Module 3: Cells Flashcards
Nucleolus
The dense body within the nucleus that contains the DNA that makes RNA in ribosomes
Golgi apparatus
The amazon shipping centre that gets proteins from the rough endoplasmic reticulum to package and transport via membrane-bound vesicles
2 types of vesicles created by the Golgi apparatus:
- secretory (sends out of the cell)
- storage (keeps within)
Free ribosomes
RNA + protein granules that functions to manufacture amino acids
Polyribosomes: groups of free ribosomes of 10-20
Lysosome
Comes from the Golgi apparatus
Has enzymes that breaks down foreign or dead material
Mitochondrian
The powerhouse of the cell
Creates all of the ATP (energy) that the cell needs
Mitochondria can replicate even if the cell isn’t in undergoing cell division
Endoplasmic reticulum
Continuous with the nuclear membrane
2 kinds: rough and smooth
- rough has ribosomes and its function is protein synthesis
- smooth doesn’t have ribosomes and its function is lipid and fatty acid synthesis
Cell membrane
Gateway of the cell
Semi-permeable
Functions: controlling the movement of substances/things in/out, detecting chemical signals
Proteins, nucleotides and other large molecules can’t penetrate so it has a lot of embedded proteins
Centrioles
Cylinder bundles of microtubules
Function: directs DNA movement in cell division
List the structures of the cell membrane
- channels
- pores
- carbohydrate molecules for cell recognition
- cholesterol for stability
- phospholipid molecules
Phospholipid molecules
Structure of cell membrane
Hydrophilic head
Hydrophobic tail
Creates the basis of the cell membrane - there are two layers where the tails face one another and the heads face the aqueous solutions inside and outside of the cell
Keep out - water soluble (ions, glucose, urea, etc)
Welcome - fat soluble (O2, CO2, steroid hormones)
Cholesterol molecule
Structure of cell membrane
- adds flexibility over a wider temperature range
- located in the non-polar layer
- impermeable to some water soluble molecules
Associated protein
Structure of cell membrane
A type of protein attached to the inside or outside of the cell
2 types learned about so far:
-structural: in the inside surface, supports and strengthens the membrane or anchors cell organs to intracellular side of membrane
- enzyme: catalyst for reactions that is attached on either side (intracellular or extracellular)
Carbohydrate molecule
Structure of cell membrane
- Associated with the extracellular membrane proteins or lipids
- creates protection = glycocalyx (key role in the immune response and recognition of other cells)
Different types of membrane proteins
Receptor - attaches chemical hormones and neurotransmitters
Enzyme - breakdowns products
Channel - allows water solvable substances entry (transportation)
Gate - transportation
Cell identity - antigens (foreign particles stimulate immune system, glycoproteins)
Transporting substances in and out of the cell with membrane proteins
- Endocytosis/exocytosis (pinocytosis for small molecules)
- Diffusion through the lipid bilayer (fat soluble)
- Diffusion through protein channels (water soluble)
- Facilitated diffusion
- Active transport
Endocytosis/exocytosis
The cell membrane engulfs substances coming in and creates a membrane around the substance (endocytosis = in)
Vesicles combine their membrane to the membrane of the cell to go out (exocytosis = out)
Simple diffusion
Substances move down their concentration gradient (from a high concentration to a low concentration)
Chemical concentration gradient - substances will move until their is equilibrium (diffusion/net-movement=0)
Diffusion with ions
+ and - attract, opposites repel
Charged ions can move down both chemical and electrical gradients
Electrochemical equilibrium
Chemical and electrical gradients are equal and opposite in force
Diffusion factors
- Size channel
- Charge on molecule
- The greater the electrochemical gradient, the greater the movement (and vice versa)
- Number of channels
Facilitated diffusion
Where substances attach to specific protein carriers
This changes the shape of the protein where it opens like a gate or the protein rotates
No energy
Powered by concentration gradient
Rate depends on number of proteins and if all of them are working its considered saturated
Competitively inhibited
Active transport
Uses energy
Protein carriers
Chemical specifity
Competitive inhibition
Osmosis
Movement of water until equilibrium (diffusion of water)
- with more solute the water concentration is lower
- remember that chemicals dissociate into their ions when put in water (NaCl becomes Na+ and Cl-)
Solute
Substance being dissolved
Solvent
Liquid doing the dissolving
Solution
What you get when you dissolve a solute in a solvent
Osmosis across a cell membrane is affected by
- the permeability of the membrane to the solutes in the intracellular and interstitial fluids
- The concentration gradients of the solutes in the intracellular and interstitial fluids
- The pressure gradient across the cell membrane
Units of osmosis
Osmoles/kg of water
Osmoles/L of solution
Tonicity
The ability of a solution to cause osmosis across a membrane
Fluid in the human cell = 300mOsm/kg water
Isotonic solution
Concentrations on the cell side and solution side are the same (intercellular = extracellular)
Hypotonic solution
less solutes in solution causes water to flow from the solution into the cell
Hypertonic solution
more solutes in the solution causes water to flow from the cell into the solution
concentration gradients an d membrane permeabilities for ions
Na+, Ca++ and Cl- all have higher concentrations outside the cell than inside
K+ has a higher concentration inside the cell than outside
Just because there is a concentration gradient doesn’t mean the ions will flow. The membrane doesn’t allow them in all the time
resting membrane potential
the charge in the cell at a normal state
-70mV in most human cells
equilibrium potentials
the equilibrium potential for ions must be applied to inside for neurons: E(K+)= -90mV E(Na+)= +60m E(Cl-) = -70mV
sodium potassium pump
active transport through a protein letting 3Na+ out and 2K+ in
Importance:
most cells will burst without
cell volume stays constance
osmosis out because 3 out and 2 in
importance of the resting membrane potential
ability to do work excitable cells (nerves and muscles = ex.)
