Organelles are small membranous bodies‚ each with a specific structure and function. Prokaryotes do have cytoplasm‚ which is the material bounded by a plasma membrane and cell wall. This contains ribosomes‚ small granules that coordinate the synthesis of proteins. Prokaryotes also have a nucleoid which is the inner interior of the cell where the DNA is organized and stored but not enclosed by the membrane. Prokaryotic cells lack membrane-bounded organelles as well as a nucleus. Their DNA is in a nucleoid
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filaments within these structures are cross-linked by accessory proteins known as actin binding proteins. These proteins connect two actin filaments through its two actin-binding sites or dimerization with actin domains. Crosslinking actin filaments can be performed by fimbrin proteins that attach filaments in a parallel fashion to facilitate movement. Thus‚ they are localized in microvilli‚ filopodia‚ and focal adhesions. Other proteins including α actinin and spectrin connect actin filaments in an
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BIOMOLECULES 1.What are macromolecules? Give examples. Macromolecules are large complex molecules that occur in colloidal state in intercellular fluid. They are formed by the polymerization of low molecular weight micromolecules. Polysaccharides‚ proteins‚ and nucleic acids are common examples of macromolecules. 2. Illustrate a glycosidic‚ peptide and a phospho-diester bond. (a) Glycosidic bond is formed normally between carbon atoms‚ 1 and 4‚ of neighbouring monosaccharide units. (b) Peptide
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other as when water molecules provide a solvent for other organic molecules. Cells are dynamic structures with constant activity The carbohydrates are unique in forming long chain polymer and also branching these chains. This is more complicated than protein where only 20 amino acids can form a long single chain. Here there can be numerous kinds of bonding forming a straight chain or long chain polymer. More over the number of repeating units are also much greater than giving the structure variation.
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cells share; however‚ there are also important differences among various cell types (for example‚ animal cells vs. bacterial cells) • [Figure 3-23] The inside of a cell is loaded (crowded‚ packed) with molecules including RNA‚ ribosomes and proteins. o A cell is already packed‚ even with these few components; without even considering other organelles and components present in cells‚ the cell is already crowded; crowding changes the behavior of cellular components • Many different
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following organelles: Nucleus‚ Ribosomes‚ Lysosomes‚ Cytoplasm‚ Nucleolus‚ Cell Membrane‚ Mitochondria‚ Endoplasmic Reticulum (ER) and Golgi Body. Insulin is a protein compound made up of more than one chain of amino acids. Amino acids are the building blocks of protein and it is these that determine the structure and function of proteins. Insulin is made within the pancreas where there are clusters of specialised cells called the islets of Langerhans. A type of cell within the islets is the pancreatic
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going to describe: Proteins‚ carbohydrates‚ lipids and nucleic acid. I will also describe the functions and why they are important in our bodies. Proteins Proteins are polymers of amino acids that are joined head-to-tail in a long chain that is then folded into a three-dimensional structure unique to each type of protein. The covalent linkage between two adjacent amino acids in a protein (or polypeptide) chain is called a peptide bond. There are twenty amino acids that make up proteins. Each amino acid has
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polar * Amino (Amines): Acts as a base; can pick up an H- from the surrounding solutions (water‚ in living organisms) * Sulfhydryl (Thiois): Two sulfhydryl groups can react‚ forming a covalent bond. This “cross-linking” helps stabilize protein structure *
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structure TWO-molecule thick (60-100Å) Lipids‚ Proteins‚ and carbohydrates Lipids form the barrier. Proteins mediate distinct functions. Non-covalent assemblies (self-assembly‚ protein-lipid interaction) Asymmetric (always) Fluid structures: 2-dimensional solution of oriented lipids and proteins Electrically polarized (inside negative ~-60mV) Spontaneously forming in water Protein/lipid ratio = 1/4 – 4/1 Carbohydrate moieties are always outside the cell Protein/Lipid ratio • Pure lipid: insulation (neuronal
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complete): • 20‚000-28‚000 genes in the human genome o The genome was found using a shotgun sequence. o 10% of the genome is Long Intersperse Nuclear Elements (=LINEs). This leaves the questions as to which part of the genome are LINEs? 80‚000-120‚000 proteins in a cell. 200‚000-2‚000‚000 peptides in a cell. o Ex: Insulin A paper looked at 30% of the genome at 5 nucleotide resolutions and found: In terms of transcripts (mRNA) may not have a poly-A tail. 43.7% of transcripts never had a poly-A tail
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