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General Features of cells - Coggle Diagram
General Features of cells
Cell Theory
All living organisms are composed of cells.
Cells are smallest units of life
Cell division
Eukaryotes : more complex cells. - DNA within a membrane bound nucleus. Internal membranes form organelles.
Compartmentalized functions
Organelles: membrane-bound.
each structure has a specific function
Variety: shape, size, and organization of cells vary. differences between species and specialized cell types
The cytosol: region of a cell that is outside the organelles but inside the plasma membrane.
cytoplasm includes: cytosol, endomembrane system, semiautonomous organelles
Animal cell:
-no cell wall
-no chloroplast
-have many small vacuoles
-nucleus is present at the center of cell
-contains lysosomes
-contains centrioles near the nucleus
-irregular in shape
Both animal and plant cells contain:
-nucleus
-mitochondria
-cell membrane
-cytoplasm
-golgi apparatus
-endoplasmic reticulum and ribosomes
Plant cells:
-cell wall
-chloroplasts
-large central vacuole
-have definite shape
-nucleus pushed to one side of the cell.
Genomes and Proteomes: DNA in each cell is identical but differs in it's proteomes.
structure determines function
protein profile varies on
which proteins are expressed
levels of expression.
which subtypes of proteins are expressed.
post- translational modifications.
Molecular synthesis:
Anabolism: synthesis of cellular molecules and macromolecules
Catabolism: breakdown of a molecule into simple components
Cytosol: a central coordinating region for metabolic activities in eukaryotes
Cytoskeleton
Intermediate filaments: intermediate in size , form twisted and rope-like structures, are more permanent in nature
Actin filaments: also called microfilaments, long, thin fibres and dynamic.
Microtubules: long, hollow, cylindrical, dynamic instability
Motor proteins
Use ATP as a source of energy
Movements
Motor protein carries cargo along the filament
Motor protein remains in place, filament moves
Motor protein and filament restrained- action of the motor protein exerts force that bends the filament.
Prokaryotes : simple cell structure - no nucleus
Features of a typical bacterial cell:
Outside plasma membrane:
cell wall- for support and protection
glycocalyx- traps water, gives protection and helps in the immunity
appendages - for movements- flagella- pilli- for attachments
Inside plasma membrane:
cytoplasm - contained within plasma membrane.
Nucleoid region- where DNA is located
Ribosomes- synthesize proteins.
Archaea
-small cells, - less common - found in extreme environments
Bacteria
-small cells, - very abundant in the environment and our body, -majority not harmful to humans, - some species cause diseases
Organelles
Nucleus: contains chromosomes- composed of DNA + proteins = Chromatin
Nuclear matrix- nuclear lamina + internal nuclear matrix = filamentous network
Ribosome assembly in the nucleolus
Nuclear envelope: double-membrane
outer membrane is continous with the ER envelope
Nucleus pores provide entryways
Materials within the nucleus are NOT part of the endomembrane system.
ER- cisternae- flattened, fluid filled tubules. Enclosed around a single compartment- ER lumen.
Smooth: lacks ribosomes, functions : detoxification, carbohydrate metabolism, calcium balance, synthesis and modification of lipids.
Rough: studded with ribosomes.
functions: protein synthesis and sorting, insertion of protein into ER membrane
Glycosylation
Golgi Body: stack of flattened, membrane-bound sacs.
Vesicles transport material between the sacs
Functions: secretion, processing, and protein sorting
Lysosomes: contain acid hydrolases that perform hydrolysis under acidic conditions.
Lipids
Proteins
Carbohydrates
Nucleic acids
Digestion of substances from outside by endocytosis
Recycling of worn-out organelles- autophagy
Many different types of hydrolases to break down:
Vacuoles:
Central: for storage and support to maintain pressure (turgor pressure in plants)
Contractile: for movement, in protists to expel water
Phagocytic: in protists and white blood cells for degradation
Peroxisomes: catalyze by removing hydrogen or adding oxygen- hydrogen peroxide a byproduct. Catalase breaks down the dangerous product into water and oxygen
peroxisomes = glyoxysomes in plant seeds.
Plasma membrane
Cell signalling
membrane transport
Cell adhesion
Semiautonomous organelles
Mitochondria: grow and divide to reproduce themselves, are semiautonomous because they depend on cell for synthesis for internal components
Function: to make ATP.
Outer and inner membrane - intermembrane space and matrix
Involved in synthesis and modification of different molecules
contain their own DNA and divide via binary fission
Chloroplasts : grow and divide to reproduce themselves, are semiautonomous because they depend on cell for synthesis for internal components
Function: photosynthesis
Outer and inner membrane- intermembrane space and thylakoid membrane
contain own DNA and divide via binary fission
Protein sorting to organelles
cotranslational sorting
For ER, Golgi, lysosomes, vacuoles, plasma membrane and secreted proteins
Begins in cytosol during translation
Involves sorting signals and vesicle transport
Post translational sorting
Most proteins for nucleus, mitochondria, chloroplasts and peoxisomes
Synthesized in cytosol and translated later