CH-2. STRUCTURE OF CHROMOSOMES CELL CYCLE AND CELL DIVISION Flashcards
What is the nucleus of a cell mainly composed of?
The nucleus of a cell is mainly composed of DNA which is organized into discrete units called chromosomes.
(Source: Text)
Who first studied chromosomes in animals?
Chromosomes in animals were first studied by a German Scientist, Walther Flemming in 1882.
(Source: Text)
What two substances form the chromatin material?
The chromatin material is formed of DNA (deoxyribonucleic acid) about 40% and Histones (a particular type of protein) about 60%.
(Source: Text)
What are genes?
Genes are specific sequences of nucleotides on a chromosome that encode particular proteins responsible for specific characteristics of an organism.
(Source: Text)
Why do new cells need to be produced?
New cells need to be produced for growth, replacement, repair, and reproduction.
(Source: Text)
What are genes?
Genes are specific sequences of nucleotides on a chromosome, that encode particular proteins which are expressed in the form of some particular feature of the body. They are the units of heredity which are transferred from parents to offspring and are responsible for some specific characteristics of the offspring.
Example sentence: The gene for eye color determines whether an individual will have blue, brown, or green eyes.
Why do new cells need to be produced?
New cells need to be produced for growth, replacement, repair, and reproduction.
Example information: Most organisms begin their life as a single cell and undergo cell division to form tissues and organs for growth.
How are new cells produced for replacement?
Cells are replaced through division of parent cells in the bone marrow. For example, 2 million red blood cells in the body are destroyed every second and replaced by new cells.
Additional information: In plants, old leaves fall off and new ones grow out as part of the replacement process.
How are new cells produced for repair?
Cells divide to cover up gaps and join broken ends in case of injuries like cuts in the skin or fractures in the bone.
Additional information: Repair of tissues in the body involves cell division to heal injuries.
How is reproduction related to cell division?
Reproduction involves the activity of dividing cells. In higher forms like humans, special cells in reproductive organs undergo a special kind of cell division (meiosis) to produce sperms and eggs.
Additional information: Sperms and eggs receive half the number of chromosomes of their parent cells, which is significant in the process of reproduction.
