MEMBRANE BOUND ORGANELLES

Regulates protein traffic and performs metabolic functions in the cell including protein synthesis, protein transport, lipid metabolism and movement, poison detoxification

Endomembrane System

• Carry out protein synthesis

• A complex of ribosomal RNA and protein

• Associated with the endoplasmic reticulum (ER) but not a part of endomembrane system

Ribosomes

What are the types of ribosomes based on cytoplasmic locales?

Free ribosomes and bound ribosomes

These ribosomes are suspended in cytosol

Free ribosomes

These ribosomes are attached to the outside of the ER nuclear envelope

Bound ribosomes

What does endoplasmic means

“within the cytoplasm”

What does Reticulum means

Little net

• Consists of membranous tubules and sacs called cisternae (reservoir for liquid)

• This separates the internal compartment

Endoplasmic Reticulum

What are the two types of ER?

Smooth ER and Rough ER

This lacks ribosomes

Smooth ER

This ER have ribosomes

Rough ER

• Synthesis of lipids

• Metabolism of carbohydrates

• Detoxification of drugs and poisons

• Storage of calcium ions (pumps calcium ions from cytosol into the ER lumen, in muscle cells)

Smooth ER

What determines the location in a cell where a protein is synthesized?

The sequence of amino acids in the N-terminal portion

Secretory proteins contain a _____ ______ at their N-terminus that directs the emerging polypeptide and ribosome to the ER membrane

Signal sequence

polypeptide moves through the ER membrane as it is being synthesized

Co-translational Translocation

proteins are synthesized to completion in the cytosol then imported to appropriate organelle across the boundary membrane

Post-translational Translocation

• Shipping and Receiving Center- Warehouse

• For receiving, sorting, and some manufacturing

• Modified and stored the proteins produced by ER before sending to other destinations

• Specialized for secretion

Golgi Apparatus

Two sides of a golgi stack

Cis face, trans face

entry face closest to the ER; cis Golgi network (CGN)

cis face

exit face at the opposite end of the stack

Trans face

contains distinct network of tubules and vesicles that serves as sorting station where proteins are segregated into different types of vesicles heading either to the plasma membrane or to various intracellular destinations

trans Golgi network (TGN)

move materials from the ER “forward” to the ERGIC and Golgi complex.

COPII-coated vesicles

move materials in a retrograde direction (1) from the ERGIC and Golgi stack “backward”

COPI-coated vesicles

move materials from the TGN to endosomes, lysosomes, and plant vacuoles. They also move materials from the plasma membrane to cytoplasmic compartments along the endocytic pathway. They have also been implicated in trafficking from endosomes and lysosomes

Clathrin-coated vesicles

are membranous sacs containing hydrolytic enzymes that break down (digest or hydrolyze) macromolecules such as proteins, lipids, nucleic acids, and carbohydrates.

Lysosomes

a process of engulfing smaller organisms or food particles e.g. macrophages – a type of white blood cells

Phagocytosis

hydrolytic enzymes are used to recycle the cell’s own organic material (from damaged organelle)

Autophagy

Large vesicles derived from the endoplasmic reticulum and Golgi apparatus.

Vacuoles

formed by phagocytosis

Food vacuoles

freshwater protists pump excess water out of the cell to maintain suitable conc. of ions and molecules in the cell

Contractile vacuoles

found in mature plant which develops by the coalescence of smaller vacuoles. Enlarge as it absorbs water enabling the cell to become larger

Central vacuoles

• Gives mechanical support to the cell and maintain its shape.

• Important for animal cells because they lack walls

• provides anchorage for many organelles

Cytoskeleton

What are the components of cytoskeleton?

Microtubules, Microfilaments, Intermediate filaments

• Locomotor appendages

• Controlled by the specialized arrangement of microtubules sheathed in an extension of the plasma membrane

Cilia and Flagella

has an undulating motion that generates force in the same direction as the

Flagella

work more like oars, with alternating power and recovery strokes generating force in a direction perpendicular to cilium’s axis

Cilia