Movement through the cell: Molecules have to move around the cell to do their jobs. Sometimes they go into, or out of an organelle. Our cells use Diffusion and Osmosis to do this job. But,……. How do large molecules get in?
Dec 25, 2015
Movement through the cell:Molecules have to move
around the cell to do their jobs.
Sometimes they go into, or out of an organelle.Our cells use Diffusion and Osmosis to do this job.But,……. How do large
molecules get in?
Crossing the Membrane
Nutrients must get in and wastes must get out.
Signaling molecules received by a cell may need to get in, while signaling molecules sent by a cell need to get out.
Fluid must be able to get in and out.
Certain ions must be able to get in and out.
Types of transport:Passive Transport:
Either by simple diffusion or through a membrane protein
Requires NO Energy
Active Transport:
Requires Energy - ATP
Always happens through a membrane protein and uses ATP to force a molecule across a membrane against concentration grandient
Big Stuff?
Membrane Proteins are adequate for bring small molecules into the cell or out of the cell.
However, a different kind of active transport is necessary to move large things into/out of the cell – vesicular transport.
There are 2 types of vesicular transport:
exocytosis and endocytosis
Exocytosis Exocytosis literally means “out of the cell” It accounts for hormone secretion, neurotransmitter
release, mucus secretion, and, sometimes, ejection of wastes. Inside the cell, the substance to be exported is enclosed in a
membranous sac called a vesicle. The vesicle will migrate to the PM fuse with it, and then rupture,
spilling the contents into the extracellular space.
Endocytosis
Reverse of exocytosis. Allows macromolecules to enter cells. The substance is progressively enclosed by an enfolding portion of the
plasma membrane. This forms a vesicle which will pinch off the plasma membrane and enter
the cytosol where it is typically digested.
Types of endocytosis are: Phagocytosis Pinocytosis (a.k.a. bulk-phase endocytosis) Receptor-mediated endocytosis
Phagocytosis Literally “cell-eating.” Cytoplasmic extensions
called pseudopods “reach out and grab” large, solid material such as a clump of bacteria or cell debris, and then engulf it.
The resulting vesicle is called a phagosome.
Usually, the phagosome fuses with a lysosome, a membranous organelle that contains digestive enzymes, and its contents are digested.
Macrophages and white blood cells are the most phagocytic cells in the body.
Pinocytosis Literally means “cell-drinking.” A bit of infolding plasma membrane
surrounds a droplet of extracellular fluid containing dissolved molecules. This creates a tiny membranous vesicle.
Most cells routinely perform this. Unlike phagocytosis, pinocytosis is
unselective!
Photosynthesis and RespirationWhere does your energy come from?
Autotroph: - having the ability to make ones own energy (food).
Heterotroph: - having to take energy from another organism.
Plants
Chemo-Autotrophs
Us!
Your Body uses Chemical Energy
ATP Adenosine Triphosphate
AdenineRibose Sugar
Three phosphatesADP - Adenosine Diphosphate (only two phosphates) is
converted to ATP In cells to store energy for cells!
Using the energy - Cells break off the 3rd phosphate and use the released energy.
PhotosynthesisThe PROCESS of using the energy from the sun to Convert CO2 and Water into Glucose and O2
The Equation:
6CO2 + 6H2O C6H12O6 + 6O2
6 Carbon Dioxides
6 Waters1 Glucose (sugar)
6 Oxygens
But it happens in two different Reactions
Light ReactionLight Reaction
and Dark Reaction
Light ReactionTake place inside the
Chloroplast at a specific place.
Stacks of individual “disks” called Thylakoids
A stack of these thylakoids is called a Granum
(grana = plural)
Chlorophyll molecules are arranged in Photosystems.When a PHOTONPHOTON of light strikes anywhere on the photosystem, electrons are passed to the center and ATP and NADPH are made.
ADPP
NADP+
H2O
ATP NADPHO2
The ATP and NADPH go outside the Grana into the space in the Chloroplasts called the Stroma
This is where the “Light Light Independent reactionIndependent reaction” takes place.a.k.a. : Calvin Cycle or
“Dark Reaction” because it can happen in the dark.
Melvin Calvin
The Light Independent Reaction goes as follows:
CO2 enters
ATP
ADP
CO3
NADPH
NADP+C6H12O6
glucose
Remaining CO units
ATP
ADP 3 – CO5
For every 6 Carbon dioxide and 6 water molecules that enter the Chloroplast, 1 glucose and 6 Oxygen is created or
6CO2 + 6H2O C6H12O6 + 6O2
But what happens if we reverse the arrow?
Now we are burning Sugar with Oxygen to get Water and Carbon dioxide.
What burns Sugar (glucose) and Oxygen together?
All living things!This Process is called
Cellular Respiration
C6H12O6 + 6O2 6CO2 + 6H2O
ENERGY
Cellular Respiration Starts
when Glucose enters the cell !
nucleus
mitochondria
Glucose
Glucose
Glycolysis: First step in
Cellular Respiration where Glucose is split in half inside the cytoplasm.Process:
Pyruvic Acids
C C
C C C
C
2-ADP 2-ATP
2-NAD+ 2-NADHto the
Mitochondria
Inside the Mitochondria: 2 Pyruvate
Molecules2 CO2
Krebs Cycle
4 CO2
8-NADH and 2-FADH2
2 ATP
Electron Transport
H2O
32 ATP
Total 34 ATP
The Two Pyruvate Molecules enter the Krebs Cycle. A total of 6 CO2 and 2 ATP are Produced.NADH and FADH2 enter the Electron Transport Chain.Water and 32 ATP are produced giving 34 total ATP produced in the Mitochondria.
O2 Enters
What happens if you can’t give the cell enough O2?
Pyruvic Acids
C C
C C C
C
2-NAD+ 2-NADH
2-ADP 2-ATP
After Glycolysis, if there is not enough O2 to go through cellular respiration, the cell converts the NADH into ATP and the Pyruvic acid breaks down into Lactic Acid
Lactic Acid FermentationGlycolysis
Lactic Acid
O2X
Let’s RecapPhotosynthesis converts Light energy from the sun into
Sugar
6CO2 + 6H2O C6H12O6 + 6O2
6CO2 + 6H2O C6H12O6 + 6O2
ATP
Respiration converts Sugar into usable energy – A T P
Notice any similarities?
Review1. Active Transport 2. Passive Transport 3. Pinocytosos
4. Exocytosis 5. Phagocytosis 6. Autotroph
7. Heterotroph 8. ATP 9. ADP
10. Light Reaction 11. Light Independent Reaction 12. Photon
13. Chlorophyll 14. Cellular respiration 15. Glycolysis
16. Pyruvic Acid 17. Electron Transport Chain 18. Krebs Cycle
19. Lactic Acid Fermentation
Questions:1. Be able to describe the process of photosynthesis.
2. What is the difference between the light and light independent reactions?
3. Describe the steps in Cellular respiration.
4. What is the difference between Cellular respiration and Lactic Acid Fermentation?