More Cell information

As you remember, there are two major groups of cells. We have prokaryotic cells and then we have eukaryotic cells. Example of a prokaryotic cell is like a bacteria. A cell membrane, cell wall. All of their DNA is organized in a nucleoid region. And they're fairly simple and fairly small.

Prokaryotic Cell Simple, small, cell membrane, cell wall. DNA-organized in a Nucleoid region

And a eukaryotic cell we're going to have a nucleus. We're going to have organelles like endoplasmic reticulum, golgi apparatus, mitochondria.

According to fossil records: Life began about 3.6 billion years ago!!! All we saw was prokaryotic cells About 2 billion years ago!!!! Eukaryotic cells showed up This puzzled scientists: There was clearly two different evolutionary pathways

The pathway of the small prokaryotic cells and then the larger eukaryotic cells. And they eventually settled on an idea called endosymbiosis. And what does that mean?

Endosymbiosis EndoSymbiosis Withintogether Bio Living

the mitochondria evolved from aerobic bacteria (example: flesh eating bacteria) that the chloroplast evolved from endosymbiotic cyanobacteria. Hypothesis: What we think is way back in the day we had these aerobic bacterium, ones that were doing cellular respiration so they were breaking down food in the presence of oxygen.

Hijackers: the mitochondria that are found in all of your cells are kind of like hijackers that have been inside our cell for billions of years. For a long time scientists would have a hard time kind of believing that this is true.

And the first scientist to really be a proponent of endosymbiotic evolution in eukaryotic cells was Dr. Lynn Margulis. And in the 1960s, I think in 1967, she wrote an article, a journal article, talking about this. This idea that maybe this is how mitochondria and chloroplasts came to be. She shopped it around and no scientific journals would pick it up. After going to about 14 different journals, one journal on theoretical ideas eventually published it. And it was kind of not laughed down, but it was put aside for a long period of time. But Dr. Margulis kept working and working and working and pretty much today we accept this as scientific fact, or as close to fact as it could be.

Symbiotic relationships: the anemone and the clown fish. So we think something like this happened, you know billions of years ago, and that created these first eukaryotic cells.

Evidence

So basically we have a type of bacteria that looks a lot like a mitochondria. They have a lot of similar properties. So what evidence do we have that mitochondria came from bacteria. We think they also may have enfolded. The membrane may have folded in on the side to create some of the complexity.

Membrane Reproduction DNA

Evidence that mitochondria and chloroplasts arose via an ancient endosymbiosis of a bacteria - Double membrane - They have their own DNA -they reproduce similarly -Asexual reproduction -DNA looks like a lot of specific types of bacteria Cell within a cell

If mitochondria are within our cells but they weren't technically part of our cells then how are they copied from generation to generation. Where do I get my mitochondria from? Well you can thank your mom for that. Mitochondria that have been passed from mother to daughter to mother to daughter all through time. That means they can't live on their own but we have this wonderful relationship where we let them make energy for us and in plants they have chloroplasts and mitochondria that came from the same origins.

Photosynthesis

I love photosynthesis because it gives me two things that I need. I need to breathe, so it gives me oxygen. And I need to eat. And so it's going to give me food. And so I love photosynthesis.

You might think it's only found in these things, plants, but it's also found in bacteria. It's found in algae. And so it's found in protists. It's found everywhere. And so photosynthesis has been around a long time. It's super important that you understand how it works.

Let's start with the site in eukaryotic cells of photosynthesis. And that's the chloroplasts. You can see how many chloroplasts we could have in a typical cell. there's a whole bunch of them.

There are a few terms you should be familiar with. First one is a thylakoid membrane. Thylakoid membrane is going to be organized like this. basically that's where the light reaction is going to take place The other big thing to understand photosynthesis is that this is filled with a liquid. If you've got a stack of thylakoids like this together we call that a granum. the liquid is called the stroma. And that's going to be the site of the Calvin cycle.

This is what's called their absorption spectrum. And what color of light they are able to absorb. And you can see that they absorb a lot of the blue. A lot of the red. But they don't absorb a lot of this in the middle, this green. If we look at what light they absorb, here's chlorophyll A and here's B. And so a quick question could be what is their least favorite color, plants?

And the the right answer would be green. Because the reflect that green light. Now this is actually puzzled scientists for a long time. And we really don't have a definitive answer as to why plants are green. Know this that if they were black they probably would get a little bit too hot. They would absorb too much light.

so let' start with an equation. Because this is simply a chemical reaction. It's a chemical reaction with a number or steps. But what are the reactants? Water and carbon dioxide.

And so how does a plant grow? It's basically taking water in from its roots and it's taking carbon dioxide in through its leaves. Through its stomata. Needs light.

I always image this picture right here. There's photo and synthesis in the word. Photo means light. And synthesis means to make. And so there are two steps in photosynthesis. The light reaction. And those are going to take place in the thylakoid membrane. And then the Calvin cycle.

We used to call this the dark reactions which is a silly term. Doesn't happen during the dark. It happen during the light. And so basically the person who worked this all out is Melvin Calvin and so we named it after him. Where does this take place? You guessed it. It takes place in the stroma or this liquid portion.

So let's kind of do a cartoon version of photosynthesis. What are the reactants again? Water, light and carbon dioxide. What are going to be the products that come out of this? It's going to be oxygen and glucose. So let's watch what happens.

Water Carbon dioxide ATP NADPH ATP Glucose

6H2O + 6CO2 + light C6H12O6 + 6O2 Water Carbon Dioxide Glucose (Sugar) Oxygen

1.Sun shines on the leaf 2.Plant absorbs sunlight 3.Uses energy to convert water & carbon dioxide = glucose Photo – light Synthesis – to make/create

Respiration

Heterotrophs Cellular Respiration Fermentation

Aerobic Anaerobic Requires O2 Does not require O2 Mitochondria Cytoplasm Lots of ATP Few ATP Conversion, citric Acid Glycolysis, Cycle & Electron Fermentation Transport Chain 2 types of Respiration: Depends on oxygen

NADH and FADH2 It is collected during cellular respiration Acts like trucks to transport energy that will be turned into ATP during the Electron Transport Chain NAPH FADH2

4 Steps of Respiration Glycolysis Conversion Citric Acid Cycle Electron Transport Chain

Glycolysis Glyco – glucose lysis – breakdown Glucose 2 Pyruvate 2 ATP & 2NADH Cytoplasm Anaerobic Pyruvate NAPH 2 ATP 2

Conversion 2 pyruvate 2 acetyl coA 2 NAPH & CO2 Aerobic Mitochondria pyruvate acetyl coA NAPH 2 CO 2

Citric Acid (Krebs) Cycle 2 Acetyl CoA broken down 2 ATP, 6 NADPH, 2 FADH2, CO2 Mitochondria Aerobic NAPH 6 CO 2 ATP 2 FADH 2 2

ATP 30 NAPH GlycolysisConversionKrebs Cycle FADH 2 2 Electron Transport Chain Stored energy in NADP & FADH2 makes ATP 1 NADH = 3ATP; 10 NADH = 3ATP 1 FADH2 = 2ATP; 2 FADH2 + 4ATP ATP 2

Total ATP Production ATP ATP 34 Glycolysis Krebs Cycle Electron Transport Chain

Anaerobic Cellular Respiration Fermentation

Fermentation – No Oxygen Alcohol Fermentation Lactic Acid Yeast Result: Alcohol & CO 2 Muscles Result: Lactic Acid Muscle Fatigue ATP 2

Energy