The cell wall is the tough‚ flexible but sometimes fairly rigid layer that surrounds some types of cells. It is located outside the cell membrane and provides these cells with structural support and protection. Just as the wall of the factory is for the factory. The wall also is the structure and strength. The cell membrane that separates the interior of all cells from the outside The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances
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A Survey of Eukaryotic Cells and Microorganisms HISTORY OF EUKARYOTES: 1. Evidence indicates that the first Eukaryotic cells first appeared on the earth approximately 2 billion years ago. Fossilized cells appear in shale sediments from China‚ Russia and Australia the date from 850-950 million years ago. 2. Biologists have discovered evidence to suggest that the eukaryotic cell evolved from prokaryotic organisms by a process of intracellular symbiosis. 3. Some of the organelles that
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Differentiating Between Prokaryotic and Eukaryotic Cells‚ Distinguish Among Plant‚ Animal‚ and Protist Cells‚ and Identifying the Organelles that are Evident in Them Introduction There are two different types of cells‚ prokaryotes and eukaryotes. Prokaryotes‚ such as bacteria‚ lack a nuclear membrane and other membrane bound organelles. Their genetic material consists of a single molecule of singular DNA. Eukaryotes‚ such as plant and animal cells‚ have a nuclear membrane and other membrane
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UNIT 1 BIOLOGY PROKARYOTIC CELLS EUKARYOTIC CELLS Without a defined nucleus. No nuclear envelope (the genetic material is not separated from the rest of the cell) Clearly differentiated nucleus with a nuclear envelope‚ which protects the genetic material. Without organelles (only ribosomes) Presence of membrane-bound organelles Smaller in size Types: plant and animal ANIMAL CELLS PLANT CELLS Cell walls absent Cell walls made of cellulose Chloroplast never present Chloroplast
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included) (not insisting on generic capitals) any two for 1 mark Animals‚ Protoctists‚ Prokaryotes;; (accept Latin equivalents) any two for one mark‚ all three for both that (they are) fertile; 1 (b) 2 1 (c) Total 4 __________________________________________________________________________________ klm Question 3 (a) GCE: Biology B – BYB4 June 2002 Mark across whole of two parts in (a) to credit the following possible points (structure) Distant object Close object Cornea suspensory
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Prokaryotic vs. Eukaryotic cells have similarities and differences. They can be found in different places. They have different ways of functioning and can be made up of different things. But just how they are very different they have some similarities that can in a way unite them and make them a part of the of a cell family. With their differences and similarities‚ they’re just here for one solemnly purpose‚ to serve whatever type of organism they are present in. A Prokaryotic cell does not have
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CELL REPRODUCTION DNA is the cell’s genetic material; chromosomes are the carriers of this genetic information. In proka-ryotes‚ the chromosome is a single circle of DNA. In eukaryotes‚ each chromosome is a complex of DNA and histone proteins found in the nucleus. BINARY FISSION Prokaryotic cells reproduce via binary fission. In this process‚ DNA Is replicated‚ and the cell splits in two roughly equal parts‚ each with a copy of the cell’s DNA. EUKARYOTIC CELL CYCLE Eukaryotic cells reproduce
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Organelle: Plasma membrane Structure: The plasma membrane has many proteins inbedded in it and is made up of two layers of phosphilipids. The structure is phospho liquid bilayer and it froms a barrier between two aqueous compartments. Function: The plasma membrane in eukaryotic cells is responsible for controlling what goes in and out of the cell. Series of proteins stuck in the membrane help the cell to communicate with the surrounding environment it’s in. This communication can include sending
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or double stranded RNA or DNA. It can also be linear or circular. Only in viruses can the genetic material be RNA. For example in HIV the virus can infect a host cell and use an enzyme transciptase to sequence a DNA molecule which is then incorporated into the genome of the cell to produce viral proteins or genetic material. Like eukaryotic chromosomes bacterial chromosomes are double stranded DNA and can be associated with proteins. These proteins are histones HU and H1 which are positively charged
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Gene expression is the ability of a gene to produce a biologically active protein. This process is regulated by the cells of an organism‚ it is very important to the survival of organisms at all levels. This is much more complex in eukaryotes than in prokaryotes. A major difference is the presence in eukaryotes of a nuclear membrane‚ which prevents the simultaneous transcription and translation that occurs in prokaryotes. Initiation of protein transcription is started by RNA polymerase. The activity
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