Quiz & Worksheet - The Structure of Chromosomes | fabula-fantasia.info
The term DNA, chromosome, and chromatin are three terms which have very distinct meanings in biology. DNA stands for deoxyribonucleic acid and refers to a. Find information, videos, and activities about DNA, genes, chromosomes, the Sanger Institute; |; URL: fabula-fantasia.info Experiment with the forces involved and measure the relationship between the . What are chromosomes? Chromosomes are tiny structures inside cells made from DNA and protein. Within each chromosome are specific sections of DNA called genes. Each gene Take a ten question quiz about this page. Go here to test.
What do they look like? When a cell is not dividing called the interphase of the cell cyclethe chromosome is in its chromatin form.
In this form it is a long, very thin, strand. When the cell begins to divide, that strand replicates itself and winds up into shorter tubes. Before the split, the two tubes are pinched together at a point called the centromere. The shorter arms of the tubes are called the "p arms" and the longer arms are called the "q arms.
For example, one chromosome may contain information on eye color and height while another chromosome may determine blood type. Genes Within each chromosome are specific sections of DNA called genes.
Each gene contains the code or recipe to make a specific protein. These proteins determine how we grow and what traits we inherit from our parents. The gene is sometimes called a unit of heredity. Allele When we talk about a gene we are referring to a section of DNA.
One example of this would be the gene that determines the color of your hair.
When we talk about the specific sequence of a gene like the sequence that gives you black hair versus the sequence that gives you blonde hairthis is called an allele. So everyone has a gene that determines their hair color, only blondes have the allele that makes the hair blonde. Human Chromosomes As we mentioned above, humans have 23 different pairs of chromosomes for a total of 46 chromosomes.
We all get 23 chromosomes from our mother and 23 from our father. Chromosomes in Different Animals Different organisms have different numbers of chromosomes: The chromosomes of a eukaryotic cell consist primarily of DNA attached to a protein core.
They also contain RNA. The remainder of this article pertains to eukaryotic chromosomes. DNA wraps around proteins called histones to form units known as nucleosomes. These units condense into a chromatin fibre, which condenses further to form a chromosome. Every eukaryotic species has a characteristic number of chromosomes chromosome number. In species that reproduce asexually, the chromosome number is the same in all the cells of the organism.
Genes And Chromosomes
Among sexually reproducing organisms, the number of chromosomes in the body somatic cells is diploid 2n; a pair of each chromosometwice the haploid 1n number found in the sex cells, or gametes. The haploid number is produced during meiosis. During fertilizationtwo gametes combine to produce a zygotea single cell with a diploid set of chromosomes. Somatic cells reproduce by dividing, a process called mitosis. Between cell divisions the chromosomes exist in an uncoiled state, producing a diffuse mass of genetic material known as chromatin.
The uncoiling of chromosomes enables DNA synthesis to begin.
chromosome | Structure & Function | fabula-fantasia.info
During this phase, DNA duplicates itself in preparation for cell division. Following replication, the DNA condenses into chromosomes.Histones And DNA Packing
At this point, each chromosome actually consists of a set of duplicate chromatids that are held together by the centromere. The centromere is the point of attachment of the kinetochore, a protein structure that is connected to the spindle fibres part of a structure that pulls the chromatids to opposite ends of the cell. During the middle stage in cell division, the centromere duplicates, and the chromatid pair separates; each chromatid becomes a separate chromosome at this point.