How are DNA, chromosomes, genes, and alleles related? | Socratic
A specific position along a chromosome is called a locus and each gene occupies a specific locus; each locus will have an allelic form. Alleles are different forms of same gene. Genes are linearly arranged on chromosomes. Chromosomes contain genetic material of cell i.e. DNA. Gene is a segment of DNA that controls the expression of a particular trait i.e. it codes for the protei (for e.g. gene for height can have 2 alleles- tall and dwarf) . What is the relationship among an allele, gene, trait, and character?.
So each of these Genes they can code for a type of protein or even a functional RNA. That's what a Gene is. Now what about an Allele?
- How are DNA, chromosomes, genes, and alleles related?
- Alleles and genes
- Genetic inheritance
When the Allele is a specific variation of the Gene. So for example, let's say that you look at the at the same stretch of DNA. We're both human beings and we have for the most part very similar DNA. So this is-- Actually let me straighten it out. Now we're both human beings and most of our genetic material is fairly similar, but we might have variations in how this Gene is coded. For example, you might have or I might have a let's say, I have a an Adenine right there, but right at that exact spot you might have a different base.
3.2: Relationships Between Genes, Genotypes and Phenotypes
You might have a, I don't know, you might have a, you might have-- Actually let me just-- You might have a Thymine right over there. So it's encoding for a protein, or you know, functional RNA that's playing the same role. Maybe it has a role in the immune system or role in your skin color or role in how your brain develops, but there's a variation.
There's a variation in how it's coded.
Now some of these variations which could arise through mutations, it might not have any impact in the function of the eventual protein that gets constructed. You might just have a different Amino Acid sometimes.
In fact, you might not even have a different Amino Acid because many times you have two Codons coding for the same Amino Acid, but even in a case you might have one different Amino Acid in a protein that has 4, Amino Acids it doesn't change how that protein acts or how it functions.
Or sometimes it might. It might change how that protein functions.
It might change how that protein regulates other things and whoever knows whatever else, and so you could imagine that you have Genes. This Gene right over here. Maybe it has a role in eye color, and because of this variation or because of other variations that show up in both cases they code for the protein that say regulates eye color, or regulates the amount of pigment you have, but because your variation right over here might lead or help lead-- And these things are very complex, it's very seldom do you have a gene just for this, but this might make you-- especially if you have a Gene like this from both of your parents, maybe this one would go for blue eyes.
Blue eyes, it somehow helps produce blue eyes.
What’s the Difference Between a Gene and an Allele?
While this, while mine somehow helps produce brown eyes. And obviously I'd want to think about which variant of this Gene that I get from my mother, and the variant of this Gene that I get from my father. We all have two copies in our regular somatic cells and our body cells.
We have except for-- If we think about the, xx and the xy chromosomes, the sex determining chromosomes, on all the other chromosomes we have two copies of the same Genes.
We just have two-- It's just they're different variants. One variant from your mother and one variant from your father, or you could say that they are different Alleles. So Alleles are just different variants. So these are two different Alleles.
BBC Bitesize - GCSE Biology (Single Science) - Genetic inheritance - Edexcel - Revision 4
They code, they're the same Gene. They're the Gene that somehow deals with eye color, but they're different variations for that Gene.Genes vs Alleles
So the Gene you're speaking generally to that region of DNA. These genes could be the same, or different versions: Alleles are different versions of the same gene.
For example, the gene for eye colour has an allele for blue eye colour and an allele for brown eye colour. For any gene, a person may have the same two alleles, known as homozygous or two different ones, known as heterozygous. A dominant allele is always expressed, even if one copy is present. Dominant alleles are represented by a capital letter, for example you could use a B. The allele for brown eyes, B, is dominant.
You only need one copy of this allele to have brown eyes. Two copies will still give you brown eyes. A recessive allele is only expressed if the individual has two copies and does not have the dominant allele of that gene. Recessive alleles are represented by a lower case letter, for example, b. The allele for blue eyes, b, is recessive. You need two copies of this allele to have blue eyes. Homozygous alleles are both identical for the same characteristic, for example BB or bb.
Heterozygous alleles are both different for the same characteristic, for example Bb. Most characteristics are a result of multiple genes interacting, rather than a single gene.