Genetics - Mutations and their Types - Lesson 20 | Don't Memorise

Summary

This video explains the concept of mutations, addressing common misconceptions about their effects. It clarifies that while mutations do exist, they do not grant extraordinary abilities, but often cause undesirable changes. Mutations are sudden changes in an organism's DNA, affecting genes or chromosomes. The video outlines two main types: genetic mutations, which disrupt protein synthesis, and chromosomal mutations, which involve changes in chromosome structure or number, leading to conditions like Down syndrome and Klinefelter syndrome. The causes of mutations, such as radiation and chemicals, are also discussed.

Takeaways

• 🧬 Mutation is defined as sudden and abrupt changes to the genetic material, primarily in DNA.
• 🚫 Unlike popular fantasies, mutations do not result in extraordinary abilities but often cause harmful or undesirable effects.
• 🔄 Mutations are categorized into two main types: genetic mutations (DNA/gene changes) and chromosomal mutations (chromosome alterations).
• 🧪 Genetic mutations involve changes to the sequence of genes, which can alter the reading frame and lead to defective proteins.
• 🔬 Chromosomal mutations affect the structure or number of chromosomes and can cause significant abnormalities.
• 📉 Deletion occurs when a part of a chromosome is removed, leading to the loss of important genes and severe abnormalities.
• 🔁 Duplication refers to the addition of extra segments in chromosomes, increasing their length and leading to abnormalities.
• ⚡ Inversion happens when a segment of a chromosome flips, which may or may not have harmful consequences.
• 🚹 Aneuploidy refers to changes in the number of chromosomes, such as Trisomy 21 (Down syndrome) and sex chromosome disorders like Klinefelter and Turner syndromes.
• 🌟 Mutagens like radiation, chemicals, and certain consumables can trigger mutations, affecting DNA, genes, or entire chromosomes.

Q & A

What is a mutation in simple terms?

A mutation is a sudden and abrupt change in the genetic material of an organism, often occurring unexpectedly and impacting the DNA, genes, or chromosomes.

Do mutations give humans extraordinary abilities, like in fiction?

No, mutations do not give humans extraordinary abilities like in fictional stories. Instead, most mutations result in undesirable or harmful changes.

What are the two major types of mutations?

The two major types of mutations are genetic mutations, which affect the DNA or genes, and chromosomal mutations, which involve changes in the structure or number of chromosomes.

How does a genetic mutation affect the protein production process?

A genetic mutation can cause a shift in the reading frame of the DNA, resulting in the production of an altered and potentially harmful protein.

What are some examples of chromosomal mutations?

Examples of chromosomal mutations include deletion (loss of a chromosome segment), duplication (repetition of a segment), inversion (flipping of a segment), insertion (addition of a segment from another chromosome), and translocation (exchange of segments between chromosomes).

What is Aneuploidy, and how does it affect chromosomes?

Aneuploidy refers to the presence of an abnormal number of chromosomes in a cell. It occurs when there are more or fewer chromosomes than the typical number, leading to genetic conditions such as Down syndrome or Turner syndrome.

What causes mutations in DNA, genes, or chromosomes?

Mutations can be caused by mutagens, which are factors like radiation, chemicals, and even certain consumable items that alter the genetic material.

What is Trisomy 21, and how does it relate to Down syndrome?

Trisomy 21 occurs when there is an extra chromosome in the 21st set, leading to a total of 47 chromosomes instead of 46. This genetic condition results in Down syndrome.

What is the difference between Klinefelter syndrome and Turner syndrome?

Klinefelter syndrome occurs when males have an extra X chromosome (XXY), while Turner syndrome occurs in females who are missing one X chromosome (XO). Both conditions result in developmental abnormalities.

How does the deletion of a chromosome segment affect an organism?

When a segment of a chromosome is deleted, important genes may be lost, leading to severe abnormalities and disrupted functions in the organism.

Outlines

00:00

🧬 Understanding Mutation: Fact vs. Fiction

The paragraph introduces the concept of mutations, addressing the common misconceptions tied to fantastical abilities such as flying or underwater breathing. While such powers are fictional, the paragraph clarifies that mutations are real but typically lead to less desirable or harmful effects. The focus of upcoming videos will be on explaining mutations, their causes, and types. The paragraph defines mutation as sudden and unexpected changes in an organism's genetic material, primarily DNA, which can alter genes or chromosomes. Two major types of mutations are introduced: genetic mutations and chromosomal mutations. The paragraph also touches on how even small changes in the DNA can affect protein production, leading to defective or harmful proteins.

05:01

🔄 Chromosomal Mutations: Deletions, Duplications, and More

This paragraph explains specific types of chromosomal mutations and how they affect chromosomes. First, it describes deletion, where part of the chromosome is lost, potentially removing crucial genes and causing serious abnormalities. Next, it introduces duplication, where a chromosome section is copied, also leading to abnormalities. Inversion, where segments of a chromosome flip, is discussed as a mutation that may or may not be harmful depending on the genes affected. Insertion occurs when part of one chromosome moves to another chromosome, and translocation is the interchange of chromosome segments between two chromosomes. All these mutations, categorized as chromosomal aberrations, alter the structure of chromosomes, leading to abnormalities.

10:03

🔢 Aneuploidy and Chromosomal Number Alterations

This paragraph explores mutations that change the number of chromosomes in an organism, specifically focusing on Aneuploidy, where the cell has an abnormal number of chromosomes. It provides examples such as Trisomy 21, where an individual has an extra chromosome in the 21st set, leading to Down syndrome. Aneuploidy can also affect sex chromosomes, with conditions like Klinefelter syndrome (XXY) and Turner syndrome (XO) described. These mutations result in either an additional or missing chromosome, causing developmental abnormalities and other effects on the organism.

💥 Causes of Mutations and Recap

The final paragraph discusses mutagens, external factors that cause mutations, such as radiation, chemicals, and certain consumables. It summarizes the two main types of mutations: those affecting the DNA or genes, resulting in shifts in the reading frame and defective proteins, and those altering chromosome structure, categorized as deletion, duplication, inversion, insertion, and translocation. It also highlights Aneuploidy, where changes in the number of chromosomes affect both autosomes and sex chromosomes. The paragraph concludes with an invitation to subscribe for more educational content.

Keywords

💡Mutation

Mutation refers to sudden and unexpected changes in the genetic material of an organism, specifically its DNA. In the video, the concept of mutation is introduced to explain that while mutations exist in reality, they do not lead to the extraordinary powers often depicted in fiction. Instead, mutations can cause harmful or undesirable changes, which is a key theme in the video.

💡Genetic Material

Genetic material, primarily DNA, is the blueprint for an organism’s structure and function. The video explains that mutations occur in this genetic material, either in the DNA or the chromosomes, leading to changes in the organism. This is essential to understanding how mutations impact the organism at a molecular level.

💡DNA

DNA, or deoxyribonucleic acid, carries the genetic instructions for the development, functioning, and reproduction of all living organisms. In the video, DNA is highlighted as the site where mutations occur, causing changes to the genetic code, which can result in the production of altered or defective proteins.

💡Gene

A gene is a segment of DNA that contains the instructions for making a specific protein. The video explains that mutations affecting individual genes can change the sequence of the gene, leading to the production of altered proteins, which may be harmful to the organism. This frames the discussion of genetic mutations and their effects.

💡Chromosomal Mutation

Chromosomal mutation refers to changes that occur in the structure or number of chromosomes. The video discusses how these mutations can disrupt normal development and lead to conditions such as Down syndrome or Klinefelter syndrome. Chromosomal mutations are categorized into types such as deletion, duplication, inversion, insertion, and translocation.

💡Aneuploidy

Aneuploidy is a condition where there is an abnormal number of chromosomes in a cell. The video uses examples like trisomy 21, which causes Down syndrome, and Klinefelter syndrome, where there is an extra X chromosome, to illustrate the consequences of having an altered number of chromosomes. Aneuploidy is a key concept for understanding chromosomal mutations.

💡Trisomy 21

Trisomy 21 is a form of aneuploidy where there is an extra copy of the 21st chromosome, leading to Down syndrome. The video explains that this chromosomal mutation results in 47 chromosomes instead of the usual 46, causing developmental and physical abnormalities in individuals with this condition.

💡Codon

A codon is a sequence of three nucleotides in DNA or RNA that codes for a specific amino acid or signals the end of protein synthesis. The video explains how mutations in the DNA sequence can alter codons, resulting in the production of a different, often defective, protein. This is part of the discussion on genetic mutations and their impact on protein synthesis.

💡Reading Frame

The reading frame refers to the way nucleotides in a DNA or RNA sequence are grouped into codons during protein synthesis. The video explains that mutations can cause a shift in the reading frame, leading to the production of an altered protein. This concept is central to understanding how genetic mutations affect the organism at a molecular level.

💡Mutagens

Mutagens are external factors, such as radiation or chemicals, that cause mutations in the DNA of an organism. The video highlights mutagens as one of the causes of mutations, which can result in either genetic or chromosomal changes, underscoring the environmental and chemical triggers behind these alterations.

Highlights

Mutation refers to sudden and abrupt changes in the genetic material of organisms.

Mutations don't give humans extraordinary powers but often result in undesirable changes.

Mutations can occur either in genes (DNA) or entire chromosomes.

Genetic mutations lead to a shift in the reading frame, altering protein synthesis.

Chromosomal mutations involve changes in chromosome structure or number.

Deletion in chromosomal mutations leads to a segment of the chromosome being lost.

Duplication in chromosomal mutations involves an extra segment, increasing the chromosome’s length.

Inversion occurs when a segment of the chromosome gets flipped, which may or may not be harmful.

Insertion happens when a segment from one chromosome is added to another chromosome.

Translocation is when two chromosomes exchange segments, altering both chromosomes.

Chromosomal aberrations cover all types of mutations that affect chromosomal structures.

Aneuploidy is a mutation that involves changes in the number of chromosomes, leading to abnormalities like Down syndrome (trisomy 21).

Klinefelter syndrome occurs when there is an extra X chromosome in males (XXY), leading to mixed masculine and feminine characteristics.

Turner syndrome occurs when females have only one X chromosome (XO), resulting in developmental abnormalities.

Mutations can be caused by mutagens such as radiation, chemicals, and certain consumable items.

Transcripts

The term Mutation

brings countless fantasies to our mind.

Right from the ability to fly high in the sky,

to that of diving deep into the oceans.

We all love to have such fantastic abilities.

But these are all fictitious.

Such fantasies don't exist.

So can we say that mutation also doesn't exist?

Hold on, that's not true.

Mutation does exist.

But Mutation doesn't lead to such drastic

changes in us humans.

We can't have mutations

that give us extraordinary powers.

Rather, most mutations give rise to concern.

They result in undesirable changes from time to time.

In these upcoming videos,

we shall majorly talk about mutation,

what causes them and their types in general.

Let's begin with the definition first.

Mutation in simple words is defined as sudden and

abrupt changes to the genetic material of organisms.

Now, let's break this down to understand it better.

Sudden and abrupt changes, means a few changes

that occur suddenly and are mostly unexpected.

These changes are usually random

and disruptive to the normal functioning of the cell.

And where do these changes occur?

They occur in the genetic material of the organism.

That means in the DNA. And as a result,

either the gene or the complete chromosome

gets affected.

So mutations are spontaneous changes that

affect the DNA

or the genes or sometimes the complete chromosomes.

Now since these are the areas that get altered

mutations are categorised on the basis of them.

The two major types of mutation are genetic mutation

and Chromosomal mutation.

Let us see these types.

Let's consider this small section of the DNA.

Let's say that this part changes into another.

Another possibility is that either this base gets deleted

or an extra gets inserted.

In either case,

the outcome is that the sequence of the gene will change.

Technically, the reading frame will change.

The ribosome assembly including the tRNA

reads the genetic code in triplets.

These triplets are called codons.

Now if there's any change in a single nucleotide,

then the entire codon will change.

Thus, the reading frame will change.

And what will this result to?

That's right... the altered gene

will give rise to a different protein than the usual one.

And there are chances that this defective protein

turns out to be a harmful one.

So any change in the DNA or in the genes

can cause a shift in the reading frame.

As a result, an altered protein is produced.

This was the first type.

Now, let's zoom out of the DNA structure.

What do we see?

Yes, we see a typical chromosomal structure.

Now tell me,

what will happen if there are any alterations

in its structure?

And what if the total number of chromosomes get

altered?

Let's find the answer in the next part.

This is a representative karyotype of a human.

By now we know what a karyotype is.

Can you try to give me some conclusions of it?

You may say that it looks perfectly normal.

But let me spot a flaw for you. Do you notice this set?

This is the 21st chromosome set.

Instead of having a normal pair of chromosomes,

here, we find a triplet.

Now you may say that it may be good for the individual

as it has an extra chromosome.

But that's not the case.

Any change in the number of chromosomes

creates a lot of defects

in the normal functioning of the body.

On this note, let's understand chromosomal mutations.

As the name says,

Chromosomal mutation means

the mutation of chromosomes.

And how exactly does it get mutated?

It can happen in two ways.

One way is where the structure

of the chromosomes gets disrupted.

The other is where the number of chromosomes are

different than the usual in the organism.

Let's have a look at each type.

This is the structure of a typical chromosome.

Now imagine, this small part gets physically removed.

This would result the chromosome in getting smaller

as its segment is lost.

This also means

that if the segment had some important genes

then they will also get lost which can result in severe abnormalities.

Such type of a mutation is called deletion.

This is where the part of the chromosome gets deleted.

Now imagine, this part of the chromosome gets duplicated.

As a result , the chromosome's length increases.

Needless to say, this will also result in some of the other abnormality in the individual.

This type of mutation is called duplication.

Now comes the next type.

These are two different gene segments.

Imagine they get flipped. Thus the chromosome will appear like this.

This is called inversion.

Do you think this type of mutation is harmful?

It may or may not be harmful

depending on which genes get flipped.

Now, let's take one more chromosome.

Imagine a part of this chromosome gets removed

and gets inserted in this chromosome.

What will be the result?

That's correct.

Both the chromosomes will change drastically.

This type of mutation is called as insertion.

And now comes the last type.

Instead of a segment getting

inserted to another chromosome,

let's imagine a situation,

where a segment from each chromosome

gets interexchanged.

So this segment will get into this chromosome

and vice versa.

This kind of mutation also results in abnormalities

as both the chromosomes get altered completely.

Any idea what this type will be named as?

Well, this type of mutation is called translocation.

All these mutations

resulting in the disruption of

normal chromosomal structures

are broadly capped under a single heading.

They are categorised as chromosomal aberrations.

Now this was about the mutations that involve

changes in the structure of the chromosomes.

What about the mutations that involve

a change in the number of chromosomes?

Let's understand that in the next part.

This is a normal chromosome,

while this is a disrupted one.

When the structure of a chromosome gets altered,

it's called chromosomal aberration.

We have seen this.

Now, let's move on to the second type.

It's the mutation that involves

a change in the number of chromosomes.

It's called as a Aneuploidy.

In literal terms a Aneuploidy means,

the presence of an abnormal number of chromosomes

in a cell.

So the carrier type of a person with trisomy 21

is an example of Aneuploidy.

The presence of

one additional chromosome in the 21st set

gives rise to a total of 47 chromosomes in a person.

So instead of a normal 46 chromosomes

this person has an additional chromosome.

To be precise an additional autosome.

This case of a Aneuploidy is called trisomy 21.

This is because

there are three chromosomes

instead of two in the 21st set.

The problem of Trisomy 21

leads to a condition called Down syndrome.

We will get into the details of these disorders

in our higher grades.

But for now,

let's focus on understanding the

chromosomal mutations.

This Aneuploidy involved an autosome.

Now tell me,

what if the number of sex chromosome alters?

So instead of XY what if an individual has XXY?

Is that even possible in the first place?

Well yes,

there can be individuals with an

additional X chromosome.

This condition is called Klinefelter syndrome.

Such individuals exhibit both

masculine as well as feminine characteristics.

Now in the case of females, imagine that

instead of addition

there is a deletion of an X chromosome.

This would mean XO.

So this individual will have only one X chromosome.

This condition is called Turner syndrome.

There are a few developmental abnormalities

in such scenarios.

These individuals have a total of 45 chromosomes only.

These were a few examples of Aneuploidy that involves

autosomes and sex chromosomes.

Now before we conclude, tell me one thing.

What causes these mutations?

How can DNA or genes or

entire chromosomes get altered?

There are several factors named mutagens

which lead to alterations.

Some of them include radiation,

chemicals and even certain consumable items.

To summarize, we have two major types of mutations.

One which involves alterations in the DNA or the genes.

These mutations result a shift in the reading frame

resulting in defective protein synthesis.

Alterations in the structure results in

chromosomal aberrations.

They can be categorised as deletion,

duplication, inversion, insertion and translocation.

The other is where

the number of chromosomes are different

than the usual in the organism.

It's called Aneuploidy.

The changes can be in the autosomes

as well as the sex chromosomes.

Here, the total number of chromosomes in a cell

are different from the usual.

This was about mutations in general.

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