Campbell Bio: Ch 6 "A Tour of the Cell"

Rough ER vs Smooth ER

Rough ER: studded with ribosomes, membrane factory, packages transport vesicles for the golgi

Smooth ER: Detoxification of poisons, lipid synthesis including steroids, calcium ion storage

Nucleus

A structure found in eukaryotes that houses the DNA of the cell

Only present in eukaryotes

Nucleolus

Can be multiple per nucleus (nucleoli)

Manufactures the subunits for ribosomes and releases them into the nucleus where it travels through the nuclear pores into the cytoplasm

Microtubules

Thickest cytoskeletal fiber (resist compression)

Serves as a means of transport for motor proteins carrying vesicles/organelles (like a highway)

Forms the mitotic spindle that pulls chromosomes apart in cell division

Provides cell structure and support

Make up cilia and flagella

Microfilaments (Actin Filaments)

Thinnest cytoskeletal fiber (resist tension/pulling)

Reacts with myosin in muscle cells to contract the cell

Cytoplasmic streaming in large plant cells to distribute nutrients/organelles

Amoeboid movement

Intermediate Filaments

Keep the organelles in place (nucleus) and does not move as often as microtubules or microfilaments

Cilia vs Flagella

Both made up of a 9 + 2 arrangement of microtubules

Cilia “row” with a power and recovery stroke while flagella undulate (like a fish tail)

Cilia are short and abundant on a cell while flagella are long and limited to 1-2 per cell

Ribosome

Made up of rRNA, consists of a small and large subunit

Translate mRNA sequences into amino acids in a polypeptide chain

Not considered an organelle due to lack of membrane

Located free floating in cytosol (makes proteins for the cell) or bound to the ER (makes proteins for export)

Mitochondria

Vital to cellular respiration and production of ATP

Has a double membrane and its own DNA

Inner folds called cristae increase surface area for cellular respiration

Chloroplasts

Vital to the calvin cycle and produce sugars for the cell

Has a double membrane and its own DNA

Name the three main intercellular junctions

Tight Junctions, Desmosomes, Gap Junctions

Plasmodesmata

Membrane lined channels between cell walls of multiple plant cells

Allow for resources to be shared amongst the cells, like proteins and nutrients.

Tight Junctions

Tightly pressed membranes of neighboring cells to form a watertight seal and prevents fluid leakage across cell membranes (think stomach lining)

Gap Junctions

Small channels formed by membrane proteins between cells that allow for cells to distribute ions, sugars, and other small molecules amongst themselves (ex. heart cells communicating to contract simultaneously)

Desmosomes

Cell structures that fasten neighboring cells into strong, flexible sheets using intermediate filaments. These sheets resist heavy mechanical stress or stretching so tissues stay intact (ex. skin)

Peroxisomes (and why compartmentalization matters)

Strips H from toxins/fatty acids, attaches to O2 creating hydrogen peroxide (H2O2) converted to water (H2O) via catalase. Keeps toxic H2O2 isolated from rest of cell

ECM

Stands for Extracellular Matrix. It is a mesh of glycoproteins (collagen and fibronectin) outside animal cells. They connect to membrane proteins (integrins).

Provides cell structure and a means for external communication to reach the cell.

Central Vacuole

Provides storage, waste disposal, and turgor pressure for plant cells.

Golgi Apparatus

Receives proteins from the ER on the cis side, modifies and sorts them, then expels them out of the trans side

Can also synthesize non protein macromolecules

Lysosomes

Membrane bound sac of digestive enzymes

Digests damaged macromolecules and organelles to recycle their materials

Utilizes compartmentalization to prevent digestive enzymes from harming the cell

Key for processes such as phagocytosis in immune cells

Cell Membrane vs Cell Wall

Cell membrane is a flexible and semi-permeable membrane in all cells. Cell wall is made up of cellulose microfibrils in an matrix of macromolecules such as pectin (like steel in steel enforced concrete) and provides rigid shape and defense in plant cells.

Cytosol vs Cytoplasm

Cytosol is the jelly-like fluid itself while the cytoplasm includes everything from the cell membrane to the nucleus (organelles included)

(Cytoplasm is like ramen noodles n all while cytosol is like the broth only)