BSC 181 1st Edition Lecture 9 Outline of Last Lecture I. Our Cells Organelles Continued II. The Cell Cycle Outline of Current Lecture III. Control of Cell DivisionIV.Protein SynthesisV. TranscriptionVI. Tissues/ Cell Shapes and TypesA. Epithelial TissuesCurrent LectureControl of Cell Division: There are certain ways that our body regulates the amount of cells that divide. For starters, there is simply not enough space for cells to keep reproduction. Also, there are chemical signals and hormones in our bodies that tells our cells when to stop. Protein Synthesis: There are three different types of RNA. DNA is the blueprint for protein synthesis, without the DNA, the synthesis would not happen. It starts with DNA being transcribed into mRNA by the codons that are on RNA. These codons are what tell the body when to start and stop translation.Messenger RNA: (mRNA), is actually a messenger of genetic information. It carries this information from the DNA to the nucleus, to the ribosomes in the cellTransfer RNA: (tRNA), these are bound to amino acids and once the messenger RNA reaches the ribosomes with the genetic information, the transfer RNA pairs with the codons of the rRNA (which are on the ribosomes) and they start the process of protein synthesisRibosomal RNA: (rRNA), like we said above, these are a part of the ribosomesTranscription: transcription is simply taking DNA (deoxyribonucleic acid) and turning it into RNA (ribonucleic acid). Notice that they are both acids (both from the same language), it is like going to from long hand in writing (DNA) to short hand (RNA). Transition on the other hand is like going from one language to another language.These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Transcription RNA Polymerase: this is an enzyme (notice the –ase ending) that supervises protein synthesis. Its function is to unwind the DNA and add the new ribonucleoside triphosphates onto the DNA. It also joins the RNA nucleotides and tells the body when to stop the process. Tissues: There are four types of tissues called Epithelial, Connective, Muscle, and Nerve tissues. In this lecture, we are only focusing on the Epithelial tissue (skin tissue). There are also three types of membranes called Cutaneous membranes, Mucus membranes, and Serous membranes.Cutaneous membranes: this is simply our skinMucus membranes: these membranes line the body cavities that are close to the outsideSerous membranes: these are found in closed ventral body cavitiesEpithelial Tissue: this is composed mostly of cells and they are held together by tight junctions and desmosomes. Under the epithelial tissue layer, there is a layer of connective tissue that helps support the epithelial tissue above it. The epithelial tissue does not have any blood vessels that go through it, but they get what they need through nerve fibers. Because our skin gets hurt so often, our skin cells regenerate very fast. There are two types of layers that epithelial cells can have. They can be one layer deep which means they are Simple. If they are two or more layers deep, they are called Stratified. There are three different shapes of epithelial cells. The flat looking cell is called Squamous. The cell that looks like a cube is called Cuboidal. The cell that looks like a column is called Cuboidal. Epithelia (Simple Squamous: means a single layer of flattened cells): Its functions deal with diffusion (moving from high to low concentration) and filtration (movement of liquids). They also create a slick lining in the lymphatic and cardiovascular systems, which makes those linings friction-reducing. Epithelia (Simple Cuboidal: means a single layer of cube shaped cells): The functions of these cells is secretion and absorption. These also have large, centrally located nuclei that are sphere shaped.Epithelia (Simple Columnar: means a single layer of column shaped cells): They have oval shaped nuclei and its functions deal with function and secretion. Something special about thesimple columnar cells layer is that there are Goblet Cells that are in these layers that produce mucus. Also, depending on where the layer is located in the body, they may or may not have cilia attached to help move materials through the body.Epithelia (Pseudostratified Columnar): (pseudo: means false) this means that there is one layer of cells but they are all jumbled up and so they are arranged in a way that does not “count” as being one layer. I definitely recommend looking at the picture that was drawn in class in order to understand what I mean. If you did not copy the picture, then I would try and find one in the book.Epithelia (Stratified Squamous: means that there are more than one layer of flat shaped cells): Stratified: means many layers, Squamous: means flat, so lots of layers of flat cells, this helps out with protection. The external cells that face the outside world is called keratinized cells. The ones that are inside the body are called non-keratinized cells.Epithelia (Stratified Cuboidal and Columnar: means more than more layer of cube shaped cells or column shaped cells): this is very rare in the body, it would be found in the pharynx, the maleurethra, and the glandular ducts. It also might occur at the transition part between two different types of tissues. Epithelia (Transitional): these are several cell layers deep with the ones closer to surface dome shaped, and the ones further into our bodies are cuboidal shaped. The important thing about this tissue type is that is can stretch which is good because one of the places it is found is in the lining of the bladder. This allows our bladder to stretch without ripping. Epithelia (Glandular): a gland is one or more cell(s) that make and secrete fluid. There are unicellular glands like the Goblet cell, or multicellular glands. There are also two different areas that the fluid is released. It can be released inside which would be called Endocrine, or outside which is called Exocrine. Keep in mind that “outside” does not necessarily mean outside of our skin. It could mean outside of something else inside the