Genotype Expression
Summary
TLDRIn this Biology Essentials video, Mr. Andersen explores how the environment influences the expression of genotypes, affecting an organism's phenotype. He uses the Himalayan rabbit as an example, where body temperature disrupts melanin production, and discusses similar phenomena in arctic foxes and hares, influenced by melatonin. The video also covers how plants like hydrangeas change flower color based on soil pH, and explains bacterial gene expression through the lac operon and its detection using MacConkey Agar, illustrating the dynamic relationship between genotype and environmental factors.
Takeaways
- 🧬 The environment can influence the expression of genotypes, affecting an organism's phenotype.
- 🐰 Himalayan rabbits naturally express the gene for melanin, but body warmth can disrupt this expression, resulting in a non-black phenotype.
- 🧊 An experiment with Himalayan rabbits showed that cooling the body core with an ice pack can enable melanin production, demonstrating environmental control over gene expression.
- 🦊 The arctic fox and arctic hare change their coat color seasonally, influenced by the hormone melatonin and its production regulated by daylight.
- 🌺 The color of hydrangea flowers can vary based on the pH level of the soil, showing that plants can also exhibit environmental genotype effects.
- 🌱 Plants use their flower colors to attract pollinators, with genes expressing differently depending on environmental factors like soil pH.
- 🦠 Bacteria can regulate the expression of their genotypes, particularly through operons, which are clusters of genes that can be turned on or off in response to environmental conditions.
- 🍦 The lac operon in bacteria is an example of gene regulation where the presence of lactose can turn on genes necessary for lactose breakdown.
- 📏 MacConkey Agar is used in labs to differentiate between lac positive and lac negative bacteria based on their ability to change the pH and color of the agar.
- 🔬 The color change in MacConkey Agar serves as a visible phenotype for bacteria, showing how environmental conditions can affect genotype expression.
- 🌐 Understanding environmental genotype effects is crucial for comprehending how traits are expressed in various species, from rabbits to bacteria.
Q & A
What is the difference between genotype and phenotype?
-Genotype refers to the set of genes an individual has, while phenotype is the physical expression of those genes, such as an organism's appearance or characteristics.
How does the environment affect the expression of genotypes?
-The environment can influence whether certain genes are expressed or not, leading to variations in an organism's phenotype. For example, temperature changes can disrupt the expression of genes responsible for melanin production in Himalayan rabbits.
What is the significance of the Himalayan rabbit in demonstrating environmental genotype effects?
-The Himalayan rabbit serves as an example of how body temperature can affect gene expression. The warm core of the rabbit's body disrupts melanin production, leading to lighter fur in cooler areas, illustrating how environmental factors can alter phenotypes.
How does the study involving shaving a Himalayan rabbit's back and applying an ice pack demonstrate genotype expression?
-By shaving the rabbit's back and applying an ice pack, researchers were able to cool the area and allow for melanin production, resulting in a black patch where the fur grew back. This shows that environmental temperature can regulate the expression of the melanin-producing genotype.
What role does the pineal gland play in the color change of arctic foxes?
-The pineal gland secretes melatonin, a hormone that is produced more during darkness. Higher melatonin levels in winter trigger the reduction of melanin production, causing the foxes to appear white for camouflage. In summer, lower melatonin levels lead to increased melanin and a darker appearance.
How do arctic foxes and arctic hares adapt their coloration for seasonal camouflage?
-Arctic foxes and hares change their fur color based on the season to blend in with their environment. In winter, they have more white fur due to increased melatonin secretion, and in summer, they have darker fur as melatonin levels decrease.
How do plants like hydrangeas change flower color in response to environmental factors?
-Hydrangeas can vary their flower color based on the pH level of the soil. A higher pH (around 6) results in pink flowers, while a lower pH (in the 5s) leads to blue flowers due to the uptake and expression of aluminum.
What is the relationship between pH and flower color variation in hydrangeas?
-The pH of the soil affects the availability of aluminum, which influences the color of hydrangea flowers. Lower pH levels allow for more aluminum uptake, leading to bluer flowers, while higher pH levels result in pink flowers.
What is an operon and how does it relate to gene expression in bacteria?
-An operon is a group of genes in bacteria that are involved in a specific function and are regulated together. The presence or absence of certain environmental factors, like lactose, can turn the operon on or off, controlling the expression of the genes within it.
How can the presence of lactose in the environment affect the expression of the lac operon in bacteria?
-When lactose is present in the environment, it can trigger the expression of the lac operon in bacteria, allowing them to break down lactose. This results in the production of acids that lower the pH of the environment, which can be detected using indicators like those in MacConkey Agar.
What is MacConkey Agar and how is it used to differentiate between lac positive and lac negative bacteria?
-MacConkey Agar is a type of growth medium used in laboratories to distinguish between bacteria that can and cannot break down lactose. It contains a pH-sensitive indicator that turns pink when the pH drops due to acid production by lac positive bacteria, allowing for easy identification of the bacteria's genotype expression.
Outlines
🐇 Environmental Influences on Genotype Expression
This paragraph discusses the concept of environmental genotype effects, which is how the environment can influence the expression of an organism's genes. It uses the example of the Himalayan rabbit to illustrate how body temperature can disrupt the expression of genes responsible for melanin production, leading to the characteristic black and white coloration. The paragraph also mentions an experiment involving shaving and cooling the rabbit's back to alter the expression of the melanin gene, demonstrating the direct impact of environmental conditions on genotype expression. The speaker then transitions to discussing how traits can be expressed differently in animals like the arctic fox and hare, and in plants, due to environmental changes.
🌡 Adaptation and Genotype Expression in Animals and Plants
The second paragraph delves into how animals like the arctic fox and the arctic hare adapt their coloration based on seasonal changes to blend in with their environment, a process influenced by the hormone melatonin secreted by the pineal gland. In winter, increased melatonin production leads to reduced melanin and a white appearance, while in summer, decreased melatonin allows for increased melanin production and a darker color. The paragraph also covers how plants, specifically hydrangeas, can vary their flower color in response to soil pH levels, with lower pH levels resulting in blue flowers due to the uptake of aluminum. Lastly, the paragraph introduces the concept of operons in bacteria and how the presence or absence of the lac operon affects the bacteria's ability to break down lactose, with a brief mention of using MacConkey Agar to differentiate between lac positive and lac negative bacteria based on color changes indicative of pH changes.
Mindmap
Keywords
💡Genotype
💡Phenotype
💡Environmental Genotype Effects
💡Melanin
💡Himalayan Rabbit
💡Pineal Gland
💡Melatonin
💡Arctic Fox
💡Hydrangea
💡pH
💡Operon
💡MacConkey Agar
Highlights
The environment can affect the expression of genotypes, influencing an organism's phenotype.
Genotypes are the genes an organism has, while phenotypes are the physical traits expressed by those genes.
Himalayan rabbits naturally express genes for melanin production, but body warmth disrupts this expression, leading to a non-uniform black color.
An experiment showed that cooling the body core of a Himalayan rabbit allows for uniform melanin production, demonstrating environmental control over gene expression.
The podcast will cover how environmental changes affect the expression of genotypes in animals, plants, and bacteria.
Arctic foxes and hares change their coat color seasonally to adapt to their environment, regulated by the pineal gland and melatonin production.
Plants, such as hydrangeas, can change flower color based on soil pH, showing environmental influence on plant phenotypes.
Bacteria can regulate gene expression through operons, such as the lac operon, in response to environmental conditions.
The lac operon in bacteria allows for the expression of genes necessary for lactose breakdown, with presence indicating 'lac positive' bacteria.
MacConkey Agar is used to differentiate between lac positive and lac negative bacteria based on pH changes and color indicators.
Gene expression in bacteria can be observed through color changes in agar, providing a visual representation of genotype expression.
Environmental genotype effects are crucial for survival and adaptation, as seen in the examples of Himalayan rabbits, arctic foxes, and plants.
The study of environmental effects on genotypes helps us understand the complexity of gene expression and its dependence on external factors.
The transcript provides insights into the interplay between genetics and the environment, highlighting the dynamic nature of biological systems.
Understanding how the environment influences gene expression can have practical applications in areas such as agriculture and medicine.
The transcript emphasizes the importance of studying genotype-environment interactions for a comprehensive understanding of biological processes.
Transcripts
Hi. It's Mr. Andersen and welcome to biology essentials video 53. This is on
environmental genotype effects. In other words, how the environment can effect genotypes.
Now remember genotypes are the genes that you have. But how those are expressed is called
your phenotype. So what you physically look like is your phenotype. But the genotype are
the genes that lie behind that. In other words, that make those proteins. That make your physical
appearance. And so basically as the environment changes, you can either express genes or not.
And so this is the Himalayan rabbit or at least a cartoon version of a Himalayan rabbit.
Himalayan rabbits are all black. But if you look at the picture, it's not all black. And
so basically what a Himalayan rabbit is doing is it's expressing the gene to make melanin
which causes the coloration that's black. However since the core of the body of the
Himalayan rabbit is warm, it disrupts the expression of that genotype. So you can't
make the melanin. And so the areas on a Himalayan rabbit that are cooler, that are away from
that core are actually able to be that black phenotype. And so you might not buy it. And
so this is a cool study that was done with Himalayan rabbits. Basically you shave the
Himalayan rabbit's back. So you get rid of all the fur on the back. And then you add,
not ice, but an ice pack to the back of Himalayan rabbit. And then you let it sit on there as
the hair grows back in. And when the hair browns back in, what you'll have is a black
patch wherever you shaved. And so what happened was by adding that ice pack you're able to
cool the temperature down. And so the core of the body is not able to heat it up. And
you can make the melanin that would naturally be there. And so basically you can regulate
whether or not that genotype is going to be expressed. I've always thought it would be
cool to have a Himalayan rabbit. Then just kind of make my name in its back in black.
But that's a little weird. So let's get on to the podcast. What am I going to talk about.
Basically I'm going to talk about how traits can be expressed or not. In other words, how
the genotypes can be expressed due to changes in the environment. I'll talk about how that
occurs in animals. I've mentioned the Himalayan rabbit. But I'll also talk about where that
might actually apply in the arctic fox or in the arctic hare. I'll also talk about how
plants can change or vary their color due to changes in their environment, notably the
pH. And then finally how bacteria can change their expression of genotypes. I'm going to
talk about the operon, especially the lac operon. But also show you how in the lab we
can use color change in bacteria to see what color or what type of a bacteria you have.
So let's start with the animal side and seasonal melanin. So this is an arctic fox. But so
is this. And so basically an arctic fox will change its color due to the season. Which
totally makes sense. In the winter, when it's snow everywhere, you want them to be white
so you can blend in for camouflage. Then in the summer you also want to blend in with
your environment. So how do they do that? Well basically they have a pineal gland. The
pineal gland sits kind of right in the core of the brain. It's right behind the eyes.
And basically it secretes melatonin. Melatonin is a hormone that's created during times of
darkness. And so during the winter they're going to secrete more melatonin. As they secrete
that melatonin, it's going to trigger the cells in the body not to produce melanin and
so they're going to have this white appearance. Now when summer comes. We're going to have
a decrease in melatonin. They're going to increase the amount of melanin and they're
going to have a dark appearance. And so that's evolved over time. Responding to the environment,
those that were able to turn off that melanin during the winter were able to survive longer.
And so we're going to see that in the arctic fox. But also the arctic hare. As they change
the amount of melanin that they have. And so we're either expressing that gene and having
the dark color or we're not expressing the gene. We can also see that same thing in plants.
And if you think about plants you might say well, they're always green. And that's the
photosynthetic parts. So the leaves obviously are always going to be a green color. That's
based on the amount of chlorophyll. But the function of the flower is to attract an animal,
notably the insects. And so basically this is the same hydrangea, it's the same species
of plant, but it's able to get different colors of flowers. And it's doing that in response
to the environment. Notably the soil environment. And so basically these ones are cultivated
by humans, but they can vary the pH of the soil. And if you have a pH in the 6s, then
you get this pink hydrangea. If lower the pH into the 5s you can get this blue hydrangea.
Basically the blue is coming from aluminum that when the pH gets lower their able to
pick up and then express that. And so the genes that they're making are dependent upon
what building blocks they have. In this case in their environment, whether they can express
it or not. So it's not like they're turning it on or off. But they're able to vary the
amount of coloration. And so that's going to give them variation in their environment.
Last thing I want to talk about was bacteria. And how bacteria can either express genotypes
or not. And when I say express it or not, the one thing that should jump to mind is
operons in bacteria. Remember basically in bacteria they have a string of genes that
are right next to each other. They can turn it on or they can turn it off. In this case
there are three genes that help the breakdown of lactose. And so you basically have a promoter
where RNA polymerase can get on. You can either make those or not. Dependent upon the presence
of lactose. If this makes no sense, make sure you watch the podcast on gene regulation.
But if you have this, then you're called lac positive. If you have the lac operon you have
this whole thing. If you don't have it, then you're lac negative. And so you're a bacteria
that can't breakdown lactose. And so a good way to differentiate between those that are
lac positive and those that are lac negative is using somethingcalled MacConkey Agar. So
you're growing colonies of bacteria on it. Basically you grow the bacteria. They'll grow
on this. They'll feed on the agar. They'll multiply over time. So you know 24 hours later
you have all these bacteria. But in the MacConkey Agar it's innovative. What they do is they
put a chemical in here that can sense the pH. Because if you're lac positive you're
going to make acids that are going to change the pH in the agar. And so basically they
put an indicator, is the word I was thinking of, that once the pH goes below 6.8 then it's
going to have a pink coloration or pink appearance. And so if you grow bacteria on MacConkey Agar,
so you can see over here we have bacteria that a lac negative. Because they don't have
that lac operon. Over here we have e. coli that are lac positive. And since they're breaking
down that lactose that's also found in the agar then they're lowering the pH and now
the indicators going to give it that pink appearance. And so it's just an example of
how a gene is either expressed and we see a phenotype. In this case that phenotype that
we don't necessarily see in the lac open we can actually see in the agar. And so that's
basically how an environment can effect genotypes. Can effect what phenotypes we see. And I hope
that's helpful.
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