chromosomes

• Chromosomes are thread-like structures located inside the nucleus of animal and plant cells.
• Each chromosome is made of protein and a single molecule of deoxyribonucleic acid (DNA).
• DNA contains the specific instructions that make each type of living creature unique.
• The X Chromosome is the largest chromosome and is found in females.
• The Y Chromosome is the smallest chromosome and is found in males.
• Chromosome Abnormalities are conditions where there are changes to the number or structure of chromosomes.
• The term chromosome comes from the Greek words for color (chroma) and body (soma) because chromosomes are cell structures, or bodies, that are strongly stained by some colorful dyes used in research.
• The unique structure of chromosomes keeps DNA tightly wrapped around spool-like proteins, called histones.
• Without such packaging, DNA molecules would be too long to fit inside cells.
• For an organism to grow and function properly, cells must constantly divide to produce new cells to replace old, worn-out cells.
• During cell division, it is essential that DNA remains intact and evenly distributed among cells.
• Chromosomes are a key part of the process that ensures DNA is accurately copied and distributed in the vast majority of cell divisions.
• Changes in the number or structure of chromosomes in new cells may lead to serious problems.
• In humans, one type of leukemia and some other cancers are caused by defective chromosomes made up of joined pieces of broken chromosomes.
• It is also crucial that reproductive cells, such as eggs and sperm, contain the right number of chromosomes and that those chromosomes have the correct structure.
• If not, the resulting offspring may fail to develop properly.
• People with Down syndrome have three copies of chromosome 21, instead of the two copies found in other people.
• Chromosomes vary in number and shape among living things.
• Most bacteria have one or two circular chromosomes.
• Humans, along with other animals and plants, have linear chromosomes that are arranged in pairs within the nucleus of the cell.
• Males with more than one X chromosome have Klinefelter syndrome, which is a condition characterized by tall stature and, often, impaired fertility.
• They are very short, usually do not undergo puberty and some may have kidney or heart problems.
• Females have two X chromosomes in their cells, while males have one X and one Y chromosome.
• Children inherit some of their traits from their mother and others from their father.
• Another syndrome caused by imbalance in the number of sex chromosomes is Turner syndrome.
• Males and females differ in a pair of chromosomes known as the sex chromosomes.
• Scientists first observed chromosomes in the late 1800s, but the nature and function of these cell structures were unclear.
• Inheriting too many or not enough copies of sex chromosomes can lead to serious problems.
• The small circular chromosome found in mitochondria is inherited from the mother and is always inherited from the female parent.
• In humans, a few conditions, including some forms of hearing impairment and diabetes, have been associated with DNA found in the mitochondria.
• Females who have extra copies of the X chromosome are usually taller than average and some have mental disability.
• Humans have 23 pairs of chromosomes, for a total of 46 chromosomes.
• Women with Turner have one X chromosome only.
• In humans and most other complex organisms, one copy of each chromosome is inherited from the female parent and the other from the male parent.
• Thomas Hunt Morgan made the link between chromosomes and inherited traits by demonstrating that the X chromosome is related to gender and eye color in fruit flies.
• A fruit fly has four pairs of chromosomes, while a rice plant has 12 and a dog, 39.
• Each species of plants and animals has a set number of chromosomes.
• The only human cells that do not contain pairs of chromosomes are reproductive cells, or gametes, which carry just one copy of each chromosome.
• When two reproductive cells unite, they become a single cell that contains two copies of each chromosome.
• This cell then divides and its successors divide numerous times, eventually producing a mature individual with a full set of paired chromosomes in virtually all of its cells.