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Hi, I'm recording again the class that I couldn't this morning, and I'm trying to do it today perfectly.

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Okay, so we were there learning to explain, if you remember, this page about mutation and evolution.

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And the first thing that I told you is quite important, and remember that I told you to write it down.

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The main thing is that you sometimes are mistaken and you think that the mutation can change

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the genetic code, and this is not true.

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The mutations do not change the genetic code, the mutations only change the information.

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And this is very important, so write it down.

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only change the genetic information that is written in the sequence of nucleotides of

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the DNA.

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Now important, important, remember that we saw this genetic code the other day.

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So this genetic code is how these nucleotides with their basis, nitrogenous bases, are going

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to be read by the ribosomes in the cytoplasm of eukaryotic cell.

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And these meanings, that means that this codon is going to meet this amino acid, is not going

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to be changed.

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Now I realize that there is a mistake in this table and it's here.

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As you can see, the second base is G, and here in this column appears U.

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So I wrote it here, the correct triplet, the correct column.

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Now let's continue with the mutation.

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So the genetic information can be changed, can be changed because sometimes are processing

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the cell that do not work properly and for instance the protein introduce a wrong nucleotide

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in the chain that is synthesizing or the system that correct the mistake doesn't work properly

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and it's not correcting the mistake so these things are going to happen as you can see here

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randomly so that means is now something that happens following some direction is unexpected

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and in general are sudden okay are beyond suddenly okay and these these chains are called

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mutation but they are changing the dna that are not mutation okay for instance recombination

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the recombination means that the dna is also altered because the two homologous chromosomes

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are going to exchange fragments between two chromatids this recombination is not a mutation

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is a natural process. Now, not all the mutations can be seen. Not all the mutations are going

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to be bad. Some mutations can be also good for the living beings. And some mutations

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happen naturally because, for instance, this mistake in the process of replication and

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and other are the result of different agents that are called mutagen and you have here

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okay the meaning and the definition of mutagen that means agent that can be physical or chemical

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okay and they alter the genetic information the mutations in general increase variability

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but I'm going to explain this later in the classroom now let's go to the point

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for one and you can see here okay how you can classify the notation according

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to different criteria and you can see there are one two three four five

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columns okay so we can use whatever we want okay let's explain one by one the

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The first one that is the type of cell affected, you can see that there are two types, somatic

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that come from a Greek word that means body, that is soma.

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So that means that are the cells of our tissues, of our brain, of our heart, muscles.

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have also the other ones that are germinal. Germinal refers to the cells that are going

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to produce the gametes. And why the geneticians are doing this difference? Because when you

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have a somatic mutation, it belongs to your body, to your tissues, but you are not going

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to transmit this mutation to your offspring. Meanwhile, the ones that affect the gametes

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and the formation of the gamete are going to be transferred to your children, in this

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case because we are speaking, for instance, of human beings, but it can happen in animals

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and can happen in plants.

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Let's explain this with a very clear example.

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Imagine that I'm very fond of sunbathing in summer time, okay?

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So year after year, I'm lying beside my pool and sunbathe.

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What happens?

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That I'm going to receive a huge amount of ultraviolet radiation.

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And the ultraviolet radiation is quite strong and enters through the skin, okay, and we

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are going to see later the, or no, or let's see now, if you go to the next page, you can

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see here, this is a representation of the layers of the skin and you can see the ultraviolet

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radiation enter and there are sometimes some ultraviolet radiation that enter at the very

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bottom and affect this cell of the hypodermis that are the cells that are producing the

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other cells and they enter inside the cells and they enter inside their nuclei and they

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change the DNA and with time, doing this year after year, the change in the DNA is so big

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that this cell is going to be so transformed that it's going to develop cancer and I'm

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going to suffer cancer skin cancer and this skin cancer is not going to be

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transmitted to my children I'm going to suffer but as my gametes my ovules that

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are inside my ovaries are not affected by this I'm not going to transmit this

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disease to my children because my mutation is somatic but if happen that I

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suffer radiation for instance x-ray that are very strong in my ovaries and this

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affect my ovules my gamete in this case my child is going to suffer a mutation

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as well now according to the course we can classify the mutation is spontaneous

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that's meant that happens in the cell okay or can be induced for instance I

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induce this with the x-ray this will be something produced by a mutagen now we

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have the third criteria criteria what are the effects of this of this

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mutation so they can be neutral does mean no effect the living bin is the

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same no change or the chains produce something good for the living bin and in

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this case we call it beneficial or can be harmful that is the case of the skin

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cancer okay now we have here resultant alleles let me explain first of all what

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is an allele so the allele is the different possibilities that a gene can

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have for instance let's think in the color of our eyes in the color of our

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eyes we can have different possibilities so if you look your classmates you can

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see that some of them have brown eyes and others have blue eyes, okay? So these are

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alleles and it's because the gene, the gene is going to produce the protein or

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the pigment that is in charge of the color of the eyes. So this gene is

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producing the pigment but there are different possibilities brown blue

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different alleles what happens that the gene is present in each chromosome of

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the pearl of homologous so if one chromosome of the pearl has the brown

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even if in the other chromosome is blue the color of the eye of this person is

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is going to be brown.

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So that means that this is the dominant allele.

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That means that when this allele is present,

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it's going to be expressed, and we can detect.

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In this case, it's very easy

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because it's the color of the eyes.

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The other version of the gene that produced the blue color,

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if it's with the dominant, cannot be seen,

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and we call it recessive.

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We only can see this color blue

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if the two homologous chromosome carry both of them,

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the same version of the recessive allele.

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In this case, in the first chromosome will be the blue,

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and in the second, homologous chromosome

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will be also the blue.

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And we are going to study this in Mendelian genetic, okay?

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That will be how these alleles can be transmitted.

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And also the most important,

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because it's the thing that the classification

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that we are going to use just now,

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is the genetic alteration.

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So we can,

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the mutation can happens in the gene.

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So now remember,

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or maybe I should explain what is a gene.

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So very important concept,

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A gene is a fragment of the DNA

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that carried information for synthesizing a protein.

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I repeat again, a gene is a fragment of DNA

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that carried information for synthesizing the protein.

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So there are mutations that affect only one fragment,

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one gene, and this is the case for example

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of maybe the skin cancer or the one that appear here

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that is the sickle cell anemia.

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And you can see here, these are red bloods, okay?

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Taking the image with an electron microscope.

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And you can see that this red blood

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has a very different shape for this one

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that is the normal one.

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This is the normal one, this is the normal one,

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and this has been altered.

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And this one is also altered, okay?

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So this mutation produce a change

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in the shape of the red blood.

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And when they have this change,

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that means that they can join

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and they can produce blood clots

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inside the veins and capillaries, okay,

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of the circulatory system, and it's quite dangerous.

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So the people that suffer this, okay,

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they have problems, okay,

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because they can suffer this blood clot,

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or if they are women, in general,

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they are going to have miscarriage during the pregnancy

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because these cells do not carry enough oxygen

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from the fetus, okay?

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So in general, the pregnancy is very difficult

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and most of the time they never end.

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That is a pity.

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So, but also because has this shape,

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the people that has this mutation

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are quite resistant to the malaria, okay?

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So as you can see, sometimes the mutation can have

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one problem, but also can have in another sense, good.

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Okay, so in nature, the things are more complex, okay?

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We try to simplify, but not always is easy, okay?

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Now, we have the second type of mutation

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that affect a chromosome, chromosomal mutation.

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That's mean a chromosome can be broken

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and can happen that some part of the chromosome is lost.

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These mutations are representing your book here.

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at the bottom. And you have here, this is the normal chromosome and the designer painted

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with colors in band. Well, the colors are not real and they are chosen in order to help

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you but the band is through there is a technique okay sorry the bands that appear here

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are a technique that is used in genetic and they produce part of the chromosome bands that are

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where the chromatin is super condensed and looks very thick, very thick and dense and in the image

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appear darker. Meanwhile, there are bands where the chromosome is loose, is not thick and appear

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gray or clear and it's the band chromosome so the part that is true and part that is not

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is not the colors are not are not real are false colors in order to help you so the bands here

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are designed with letters as you can see and this is the normal one and you can see one

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that lacks the bands A and B, the yellow and blue. So that means that some part of

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the chromosome is lost, and this is called the election. Or sometimes happens

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that these two bands, for instance, are repeated, copied again, and we call it

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duplication, okay? Or happens that the bands are upside down and appear in

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in another order, as you can see here, inversion.

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Or even can happen that one part of the chromosome

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goes to another chromosome that is not the homologous

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because it not will be recombination.

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Take this into account, okay?

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So here you can see that appear the yellow and the blue

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and the red and appear with letter.

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Meanwhile, this chromosome has bands that appear in gray,

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in different scales of gray,

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and they have number in order that you can distinguish, okay?

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And there is a mix between the colors and the grays.

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And the gray part is in the previous,

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in the other, in the bigger chromosome.

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And you can see here, one and two.

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So we call it truss location.

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So it's an exchange.

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One part goes to another chromosome.

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In general, when this happen,

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always causing a problem and a disease, okay,

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to the living being.

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Now, and finally,

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we have genomic or numeric mutation.

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Does mean that is going to affect,

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is going to affect the number of chromosome

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that appear in the cell or in the living being and there are two types and you need to remember

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this vocabulary so we study this carefully because i know that is difficult for you okay

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and you employed it this means that we have one chromosome or two or three whatever

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more chromosomes than normally or we lack of one or two, three chromosomes, okay?

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So, for instance, instead of having in human beings, as you know, we have 46 chromosomes

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and instead of having 46, we have 47 or maybe 49 or maybe we have instead of having 46,

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we have 45, lacks one, okay?

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When this happens and we have one more or less, we have always a sickness, a syndrome, okay?

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The most common, and I suppose that you know, is the Down syndrome.

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That means that this kind of person has 46 chromosomes and they have one extra chromosome in the pair that is the pair 41.

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So that means that it's one of the smallest chromosomes for our cells.

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And also we have a haploid.

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In this case, it's the set of the chromosome.

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The set of the chromosomes in this case is referred to the haploid number of chromosomes

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that is going to be multiplied.

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So instead of having 2 sets, instead of being diploid as we are, this living being is going

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to be triploid, that means it's going to have 3 sets, 3n as you can see here, or maybe 4n.

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So this kind of mutation is rare inside the animal kingdom.

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Animals is very rare, but in the plant kingdom is very frequent.

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In fact, plants use this type of mutation in order to produce new species.

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Let me give you a common example that you can see now in the market.

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So now, very soon, strawberries are going to be in the market and they are extraordinary

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big.

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It's because they are polyploid, that means the scientists multiply the number of chromosomes.

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of being deployed, they can be PEN-deployed, okay? So no 2N, maybe 5N or whatever. And

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what happens? That now the fruit is getting bigger and bigger, and the strawberries are

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getting bigger and bigger, okay? So, very important thing. Now, in the next page, okay,

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We have more explanation about the agent that can cause mutation, that are mutagens.

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You have here the classification and you have three types.

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First of all, physical ones, that is the case in general of the radiation, and you can see

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that is the ultraviolet rays, the gamma rays, the beta rays, or the X rays, okay?

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So these rays, that means something that we use in the hospital also can damage our cells,

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So it's not very convenient to take a lot of this treatment or X-ray image because they

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can alter.

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And if you see or if you are the voice in the classroom, if you go to the hospital and

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you need to do an X-ray of one of your legs,

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probably, okay, the person that is in charge

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will use, okay, a slice of lead to cover your test

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because as the test are outside of the body,

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there is a high risk that this radiation

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can affect your gametes.

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So in order to prevent that,

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they cover with this layer of lead

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and the lead is a very dense metal

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that is going to absorb the radiation.

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Even the person that is in charge of the machine

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and is doing the X-ray image

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is going to keep herself away of the machine

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and after, okay, also layer of lead

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lead that is protecting him or her of the radiation.

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Now we have a lot of chemical mutagens around us, okay, and you have here the number of

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substances that can alter our DNA, 6 million, imagine.

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Some of them are very common, okay, for instance, nicotine, and you can see here an image of

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the cigarette with all the chemicals that you, if you smoke, you are going to introduce

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in your lungs and if you continue smoking that means that you are going to develop lung

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cancer.

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And this is very difficult to detect because the lungs do not produce pain.

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The people in general feel tired but it is sometimes very normal because we work quite

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a lot and they don't pay attention to that but because they are not suffering any pain

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and when they finally have metastasis maybe in the brain or maybe in the bones is when

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they realize okay so it's very very healthy to smoke and I expect that you

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are going to be healthy people and you do not notice but now we have also

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biological mutagens that are virus okay and these virus are well nowadays we do

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not consider living beings virus is not even a cell they are only active if they

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are inside our cells but when they are there inside they are able to send a

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copy of their DNA to the nuclei of our cell and introduce this segment this

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virus DNA inside a chromosome of our cell so it's changing our genetic

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information and it's going to happen that we are going to have our this

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virus in our genome in our nuclei and it can stay there maybe years till we are

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sick and weak and then the virus go out and begin to reproduce and we will be

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sick okay that is what happens with the immunodeficiency virus okay that produce

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the SIDA okay that the people was infected they didn't suffer anything

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they maybe during the ten year but they spread the virus okay so and there also

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and other ones that are transposons.

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Transposons are also virus that copy themselves

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and introduce the copy in the other chromosome.

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So at the end we have copies of this virus

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in all the chromosomes.

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And sometimes not only one copy,

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we have two or three copies, okay?

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So this is also a big alteration of the DNA.

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of the DNA.

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Now, because mutation change the genetic information,

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they produce different genetic information

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and they increase the genetic variability

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of this information in one species or in one individual.

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Okay, so in order to finish the classroom, okay, you are going to do this exercise 27, okay, and you need to think in all the information that we studied during this day, and I will correct this on Monday, okay?

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So thanks a lot and see you on Monday.

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oh my goodness i can't stop this now always problems

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okay guys let me try if i can stop now

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this