Module 3- Midterm- Cells Flashcards
Golgi Apparatus Discription
-packaging proteins from rough ER into membrane-bound vesicles
produce 2 different types of vesicles:
-secretory vesicles (transport proteins to
extracellular environment)
-storage vesicles (lysosome, where contents are
stored within the cell)
Free Ribosomes Description
- dense granules of protein and RNA
- manufacture proteins from amino acids under control of cells DNA
- form in groups of 10-20, called polyribosomes
Mitochondrion Description
- where most ATP is generated
- number of mitochondria in each cell depends on demand of energy
- can replicate itself without cell division (during times of increased demand, like working out)
Endoplasmic Reticulum Description
- site for synthesis, storage, transport of lipid and protein molecules
- proteins manufactured are packaged into vesicles and sent to Golgi
- rough ER= proteins
- smooth ER= lipids
Cell Membrane Description
- role in detecting chemical signals from other cells
- forms links with adjacent cells
- regulate passage of substances
Centriole Description
-bundles of microtubules responsible for directing DNA movement during cell division
Nucleolus Description
-contains DNA that produces RNA found in ribosomes
Phospholipids and the Cell Membrane
- phosphate head
- fatty acid tail
- lipid bilayer: heads face toward water
- barrier to water and water-soluble substances such as: ions, sugar, urea
- oxygen, carbon dioxide and steroid hormones pass easily
Membrane Protein Responsibilities
- receptors for chemical attachment of hormones and neurotransmitter
- enzymes that help chemical reactions or breakdown molecules
- Ion channel or pore for water-soluble substances
- Membrane transport carriers
- Cell-identity markers, antigens or glycoproteins
Membrane Transport Mechanisms
- Endo/exocytosis
- Diffusion through the lipid bilayer
- Diffusion through a protein channel
- Facilitated diffusion
- Active transport
What is diffusion?
- movement of substance from high concentration to low
- substance continues to move until net zero/equilibrium ( substance still moves)
Electrical Gradient- Diffusion
- electrically charged molecules tend to move toward areas of the opposite charge
- positive move to negative, down their gradient
Electrochemical Equilibrium
- if chemical and electrical gradients are in opposite directions, the ion movement will depend on the balance of the two gradients
- will stop moving when molecules reach electrochemical equilibrium (equal and opposite in direction)
Diffusion of Lipid Soluble Substances
- oxygen, carbon dioxide, and steroid hormones
- can diffuse right through
Diffusion Factors
- Size of protein channels (sugar too large)
- Charge on molecule (like charges repel)
- Electrochemical gradient
- Number of channels in the membrane
Facilitated Diffusion
- substances that cannot pass or are too large for channels can still pass through fast
- molecules attach to protein carriers on membrane and cause change in shape in the protein
- after protein changes shape, which opens a protein channel or the protein rotates the molecule to the inner surface of the membrane where it is released
How does Simple diffusion and Facilited diffusion differ?
- rate of transport is determined by amount of available proteins
- once all carriers are saturated, the system cannot operate any quicker
- the speed at which the carriers change shape is limited
- shows chemical specificity
- may be competitively inhibited
What is chemical specifity?
-a given carrier protein will only interact with a specifically shaped molecule
What is competitive inhibition?
-may be inhibited by molecules that are very similar in shape
Active Transport
- requires protein carriers that span the cell membrane
- can be saturated, shows chemical specificity, competitive inhibition
- Requires ATP
- moves molecules from low to high conc’
- example of this is sodium potassium pump
What is osmosis?
- requires special pores
- the amount of water that diffuses out, diffuses in
- in certain conditions, there can be a concentration difference of water across the membrane, when this happens there is a net movement of water, down the concentration gradient
- pure water has a high concentration in water and a low concentration in solute
- a solution that has a high concentration in solute, has a low concentration in water
what is a solute?
-substance that is being dissolved into a liquid
what is a solvent?
- is the liquid that is doing the dissolving
- generally water
what is a solution?
- is what you get when you dissolve a solute in a solvent
- the final product
Osmosis across the membrane is affected by:
- permeability of membrane to solute in the inter/intraceullular fluid
- concentration gradients of solutes in intra/intercellular fluid
- pressure gradient across the cell membrane
what is an osmole?
-unit used to describe the amount of osmotically active particles in a solution
what is tonicity?
- ability of solution to cause osmosis across membrane
- fluid concentration in human is 300 MoSm/kg water
what is an isotonic solution?
- has same concentration as body fluids
- no osmosis occurs if you were to place RBC in this solution
what is a hypotonic solution?
- has lower concentration compared to celluar fluids
- the cell swells
- 200mosm solution
- more water in this solution
what is a hypertonic solution?
- higher concentration compared to the cell
- 400mosm
- causes osmosis
- cell shrinks
- less water in this solution than the cell
concentration gradients
- Na, Ca and Cl all have higher conc’ outside cell (try and move into cell)
- K has higher conc’ inside cell ( try and move out of cell)
- just because there is a gradient, does not mean ions will flow in this direction, it is up to the cell membrane to allow this
membrane permeabilities
- Na, Cl, Ca are not very permeable to the membrane, have few channels for this
- membrane is more permeable to K, so some leaks down concentration gradient
Resting membrane potential
- electric potential difference across the membrane, which present in all cells even in resting state
- 70mv (negative because inside the cell is -)
- ion have difference on resting potential depending on permeability and concentration gradient
Equilibrium potentials
-when the chemical gradient and the electrical potential are equal in magnitude and opposite in direction, no net movement it is called an electrochemical equilibrium
what is the equilibrium potential for Na+?
60+ mv
what is the equilibirum potential for K+?
-90mv
what is the equilibrium potential of Cl-?
-70mv
