Unit Seven: Cell Structure And Function, Cell Transport, And Cell Communication Flashcards
How large are cells?
1 um to 5 cm
What basic structures are present on all cells?
Plasma membrane
Nuclear region
Cytoplasm
Ribosomes
Why are cells surface to volume ratio important?
The bigger the ratio the harder it is to divide and small cells function more effectively
What are the domains of prokaryotes?
Archaea
Bacteria
What is included on the eukaryotic domain?
Protista
Fungi
Plants
Animals
Theory of endosymbiosis
Organelles were once free living bacteria that were incorporated into a larger eukaryotic cell
What is the role of the plasma membrane?
Regulate movement of materials into and out of the cell and protect it from the outside environment
Phospholipids
Made of glycerol, phosphate (polar), and 2 fatty acid tails (non-polar) and a phospholipid via layer forms around the cell membrane
Integral proteins
Channel, carrier, cell recognition, receptor, and enzymatic proteins
Channel proteins
Allows molecules to pass through
Carrier proteins
Combine with a substance and help it pass through
Cell recognition proteins
Identify cell to surrounding cells
Receptor proteins
Bind to a molecule causing a change in cell activity
Enzymatic proteins
Catalyze cellular reactions
Fluid mosaic model
Singer and Nicholson suggested this to describe the ingredients and consistency of the plasma membrane. It is fluid because the individual components are loosely held together and there is latteral movement of the parts and mosaic because of th various components
Glycolipid and glycoproteins
Carbohydrate chains attached to protein or phospholipids to function adhesion, reception, and cell recognition
What can pass through the plasma membrane?
Water, small, non-charged molecules can pass freely
Large molecules need to be transported by vesicle formation
Passive transport
Not everything can pass through
Diffusion
Movement of molecules from high to low concentration until solute and solvent are evenly distributed
Facilitated diffusion
Uses carrier proteins to move from high to low concentration until solute and solvent are eual
Osmosis
The movement of water molecules down a concentration across a semipermeable membrane from high to low concentration
Osmotic pressure
Pressure that develops in a system due to osmosis
Water potential
Move from an area of higher water potential to lower water potential and is directly proportional to the pressure on a system
Water potential equation
W=Wp+Ws
Water potential equals pressure potential plus solute potential
Wp
Usually 0
Ws
-iCRT (bars)
i
Ionization constant
C
Molar concentration
R
Pressure constant (0.0831 liters/mole of degrees Kelvin)
T
Temperature degrees Kelvin (273+degrees Celsius of a solution)
Isotonic
Solute concentration is the same inside and outside a membrane
Hypotonic
Lower concentration of solute causes turgor pressure
Hypertonic
Higher concentration of solute causes plasma lysis or the shrinking of a plant cell
How will water always move?
From a hypotonic solution to a hypertonic solution
Active transport
The movement of molecules against a concentration gradient to concentrate molecules or to create a gradient. It requires a carrier protein.
How does it result in a concentration for active transport?
Sodium or potassium pump nerve cell membranes
How does a proton gradient result in active transport?
Electrical gradient and proton pump membranes of mitochondria or chloroplasts
Endocytosis
Takes in a substance
Exocytosis
Eliminates waste
Phagocytosis
Takes in food particles and other cells
Pinocytosis
Takes in liquid and small particles
What does end, phago,pinco, and exocytosis all require?
ATP
What are the type of junctions between cells?
Anchoring, tight, gap junctions, and plasmodedmata
Anchoring junctions
Attach cells to one another by adhesion junctions and desmosomes
Tight junctions
Membrane proteins of adjacent cells attach to one another
Gap junctions
Channels between cells that allow for exchange of small molecules
Plasmodedmata
Channels between plant cells
Homeostasis
Maintenance of constant internal body conditions by using sensory receptors, integrators, and effectors
Negative feedback loop
Detects and reverses disturbances from normal levels. Disturbance triggers change which restores homeostasis
Positive feedback loop
The maintenance of a disturbance for a specific purpose
Excretory system
Maintains water and ion balance in the body (osmoregulation) and to excrete waste and maintain homeostasis
What are the challenges of freshwater organisms with respect to water and ion balance?
They are hypertonic to the environment so they face challenges gaining water. The solution is active transport salt into cells in gills to produce diluted urinie
What are the challenges of salt water organisms with respect to the water and ion concentration?
They are hypotonic to their environment so they lose water the solution is to drink water excrete salt through their gills
What are the challenges of terrestrial organisms with respect to the ion and water balance?
They face problems getting rid of excess solutes and toxins without losing too much water
What is the structure of the human excretory system?
Filtration
Reabsorption and secretion
Excretion
Filtration
Blood pressure pushes small molecules out of capillaries through a semi-permeable membrane into the nephron
Reabsorption
Removing the good things for the filtrate back into the blood
Secretion
Moving potentially harmful substances from the blood into the filtrate or urinie
Excretion
Waste is released
How is water and salt balance maintained in the kidneys?
ADH increases reabsorption and decreases secretion from the posterior pituitary and aldosterone from the adrenal cortex stimulated reabsorption of sodium ions
ADH in the kidneys
Released into the blood stream from pituitary gland
Triggers osmoreceptors in the hypothalamus is to increase osmolarity of the blood
Osmorectors promote thirst
Drinking reduces osmolarity of the blood, inhibits secretion
ADH binds to specific membrane receptors on a nephron
cAMP second messenger system is activated
Vesicles containing aquaporin channels fuse with cell membrane lining the lumen of the collecting tubule
Additional aquaporin channels increase the rate of water reabsorption by the collecting tubule
What is the purpose of cell communication?
Multicellular organisms to carry out crucial functions and is evidence of common ancestry
What is the difference between local and long distance signaling?
Local signaling is between adjacent cells while long distance is throughout the body
Local signaling
Direct contact signal molecules pass between cells through cell junctions and contact between surface molecules. Messenger molecules local regulators travel short distances.
Long distance signaling
Chemical or hormones go to target cells and electrochemical go to nervous systems
3 steps of cell communication
Reception
Transduction
Response
Membrane receptor vs intracellular receptor
Membrane receptor is embedded in the cells plasma membrane while an intracellular receptor in cytoplasm or nucleus of a target cell. They bind to a chemical signal for cell signaling. The intracellular receptor is used if chemical signal is non-polar can cross the membrane.
What turns on and off transcription?
Hormone or receptor complex
What are possible methods of transduction?
Binding of a chemical signal causing conformational change in the receptor which triggers activities inside. Can be one step or a series of steps involving relay molecules or proteins and or second messengers
Possible response to cell communication
The cytoplasm likes open and close ion channel and change cells metabolism or in the nucleus transcription of a gene is turned on and off. The response to the same chemical can be different in different cells.
