- Contains most genes of the cell - Contains nucleolus - Membrane bound organelle (nuclear envelope: phospholipid bilayer) - Helps direct protein synthesis (synthesis of mRNA)

- Control cellular structure/ activities - site of DNA replication/ mRNA production - Produces ribosomes (nucleolus)

- Double membrane (lipid bilayer with an inner & outer membrane) - Contains pores (due to fusion of 2 membranes /To regulate entry & exit of the cell) - On nuclear side: Nuclear lamina (network of proteins that help maintain the shape of the nucleus)

- Made rRNA + proteins - Composed of 2 subunits - 2 types: Free; - in cytosol - make proteins functionning in cytosol Bound; - attached to endoplasmic reticulum or nuclear envelope - make proteins for membranes (aquaporin) and for secretion (insulin)

lacks ribosomes - Synthesizes lipids (like hormones) - Metabolizes carbohydrates - Detoxifies drugs and poisons (liver) - Stores calcium ions (muscle)

attached to ribosomes - membrane production (membrane bound proteins) - protein synthesis (secretory proteins; glycoprotein) - Distributes transport vesicle (protein surrounded by membranes)

- flattened membranous sacs = cisternae - contains cis (receiving) and trans (shipping) sides

- Membrane enclosed sacs of hydrolytic enzymes - has an acidic environment (pH=5) - enzymes (proteins) synthesized in RER; processed by Golgi

- membrane bound sacs - perform different functions in different cels

- For plants cells - found in mature plant cells - stores organic compound, inorganic ions, metabolic by-products; offers protection

Organelles Flashcards by Diakaria Diallo

Nucleus

Contains most genes of the cell
Contains nucleolus
Membrane bound organelle (nuclear envelope: phospholipid bilayer)
Helps direct protein synthesis (synthesis of mRNA)

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Functions of nucleus

Control cellular structure/ activities
site of DNA replication/ mRNA production
Produces ribosomes (nucleolus)

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Nuclear envelope

Double membrane (lipid bilayer with an inner & outer membrane)
Contains pores (due to fusion of 2 membranes /To regulate entry & exit of the cell)
On nuclear side: Nuclear lamina (network of proteins that help maintain the shape of the nucleus)

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Function of nuclear membrane

Separate nucleus from cytoplasm

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Nucleolus

Site of rRNA synthesis

- Assembles rRNA + proteins into ribosomal subunits (large & small)

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Function of Ribosomes

Site of protein synthesis

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Ribosomes

Made rRNA + proteins
Composed of 2 subunits
2 types:
Free;
in cytosol
make proteins functionning in cytosol
Bound;
attached to endoplasmic reticulum or nuclear envelope
make proteins for membranes (aquaporin) and for secretion (insulin)

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Endomembrane system

Transport system of proteins
- Nuclear envelope
- Endoplasmic reticulum 
- Golgi apparatus 
- Vacuoles
- Lysosomes
- Plasma membrane
connected directly through physical contact (Nucleus-ER) or indirectly by transport vesicles

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Smooth ER

lacks ribosomes

Synthesizes lipids (like hormones)
Metabolizes carbohydrates
Detoxifies drugs and poisons (liver)
Stores calcium ions (muscle)

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Rough ER

attached to ribosomes

membrane production (membrane bound proteins)
protein synthesis (secretory proteins; glycoprotein)
Distributes transport vesicle (protein surrounded by membranes)

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Endoplasmic Reticulum

Network of tubules and sacs (cisternae)
continuous with nuclear envelope
2 regions : Rough & smooth

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Golgi apparatus

flattened membranous sacs = cisternae

- contains cis (receiving) and trans (shipping) sides

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Functions of Golgi Apparatus

Modifies, sorts and packages glycoproteins from rough ER
Receives vesicles from rough ER (cis)
Ships vesicle to other end (trans)
Produces polysaccharides
Makes lysosomes

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Lysosomes

Membrane enclosed sacs of hydrolytic enzymes
has an acidic environment (pH=5)
enzymes (proteins) synthesized in RER; processed by Golgi

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Functions of Lysosomes

1) Intracellular digestion:
- Lyosomes fuse with food vacuole produced by phagocytosis (cell engulating another cell or food particle)
2) Recycles old/damaged organelles:
- called autophagy
- components released into cytosol for re-use

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Vacuoles

membrane bound sacs

- perform different functions in different cels

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Food vacuoles

formed by phagocytosis

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Contractile vacuole

pumps excess of water out of cells (paramecium)

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Central vacuole

For plants cells
found in mature plant cells
stores organic compound, inorganic ions, metabolic by-products; offers protection

Functions of mitochondria

Energy metabolism

- site of cellular respiration (ie.: ATP production)

Mitochondria

Found in eukaryotic cells including plants
Number of mitochondria varies with level of metabollic activity
Surrounded by a double membrane (lipid bilayer)
Outer:
-smooth
highly permeable to small molecules & ions
Inner:
extensively folded into cristae (increase surface area)
contains enzymes for cellular respiration
2 compartments:
intermembrane space
mitochondrial matrix: filled with DNA, ribosomes (free), enzymes

Chloroplasts

Found in plants &amp; algae
Surrounded by a double membrane:
- both membrane are smooth
- inner membrane surrounds stroma
2 compartments:
- intermembrane space
- Stroma: DNA, ribosomes and enzymes photsynthesis as well as Thylakoids

Function of chloroplast

Site of photosynthesis (converts light energy to chemical energy)

Thylakoids

membranous sacs
contain chlorophyll (green pigment)
involved in photosynthesis
stacked into grana (granum)

Peroxisome

- Found in both plants (glyoxysomes) and animal cells - single lipid bilayer - no ribosomes or DNA

Functions of peroxisomes

- Breakdown of fatty acids (also fuel for cellular respiration - Detoxification alcohol/ harmful substances

Cytoskeleton

- network of protein fibers - found in cytoplasm - Dynamic = dismantled in one part of the cell and reassembles in another part - 3 types of fibers: Microtubules, Microfilaments and Intermediate filaments

Functions of cytoskeleton

- Mechanical support & maintains cell shape - Organelle movement - Cell movement

Microtubules

- Thickest - Hollow rods - Constructed from the protein tubulin - Controlled by the centrosome (MT organizing center)

Function of microtubules

- Cell division : Chromosomes movement (ie: mitotic spindle) | - Cell movement: Cilia or flagella

Cillia & Flagella

- locomotive projection of cells - move material across a surface (Ex. Cillia: Mucus in resp tract; egg in fallopian tube) otr move cell (ex. Flagella sperm) - Differences: Cilia: Short, large number on cell Flagella: Long, one or few per cell

Microfilaments

- Thinnest - Solid rods - Constructed from the protein actin

Functions of microfilaments

- Cell division: by separating the cytoplasm (cytokinesis) - Cell movement: by pseudopodia - Muscle contraction Cytoplasmic streaming: circular flow of cytoplasm within cell

Pseudopodia

Cellular arm-like extensions

Intermediate filaments

- intermediate in size | - diverse: differ in size and composition depending on cell type (ex: keratin)

Functions of intermediate filaments

- Anchors nucleus and organelles | - Forms nuclear lamina (maintains nucleus shape)

Extracellular components

- Cells synthesize and secerte materials that are external to the plasma membrane - Cell walls, the extracellular matrix (ECM), cell junctions

Cell walls

- Found in prokaryotes, fungi, some protists, plants but NOT animals - Composition varies from species to species

Functions of cell walls

- protects cell - maintains cell shape - Prevent excessive uptake of water

Extracellular Matrix (ECM)

- Found in animal cells - Network of macromolecules secreted by cells - contains: Glycoproteins (collagen most abundant) Proteoglycans (small protein rich in sugar) Fibronectin Integrins: Transmembrane protein, Bind ECM (fibronectin) on one side; Cytoskeleton (microfilaments) on the other side, connect ECM to cytoskeleton

Functions of ECM

- Anchorage of cells in tissues | - Cell movement

Cellular junctions

Neighboring cells adhere, interact and communicate through direct physical contact via cellular junctions - Plasmodesmata (Plants) - Tight junction - Desmosomes - Gap junctions

Plasmodesmata

- Communicating channels in plants - Perforate plant cell walls - Allow movement of H2O, small solutes etc from cell to cell

Tight junctions

- Membrane of neighboring cells are fused - prevents leakage of fluid Ex: intestinal epithelium (stomach ph= 2; intestine ph=7), kidneys (seperate blood & urine)

Desmosomes

- Anchoring junctions - Fasten cells together into strong sheets - Withstand mechanical stress Ex: muscle,skin

Gap junctions

- Communicating junctions in animal cells - cytoplasmic channels between adjacent cells - Small molecule may pass( salts, sugar, amino acids etc)