This lesson will discuss the structure of chromosomes by looking at:
When a cell is getting ready to divide, genetic information in the form of DNA will condense into structures called a chromosomes. This is how genetic information is passed from parent to offspring. Homologous chromosomes are chromosomes that contain the same set of genes and are the same length and shape. One is from the mother of the other is from the father.
There are two types of chromosomes within our body:
The chromosome number is the number of chromosomes in a species cells. Each species has its own number of chromosomes.
For humans, the chromosome number is 46. This means that we have 46 chromosomes, or 23 pairs, in our cells. Of those 46 chromosomes, most of them are autosomes. Only two of those chromosomes are sex chromosomes. A mouse has a total of 40 chromosomes.
Chromosomes are only visible in this form when the cell is preparing to divide. The rest of the time, our genetic information can be found in the form of chromatin, which has a balled-up thread-like form, and is found within the cell's nucleus.
DNA is said to be in the structure of a double helix, or ladder that has been twisted. The outside part of the ladder is made up of a phosphate-sugar backbone, that is phosphate and deoxyribose sugar molecules.
The rungs of the ladder are made up of four nitrogenous bases:
These nitrogenous bases compose two base pairs. Adenine always pairs with thymine and cytosine always pairs with guanine.
Chromosomes the form DNA takes when it is a cells is getting ready to divide, and are only visible during this time. Homologous chromosomes are chromosomes that contain the same set of genes. There are two types of chromosomes within our body: autosomes and sex chromosomes. The chromosome number is the number of chromosomes a species has in it’s cells. DNA, the genetic information that makes up chromosomes, come in the form of a double helix. It is made up of phosphate and deoxyribose sugar molecules as the backbone of the structure with adenine/thymine or cytosine/guanine base pairs in between.
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Source: SOURCE: THIS WORK IS ADAPTED FROM SOPHIA AUTHOR AMANDA SODERLIND
A condensed DNA structure.
All of the chromosomes in the body except for sex chromosomes.
Chromosomes associated with sex and gender.
Chromosomes that are paired together that are the same length and shape and contain the same sets of genes. Typically, one of the homologous pair is contributed by each parent.