What is an Allele? Quick Definition

Summary

In this 'Quick Definitions' video, John Perry explains the concept of an allele in genetics. An allele is an alternative version of a gene, which can determine traits like eye color in organisms. For instance, a frog might have a 'yellow allele' for its eye color gene, while another frog could have a 'red allele'. Alleles can arise through mutations and compete within a population. If an allele offers a survival advantage, it can become dominant, leading to the fixation of that trait within the population. The video simplifies complex genetic concepts, making them accessible to viewers.

Takeaways

• 🧬 Genes are stretches of DNA that code for specific proteins or serve as templates for functional RNA chains.
• 👁️ An allele is an alternative version of a gene, such as one that codes for a different eye color in a frog species.
• 🐸 Multiple genes and environmental factors often interact to determine an organism's traits, like eye color.
• 🧬 Most animals have two copies of their DNA, meaning they can have two different alleles for a gene.
• 🌱 Most alleles do not affect an organism's observable traits.
• 🔄 New alleles are created through mutations, which can introduce variations into a population's gene pool.
• 🦎 If a new allele provides a survival advantage, it may become more common over generations, potentially leading to the fixation of that allele in the population.
• 🏆 When an allele becomes dominant in a population, it can lead to the extinction of other alleles.
• 👕 The video is from the 'Stated Clearly' series, which provides clear explanations of scientific concepts.

Q & A

What is a gene in genetics?

A gene is a stretch of DNA that codes for something, either specific proteins or functional chains of RNA, which in turn produce traits in organisms.

How do genes relate to an organism's traits?

Genes code for proteins and RNA chains that produce traits, such as eye color and bone length, so genes indirectly code for an organism's traits.

What is an allele?

An allele is an alternative version of a specific gene, which can result in different expressions of a trait, like different eye colors in the example of the frog.

Why are alleles important in genetics?

Alleles are important because they provide variation within a species, which can lead to different traits and potentially influence survival and reproduction.

How do new alleles come into existence?

New alleles come into existence via mutations, which are changes in the DNA sequence that can create new versions of genes.

Can an organism have more than one allele for a gene?

Yes, most animals have two copies of their DNA, meaning a single animal can have two different alleles for any given gene in its genome.

What is the term for when an allele becomes dominant in a population?

When an allele dominates an entire population, replacing other versions, this is called fixation.

How can an allele provide a survival advantage?

An allele might provide a survival advantage if it helps an organism better adapt to its environment, such as blending in to avoid predators.

What happens to an allele that does not provide a survival advantage?

Alleles that do not provide a survival advantage may be outcompeted by other alleles and could eventually become extinct within a population.

Are all alleles observable in an organism's traits?

No, most alleles do not have any observable effect on an organism's traits, and their influence may be subtle or require specific environmental conditions to manifest.

How does the presence of multiple genes and environmental factors affect an organism's traits?

Multiple genes and environmental factors can interact in complex ways to determine an organism's traits, making the relationship between genes and traits not always straightforward.

Outlines

00:00

🧬 Understanding Alleles in Genetics

The paragraph introduces the concept of an allele in genetics. It explains that a gene is a segment of DNA that codes for proteins or serves as a template for RNA, which in turn affects traits in organisms. An allele is described as an alternative version of a gene. Using the example of a frog's eye color gene, the paragraph illustrates how different alleles (yellow and red eye color alleles) can exist within a species. It also touches on the idea that most animals have two copies of their DNA, allowing for the possibility of having two different alleles for a gene. The paragraph concludes with the concept of allele competition and fixation, where an allele can become dominant in a population, leading to the extinction of other alleles.

Keywords

💡Gene

A gene is a segment of DNA that contains the instructions for making proteins or functional RNA molecules. In the context of the video, genes are the fundamental units of heredity that determine traits in organisms. The script uses the example of an 'eye color gene' to illustrate how genes code for specific traits, such as the color of a frog's eyes.

💡Allele

An allele is a variant form of a gene. The video script explains that alleles are alternative versions of a gene that can result in different expressions of a trait. For instance, the script mentions 'yellow allele' and 'red allele' of the eye color gene, which determine whether a frog has yellow or red eyes.

💡DNA

DNA, or deoxyribonucleic acid, is the molecule that carries genetic instructions for the development, functioning, and reproduction of all known living organisms. The video script refers to DNA as the long stretch of molecules that genes are part of, and it codes for proteins or RNA.

💡Proteins

Proteins are large biomolecules that play a crucial role in the structure, function, and regulation of an organism's cells, tissues, and organs. The video script mentions that genes code for specific proteins, which are essential for the traits of an organism.

💡RNA

RNA, or ribonucleic acid, is a molecule similar to DNA that plays a role in various biological functions, including the coding, decoding, regulation, and expression of genes. The script explains that genes can act as templates for functional chains of RNA.

💡Traits

Traits are the characteristics or qualities of an organism that result from the interaction of its genotype with the environment. The video script uses 'eye color' and 'bone length' as examples of traits that are determined by genes.

💡Mutations

Mutations are changes in the DNA sequence that can result in the creation of new alleles. The video script explains that new alleles come into existence via mutations, which can potentially give a survival advantage to the organism carrying them.

💡Genome

A genome is the complete set of genetic information for a particular organism. The script mentions that most animals have two copies of their DNA, meaning they have two versions of each gene in their genome, which can be two different alleles.

💡Environmental Factors

Environmental factors are external conditions that can influence an organism's traits. The script notes that in real life, multiple genes and environmental factors work together to determine an animal's traits, such as eye color.

💡Fixation

Fixation is the process by which an allele becomes the only version of a gene in a population. The video script uses the example of the 'yellow allele' potentially dominating the population and causing the extinction of the 'red allele' to illustrate fixation.

💡Heredity

Heredity is the passing on of genetic information from one generation to the next. The video script touches on the concept of heredity by discussing how genes and alleles are inherited and can determine the traits of offspring.

Highlights

A gene is a stretch of DNA that codes for something, usually proteins or functional RNA chains.

Genes indirectly code for traits like eye color and bone length.

An allele is an alternative version of a specific gene.

Alleles can determine observable traits such as eye color in organisms.

The example of a frog with different eye color alleles illustrates the concept of alleles.

In reality, multiple genes and environmental factors contribute to an organism's traits.

Most animals have two copies of DNA, meaning they can have two different alleles for a gene.

Many alleles have no effect on an organism's observable traits.

New alleles arise through mutations.

An allele can provide a survival advantage, leading to its dominance in a population.

The yellow eye allele in frogs might offer better camouflage, enhancing survival.

Over generations, an advantageous allele can outcompete others, leading to fixation.

Fixation occurs when an allele dominates an entire population.

The key takeaway is understanding that an allele is an alternative version of a gene.

John Perry provides a clear definition of an allele in genetics.

Stated Clearly offers new t-shirts for sale, showcasing their brand's presence.

Transcripts

hello you are watching quick definitions

stated clearly what is an allele in

genetics as we've learned in earlier

videos a gene is a stretch of DNA

usually a long stretch of DNA that codes

for something what exactly do genes code

for technically they either code for

specific proteins or they act as

templates for functional chains of RNA

but because proteins and chains of RNA

go on to produce traits things like eye

color and bone length we can say that in

organisms genes in a roundabout way code

foreign organisms traits an allele is an

alternative version of a specific gene

if that sounds confusing that's okay it

should become clear once we see a

simplified example let's say there is a

gene in a species of frog that codes for

the frog's eye color we will call it the

eye color gene no need to get too

creative here this frog has a version of

the eye color gene an allele of the eye

color gene that codes for yellow eyes he

has the yellow allele of the eye color

gene his buddy here has a different

allele a different version of the eye

color gene he has the red allele of the

eye color gene now this hypothetical

example is overly simplistic in real

life there are multiple different genes

and sometimes environmental factors that

all play together to determine an

animal's eye color also most animals

have two copies of their own DNA meaning

that a single animal can actually have

two different alleles or two different

versions of any given gene in its own

genome furthermore most alleles don't

have any actual effect at all on a

creatures observable traits but don't

worry about any of these technicalities

for now the important thing to

understand is this an allele is an

alternative version of a specific gene

that's it new alleles new versions of

old genes come into existence via

mutations once a new allele exists it is

forced to compete with other alleles in

the population for example when the

yelloweye allele happened to emerge

within our hypothetical frog species it

might have given its host a survival

advantage because its host could better

blend into its environment and hide from

predators because of this over many many

generations the yellow allele could

dominate the population completely out

competing the red allele causing the red

alleles extinction when an allele

dominates an entire population we call

this fixation so there you have it an

allele as an alternative version of a

specific gene I'm John Perry and that

was a quick definition of an allele

stated clearly

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