Cell-structure powerpoint presentation.pptx

cell

1. Cell structure RIBOSOME

2. George E. Palade The ribosome is a complex molecule made of ribosomal RNA molecules and proteins that form a factory for protein synthesis in cells. In 1955, George E. Palade discovered ribosomes and described them as small particles in the cytoplasm that preferentially associated with the endoplasmic reticulum membrane. 2

3. ribosome Ribosomes are made of proteins and ribonucleic acid (abbreviated as RNA), in almost equal amounts. It comprises of two sections, known as subunits. The tinier subunit is the place the mRNA binds and it decodes, whereas the bigger subunit is the place the amino acids are included . 3

4. ribosome Ribosomes seen in the chloroplasts of  mitochondria  of eukaryotes are comprised of big and little subunits composed of proteins inside a 70S particle. 4

5. Ribosome of plant cell 5 Plant cell do have ribosomes and they are composed of proteins and ribosomal RNA. The ribosomes in a plant cell are found in the cytoplasm, the surface of the rough endoplasmic reticulum, the mitochondria and on chloroplasts. There are two types of ribosomes - free ribosomes and attached ribosomes. 

6. Ribosome of plant and animal cell 6

7. Ribosome of animal cell 7 All living cells contain ribosomes, tiny organelles composed of approximately 60 percent ribosomal RNA ( rRNA ) and 40 percent protein. However, though they are generally described as organelles, it is important to note that ribosomes are not bound by a membrane and are much smaller than other organelles. Some cell types may hold a few million ribosomes, but several thousand is more typical. The organelles require the use of an electron microscope to be visually detected.

8. Ribosome of plant and animal cell 8

9. Ribosome of bacterial cell 9 All living cells contain ribosomes, tiny organelles composed of approximately 60 percent ribosomal RNA ( rRNA ) and 40 percent protein. However, though they are generally described as organelles, it is important to note that ribosomes are not bound by a membrane and are much smaller than other organelles. Some cell types may hold a few million ribosomes, but several thousand is more typical. The organelles require the use of an electron microscope to be visually detected.

10. Ribosome of plant and animal cell 10

11. Bacterial cell 11

12. Importance of ribosome 12 Ribosome Structure and RNA Ribosomes consist of two basic components, a large component and a small component, made up of RNA molecules. Codons and Protein Synthesis The mRNA carries the genetic information encoded in the original DNA, acting as a messenger to produce the appropriate proteins, hence the name.

13. Importance of ribosome 13 Free and Membrane-Bound Ribosomes Ribosomes are found in two locations in the cell. Free ribosomes are present in the cytosol, the watery fluid inside the cell and are not attached to any other structure. Membrane-bound ribosomes are attached to a structure known as rough endoplasmic reticulum. Proteins Produced by Free Ribosomes Ribosomes are important because they are responsible for protein synthesis. Free ribosomes, in particular, are important because they produce proteins essential for internal cellular activity, which are not synthesized elsewhere.

14. functions of ribosome 14 It assembles amino acid to form proteins that are essential to carry out cellular functions. The DNA produces mRNA by the process of DNA transcription. The mRNA is synthesized in the nucleus and transported to the cytoplasm for the process of protein synthesis. The ribosomal subunits in the cytoplasm are bound around mRNA polymers. The tRNA then synthesizes proteins. The proteins synthesized in the cytoplasm are utilized in the cytoplasm itself, the proteins synthesized by bound ribosomes are transported outside the cell.

15. Comparison of structure 15 Animal cells  and  plant cells  are similar in that they are both eukaryotic  cells . These cells have a true  nucleus , which houses  DNA  and is separated from other cellular structures by a nuclear membrane. Ribosomes are special because they are found in both prokaryotes and eukaryotes. While a structure such as a nucleus is only found in eukaryotes, every cell needs ribosomes to manufacture proteins. Ribosomes in prokaryotes use a slightly different process to produce proteins than do ribosomes in eukaryotes. Fortunately this difference presents a window of molecular opportunity for attack by antibiotic drugs such as streptomycin. Unfortunately some bacterial toxins and the polio virus also use it to enable them to attack the translation mechanism.