carboxylase

Sulfur granules

Thiobacillus - sulfur bact.

Derive energy

sulfur-containing compounds

oxidising sulfur

Energy reserve

Lipid inclusios

Storage material -polymer poly-beta-hydroxybutyric acid

Polysaccharide granules

Diffentiate by using iodine

starch granules: blue

glycogen granules: reddish brown

Consists glycogen and starch

Metachromatic granules

Stain red with certain blue dyes such as methylene blue

Large inclusions

Storage of carbon, phosphate and other substance
Ribosomes
RNA or rRNA
sites for protein synthesis
Nuclear area or nucleoid
Plasmid
contain genetic information
Cytoplasm
Intracytoplasmic membranes

Anammoxosome in Planctomycetes

Plasma membrane infoldings

consist of 80% water and primarily contain protein, carbohydrates and lipids
substance of the cell within plasma membrane
Plasma membrane
The movement of materials across membranes

Active process

Group translocation

Active transport

Passive processes

Osmosis

Facilitated diffusion

Simple diffusion

Uptake of Nutrients - Getting Through Barriers

Some unique substances may required

Micronutrients (trace elements)

Macroelements (macronutrients)

Destruction

Disinfectants - alcohols and quatenary ammonium compounds

Lysis: cells burst

Plasmolysis: cells shrink

Cause leakage of intracellular contents

Function

Captures energy as ATP

Carries on respiration

Assists in DNA replications

Synthesis cell wall components

Selectively permeable barrier

Detection of environmental cues for chemotaxis
Location for metabolic processes
Mechanical boundary of cell, nutrient and waste transport

Characteristics

Cell division by binary fission
No membrane bound organelles
Smaller in size