- fundamental biological unit
- smallest and simplest biological structure possessing all the characteristics of the living condition
- all living orgaisms composed of one or more cells
- every activity taking place in the living orgainism is ultimately related to metabolic activities in the cell
•Major component of cell membranes-- make up the lipid bilayer.
•Phosphate head attached to fatty acid tails.
Proteins Embedded in Cell Membrane
- •Serve as receptors
- •Diffusion channels
- •Facilitated diffusion channels
- •Active transport channels
- the movement of molecules from high to low concentration
- •Kool Aid moves from high concentration to low concentration
- •Passive transport is diffusion across a membrane
- Perfune disfuses through air
- •Movement of water across a membrane
- •Water moves from where there is less solute to where there is more to
- try to even it out
- •Hypertonic has more solute
- •Hypotonic has less solute
- •Isotonic same amount of solute on both sides
has more solute (greater osmolarity)
has less solute (lower osmolarity)
same amount of solute on both sides (no net flow of water)
- diffusion with help of a protein
- •Some molecules can’t get all the way through membrane
- •Remember heads of phospholipids are charged but inside is not
- •Few molecules can pass all the way through.
- •Uses ATP energy
- •Moves a solute against its concentration gradient (to where more concentrated)
- •Large molecules cannot pass through the membrane
- •Vesicle moves to plasma membrane, fuses, and releases substance
- •Endocytosis is opposite
flow of water from the hypotonic to the hypertonic solution
plant cell in hypertonic solution - water moves out of the cell; the protoplast (cytoplasm enclosed by plasma membrane)shrinks and may pull away from cell wall - cell is described as plasmolyzed
plant cell in isotonic solution - no net tendency for water to enter so cells become limp
- pressure of the protoplasm on the cell wall due to the intake of water
- plant cell in a hypotonic solution - water moves inside (into central vacuole) until protoplasm pushes on cell wall. Cell wall restricts expansion (tugor pressure) and begins to push water back out. Water enters and leaves the cell at the same rate.
plant cell is stiff - plants prefer hypotinic solution
measure of solute concentration per liter or solute (number of solute particles disolved in the solution
Is fresh water hypotonic, hypertonic, or isotonic to orgainc cells?
Fresh water is hypotonic to living cells. Living cells are isotonic to seawater.
concentrate of solute in a solution
Osmotically active substance
solute that causes osmosis to occur - glucose outside a membrane that is not permiable to glucose - water will go through the membrane to dilute the glucose
the concentration of somethings chances over a certain distance - dye in water diffused along the concentraion gradient from hightest concentraion to lowest until the whole class is equal
- the potential energy of water
- Water potential quantifies the tendency of water to move from one area to another due to osmosis, gravity, mechanical pressure, or matrix effects such as surface tension.
lysis - blood cell in hypotonic solution - water rushed in and cell membranes burst
crenate - blood cell in hypertonic solution - water leaves and cells shrivel
- Respiration uses the oxygen and produces carbon dioxide.
- AEROBIC - USES OXYGEN
- C6H12O6(glucose)+ 6O2 → 6CO + 6H2O+ATP(energy)
- Takes several steps -occur through the movement of electrons
- Redox ReactionsTwo hydrogen atoms are removed from glucose (oxidation) and transfered to a coenzyme called NAD+ which becomes NADH + H+NADH transfers electrons to the electron transport chain.
- On the chain the transfer of electrons from one molecule to another releases energy, which can be used to make ATP.
- anaerobic process - uses no oxygen
- transfers the energy in glucose bonds to bonds in ATP
- oxidation-reduction reactions
- Substances are oxidized that lose electrons
- Substances are reduced that gain electrons.
- In this example the carbon compound is oxidized
- C4H2O → C4O + 2H
- Where do these hydrogens go? They reduce NAD+
- NAD+ + 2H → NADH + H+
What is NAD+?
NAD+ is an electron acceptor important to the process of cell respiration
Derived from the vitamin niacin.
- Niacin is an essential vitamin and must be gotten from the diet. Found in green
- veggies, peanuts, potatoes,and meat.
Deficiency results in pellagra
The Details of Respiration
3 Main Stages
- –Glycolysis (cytoplasm)
- –Krebs Cycle (mitochondria) - also called Citric Acid Cycle
- –Electron Transport Chain (mitochondria) - also called Oxidative Phosphorylation
- Breaks glucose into pyruvic acid (6 carbons to 3carbons)
- Beginswith 1 molecule ends with 2
- Series of 9 steps; enzymes needed; several intermediates
- Produces 2 net ATP and 2 NADH
Pyruvic Acid Prepares for Krebs Cycle
- NAD+ goes to NADH
- Carbon atom released as CO2
- Pyruvic acid transformed to Acetyl CoA
- Coenzyme A is derived from vitamin B
- Coenzyme A is recycled after start of Krebs cycle
At end of Krebs Cycle
- 4 ATP
- 10 NADH
- 2 FADH2
- On to electron transport chain to make more energy.
Electron Transport Chains
- NADH will give electron to electron carrier.
- Electron carriers are proteins
- Last step is oxygen.
- ATP is produced as electrons fall toward oxygen.
- Process allows cell to harvest energy as the electron falls (water wheel).
So how is ATP made?
- Remember ATP is made from ADP by phosphorylation
- A special enzyme ATP snythase can use the energy created by the electron transport chain to add a phosphate to ADP
- CreatesATP molecules
So How Much ATP from 1 Glucose?
- 4 ATP from glycolysis and Krebs cycle
- Estimated 34 from electron transport
- Total of 38 ATPs from 1 molecule of glucose– about 40% of energy present
What if there is no oxygen? Can a cell survive?
Yes, many organisms can survive just on glycolysis
- Yeast produce alcohol and CO2 through fermentation (recycles NAD+)
- Lactic acid fermentation can be done by muscle cells in strenuous exercise
Is glucose the only material that can be used to make ATP?
No, proteins and fats can also be used.
And ATP can be used to make macromolecules needed for cell function
aerobe is an organism that can survive and grow in an oxygenated environment
- anaerobe is any organism that does not require oxygen for
- growth, could possibly react negatively and may even die in its
A facultative anaerobic organism is an organism, usually a bacterium, that makes ATP by aerobic respiration if oxygen is present but is also capable of switching to fermentation
- A cofactor is a non-protein chemical compound that is bound to a protein
- and is required for the protein's biological activity.
ATP synthase is a general term for an enzyme that can synthesize adenosine triphosphate (ATP) from adenosine diphosphate (ADP) and inorganic phosphate by using a form of energy.
Enzymes are proteins that catalyze (i.e., increase the rates of) chemical reactions. In enzymatic reactions, the molecules at the beginning of the process are called substrates, and the enzyme converts them into different molecules, called the products. Almost all processes in a biological cell need enzymes to occur at significant rates
- Oxidation is the loss of electrons or an increase in oxidation state by a molecule, atom, or ion.
- oxidation of carbon to yield carbon dioxide (CO2)
Reduction is the gain of electrons or a decrease in oxidation state by a molecule, atom, or ion.
Redox (shorthand for reduction-oxidation reaction) describes all chemical reactions in which atoms have their oxidation number (oxidation state) changed
Kinds of Passive Transport
Diffusion - molecules move from high to low concentration
Osmosis - water moves through membranes looking for isotonic
Facilitated - protein used to move large molecule (sugars, amino acids, ions, water) - uses no energy
Aquaporin - protein that ONLY water can use to move fast
- Uses Energy - against the concentration gradient
- 1. Exocytosis - movement of molecule out of cell - secretions (insulin) - cells form vaccuole around it and pushes it out of cell
- 2. Endocytosis - movement of molecules into the cell
- a. Phagocytosis - eating - bringing food into cell
- b. Pinocytosis - drinking - bring fluids into cell
- c. Receptor-mediated - receptor proteins are embeded in the membrane that collect a specific substance.
Amoebas move by streaming its body forward and pulling up behind
How do lysosomes move through the cell?
move across Intermediate filaments
3 Types of Endocytosis
- 1. Phagocytosis - eating - bringing food into cell
- 2. Pinocytosis - drinking - bring fluids into cell
- 3. Receptor-mediated - receptor proteins are embeded in the membrane that collect a specific substance.
- important function of membrane
- allows some substances to cross more easily that others
What two molecules can move easily through the plasma membrane?
CO2O2 - oxygen
- occurs in the membrane on the cristae of the mitochondria
- Electron Transport Chain = (H+) gradient across the membrane (out)
- +Chemiosmosis = ATP synthesis powered by the flow of H+ back across the membrane
lactic acid fermentation
- pyruvate is reduced (by NADH) to lactate (ionized form of lactic acid)
- Gives off NO CO2