Bio Notes

Bio notes 2/4/13

Sunlight + 2H (little 2) O + 2O (little 2) - 2O (little 2) + C (little6) H (little 12) O (little6)

Sunlight+ water+ carbon dioxide oxygen + glucose

Supports all life on Earth
Changing sunlight (solar energy) to glucose (chemical energy)
Where? Leaves

Leaf structures

------------------------------------------------- epidermis ------------------------------------------------- palisade mesophyll- top 1-2 layers under epidermis—very regular, column like, tightly packed,, lots of chloroplasts (capture sunlight)

spongy mesophyll-irregular shape lots of spaces between cells important for gas exchange stomata- pore,, cells on the side are guard cells regulate moisture movement in and out of cell

-------------------------------------------------
Epidermis

Chloroplasts

Double membrane around the outside

3rd membrane makes flattened sacs called thyla koids grana- stacks of thyla koids thyla koid space is the space in the spring like structures space—chlorophyll chlorophyll and other pigments- capture H. energy, reflect green light, best at using violet, blue and red light

sunlight- various wavelengths of energy, different energy content down wavelength= up energy gamma rays- x rays- UV rays- visible light (most that reach Earth’s surface)- IR (infrared)- micro –radio highest energy to lowest energy

photosynthesis
2 sets of reactions photo- light (refers to 1st set of reactions) captures light energy solar energy is transformed into chemical energy (ATP) synthesis-making something new dark reactions light independent chemical energy (ATP) transform to another form chemical energy (C(6)H(12)O(6)) glucose

Photosynthesis
Equation reminder
FAD and NAD

Light Reactions
1st set of reactions light dependent
ATP is produced from solar energy

Let’s get started
Chlorophyll within chloroplasts capture light energy
Electrons become excited
Move to nearby electron acceptor

Hydrolysis
Water is split
H (2) o 2e + 2H+ + ½ O (2)
Electrons + hydrogen ions + oxygen
So in the 1st set of reactions solar energy and water are used and oxygen is produced

Electron transport chain
Chain of electron acceptors
Electrons move from one carrier to the next to the next

Hydrogen
Temporarily stays in thylakoid space
Build up of hydrogen within space creates hydrogen ion gradient
Hydrogen flowing out of the thylakoid space is tied to the production of ATP

Calvin Cycle
2nd set of reactions dark reactions light independent big picture for Calvin Cycle uses carbon dioxide and produces glucose cyclic pathway with many intermediates
ATP changed to glucose (1 form chemical energy changed to another form chemical energy)

What happens?
CO(2) + RuBP 6 Carbon molecule
This is a rate limiting step
6 carbon molecule then goes through series of steps to eventually make glucose glucose is what plants and animals metabolize to produce ATP for all energy needs

Why all the trouble
End of 1st reactions ATP
2nd reactions take ATP and make glucose why do plants perform the 2nd set of reactions when the first produces ATP and ATP is what is needed to fuel the body
Nitroglycerine vs. Dynamite
Same as ATP vs glucose

Cellular Respiration

Glucose + oxygen 6CO(2) + 6H(2)O + energy (ATP)

Where
Glycolysis- in cytoplasm
Remaining steps in mitochondria
Mitochondria+ “power house” of the cell

What is cellular respiration?
Step- wise release of energy from carbohydrates and other molecules
Aerobic- process- requires oxygen

Efficiency
About 40% efficient
Means about 40% of food used to make ATP rest lost as heat
Perspective car about 25% efficient

Enzymes
2 needed for cellular respiration are NAD+ and FAD both are electron carriers both present in cell

glycolysis takes place in cytoplasm used by nearly all organisms anaerobic- does not require oxygen overall- breakdown of glucose into 2 pyruvate molecules

details?
Glucose split into two 3 carbon molecules called PGAL
PGAL loses electrons to NAD+ and gives up phosphate to ADP to make ATP
Water is given off and 2 pyruvate molecules are made
Overall… this step makes 2 new ATP

Pyruvate
Pivotal metabolite
If oxygen present, enters mitochondria for remainder of cellular respiration
If oxygen not present, stays in cytoplasm and undergoes fermentation

No oxygen?
Fermentation occurs
Pyruvate stays in the cytoplasm and undergoes fermentation
Anaerobic process

What happens?
Think… what produced by fermentation?
Pyruvate broken down to produce alcohol by releasing carbon dioxide
Or produces one of several organic acids such as lactate (lactic acid)

ATP from fermentation
NO new ATP is made during fermentation
Organisms that use fermentation only gain the 2 ATP made in glycolysis

Many types—2 examples 1. alcoholic fermentation
EX. yeast- generates alcohol and carbon dioxide Carbon dioxide is what makes bread rise
2. lactic acid fermentation animal cells- including humans produce lactate

When in Animals
Think… when might there be a shortage of oxygen in your body?
Muscle cells more likely to use fermentation than other cells in the body
Working out, temporary short supply of oxygen
During heart attack—heart muscle deprived of oxygen

Efficiency
Produces low yield of 2 ATP (remember this is the ATP made in glycolysis prior to fermentation)
So about 2% efficient

Essential to humans
Provides a rapid burst of ATP

Why not fermentation all the time in humans?
Much less efficient than cellular respiration 40 vs. 2%
Lactate toxic to cells Changes pH Causes “muscle burn”

Fermentation and other organisms
Many single- celled organisms use glycolysis as their only source of ATP
They then use fermentation to get rid of the byproducts
They do not need cellular respiration because their energy demands are less