WHAT IS CHROMOSOME- AN OVERVIEW
DEFINITION
A chromosome is bundles of tightly coiled DNA molecule (genetic material) of an organism, located within the nucleus of almost every cell in our body. Chromosomes are the carrier of genes.
In plant and animal cells, DNA is tightly packaged into thread-like structures called chromosomes, Whereas, DNA floats freely around the cell in bacteria.
- Chromatids- One of the two identical parts of the chromosome.
- Centromere- The point where the two chromatids touch.
- Short arm (p)
- Long arm (q), Centromere holding it all together at the center. while, Telomere refers to section of DNA found at the ends of chromosome, protects the end of chromosomes by forming a cap.
Read also…TYPES OF CHROMOSOME-STRUCTURE&DEFINITION
IMPORTANT FACTS
- In all the species, there are a certain number of chromosomes. For example, Humans have 23 pairs of chromosomes (22 pairs of autosomes and one pair of sex chromosomes), giving a total of 46 per cell.
- German scientists Schleiden, Virchow and Bütschli were among the first scientists who recognized the structures now familiar as chromosomes.
- The word chromosomecomes from the Greek “chroma” means “colour”and “soma” means body” describing their strong staining by particular color substance.
- The term was coined by the German scientist von Waldeyer-Hartz, referring to the term chromatin, which was itself introduced by Walther Flemming, who discovered cell division.
- Chromosomes are normally visible under a light microscope only when the cell is undergoing the metaphase of cell division (where all chromosomes are aligned in the center of the cell in their condensed form). So this stage is considered best for the study of chromosome.
- In prokaryotes, there is a single chromosome which is circular in shape and is called genophore (without histone), whereas in eukaryotes, chromosomes are rod shaped.
Read more…
CHROMOSOMAL THEORY OF INHERITANCE
DIFFERENCE BETWEEN GENE AND ALLELE
MENDEL’S LAW OF INHERITANCE
LINKAGE AND CROSSING OVER-AN OVERVIEW
HOMOLOGOUS CHROMOSOMES-AN OVERVIEW & FUNCTION
SYNAPSIS MEANING- PROCESS & FUNCTION
CELL STRUCTURE AND FUNCTION
MITOSIS & MEIOSIS- CELL DIVISION
DIFFERENCE BETWEEN PROKARYOTIC AND EUKARYOTIC CELLS
DIFFERENCE BETWEEN PLANT CELL AND ANIMAL CELL