Unit 5 Reading.txt - Introduction When a cell divides, one...

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IntroductionWhen a cell divides, one of its main jobs is to make sure that each of the twonew cells gets a full, perfect copy of genetic material. Mistakes duringcopying, or unequal division of the genetic material between cells, can lead tocells that are unhealthy or dysfunctional (and may lead to diseases such ascancer).But what exactly is this genetic material, and how does it behave over thecourse of a cell division?DNA and genomesDNA (deoxyribonucleic acid) is the genetic material of living organisms. Inhumans, DNA is found in almost all the cells of the body and provides theinstructions they need to grow, function, and respond to their environment.When a cell in the body divides, it will pass on a copy of its DNA to each ofits daughter cells. DNA is also passed on at the level of organisms, with theDNA in sperm and egg cells combining to form a new organism that has geneticmaterial from both its parents.Physically speaking, DNA is a long string of paired chemical units (nucleotides)that come in four different types, abbreviated A, T, C, and G, and it carriesinformation organized into units called genes. Genes typically provideinstructions for making proteins, which give cells and organisms theirfunctional characteristics.Image of a eukaryotic cell, showing the nuclear DNA (in the nucleus), themitochondrial DNA (in the mitochondrial matrix), and the chloroplast DNA (in thestroma of the chloroplast).Image of a eukaryotic cell, showing the nuclear DNA (in the nucleus), themitochondrial DNA (in the mitochondrial matrix), and the chloroplast DNA (in thestroma of the chloroplast).In eukaryotes such as plants and animals, the majority of DNA is found in thenucleus and is called nuclear DNA. Mitochondria, organelles that harvest energyfor the cell, contain their own mitochondrial DNA, and chloroplasts, organellesthat carry out photosynthesis in plant cells, also have chloroplast DNA. Theamounts of DNA found in mitochondria and chloroplasts are much smaller than theamount found in the nucleus. In bacteria, most of the DNA is found in a centralregion of the cell called the nucleoid, which functions similarly to a nucleusbut is not surrounded by a membrane.A cell’s set of DNA is called its genome. Since all of the cells in an organism(with a few exceptions) contain the same DNA, you can also say that an organismhas its own genome, and since the members of a species typically have similargenomes, you can also describe the genome of a species. In general, when people

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Term
Spring
Professor
Eloiza Davi
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