Cell Processes

All About Cells! Cells are the most basic unit of life. What are some ways that cells carry out life processes?

Process: Maintaining Homeostasis Living cells can only function within a narrow range of such conditions as temperature, pH , ion concentrations, and nutrient availability. Organisms need a way to maintaining internal stability in spite of environmental change.

Process: Maintaining Homeostasis Homeostasis = a stable internal environment Cell membrane – separates the internal environment from the outside. Selectively permeable – regulates what enters and leaves the cell.

Process: Transport of Molecules All cells acquire the molecules and ions they need for life from from their surrounding extracellular fluid Extracellular fluid

Simple Diffusion

Facilitated Diffusion Glucose molecules High Concentration Extracellular fluid Cell Membrane Low Concentration Protein channel

Osmosis

Active Transport Active transport is used to move ions or molecules against a concentration gradient (low concentration to high concentration). Movement against a concentration gradient requires energy. The energy is supplied by ATP which is released by breaking a phosphate bond to produce ADP:  ATP ®  ADP + Pi + energy The Sodium-Potassium Pump The sodium-potassium pump uses active transport to move 3 sodium ions to the outside of the cell for each 2 potassium ions that it moves in. It is found in all human cells, especially nerve and muscle cells. One third of the body’s energy expenditure is used to operate the sodium-potassium pump. One phosphate bond in the ATP molecule breaks, releasing its energy to the pump protein.  The pump protein changes shape, releasing the sodium ions to the outside.  The two potassium binding sites are also exposed to the outside, allowing two potassium ions to enter the pump. When the phosphate group detaches from the pump, the pump returns to its original shape.  The two potassium ions leave and three sodium ions enter.  The cycle then repeats itself.

Process: Energy conversions Can you build the photosynthesis equation? Build the photosynthesis equation

GLUCOSE ( C6H12O6 )

GLUC ( C6H OSE 12O6 )

GLUC ( C6H OSE 12O6 )

ENERGY OSE 12O6 ) GLUC ( C6H

(Adenosine Triphosphate) ENERGY ATP (Adenosine Triphosphate)

Can you build the equation for cellular respiration?

(energy for the cell to use for other processes) C6H12O6 + 6O2    6CO2 + 6H2O + ATP (energy for the cell to use for other processes)

An analogy can be drawn between the process of cellular respiration in our cells and a car. The mitochondria are the engines of our cells where sugar is burned for fuel and the exhaust is CO2 and H2O. Note that in a car that burned fuel perfectly, the only exhaust should theoretically be CO2 and H2O also

Process: Synthesis of New Molecules Proteins play a role in nearly all biological processes. Examples of protein functions: structure (cell membrane proteins, cytoskeleton proteins, proteins of the connective tissue), enzymes for cell reactions (enzymes are proteins), energy storage osmotic regulation (albumin), transport (membrane channels) immune protection (antibodies), movement (contractile proteins), information (hormones, membrane receptors, intracellular signalers)

The nucleus contains DNA – the “blueprint” for creating proteins

Protein synthesis: