How are DNA, chromosomes, genes, and alleles related? | Socratic
DNA is the chemical that chromosomes and genes are made of. DNA itself is made up of four simple chemical units that are abbreviated as A. Chromosomes carry genetic information in a molecule called DNA. that when a cell divides each new cell produced has the same genetic information. DNA. Marketing Director: Rich Pirozzi. Production Experimental Proof of the Genetic Function of DNA. 3. Genetic Connection: This Land Is Your Land, This Land Is My Land Linkage and Recombination of Genes in a Chromosome.
These are long strands of DNAwhich are made up of many genes. A gene is a small section of DNA on a chromosome, that codes for a particular sequence of amino acidsto make a specific protein. It is the unit of heredityand may be copied and passed on to the next generation. DNA is a large and complex polymer, which is made up of two strands forming a double helix.
DNA determines the characteristics of a living organism. With the exception of identical twins, each person's DNA is unique. The order of these letters makes up an organism's genetic code.
An organism's genome is one copy of all of their DNA. With the exception of identical twins, no two people's genomes are the same.
Some characteristics are controlled by a single gene, such as fur in animals and red-green colour blindness in humans. Each gene might have different forms, and these are called alleles. The diagram shows the relationship between the cell, its nucleus, chromosomes in the nucleus, and genes. Chromosomes are made from genes which are made from the DNA double helix Chromosomes are found in the nucleus of a body cell in pairs.
One chromosome of each pair is inherited from the mother and the other one is inherited from the father. The chromosome in each pair carries the same gene in the same location. These genes could be the same, or different versions: There are two specific events that contribute to everyone being so different. Let's see what they are.
How are DNA, chromosomes, genes, and alleles related?
As you know, our DNA helps determine what we look like, how we act, what diseases we might get and a whole lot more. And ultimately what DNA we get is determined from the egg and sperm that combined to make us.
So to understand why siblings are so different from each other, we need to figure out how sperm and eggs get their DNA. First off, as you probably know, all of our DNA is packaged and stored along with some proteins in our cells as chromosomes click here to learn more about chromosomes.
Most of our cells have 23 pairs of chromosomes for a total of One set of 23 comes from mom and the other 23 from dad. The egg and sperm cells are an exception--they have only 23 chromosomes each. A sperm from the man combines with a woman's egg in her womb to make a zygote. The zygote ends up with a total of 46 chromosomes and can now grow into a baby.
Sperm and eggs end up with the DNA they get through a process called meiosis. When cells normally make new copies of themselves, each of the new cells ends up with 46 chromosomes at least for humans.
BBC Bitesize - GCSE Biology (Single Science) - Genetic inheritance - Edexcel - Revision 4
However, in meiosis, each new cell ends up with How are the 23 chosen? For each of the 23 pairs, one of the two goes into the sperm or the egg. The choice of which of the pair of each chromosomes is totally random. So if nothing else were involved what would be the chances of having exactly the same kids?
As you'll see, not very likely at all. To figure this out, we need to look at statistics sorry about that! Let's name the twin sisters Sally and Jane.
And their common partner, Bob.
- Cell division - AQA
We'll also figure out the chances of Bob making the exact same sperm. And finally we'll figure out how likely it is that two of the exact same sperm from Bob will fertilize the exact same eggs from Sally and Jane. To make this daunting task simpler, let's imagine that people have 1 giant chromosome.
So Sally, Jane and Bob each have two copies of this single chromosome. To keep track of whose chromosome is whose, we'll give them different names. Sally's and Jane's pair will be A and a remember, they are identical twins, so they both have the exact same DNAand Bob's will be B and b.
OK, let the fun begin! The same is true for Jane. So what are all the possibilities of sperm and egg meeting in this example? So the chances of Sally and Jane having the same baby are 1 in 4. Now let's try 2 chromosomes. Jane and Sally will have two copies of these 2 chromosomes which we will name as A, a, C, and c and Bob's as B, b, D, and d.