"Discover how our immune system defends the body against bacteria and viruses, the single-celled microorganisms responsible for many illnesses. Learn about the immune responses that protect us from infections caused by these tiny invaders."
#ImmuneSystem #BacteriaAndViruses #VirusProtection
#ImmuneSystem #BacteriaAndViruses #VirusProtection
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00:00Today on The Lab Report, we'll learn that bacteria are living things made of only one cell,
00:06and they're found almost everywhere on Earth.
00:09That viruses hijack cells because they can't reproduce on their own.
00:14And our immune system can eliminate most bacteria and viruses.
00:19Hey, I'm Dr. Jeff, and today we're learning about bacteria and viruses.
00:24Adam, Caroline, have you seen bacteria before?
00:27No, I thought they're too small to see.
00:29Too small for our eyes, but with a special microscope that can magnify things a thousand times, we can see them.
00:36Take a look.
00:37Whoa, they're so tiny.
00:39Wait, let me see.
00:41Cool.
00:42What kind of bacteria are these?
00:44Those are E. coli bacteria.
00:46Isn't that dangerous?
00:48Some kinds of E. coli can be harmful, but this kind is totally harmless.
00:53In fact, harmless bacteria are everywhere.
00:56There's millions of bacteria inside this beaker of regular water, and billions inside just one scoop of dirt.
01:06And there's trillions of bacteria inside our own bodies.
01:10What?
01:10Not in my body.
01:11They live in your stomach, on your skin, and almost everywhere else, too.
01:16In fact, about 30% of your own poop is actually living and dead bacteria.
01:23That's gross.
01:24It's awesome.
01:25Bacteria are single-celled living things that can be found almost anywhere on the planet.
01:31Here are bacteria cells compared to animal cells.
01:35Wow, the bacteria cells are so much smaller.
01:38About 100 times smaller.
01:40No wonder you need a special microscope to see them.
01:43Also, it looks like the animal cell has a nucleus where the DNA is stored.
01:47And DNA is the genetic material needed to make new cells.
01:50That's right.
01:51In plant and animal cells, DNA is stored in a nucleus.
01:56Bacteria don't have a nucleus, so their DNA just floats around in the cell.
02:01You probably know that some kinds of bacteria can make us sick.
02:05But other kinds of bacteria can be very helpful.
02:09What do all these things have in common?
02:12Thanks, Eddie.
02:13Cheese?
02:14Sauerkraut?
02:15Yogurt?
02:16Dr. Jeff, I think you brought the wrong samples.
02:19Nope, they are the right samples.
02:21All these foods are made using bacteria.
02:25For example, cheese is made when bacteria break down milk.
02:29Look, bacteria are also responsible for the sour taste in sauerkraut.
02:34And bacteria also help us make yogurt.
02:37Now that we know a little bit about bacteria, let's see how they grow.
02:43This is called a petri dish.
02:46It contains a jelly that bacteria like to eat.
02:49If we rub just a few bacteria cells on the surface, we should be able to see them grow.
02:55So, if bacteria is everywhere, can we just collect samples from different areas in the lab?
03:01That is a great idea.
03:03Let's use some clean swabs to rub different surfaces in the lab.
03:08Then, we can transfer any bacteria on the swab to the petri dish like this.
03:14Simple.
03:16Then, label it, tape it shut, and dispose of the swab in the bleach.
03:21Got it?
03:22Let's do it.
03:23Here we go.
03:23Let's do it.
03:24Let's do it.
03:25Let's do it.
03:26Let's do it.
03:44Great job.
03:45Now, let's put these petri dishes into the incubator, keep them warm, and we'll check on them in just a few days.
03:53Let's do it.
03:54Let's do it.
03:55Let's do it.
03:56Let's do it.
03:57Let's do it.
03:58Let's do it.
03:59Let's do it.
04:00Let's do it.
04:01Amazing.
04:02Bacteria really are everywhere.
04:05What makes these little dots?
04:07Those are called bacteria colonies.
04:09They form because bacteria make more of themselves by copying their DNA and then splitting in half.
04:16So it's like they're cloning themselves?
04:18Exactly what it is.
04:19Some bacteria like E. coli can split every 20 minutes again and again and again.
04:26And then they become millions over just one day.
04:29Each of these dots is actually millions of bacteria.
04:33But I wonder if any of these are the dangerous kind.
04:36We don't want to find out.
04:38So we're going to keep these tapes shut and dispose of them properly.
04:41As you know, some bacteria can be dangerous, like these.
04:46Oh, look at those cute little bacteria.
04:50Here you go.
04:51Go ahead and read the labels.
04:53This one represents Borrelia burgdeferi, the bacteria that causes Lyme disease.
04:58It is carried by ticks and then given to humans and it gives people rashes and a fever?
05:05Oh, this little guy is Streptococcus pyogenes.
05:09It's the bacteria that causes flesh-eating disease.
05:12It ruins human flesh and it often requires amputation.
05:16Yikes.
05:17And I have Salmonella typhemerium, a bacteria that causes salmonella.
05:23It gives you food poisoning and some nasty diarrhea.
05:26Ew.
05:27How do people avoid these bad bacteria?
05:31To answer that, let's learn about how bacteria spread.
05:37To represent bacteria, I'm covering my hands with a special liquid that can glow under ultraviolet light.
05:44Take a look at our hands.
05:48Mine are glowing and yours are not.
05:51Now let's turn the lights back on and shake hands.
06:02I don't see anything on my hands.
06:04Let's try it with the ultraviolet light.
06:08Whoa, that's crazy.
06:09Touching is a common way bacteria spread from person to person.
06:13This definitely shows that we need to wash our hands.
06:16Especially when we're around someone sick.
06:18Exactly.
06:19And if you do get sick, we can kill most bacteria with antibiotics.
06:23When I go to the doctor and I'm sick, I almost never get antibiotics.
06:27That's because antibiotics only kill bacteria.
06:30They don't have any effect on viruses, which cause most colds and flus.
06:37A virus is a tiny piece of genetic material, like DNA or RNA, surrounded by a protective shell.
06:44That's it? How does it move?
06:46Interestingly, it doesn't move on its own.
06:49They also don't eat anything.
06:51But wait, I thought you said that all cells take in nutrients, reproduce and have genetic material.
06:58So by that definition, a virus isn't even alive.
07:01You both make great points.
07:03It's actually a classification problem scientists have wondered about for a long time.
07:09Viruses don't eat, they don't drink, they can't even reproduce on their own.
07:14That's why viruses hijack cells to make more copies of themselves.
07:19Lucky for us, most viruses on Earth only infect and kill bacteria.
07:25Those viruses look like this.
07:27That's a virus? It looks like a lunar lander.
07:30This kind of virus lands on a bacteria cell and injects its genetic material inside.
07:37Then, the cell will use the virus's genetic material to make more copies of itself.
07:42Once the new viruses build up, they burst out of the cell, killing it.
07:47And then those new viruses go on to infect more cells.
07:52So what kind of viruses can infect human cells?
07:54The most well-known are viruses that cause colds and flus.
07:58They usually have a round and spiky shape, but they work in the same way.
08:03They float around until they touch a cell.
08:06Then they transfer their genetic material inside where more copies are made.
08:12Then the viruses burst out of the cell and infect more cells.
08:16That's right. The thing about viruses is they can spread fast.
08:20Have you heard of going viral?
08:22Yeah, like a viral video?
08:24Exactly like that. The word viral comes from the way viruses spread fast.
08:29Let's imagine one person is infected by a virus.
08:33And that person infects five other people by coughing, touching, or sneezing.
08:37And then the next day, those five people give it to another five people each, making 25.
08:44Which each give it to another five people each, to become 125.
08:48Then 625, 3,125, 15,625, 78,125, 390,625, and then it's over a million.
09:00This is what happens when something goes viral.
09:03Just like if everyone shared your video with five friends each, it gets millions of views in just a few days.
09:10Viruses can spread the same way. In fact, they were going viral before videos even existed.
09:17So that's like what happened with the coronavirus that caused COVID-19.
09:21It started with just one person and then spread around the world to millions of people.
09:27Yes. One of the reasons it went viral is because the virus that causes COVID-19 infects cells in the lungs.
09:34Each time you cough or even speak, tiny droplets of liquid that carry the virus are launched out of your mouth.
09:42They fly through the air and can land on other people.
09:45So that's why when a virus breaks out, people should stay home when they're sick so that they don't infect others.
09:52They should also wash their hands, not touch their face, and cough into their elbows so that they don't get it on their hands.
09:59Exactly. Those precautions help slow the spread.
10:02And thanks to our immune system, our body can fight off nearly every bacterial and viral infection.
10:08Yes. The immune system is a body system made of specialized cells that circulate in your blood.
10:14They look for intruders like viruses and bacteria. And then they tell other cells in the immune system to fight them off.
10:22And once we win the fight, instructions on how to beat the intruders in the future are stored in the cells.
10:27And knowing this, scientists have learned how to create vaccines, which train the body to identify and kill invaders before they attack.
10:36So understanding viruses and bacteria can literally save lives. Let's explore the kinds of careers you can have studying them.
10:43A microbiologist is a type of scientist that studies microscopic organisms like bacteria.
10:54Studying bacteria can help scientists develop new antibiotics.
10:58A famous antibiotic called penicillin is naturally made by fungi and used to kill bacteria.
11:04A microbiologist discovered this, and we now use penicillin to treat bacterial infections.
11:09Bacteria can also be used to produce fuels for cars.
11:13When bacteria eat sugar, they can produce alcohols, which could one day be put into cars and burned as renewable fuel.
11:20The scientists that study viruses are called virologists.
11:23When they study viruses that infect humans, they may have to take extra precautions to avoid infection by wearing protective suits.
11:31Virologists help us understand how viruses work so we can figure out how to stop them from infecting humans.
11:38For example, if we can understand the protein spikes on the virus's surface, we could make medicines to attach to them and block the virus from entering cells.
11:48These are just two of the many important careers that make the world a better place by studying bacteria and viruses.
12:00Today, I'll show you how to grow mold, which is another type of microorganism.
12:05Today's lesson focused on bacteria and viruses.
12:07But there's another category of microbes that we didn't have time for.
12:11Fungi.
12:12Things like yeast, mushrooms, and mold.
12:15For this activity, you will need two slices of bread, two sealable plastic bags, tape, a marker, a spray bottle of water, and adult supervision.
12:26First, spray three squirts of water on each slice of bread.
12:30Then, with your marker, write COOL on one bag.
12:33And on the other, write WARM.
12:35Next, add your bread.
12:37Now, close the bags and tape the seals airtight.
12:40Don't open it again, even after you finish the project.
12:43Put the bag labeled COOL in the fridge, and put the other bag somewhere warm and dark, like a kitchen cupboard.
12:49After the week is over, they will look like this.
12:52Here is the one that was not refrigerated.
12:54Look at all that mold.
12:56Ugh.
12:57And here is the one that was in the fridge.
12:59Nothing.
13:00This shows how cold temperatures slow the growth of microbes.
13:03That's why we have refrigerators.
13:04Things last longer in the fridge because bacteria and fungi grow slower in the cold.
13:09And remember, keep the bag sealed and throw the whole thing away.
13:13Try it yourself.
13:15Thanks, Adam.
13:16Now let's review.
13:17Today, we learned that bacteria are single-celled living things found almost everywhere on Earth.
13:23Viruses cannot reproduce on their own, so they hijack cells to make more of themselves.
13:28And humans have a body system called the immune system to fight off viruses and bacteria.
13:34Join us next time on The Lab Report.
13:37I'm Dr. Jeff.
13:38I'm Adam.
13:39I'm Caroline.
13:40And remember, always question, always wonder.