...Structure and Function The word protein was first coined in 1838 to emphasize the importance of this class of molecules. The word is derived from the Greek word proteios which means "of the first rank". This chapter will provide a brief background into the structure of proteins and how this structure can determine the function and activity of proteins. It is not intended to substitute for the more detailed information provided in a biochemistry or cell biology course. Proteins are the major components of living organisms and perform a wide range of essential functions in cells. While DNA is the information molecule, it is proteins that do the work of all cells - microbial, plant, animal. Proteins regulate metabolic activity, catalyze biochemical reactions and maintain structural integrity of cells and organisms. Proteins can be classified in a variety of ways, including their biological function (Table 2.1). Table 2.1 Classification of Proteins According to biological function. | Type: | Example: | Enzymes- Catalyze biological reactions | ß-galactosidase | Transport and Storage | Hemoglobin | Movement | Actin And Myosin in muscles | Immune Protection | Immunoglobulins (antibodies) | Regulatory Function within cells | Transeription Factors | Hormones | Insulin Estrogen | Structural | Collagen | How does one group of molecules perform such a diverse set of functions? The answer is found in the wide variety of possible structures for proteins. In the...
Words: 3612 - Pages: 15
...or more long chains of amino acid residues. Proteins perform a vast array of functions within living organisms, including catalyzing metabolic reactions, DNA replication, responding to stimuli, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific three-dimensional structure that determines its activity. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20-30 residues, are rarely considered to be proteins and are commonly called peptides, or sometimes oligopeptides. The individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues. The sequence of amino acid residues in a protein is defined by the sequence of a gene, which is encoded in the genetic code. In general, the genetic code specifies 20 standard amino acids; however, in certain organisms the genetic code can include selenocysteine and—in certain archaea—pyrrolysine. Shortly after or even during synthesis, the residues in a protein are often chemically modified by posttranslational modification, which alters the physical and chemical properties, folding, stability, activity, and ultimately, the function of the proteins. Sometimes proteins have non-peptide groups attached, which can...
Words: 2229 - Pages: 9
...which function in different way. One of the main difference between plant cells and animal cells is that plant cells have a cell wall, whereas animal cells don't. Instead of cell wall animal cells have cell membrane but the plant cells have both cell wall and cell membrane. The cell wall in plant cells work as a 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...
Words: 1326 - Pages: 6
...Explain and give examples of why proteins are essential to cell function * The basic structure of an amino acid * Describe the 4 levels of protein structure, and give examples of each * Explain what an enzyme is, understand why enzymes are needed to help chemical reactions, and know the role of the active site * Revisiting the Theory of Chemical Evolution * Modern life arose through a series of endergonic chemical reactions. 1. Production of small organic compounds * i.e., formaldehyde (H2CO), hydrogen cyanide (HCN) 2. Formation of mid-sized molecules from these small compounds * i.e., amino acids, simple sugars 3. Mid-sized building blocks combine to form large molecules. * i.e., proteins, complex carbohydrates 4. Life became possible when one of these large molecules self-replicated. * Organic Molecules * Large organic molecules are called macromolecules * Four major categories of macromolecules: 1. Proteins 2. Nucleic Acids 3. Carbohydrates 4. Lipids * Several of these are long chains of smaller subunits. * The smaller subunits are known as monomers * The long chains of monomers are known as polymers * Four groups of Macromolecules * Building Macromolecules – Monomers and Polymers * Molecules, such as amino acids, are individual units called monomers. They link together (polymerize) to form polymers, such as proteins. * Macromolecules are...
Words: 1630 - Pages: 7
...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...
Words: 5464 - Pages: 22
...Cell Membrane Cells are made of many vital parts that work together and perform specific functions. One important part of the cell structure is the cell membrane also known as the plasma membrane or cytoplasmic membrane. Historically, the plasma membrane was also referred to as the plasmalemma. The cell membrane is a microscopic lipid-based sheath that encloses the cytoplasm of a cell and separates the interior of all cells from the outside environment. It acts as a gatekeeper to ions and organic molecules such as DNA, RNA and other proteins by its selectively permeable barrier which enables the cell to regulate its internal environment and keep out foreign molecules that might damage or destroy the cell's contents, including molecules essential for life. Cell membranes also functions in different cellular processes such as cell adhesion, cell signaling and serve as the attachment surface for several extracellular structures. FUNCTION All prokaryotic cells have a phospholipid bilayer called the plasma membrane. It defines the boundary between the inside and outside of the cell even though it is found on the inside of the prokaryotic cell wall. The cytoplasm and other prokaryotic cellular contents are found inside the plasma membrane. On the other hand, all eukaryotic cells have a plasma membrane as well, but they also have additional phospholipid membranes surrounding internal structures which plays important role in the growth, survival, and development of the cell. Thus,...
Words: 1098 - Pages: 5
... Learning outcomes: 1. Explain how a cell can make a variety of large molecules from a small set of molecules 2. Define monosaccharides, disaccharides, and polysaccharides and explain their functions 3. Define lipids, phospholipids, and steroids and explain their functions 4. Describe the chemical structure of proteins and their importance to cells 5. Describe the chemical structure of nucleic acids and how they relate to inheritance Copyright © 2012 Pearson Education, Inc. Rearrange these in the correct order: INTRODUCTION TO ORGANIC COMPOUNDS © 2012 Pearson Education, Inc. 3.1 Life’s molecular diversity is based on the properties of carbon Carbon-based molecules are called organic compounds. Methane (CH4) is one of the simplest organic compounds. – Four covalent bonds link four hydrogen atoms to the carbon atom. – Each of the four lines in the formula for methane represents a pair of shared electrons. © 2012 Pearson Education, Inc. Three representatives of methane (CH4) Structural formula Ball-and-stick model Space-filling model The four single bonds of carbon point to the corners of a tetrahedron. Different bond angles and shapes occur when carbon atoms form double bonds. Hence, a molecule’s shape determines its function 3.1 Life’s molecular diversity is based on the properties of carbon Compound composed of only carbon and hydrogen are called hydrocarbons. Carbon, with attached hydrogens (aka carbon...
Words: 4247 - Pages: 17
...(V. Undergrad-0814) Proteins are made up of smaller units called amino acids. Hundreds or thousands of amino acids in long chains form a protein molecule. There are 20 different types of amino acids that combine to make a protein. Amino acids are classified into three groups: essential amino acids, non-essential amino acids, and conditional amino acids. Essential amino acids cannot be made by the body and must come from food. Non-essential amino acids can be produced by the body even if not obtained through food ingested (Wolfe,2000). Conditional amino acids are needed at times of stress, like an illness. Proteins can be described as polar and non-polar depending on how they interact in the environment. Polar and non-polar chemical trait allows for the amino acid to direct themselves toward water (hydrophilic) or away from water (hydrophobic). Valine is an essential amino acid that enables chemical messages to be transmitted from the brain. Valine’s chemical structure is C5H11NO2 and is a branched chain amino acid. Valine is non-polar in nature so it is not a charged molecule. Valine is hydrophobic and if found deep inside the structure for this reason. Valine is important to muscle function as the muscle recovers from strenuous activity. The amino acids sequencing of a protein decides its structure and function. Protein function is also dependent on its structure but some changes can disrupt the structure. When a protein loses function it is denatured. Changes that...
Words: 952 - Pages: 4
...different functions of proteins in the body are structural proteins, storage proteins, contractile proteins, transport proteins, defensive proteins, signal proteins, and Enzymes. Structural proteins provide support for hair, horns, feathers, spider webs, and connective tissues. Storage proteins provide a source of amino acids for plants and animals that are developing such as seeds and eggs. Contractile proteins are primarily in muscles. Transport proteins transports oxygen from an animals lungs to other parts of the body. Defensive proteins protect the body as antibodies. Signal proteins conveys messages between cells. Enzymes change the rate of a chemical reaction without being changed. 2. There are 20 different kinds of amino acids in a protein. Amino acids consists of a central carbon atom bonded to four covalent partners. Three of the attachments are consistent within each amino acid, a carboxyl group, an amino group, and a hydrogen atom. What makes each amino acid different from another is that the fourth bond of the central carbon has a different radical group. 3. A protein polymer is called a polypeptide. A polypeptide is made of 100 or more amino acids bonded by dehydration reactions. The bonded amino acids are called peptide bonds. 4. The difference between a polypeptide chain and a protein is that a protein needs more than one polypeptide to be functional. Polypeptide is only one part of the overall protein. 5. The four levels of a protein structure are the...
Words: 605 - Pages: 3
...SCIE207 Phase 2 Lab Report Title: Animal and Plant Cell Structures 1. Animal Cell: [pic] |Number |Cell Structure |Description and Function | |1 |Nuclear Pore |Nuclear pores are large protein structures that cross| | | |the nuclear envelope, which is the double membrane | | | |inclosing the eukaryotic cell nucleus. The function | | | |of a nuclear pore is to control the way of molecules | | | |between the nucleus and cytoplasm, allowing some | | | |material to go through the membrane. | |2 |Chromatin (DNA) |Chromatin is the combined material of DNA and | | | |proteins. Chromatins are what make up the entire | | | |nucleus of a cell. The function of a chromatin is to | | | ...
Words: 1323 - Pages: 6
...this amount, they appear as one object. THE LIGHT MICROSCOPE Light microscopes use a number of lenses to produce an image that can be viewed directly at the eyepiece. Light passes from a bulb under the stage, through a condenser lens and then through the specimen. This beam of light is passed through an objective lens and then the eyepiece lens. The light microscope usually has a number of objective lenses which can be rotated into position, these are x4, x10, x40 and x100 lenses. The eyepiece lens then magnifies the image again by x10. So the final magnifications the microscope is capable of producing are x40, x100, x400 and x1000. overall magnification = objective lens magnification x eyepiece lens magnification You can view some specimens directly using the light microscope. Others have to be prepared to get around...
Words: 8313 - Pages: 34
...For viewing living cells • Electron microscope (EM) has magnification up to 1,000,000x o Scanning EM (SEM) for viewing surface features o Transmission EM (TEM) for viewing internal structures [pic][pic][pic] B. Why are cells small? • A cell’s surface area-to-volume ratio limits its size • Volume increases faster than Surface Area • Larger cells do not have enough Surface Area to support their Volume • Organisms get larger by becoming multicellular [pic] C. There are two major categories of cells. [pic] D. All cells are surrounded by a plasma membrane. • Prokaryotic AND eukaryotic cells are surrounded by a plasma membrane • Eukaryotic cells also have internal membranes • All membranes act as selective barriers • All membranes are built from proteins and phospholipids • Form phospholipid bilayer when exposed to water o Hydrophilic on outside, hydrophobic on inside • Membranes are described by the fluid mosaic model o Fluid because they have the consistency of salad oil o Mosaics because of the diversity of proteins they contain [pic] [pic] II. PROKARYOTIC CELLS ARE SMALLER AND SIMPLER. A. All prokaryotic cells are unicellular organisms. • All prokaryotes have a plasma membrane...
Words: 966 - Pages: 4
...The functions of protein are linked to their shape Proteins are polymers of amino acids joined by strong peptide bonds. The combination of any of the twenty amino acids in any length and sequence allows an almost infinite number of possible structures and functions. The sequence of amino acids in the polypeptide chain is termed the primary structure. The primary structure is unique to a given protein. The primary structure can fold regularly to form either an α-helix or β-pleated sheet. The secondary structure is held together by hydrogen bonds between adjacent peptide bonds. The primary structure can further fold in an irregular but not random manner to form an overall three dimensional shape that more specifically determines the biological functions of the individual protein. This 3D structure is held together by bonds formed between the R-groups of amino acids. For movement, animals use muscle contraction. Muscle fibres are composed of two protein filaments, myosin which is a thick filament and actin which is thinner. Actomyosin cross-bridges can form between the two which move relative to one another on hydrolysis of ATP drawing actin into myosin. This sliding filament theory shows how a sarcomere contracts. This contraction is used in a variety of applications including constriction or dilation of blood vessel to modify blood flow through tissues, pupil diameter to control light entry into eyes or the generation of a force at a joint to move a hand away from a hot...
Words: 932 - Pages: 4
...is the characterization and identification of all proteins that expressed by a genome or tissue and understanding how these proteins function (Mohanty, 2005). Besides, the purpose of proteomics is not only to recognize all the proteins in a cell but also to generate a complete three-dimensional (3D) map of the cell indicating where the proteins are located. To achieve these goals require the involvement of a large number of different fields such as biochemistry, molecular biology and bioinformatics. Many different areas of study are now grouped under the proteomic such as sequence and structural proteomics, expression proteomics, interaction proteomics and functional...
Words: 847 - Pages: 4
...about proteins? Proteins are important molecules in cells, is one macromolecule organic. They are compound of large amino acid chains and distingue of the rest of the macromolecule by containing Nitrogen; they are involucre in the many processes of the organism, such as: the formation of membranes of the cells (structure), bioregulation (enzymes) and defense (antibodies). The structure three-dimensional and specific function of proteins this defined by the sequence of amino acids, this information this codified in the DNA, therefore the protein synthesis from DNA. Proteins can be described according their function, for example: some types of hormones, transmit signals to coordinate biological processes between different cells, performing as messenger; other may be the transporter the small molecules within cells and throughout the body. They are also can be classified based on Shape (Globular or Corpuscular Proteins, Fibrous or Fibrillar Proteins), composition and solubility (Fibrous or Fibrillar Proteins, Conjugated or Complex Proteins or Heteroproteins) on the type of prosthetic group present. There are four structural levels of organization to describe the Proteins based on the complexity of the molecule. They are Primary Structure, Secondary structure, Tertiary structure and Quaternary structure. 2. What do you like most, chicken or beans? Explain, persuade and illustrate your point of view 3. Give a proposal to solve some problems around proteins, for...
Words: 414 - Pages: 2
