Lesson video

Hello and welcome to this lesson from the unit DNA and the genome.

The title of today's lesson is "The Genome, the Environment, and Phenotype".

And what we're going to be looking at today is what the genome is and what it codes for, how the environment can have an impact on an organism's appearance and on its function.

And we'll look at what this term phenotype means.

My name's Mrs. Barnard and I'm going to be taking you through today's lesson.

So by the end of today's lesson, you should be able to describe how an organism's genome and its environment influence its characteristics.

So we've got some keywords in today's lesson and our keywords are genome, gene, protein, phenotype and enzyme.

If you want to write down the definitions you can pause the video now.

If not, we will be going through them at different parts in today's lesson, so you can do it as we go along.

So our lesson today is in two parts.

So part one is the genome.

So what that is and its function and how it affects the living organism and phenotype.

What does that word mean and how does that lead to the appearance and the functioning of all living organisms? So we're gonna start with our first part of today's lesson, which is the genome.

So all living organisms have a genome, whether that's a bacteria or a plant or an animal or a fungi.

And the genome is all of the DNA of an organism.

And all living organisms have their genetic material as DNA.

The genome includes all of the genes which provide the instructions for the features for those living organisms. And hopefully you know that that DNA is packed inside the nucleus of animal plant and fungi cells and in the cytoplasm of bacteria cells.

So most cells in an organism will have a copy of the genome, and all living organisms have a genome made of DNA.

The reason we say most cells is 'cause there are some cells that may not have a nucleus, for example, red blood cells, but most cells will have a copy of the genome.

So here is a little image to show you what we mean.

So all of the DNA that's wrapped up inside that nucleus is termed the genome.

And that goes on and on and on because there's so much of it in there.

The genome includes all of the genes and the non-coding sections of DNA.

So we've got these sections of DNA that don't code for anything.

People used to call that junk DNA, but now we know it does have a role.

The genes hold the instructions for making proteins and they give an organism its inherited features.

So we can see here on our DNA, there's sections that are genes and there's sections that are non-coding.

So some sections of the DNA and the genome do not code for features and processes.

And these sections are not genes.

These non-coding sections of DNA are found between genes.

They don't code for proteins, but it doesn't mean that they don't have a role.

Some of these sections in the DNA help to control when the genes will be used to produce proteins.

So when those proteins in a day or in a lifetime will actually be produced.

And here's a little image to show you what we mean.

So the gene sections will code for proteins, and those non-coding sections will help to control when those genes are actually read and those proteins are formed.

So time for a quick check, choose the correct statements that complete the sentence the genome is.

So once you've decided which of those statements are correct, then come back and we will see how you've got on.

Okay, let's see how you got on with that then.

So the genome is, the genome is all of the DNA of an organism and it is all of the genes and the non-coding DNA of an organism.

So if you've got those right, then well done.

Let's move on.

So the proteins that the genes code for produce inherited features that you can see and are involved in inherited processes that you can't.

So for example, there'll be lots of chemical reactions that take place in order for germination to occur in plants, but you won't necessarily see those taking place within the seed.

But then there's also proteins that will code for things that you can see, like the colour of hair or also how curly your hair is.

So DNA is a chemical molecule and it carries a genetic code.

And the genetic code provides the instructions to build those proteins, those proteins that are needed for either processes or that we can see in an appearance.

And that genetic code is made out of four chemical groups, A, T, C, and G.

And the order of those chemical groups will determine the genetic code.

And that genetic code then goes on to make proteins.

So these chemical groups, when they're bonded together, will form the nucleic acid chains that make up DNA.

The order that the different nucleotides are within a gene determines the structure of the protein it codes for.

So here's our model picture of a gene, which is a section of DNA that codes for a protein.

And if we look at it closely, we can see that it's made up of this code.

So it's made up of these repeating groups nucleotides.

And then within those nucleotides they've got this smaller chemical group that gives the code, it's the base, and that code will determine the structure of a protein, and that protein will give us a feature.

So let's have a quick check, put these structures in the correct order to describe the production of an inherited feature.

So pause the video while you do that and then we'll come back and we'll see how you got on.

Okay, then let's see how you got with that.

So putting these structures in the correct order to describe the production of an inherited feature.

So the first stage is that we have the gene, and then within the gene we've got the genetic code.

And then that genetic code will give us the instructions for building a protein and then that protein will give us a feature.

So if you've got those in the correct order, then well done.

Okay, move on, next, what I'd like you to do is to match the keyword to its correct definition.

So we've got five key words.

We've got nucleotide, gene, genetic code, protein and genome.

So again, pause the video while you decide and then we'll come back and we'll see how you got on.

Okay, let's see if we've got all those matched correctly.

So we should have, our nucleotide should be matched up to small chemical groups that make up DNA.

There are four types.

We should have gene matched up to a section of DNA that carries the genetic code for a protein.

Then we should have genetic code matched up to the order of nucleotides in a gene.

It gives instructions for the structure of a protein.

And then we should have protein, a chemical substance whose structure is coded for by the genetic code in genes.

And then finally, genome is all of the genes and non-coding DNA of an organism.

So if you've got all of those correct then well done.

So time for another practise task.

Sam has started to draw a diagram to show how genes in the genome lead to the formation of physical features.

So you can see here that she's drawn a little diagram of DNA.

She's put some labels on it to start it off, but she hasn't finished the diagram in order to get all the way to physical features.

And she's missed a few labels off the start.

That would be quite useful in describing this process.

So here's your task.

Sam has missed some useful labels off the start of the diagram, and it is incomplete, copy and complete the diagram to explain how genes in a genome leads to the formation of physical features.

So you'll need a little bit of time to do this.

Make your diagram nice and big so you can see the labels clearly.

And then we'll come back and we'll look at them a model answer at the end.

So pause the video while you do that.

Okay, let's have a look at how you got on with that then.

So you job was to copy and complete the diagram, so adding labels in and finishing it off to show how we get all the way to physical features.

So what we could have added on there is the genomes, just to show that that is all the non-coding DNA as well as the genes.

And we've got those on there.

We've showed that this is DNA.

So we've got labelled on there for DNA and a section of that DNA.

So those small units that make it up are called nucleotides.

And you can see that's labelled on the diagram there at the bottom.

And then we've got labelled on that the nucleotides are linked across the middle.

Now, if you'd said the bases are linked across the middle, that's also correct.

And then Sam, she already had the genetic code on her diagram, we've labelled it genetic code.

And from that genetic code from the gene, we get our protein structure and then onto our inherited feature, EG, eye colour.

And I might have drawn a little picture of something there that is an example of an inherited feature.

If you haven't got all the labels on your diagram, then there's some time now to just add those on.

Otherwise, well done, that's good work.

And let's move on to the next part of our lesson, which is phenotype.

The protein structure produces the inherited features and controls processes.

And these features and processes are called an organisms phenotype.

So therefore, the phenotype is the physical characteristics of an organism.

So here we go, we've got protein structure, and that could give you a phenotype, for example, colour or a phenotype, for example, ear shape.

So it gives us the physical characteristics of a living organism.

So proteins can be structural or functional.

So structural proteins are used in the structure of a characteristic, whereas functional proteins are involved in chemical reactions and biological processes.

So for example, we've got structural proteins in our skin like keratin or collagen, and then we've also got keratin in our hair.

And these things give the structure of those particular features.

But then we've also got proteins that are involved in functional proteins.

For example, colour pigments in flowers or in the skin or in hair.

So an enzyme is an example of a functional protein.

Now, enzymes are really important in biology because they control all the processes in living organisms because they act as catalysts.

So they're involved in all chemical reactions and they speed up reactions without being used up.

So we've got a protein structure.

And then this particular protein structure, if we look at it as a model, you can see that it's got this shape called the active site.

And that active site is where substances, which we call substrates, can bond and they can either be joined together or taken apart.

So all the chemical reactions in the body are sped up by these enzymes.

They're really, really important group of proteins.

So it's not used up in a reaction in enzyme.

It can be used over and over again.

And it catalyses that reaction by speeding it up in the lower temperatures that we find inside living organisms. And the products that it produces can lead to phenotypic features, so to our phenotype.

So here is an example picture of how they might work.

So an enzyme might catalyse a reaction where it joins chemicals together.

So you can see those two substrates will enter the active site, they'll bond together.

And then when they're released as a product, that product could give us some kind of characteristic or the opposite could happen.

A substrate could enter the active site and it could be broken down into products.

And again, those products could give us a characteristic that is part of our phenotype.

So time for a quick check.

For each phenotype below, choose whether a structural or functional protein would be involved.

So for A, B, C, and D, can you write structural or functional next to each one or FNS? Pause the video and then we'll come back and we'll see how you've got on.

Okay, so let's look at these one at a time.

So a little bit of a clue in this one 'cause it says the digestive enzyme.

So enzymes are functional.

Muscle fibres form the structure of our muscles.

So they are structural colour pigment, again, is functional, and hair is part of our structure.

So it is structural.

So if you've got all those right, then well done.

Let's move on to the next part of our lesson.

So only features that result at least partly from the genetic code of an organism's genes are defined as a phenotype.

So for example, flower colour and eye colour are phenotypic because they result from the genetic code of a gene, whereas damage is not phenotypic because it results from the environment or lifestyle.

And a couple of examples here of a leaf that's been eaten or a scar.

So the environment is the surroundings of an individual organism such as sunlight, pollutants, or the availability of nutrients.

So we can see a sunflower here in a high temperature compared to optimum temperature, and it looks different, but that's been impacted by its environment.

And a herb plant here with a lack of water, again, it's been affected by its environment, whereas a lifestyle of a person is the things that they do and the choices that they make, such as diet or exercise or fascia.

And they made a change the appearance or the functioning.

So for example, body piercing or exercising, both lifestyle and environment can have an effect on the phenotype of an organism.

They could alter the physical characteristics of an organism that was originally coded for by genes.

So let's look at an example of how they might cross over.

So a combination of genetic code with lifestyle and environment can impact phenotypes.

So we've got muscle shape and size here, and they're gonna be affected by your genes, but also your lifestyle.

So maybe how much exercise or weights that have been lifted or how much protein is eaten.

And then some phenotypic characteristics are more difficult to see and they might be affected by the environment.

So features that might be difficult to see are processes such as digestion in animals or germination in plants.

But germination will be affected by genes, but also by the environment.

So things like availability of nutrients or water or temperature.

So some phenotypic characteristics are determined only by the genetic code in genes and cannot be changed by environment or lifestyle.

So for example, even if you wear a coloured contact lenses, your inherited eye colour will still be the same underneath.

And human blood type is determined by the genetic code in the genes, and that will not be changed.

So that can't be changed by lifestyle or environment.

So time for a quick check.

The phenotype of an organism is only caused by its genes.

So first of all, I want you to decide whether that's true or false.

And then once you have decided, could you justify your answer with one of the statements below? So choose which of those statements you think.

So pause the video and then we'll come back and we will see how you've got on.

Okay, so the phenotype of an organism is only caused by its genes.

This is false.

And the statement that best justifies that is this one.

The phenotype is caused by its genes, but it can also be affected by lifestyle and environment.

So we've got that right then well done.

So we've got a confidence grid now.

So what I would like you to do is for each of the statements, decide whether you think it is correct or incorrect.

And once you've decided whether it's correct or incorrect, how sure are you? So are you sure it's correct or you think it's correct? Are you sure it's incorrect or do you think it's incorrect? So pause the video while you decide, and then we'll come back and we'll see what the correct answers are.

Okay, so let's have a look at this.

So the phenotype is the physical characteristics of an organism.

So this is correct.

So if you put your tick in either of those two columns, then you're right.

The phenotype of an organism is always visible.

That is incorrect because sometimes it is to do with a functional process that you can't see.

So examples that we've looked at so far are digestion and germination.

The phenotype is only affected by the protein coded for in the genes.

This is incorrect 'cause the phenotype can also be affected by the lifestyle and the environment and lifestyle environment can affect the phenotype.

This is correct.

So if you've got those right, then well done.

So either of those two columns.

So those two ticks are your two options.

So time for an activity now.

So Sofia and Lucas are looking at a raspberry plant and they're suggesting some phenotypic characteristics.

They're also considering whether they might be affected by lifestyle and environment.

So Lucas says the colour of the raspberries is a phenotype coded for by genes, and Sofia says yes, but it could also be affected by water and nutrient availability in the environment.

So what I would like you to do is I would like you to suggest some other phenotypic characteristics of this raspberry plant and then say whether they might be affected by the environment, and you might give some examples of things in the environment that might affect them.

So pause the video while you do this activity, and then we will come back and we'll have a look at what you found.

Okay, so hopefully you found a few more examples of phenotypes that are affected by the environment.

Here are some examples, but you might have some others.

So we've got the size of the raspberries are a phenotype, and that could be affected by water and nutrient availability in the environment.

Also, maybe sunlight, temperature.

The colour of the leaves are a phenotype that could be affected by the availability of sunlight and temperature in the environment.

Again, also other things like water.

These are just examples.

The number of raspberries formed are a phenotype.

So remember, raspberries come from flowers.

So that could be affected by the number of pollinators in the environment.

So if you've got those or any other examples where you suggested a phenotype and then suggested some environmental factors, then well done.

So that brings us to the end of today's lesson.

So the genome is all of the DNA of a living organism.

It is made up of genes and non-coding sections of DNA.

The genes carry the genetic code that is used as instructions by cells to make structural and functional proteins.

Structural proteins are used in the structure of an organism.

So for example, hair, and functional proteins in chemical processes, for example, enzymes.

The physical characteristics of an organism are called the phenotype.

Some characteristics in an organism's phenotype are determined only by its genome.

For example, eye colour.

Most characteristics in the phenotype are influenced by the organism's genome and its interaction with its environment.

So well done for your work in today's lesson.