1 Flashcards
Cell Theory
All organisms are composed of cells
Cells are the basic unit of life
All cells come from preexisting
*viruses are not composed of cells, not an organism
Eukaryotic
membrane bound organelles, capable of mitosis
*mature red blood cells don’t have nuclei, expel it during maturation process
Prokaryotes vs Eukaryotes
Prokaryotes: 1 circular DNA chromosome
Eukaryotes: many linear chromosomes composed of chromatin, nucleus held by double phospholipid membrane (nuclear envelope) which is porous
- Pores are protein complexes which allow exchange of biomolecules (RNA, protein)
Nucleoli
Dense regions in nucleus which assemble ribosomes
Cytoplasm
Contains organelles suspended in cytosol, where sub cellular components are trafficked.
Endosymbiotic Theory
Mitochondria arose when a bacterium was engulfed by another cell and used for energy
Mitochondria
Contain circular mtDNA that make some proteins
Maternally inherited, all mitochondria come from egg
- Cell can contain thousands, mutations in mtDNA lead to serious disorders
- Replicate via binary fission independently of cell like bacteria, DNA replicated and cell splits
Powerhouse of the cell, make cells energy

Mitochondrial Matrix: what processes occur?
Makes ATP using citric acid (Krebs) cycle
- Electron transport chain and ATP synthase embedded in inner membrane
- Inner membrane invaginate (folds back on itself to form pouch) as cristae (increases surface area)
Endoplasmic Reticulum (ER)
continuous with nuclear envelope
Rough and Smooth ER
calcium storage, protein synthesis and lipid metabolism.
Rough ER
Ribosomes embedded which synthesize proteins fed to rough ER for 3D folding and modification
- Glycosylation: add carbohydrate group
- Proteolytic cleavage
- Disulfiide bridges
Membrane bound ribosomes usually form secreted proteins/membrane bound proteins
- Free ribosomes in cytoplasm synthesize intracellular proteins
Smooth ER
- No ribosomes
- lipid metabolism
- steroid hormone precursor synthesis (cholesterol)
- detoxification (liver cells have extensive smooth ER)
- stores calcium in muscle cells for contraction
synthesizes lipids, phospholipids as in plasma membranes, and steroids. Cells that secrete these products, such as cells of the testes, ovaries, and skin oil glands, have an excess of smooth endoplasmic reticulum.

Golgi apparatus (post office)
Once protein is synthesized, packaged into vesicles and sent to Golgi apparatus (post office)
- chambers called cisternae
- receives transport vesicles at cis face, modifies them and send to trans face, then they leave

Lysosome
garbage disposal, extracellular stuff enters cell through endocytosis
- vesicle pinches off from cell membrane then fuses with lysosome
Autophagy: intracellular waste fuse with lysosome for degradation
- Digestive enzymes in lysosomes function at acidic pH, pH of cytoplasm is basic so they can’t function
Peroxisome
Accumulates and neutralizes peroxides, protect against oxidative stress
- *- Peroxides:** generate reactive oxygen species harmful to the cell
- Peroxisome breaks down fatty acids through beta oxidation
- Formed in ER

Cytoskeleton fibers (3 types)
Fibers that act as structure
- Microfilaments (smallest)
- Microtubules
- Intermediate filaments (largest)
Microfilaments
Two intertwined strands of actin polymers (F-actin)
- single actin monomer is a globular protein called G-actin
Cell movement and formation of cleavage furrow (indentation of the cell’s surface that begins the progression of cleavage) and interact with protein myosin to initiate muscle contraction
Polar
Microtubules
wider, polymers of a-tubulin and B-tubilin
- Maintain structural integrity of cell
- Highways for motor proteins to traffic vesicles
- Form mitotic spindles (separate chromosomes)
- In Eukaryotic flagellum and cilia, involved in cell motility
Polar
Kinesin
Traffics vesicles OUTWARD of cell
Dynein
Traffics vesicles INWARD
Centrosomes
Composed of two centrioles, microtubule organizing centers
Flagellum
Tail of cells such as sperm, moves back and forth powered by ATP in Eukaryotes to move
*In Prokaryotes, use rotary motion and powered by proton gradient, composed of flagellin protein and not microtubules
Cilia
Help move substances along cell surface
ex. in lungs cilia help clear out mucus and line Fallopian tubes (egg –> uterus)
Polarity of microtubules and microfilaments
Used for polymerization and depolymerization, adding monomers to positive end and removing from negative end
- Treadmilling: both at same time
Capping proteins
Halt polymerization, prevents growth and shrinkage































































































































































