Seminar 5: Exploring Cell types Flashcards
what is the cytoplasm composed of ?
cytosol + cytoskeleton
what is the cytoplasm?
- entire space inside cell (excl. nucleus)
- gel-like, contains organelles & supports cellular activities
- moves by cytoplasmic streaming
what is the cytosol
- liquid part of cytoplasm (excl. organelles)
- made of ions, H2O, small molecules & soluble proteins
- LESS DYNAMIC than cytoplasm (not much VISIBLE movement)
what is the cytoskeleton & what is it composed of?
anchor organelles, scaffolding/structural part of cytoplasm
composed of:
- microfilaments
- intermediate filaments
- microtubules
desc the microfilament & its functions
2 actin polymers into fine, small wires
- Contraction of cell (animal, contractile ring)
- Cell motility (cytoplasmic streaming)
- Maintain shape & cell structure
desc the intermediate filaments & its functions
thick cables of fibrous proteins (keratin)
- Anchors organelles
- Formation of nuclear lamina (membrane)
- Helps cell deal w/ mechanical stress (take some tension)
desc the microtubule & its func
Alpha & Beta tubulin wrapped into tube.
- Framework for motor proteins
- Allow cell movement
- Aids in chromosomal movement in cell division
what is the order of size of the components of the cytoskeleton?
microfilament > intermediate filament > microtubule
what is the order of the secretory pathway?
Nucleus > RER > Golgi > Vesicle > Cell membrane
desc func of RER in secretion
- Ribosomes on surface synthesise proteins from mRNA
- Transport to golgi in vesicle
desc func of golgi in vesicle
- Vesicle enters @ Cis face, leave @ Trans
- Package & process proteins
(Modify by adding/removing) - Products are pinched off in vesicle
desc func of vesicle in secretion
- Export: go to cell membrane, exits via exocytosis
- Use w/in cell: lysosome
desc func of plant vacuole
- Store nutrients & pigments
- Breakdown material
- Maintains cell turgor/pressure
desc func of lysosome
- Break down ingested materials (v. acidic interior w/ enzymes)
- Phagocytosis or Autophagy (break old organelles)
- Prod of digestion used to make NEW PROD
- Digest pathogens
desc func of microbodies (not part of endomembrane system)
Peroxisomes: break down a.a
Glyoxysomes: breakdown F.A
desc the phospholipid bilayer
- NP & P parts
- P = phosphate head, NP = F.A tails
- cholesterol embedded w/in
- NP &/or small molecules can pass thru (via diffusion or dissolve in bilayer)
- P &/or large molecules can’t pass easily
what does cholesterol do w/in the bilayer
- decreases membrane fluidity by decreasing phospholipid movement
- OH grp in cholesterol binds to phosphate head (both P), rest of molecule forms DF w/ F.A tails (NP)
- this anchors the tails in the bilayer to PREVENT MOVEMENT
define hypotonic sol
- sol outside cell has LOW solute conc
- H2O will flow into the cell to increase the conc of the sol
- becomes LESS diluted & MORE CONCENTRATED
- the cell will lyse
define isotonic sol
conc same inside & outside a cell
define hypertonic sol
sol outside cell has HIGH solute conc
- H2O from inside cell flows OUT to decrease conc
- causes cell to shrivel
what is facilitated diffusion
Passive movement through a membrane involving a specific carrier protein; does not proceed against a concentration gradient.
what is active transport
energy-dependent transport of a substance across a biological membrane against a concentration gradient—that is, from a region of low concentration (of that substance) to one of high concentration
what is the diff b/w active transport & facilitated diffusion
active req energy, transport from low to high conc
facilitated is opposite
what is pinocytosis
Endocytosis by a cell of liquid containing dissolved substances w/in vesicles.
what is phagocytosis
endocytosis by a cell of solid substances which are fused into a vesicle
what are integral membrane proteins
Proteins that are at least partially embedded in the cell membrane.
what is receptor mediated endocytosis?
cells absorb extracellular molecules by the ligand binding to receptors on the membrane
- triggers inward budding of membrane to form a vesicle which contains the ligand
what is a transmembrane protein
An integral membrane protein that spans the phospholipid bilayer.
what are anchored membrane proteins
Proteins that are associated with the membrane by covalent attachments to lipids.
what are cell junctions
Specialised structures associated w/ the cell membranes of epithelial cells
- Some contribute to cell adhesion, others to intercellular communication.
what is endocytosis
A process by which liquids or solid particles are taken up by a cell through invagination of the cell membrane
