...protection layer outside the cell membrane which also provides structure for the plant cell. It is seen as a shape giver to the plant. Likewise it also purify or determine the substances that goes in and out of the cells which protect the cells from being damage. Although all plant have cell wall but they are constructed in different way for different plants and also they act in different way which depend in the plants type. For example the world tallest tree Hyperion needs a very firm and stern cell wall so that it can stand still and grow to its fullest height. Whereas, for small plant like Hebe needs more mobility so it can bend but not break. Fig 1: Cellulose (Sugar Chain) The cell wall are made of cellulose. Cellulose is a type of fibres that is made up of sugar molecules which is formed in a long chain like structure to strengthen the cell. Cellulose is made up of complex sugar because it is used in both protection as well as structure. It's main function is to give strength to the cell wall. Nucleus and Nucleolus Plants cells and animals cells are different when it comes to the shape and some organelles in their cells but they have some similarities. One of the main similarity is the nucleus which is one of the most important things for the cells to have because its a control house for both plant and animal cells. It controls the cells and is consider as the brain of the cells. If we look at the structure of the nucleus than we...
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...AS Biology: OCR Syllabus Module 1.1.1 3.1 AS Unit: Cells, Exchange and Transport Module 1: Cells 1.1.1 Cell Structure Candidates should be able to: (a) state the resolution and magnification that can be achieved by a light microscope, a transmission electron microscope and a scanning electron microscope; Light Microscope Transmission Electron Microscope Scanning Electron Microscope Resolution 0.2 μ (200nm) 0.2nm 0.2nm Magnification ≈ ×1500 / 2000 Over 500 000 250 000 (b) explain the difference between magnification and resolution; Resolution “the ability of an optical system to distinguish between two adjacent objects” Magnification increases the apparent size of an object” Resolving power “the degree of detail that can be seen with a microscope” The resolving power is inversely proportional to the wavelength of the radiation used (i.e. the shorter the wavelength, the greater the resolution). (c) Stains: (d) explain the need for staining samples for use in light microscopy and electron microscopy; - most biological structures are transparent the stain gives a contrast between different structures the stain combines with certain chemicals in the structure - Iodine solution: Starch → blue-black - Eosin solution: cytoplasm → pink - Feulgens agent DNA → dark red / purple - Aceto-orcein agent calculate the linear magnification of an image (HSW3); Page 1 of 8 AS Biology: OCR...
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...Characteristics * Cell wall * Plasma Membrane * Cytoplasm * Ribosome * Plasmid * Flagella * Pilli * Capsule Characteristic Features and Functions Cell Wall: * Cell walls of bacteria are made up of glycoprotein. * The main function of cell wall is it helps in providing support, mechanical strength and rigidity to cell and to also protect against osmotic substances. * It also protects the cell from bursting in a hypotonic medium. Plasma Membrane: * It is also known as cytoplasmic membrane (or) cell membrane. * It is composed of phospholipids, proteins and carbohydrates, forming a fluid-mosaic. * It helps in transportation of substances including removal of wastes from the body. * It helps in providing a mechanical barrier to the cell. * Plasma membrane acts as a semi permeable membrane, which allows only selected material to move inside and outside of the cell. Cytoplasm: * Helps in cellular growth, metabolism and replication. * Cytoplasm is the store houses of all the chemicals and components that are used to sustain the life of a bacterium. * There is also regulation of substances being transported in and out of the cell with the use of cytoplasms. Ribosome: * A tiny granule made up of RNA and proteins. * They are the site of protein synthesis therefore take part in such process. * They are freely floating structures that helps in transferring the genetic code. Plasmid: * Plasmids...
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...Transmembrane Segments Form Tertiary Hairpins in the Folding Vestibule of the Ribosome LiWeiTu Department of Physiology, University of Pennsylvania, Philadelphia., , PA 19104-6085, USA ⁎Corresponding author. Edited by R. Ruben L. Gonzalez J Mol Biol 2013 Abstract Folding of membrane proteins begins in the ribosome as the peptide is elongated. During this process, the nascent peptide navigates along 100 Å of tunnel from the peptidyltransferase center to the exit port. Proximal to the exit port is a “folding vestibule” that permits the nascent peptide to compact and explore conformational space for potential tertiary folding partners. The latter occurs for cytosolic subdomains, but has not yet been shown for transmembrane segments. We now demonstrate, using an accessibility assay and an improved, intramolecular crosslinking assay, that the helical transmembrane S3b–-S4 hairpin (“paddle”) of a voltage-gated potassium (Kv) channel, a critical region of the Kv voltage sensor, forms in the vestibule. S3–-S4 hairpin interactions are detected at an early stage of Kv biogenesis. Moreover, this vestibule hairpin is consistent with a closed-state conformation of the Kv channel in the plasma membrane. AbbreviationsERendoplasmic reticulumPTCpeptidyl transferase centerVSDvoltage sensor domainPEG-MALpolyethylene glycol maleimidePDMphenyldimaleimideBMHbismaleimide hexaneLDSlithium dodecyl sulfatePBSphosphate-buffered saline Keywordsfolding of nascent peptidespotassium channel voltage...
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...Review Biology Test #1 Chapter 3: Water and life • Polar covalent bonds in water result in Hydrogen bonding between the molecules. These bonds give water its special properties • In presence of water, ionic bonds are weak and covalent bonds are strong. Without water, ionic bonds are stronger. • Each water molecule can make 4 hydrogen bonds. • Water properties: 1. Polarity 2. Surface tension 3. Cohesion 4. Adhesion 5. Capilarity 6. High specific heat 7. Heat bank 8. Heat of vaporization allows evaporation cooling. 9. Abundant and versatile solvent 10. Solid is less dense than liquid 11. It is a reactant and a product in many biological reactions (Photosynthesis, dehydration reaction, hydrolysis…) 12. It can ionize into H3O+ and OH- • When substances dissolve in water, water molecules form hydration shells by breaking their attractions to other water molecules and attracting to the solvate particles. • The dissociation of water molecules into Hydronium and hydroxide ions is a reversible reaction that occurs in a state of equilibrium (pure water). • The concentration of each ion in pure water is 10-7 M. [OH-][H3O+] = 10-14 M. This way, whenever we know the concentration of one ion, we can calculate the concentration of the other. • Adding acids and bases can change these concentrations of ions in water • When acids dissolve in water, they donate H+, increasing the concentration of hydrogen ions. This results in an acidic solution • When bases dissolve in water...
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...the fundamental natural phenomena and processes of plant life, the classification and description of plant diversity; applied topics which study the ways in which plants may be used for economic benefit in horticulture, agriculture and forestry and organismal topics which focus on plant groups such as algae, mosses or flowering plants. Core topics Cytology — cell structure, chromosome number Epigenetics — Control of gene expression Paleobotany — Study of fossil plants and plant evolution Palynology — Pollen and spores Plant biochemistry — Chemical processes of primary and secondary metabolism Phenology — timing of germination, flowering and fruiting Phytochemistry — Plant secondary chemistry and chemical processes Phytogeography — Plant Biogeography, the study of plant distributions Phytosociology — Plant communities and interactions Plant anatomy — Structure of plant cells and tissues Plant ecology — Role and function of plants in the environment Plant evolutionary developmental biology — Plant development from an evolutionary perspective Plant genetics — Genetic inheritance in plants Plant morphology — Structure of plants Plant physiology — Life functions of plants Plant reproduction — Processes of plant reproduction Plant systematics — Classification and naming of plants Plant taxonomy — Classification and naming of plants Applied topics[edit] Agronomy — Application of plant science to crop production Arboriculture — Culture and propagation of trees Biotechnology — use of...
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...BIO 264 - Human Anatomy and Physiology Chapter 3 – Cell Biology and Genetics PART A 1. Describe the structure of a typical animal cell. Describe the structure and function of each of the cell parts labeled in Figure 3.1, plus cytosol, cytoplasmic inclusions, and flagella. * Plasma Membrane- Outer boundary of the cell, through which the cell interacts with its external environment. * Nucleus- It directs cell activities, most of which take place in the cytoplasm. * Flagellum- Extension of the plasma membrane containing doublets of parallel microtubules./ in humans, it propels spermatozoa. * Microvilli- Extension of the plasma membrane containing microfilaments. /increase surface area of the plasma membrane for absorption and secretion; modified to form sensory receptors. * Cilia- Extensions of the plasma membrane containing doublets of parallel microtubules./ Move materials over the surface of cells. * Cytoskeleton- * Proteasomes- tubelike protein complexes in the cytoplasm./ Break down proteins in the cytoplasm. * Peroxisome- Membrane bound vesicle/serves as one site of lipid and amino acid degradation; breaks down hydrogen peroxide. * Centrioles-pair of cylindrical organelles in the centrosome, consisting of triplets of parallel microtubules./ Serves as centers for microtubule formation; determine cell polarity during cell division; from the basal bodies of cilia and flagella. * Centrosome- * Cytoplasmic organelles- Ribosomal RNA...
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...Campbell's Biology, 9e (Reece et al.) Chapter 6 A Tour of the Cell This chapter introduces the topics of microscopy and cell fractionation, followed by a review of the cell and the major organelles and structures of eukaryotic cells. A challenge with this chapter is to keep this data from simply being a list of parts. In addition to the structure and function of individual organelles, questions probe student understanding of the cell as a dynamic, interconnected system: the flow of membrane and proteins in the endomembrane system to the plasma membrane; the flow of information from the nucleus to the cytoplasm; and the connection between the cytoskeleton, the plasma membrane, and the extracellular matrix. An evolutionary perspective goes beyond structural distinctions between prokaryotes and eukaryotes to examine theories concerning the evolutionary origins of eukaryotes and key eukaryotic cell structures. Multiple-Choice Questions 1) When biologists wish to study the internal ultrastructure of cells, they can achieve the finest resolution by using A) a phase-contrast light microscope. B) a scanning electron microscope. C) a transmission electronic microscope. D) a confocal fluorescence microscope. E) a super-resolution fluorescence microscope. Answer: C Topic: Concept 6.1 Skill: Knowledge/Comprehension 2) The advantage of light microscopy over electron microscopy is that A) light microscopy provides for higher magnification than electron microscopy...
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...CHAPTER 9: NUCLEIC ACIDS 9.1 Levels of Structure in Nucleic Acids Primary (1o) Structure – order of bases in the polynucleotide sequence Secondary (2o) Structure – 3D conformation of backbone Tertiary (3o) Structure – supercoiling of the molecule Quaternary (4o) Structure – interaction between DNA & proteins Two principle types of nucleic acids - DNA (deoxyribonucleic acid) - RNA (ribonucleic acid) How do DNA and RNA differ? Ribosomes: polypeptide-generating machinery of the cell Tobacco mosaic virus: nucleic acid strand winds through a cylinder of coat-protein subunits 9.2 The Covalent Structure of Polynucleotides Nucleotides: monomers of nucleic acids 1. Nitrogenous base 2. Sugar 3. Phosphoric acid residue Order of nucleic acids of DNA contains the information necessary to produce the correct amino acid sequence in the cell’s proteins What are the structures and components of the nucleotides? Nucleic acid bases (nucleobases): one or two-ring nitrogenous aromatic compound - Pyrimidines – single-ring aromatic compounds Cytosine – DNA & RNA Thymine – substitute for Uracil in DNA (sometimes in RNA) Uracil – RNA only - Purines – double-ring aromatic compounds Adenine – DNA & RNA Guanine – DNA & RNA Methylation can modify bases Nucleoside - base + sugar covalently bonded - lacks phosphate group - base forms a glycosidic linkage with sugar Ribonucleoside: β-D-ribose Deoxyribonucleoside: β-D-deoxyribose The glycosidic...
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...003 Chapter 03 Cell Biology and Genetics Student: ___________________________________________________________________________ 1. The structural and functional unit of all living organisms is the A. ribosome. B. cell. C. organ. D. organelle. E. plasma membrane. 2. All of the chemical reactions within a cell are known as cell A. reproduction. B. metabolism. C. communication. D. inheritance. E. movement. 3. Cells produce and respond to chemical and electrical signals as a means of A. communicating. B. metabolizing. C. reproducing. D. synthesizing. E. using energy. 4. Which of the following is NOT a characteristic function of a cell? A. reproduction and inheritance B. metabolism and energy use C. movement D. synthesis E. communication 5. Which of the following could be used to study general features of cells? A. a magnifying glass B. scanning electron microscope C. transmission electron microscope D. binoculars E. light microscope 6. In order to study in detail the anatomy of internal cell parts, it would be best to use A. x-rays. B. flashlights. C. a transmission electron microscope (TEM). D. tissue cultures. E. a scanning electron microscope (SEM). 7. The plasma membrane A. separates the nucleus from the rest of the cell. B. is a rigid protein membrane. C. is not permeable. D. has a single layer of phospholipids. E. regulates movement of materials into and out of the cell. 8. The environment outside the plasma membrane is most appropriately...
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...Explain the chemical basis of hydrogen bond formation in biology. Discuss the role of hydrogen bonding in the structure and function of biological macromolecules. Your essay should refer to DNA, RNA and proteins. A hydrogen bond is a particularly strong type of intermolecular force which is essential in many biological macromolecular structures and is formed when a hydrogen atom from one molecule covalently bonds to a highly electronegative atom on another molecule, usually nitrogen, fluorine or oxygen. The bond is a particular case of dipole dipole attractions where the large electronegativity difference between the small hydrogen atom and the nitrogen, fluorine or oxygen atom results in the electron pair being pulled away from the hydrogen. Given its small size and the fact that it has no other electrons to shield the nucleus, the hydrogen atom exerts a strong attractive force on a lone pair in the electronegative atom of a neighboring molecule. Hydrogen bonds play a key role in ensuring that many biological molecules adopt and subsequently retain their correct three dimensional structure. This is particularly the case in proteins and nucleic acids. Therefore this essay will examine the importance of hydrogen bonds in the nucleic acids RNA and DNA and finally their role in protein structure. It is important to understand the chemical basis of a hydrogen bond before moving on to explain their significance. As already described, the small hydrogen atom exerts a strong attractive...
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... | | | | | | | | | | | | | | | | | |Bonding (how units combine – |1st structure-strong covalent |Strong covalent glycoside |Rarely ever forms polymer |covalent bonds b/w sugar | |polymers |peptide bonds (c-n) |bond (C-OH) |units (aggregates) |and phosphate | | |2nd structure- weak hydrogen bonds | | |Hydrogen bond b/w nitrogen | | |3rd structure-sulphide | |...
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...PYF12 3/21/05 8:04 PM Page 191 Chapter 12 Gene expression and regulation Bacterial genomes usually contain several thousand different genes. Some of the gene products are required by the cell under all growth conditions and are called housekeeping genes. These include the genes that encode such proteins as DNA polymerase, RNA polymerase, and DNA gyrase. Many other gene products are required under specific growth conditions. These include enzymes that synthesize amino acids, break down specific sugars, or respond to a specific environmental condition such as DNA damage. Housekeeping genes must be expressed at some level all of the time. Frequently, as the cell grows faster, more of the housekeeping gene products are needed. Even under very slow growth, some of each housekeeping gene product is made. The gene products required for specific growth conditions are not needed all of the time. These genes are frequently expressed at extremely low levels, or not expressed at all when they are not needed and yet made when they are needed. This chapter will examine gene regulation or how bacteria regulate the expression of their genes so that the genes that are being expressed meet the needs of the cell for a specific growth condition. Gene regulation can occur at three possible places in the production of an active gene product. First, the transcription of the gene can be regulated. This is known as transcriptional regulation. When the gene is transcribed and how much it is...
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...1. Write an essay on protein structure and synthesis Protein synthesis is a cellular process leading to the production of proteins. This term is also synonymous to protein translation. It begins with a sequential process of transcription of DNA into mRNA, which is then used as input for translation after exon-intron splicing. The addition of successive tRNA molecules based on the code of mRNA matched up by base-pairing through their anti-codons in the ribosomes creates the nascent protein. After the protein chain has been synthesized, post-translation modification occurs, e.g. phosphorylation, motifs added to the protein. This may happen at various levels: secondary (alpha-helix, beta-sheets, turn, random coiling), tertiary and quarternary. Protein synthesis is also the process wherein peptide bonds between two amino acids whose formation is controlled. The synthesis begun when the mRNA combines in a little subunit of ribosomes close to an AUG sequence in mRNA. Start codon which is the AUG codon is being such because it does the coding of the first amino acid to be made of protein. “The AUG codon base-pairs with the anticodon of tRNA carrying methionine. A large ribosomal subunit binds to the complex, and the reactions of protein synthesis itself can begin. The aminoacyl-tRNA to be called for next is determined by the next codon (the next three bases) on the mRNA. Each amino acid is coded for by one or more (up to six) codons” (Center for Bioenergy and Photosynthesis...
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...components of the cell include the cell membrane, cytoplasm, the nucleus, nucleolus, nuclear membrane, endoplasmic reticulum (smooth ER and rough ER), mitochondria, Golgi apparatus, lysosomes, ribosomes and vacuoles. The cell membrane – The cell membrane otherwise known as the plasma membrane is located on the surface of a typical animal cell. The cell membrane is made up of a phospholipid bilayer and is a selectively permeable membrane that allows substances to pass in and out of the cell. This selectively permeable membrane means that only water, gases and other nutrients are able to pass through whilst keeping toxins out. The lipid bilayer of the cell membrane aids in the protection of the cell, as it helps to control the movement of particles that pass in and out of the cell. The structure of the phospholipid is made up of hydrophilic heads and hydrophobic tails. Cytoplasm – The cytoplasm is a gel-like substance that is clear in colour made up of 80% water and also contains enzymes, salts, organelles and other organic molecules. It consists of all the contents outside of the nucleus and is encased within the cell membrane. The cytoplasm aids in moving materials around the cell, and is a solvent that allows nutrients and waste products within it to dissolve. The organelles inside of the cell are suspended in the fluid which is contained in the cell, otherwise known as cytosol. Cytoplasm contains molecules which aids in breaking down waste, and is...
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