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Chapter 2 biomolecule and cell structure and tissue

Biomolecules

What are the elements most common in huaman physiology?
1, Cargon (C), 2, Hydrogen (H), 3, Oxygen (O)

What is organic molecules?
Molecules that contains carbon are known as organic molecules, because it was once though t that they existed in or were derived from only plants and animals.

What is biomolecules?
Organic molecules associated with living organisms are called biomolecules.

What are the four kinds of biomolecules?
1, Carbohydrates 2, lipids 3, proteins 4, bucleotides
The first three groups are used by the body for energy and as the building blocks for cellular components. The fourth group, the nucleotides includes : DNA and RNA, the structural components of genetic material. Nucleotides also includes biomolecules which carry energy, such as ATP, cAMP

Carbohydrate are chemical compounds that contain oxygen, hydrogen, and carbon atoms. They consist of monosaccharide sugars of varying chain lengths and that have the general chemical formula C_n(H₂O)_n or are derivatives of such.

Certain carbohydrates are an important storage and transport form of energy in most organisms, including plants and animals. Carbohydrates are classified by their number of sugar units: monosaccharides (such as glucose and fructose), disaccharides (such as sucrose and lactose), oligosaccharides, and polysaccharides (such as starch, glycogen, and cellulose).

Monosaccharides are the simplest form of carbohydrates. They consist of one sugar and are usually colorless, water-soluble, crystalline solids. Some monosaccharides have a sweet taste. Examples of monosaccharides include glucose(6 carbon) (dextrose), fructose, and galactose and ribose (5carbon).Monosaccharides are the building blocks of disaccharides like sucrose (common sugar) and polysaccharides (such as cellulose and starch). Further, each carbon atom that supports a hydroxyl group (except for the first and last) is chiral, giving rise to a number of isomeric forms all with the same chemical formula. For instance, galactose and glucose are both aldohexoses, but they have different chemical and physical properties.

Disaccharide is a sugar (a carbohydrate) composed of two monosaccharides.The two monosaccharides are bonded via a condensation reaction. This bond can be between the 1-, 4-, or 6-carbon on each component monosaccharide. So, even if both component sugars are the same (e.g., glucose), different bond combinations result in disaccharides with different chemical and physical properties.

• sucrose (known as table sugar, cane sugar, saccharose, or beet sugar)
• lactose (milk sugar)
• maltose produced during the malting of barley

Polysaccharides (sometimes called glycans) are relatively complex carbohydrates.
They are polymers made up of many monosaccharides joined together by glycosidic linkages. They are therefore very large, often branched, molecules. They tend to be amorphous, insoluble in water, and have no sweet taste.
When all the constituent monosaccharides are of the same type they are termed homopolysaccharides; when more than one type of monosaccharide is present they are termed heteropolysaccharides.
Examples include storage polysaccharides such as starch and glycogen and structural polysaccharides such as cellulose and chitin.Polysaccharides have a general formula of C_n(H₂O)_n-1 where n is usually a large number between 200 and 500.All living things store glucose for energy in the form of a polysaccharide, and some cells produce polysaccharidees for structural purpose as well. Yeast and bacteria make a glucose storage polymer called dextran. Animal cells make a storage polysaccharide called glycogen, which is foiund in all tissues of the body. Many invertabrate anmals make a tructural polysaccharide called chitin. Plants make two types of polysacchariade: the storage moledule: starch, which human can digest, and the tructural moledule cellulose, which human can not digest. It is the most abundant organic molecule on earth.

Starch :Starches are glucose polymers in which glucopyranose units are bonded by alpha-linkages. Amylose consists of a linear chain of several hundred glucose molecules. Amylopectin is a branched molecule made of several thousand of glucose units.
Starches are insoluble in water. They can be digested by hydrolysis catalyzed by enzymes called amylases, is a digestive enzyme classified as a saccharidase (an enzyme that cleaves polysaccharides). It is mainly a constituent of pancreatic juice and saliva, needed for the breakdown of long-chain carbohydrates (such as starch) into smaller units.which can break the alpha-linkages. Humans and other animals have amylases, so they can digest starches. Potato, rice, wheat, and maize are major sources of starch in the human diet.

Glycogen: is the storage form of glucose in animals. It is a branched polymer of glucose. Glycogen can be broken down to form substrates for respiration, through the process of glycogenolysis. This involves the breaking of most of the C-O-C bonds between the glucose molecules by the addition of a phosphate, rather than a water as in hydrolysis. This process yields phosphorylated glucose molecules, which can be metabolized with a saving of one ATP molecule.

Glycogenolysis is the catabolism of glycogen (requiring removal of glucose unit from glycogen and addition of phosphate) thus producing glucose 1-phosphate, and subsequently reconfigured (C-1 -> C-6) to yield glucose 6-phosphate, a potent reaction intermediary leading to glucose available to the blood and brain, pyruvic acid (yet another potent intermediate) or reverting to glycogen if not immediately needed, as metabolically necessary. Both glucagon and epinephrine stimulate glycogenolysis.

Glycogenolysis requires three enzymes :

• Glycogen phosphorylase
• Debranching enzyme transferase & α-1,6-Glucosidase (bifunctional enzyme)
• Phosphoglucomutase

The liver also contains an additional enzyme, glucose 6-phosphatase, which cleaves the phosphate group to form free glucose.

Glycogenolysis transpires in the muscle and liver tissue, where glycogen is stored, as a hormonal response to epinephrine (e.g., adrenergic stimulation) and/or glucagon, a pancreatic peptide triggered by low blood glucose concentrations.

Of note, oral administration of glucagon is a common human medical intervention when intravenous access is unavailable in diabetic emergencies.

Hydrolysis is a chemical process in which a molecule is split into two parts by the addition of a molecule of water.

Cellulose :The structural components of plants are formed primarily from cellulose. Wood is largely cellulose and lignin, while paper and cotton are nearly pure cellulose. Cellulose is a polymer made with repeated glucose units bonded together by beta-linkages. Humans and many other animals lack an enzyme to break the beta-linkages, so they do not digest cellulose. Certain animals can digest cellulose, because bacteria possessing the enzyme are present in their gut. The classic example is the termite.

Lipids: the most diverse biomolecules

Lipids: are biomolecules made up of carbon, hydrogen, and oxygen, like the carbohydrate, but as a rule they contain must less oxygen. one class of aliphatic hydrocarbon-containing organic compounds essential for the structure and function of living cells. Lipids are characterized by being water-insoluble but soluble in nonpolar organic solvents. lipids are not very soluble in water because their nonpolar structure. Most lipids have some polar character in addition to being largely nonpolar. Generally, the bulk of their structure is nonpolar or hydrophobic ("water-fearing"), meaning that it does not interact well with polar solvents like water. Another part of their structure is polar or hydrophilic ("water-loving") and will tend to associate with polar solvents like water. This makes them amphiphilic molecules (having both hydrophobic and hydrophilic portions). In the case of cholesterol, the polar group is a mere -OH (hydroxyl or alcohol). In the case of phospholipids, the polar groups are considerably larger and more polar,

Fat and oil: lipids are called fat if they are solid at room temperature and oils if they are liquid at room temperature. Most lipids derived from animal sources, like lard, are fats, whereas most plant lipids are oils.

Pospholipids:Phospholipids are a class of lipids formed from four components: fatty acids, a negatively-charged phosphate group, an alcohol and a backbone. Phospholipids with a glycerol backbone are known as glycerophospholipids or phosphoglycerides. There is only one type of phospholipid with a sphingosine backbone; sphingomyelin. Phospholipids are a major component of all biological membranes, along with glycolipids and cholesterol. or, more precisely, glycerophospholipids, are built on a glycerol core to which are linked two fatty acid-derived "tails" by ester linkages and one "head" group by a phosphate ester linkage. Fatty acids are unbranched hydrocarbon chains, connected by single bonds alone (saturated fatty acids) or by both single and double bonds (unsaturated fatty acids). The chains are usually 10–24 carbon groups long. The head groups of the phospholipids found in biological membranes are phosphatidylcholine (lecithin), phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol, whose head group can be modified by the addition of one to three more phosphate groups. While phospholipids are the major component of biological membranes, other lipid components like sphingolipids and sterols (such as cholesterol in animal cell membranes) are also found in biological membranes.

Fatty acid: a fatty acid is a carboxylic acid (or organic acid), often with a long aliphatic tail (long chains), either saturated or unsaturated.Carboxylic acids are organic acids characterized by the presence of a carboxyl group, which has the formula -C(=O)-OH, usually written as -COOH. In general, the salts and anions of carboxylic acids are called carboxylates.The simplest series of carboxylic acids are the alkanoic acids, R-COOH, where R is a hydrogen or an alkyl group. Compounds may also have two or more carboxylic acid groups per molecule.

Saturated:1, a saturated compound has the maximum amount of hydrogens possible: i.e., no double bonds or, in a hydrocarbon chain, every carbon atom is attached to two hydrogen atoms. Of simple hydrocarbons, alkanes are saturated, and alkenes are unsaturated. In the modern treatment of electronic structure, unsaturated compounds are characterized by pi electron systems. The term is applied similarly to the fatty acid constituents of lipids, where the fat is described as saturated or unsaturated, depending on whether the constituent fatty acids contain carbon-carbon double bonds.

Unsaturated :is used when any carbon structure contains double or occasionally triple bonds. Many vegetable oils contain fatty acids with one (monounsaturated) or more (polyunsaturated) double bonds in them.

1. In biochemistry the term saturation refers to the fraction of total protein binding sites that are occupied at any given time.

What are the most important form of lipid in the body?

Fatty acids in the body link to glycerol to form mono,di-or triglycerides. triacylglycerols are the most important form of lipid in the body; more than 90% of our lipids a re in this form, triglyceride levels in the blood are also important as a predictor of artery disease, an elevated fasting triglyceride level is linked to a higher risk of disease.

steroid : is a lipid characterized by a carbon skeleton with four fused rings. Different steroids vary in the functional groups attached to these rings. Hundreds of distinct steroids have been identified in plants and animals. Their most important role in most living systems is as hormones. clolesterol is the source of steroids in the human body. It is also an important component of animal cells memberane.

clolesterol:is a sterol (a combination steroid and alcohol) and a lipid found in the cell membranes of all body tissues, and transported in the blood plasma of all animals.Most cholesterol is not dietary in origin, it is synthesized internally. Cholesterol is present in higher concentrations in tissues which either produce more or have more densely-packed membranes, for example, the liver, spinal cord and brain, and also in atheroma. Cholesterol plays a central role in many biochemical processes, but is best known for the association of cardiovascular disease with various lipoprotein cholesterol transport patterns and high levels of cholesterol in the blood.

Cholesterol is required to build and maintain cell membranes; it makes the membrane's fluidity - degree of viscosity - stable over bigger temperature intervalsCholesterol also aids in the manufacture of bile (which helps digest fats), and is also important for the metabolism of fat soluable vitamins, including vitamins A, D, E and K. It is the major precursor for the synthesis of vitamin D, of the various steroid hormones, including cortisol and aldosterone in the adrenal glands, and of the sex hormones progesterone, estrogen, and testosterone.

Cholesterol is minimally soluble in water; it cannot dissolve and travel in the water-based bloodstream. Instead, it is transported in the bloodstream by lipoproteins - protein "molecular-suitcases" that are water-soluble and carry cholesterol and fats internally. The proteins forming the surface of the given lipoprotein particle determine from what cells cholesterol will be removed and to where it will be supplied.

Eicosanoids: are a class of oxygenated hydrophobic molecules that largely function as autocrine and paracrine mediators. Eicosanoids derive from 20-carbon polyunsaturated essential fatty acids, most commonly arachidonic acid (AA) in humans. The IUPAC and the IUBMB use the equivalent term Icosanoid. The main eicosanoids are thromboxanes, leukotrienes, and prostaglandins. eicosanoids are regulatore of various physiological functions.

Essential fatty acids, or EFAs, are fatty acids that are required in the human diet. This means they cannot be synthesized by the body from other fatty acids and must be obtained from food.They were given the label "essential" when researchers found that removal of fatty acids from the diet harmed the normal growth of young children and animals

Protein : the most versatile biomolecules

Protein: is a complex, high-molecular-weight organic compound that consists of amino acids joined by peptide bonds.

Amino acid: 20 different amino acids commonly occur in natural proteins, and these building blocks may be assembled in an almost infinite number of combinations. They form short polymer chains called peptides or polypeptides which in turn form structures called proteins. The process of such formation is known as translation, which is part of protein synthesis.

all amino acids have a similar core structure: 1, a central carbon atom is linked to a hydrogen atom, 2, a nitrogen-containing amino group, 3, a carboxyle group, and 4, a groupd of atoms designated "R" that is different in each of the amino acids. The "R" groupd differ in their size, shape , and ability to form hydrogen bonds or ions. Because of thie R groups, each of the different amino acids reacts with other molecules in unqiue ways.

Essential amino acids: Human body can synthesize all but nine of the 20 protein-forming amino acids, those nine, which must come from dietary proteins, called essential amino acids.

Proteins are the major dietary source of nitrogen because the nitrogen in the amino acid group.

Several amino acids that do not occur in proteins but have important physiological functions:

Homocysteine: a sulfur-containing amino acid that occurs normally in the body but which in excess is linked to heart disease. Y-amino butyric acid(GABA): a chemical made by nerve cells; creatine: a molecule that stores energy when it bind to a phosphate group.

peptide bond: is a chemical bond formed between two molecules when the carboxyl group of one molecule reacts with the amino group of the other molecule, releasing a molecule of water (H₂O). This is a dehydration synthesis reaction, and usually occurs between amino acidsThe resulting C-NO bond is called a peptide bond, and the resulting molecule is called an amide. Polypeptides and proteins are chains of amino acids held together by peptide bonds. The backbone of PNA is also held together by peptide bonds. (peptide :2-9 amino acids in a amino acid chain)

Polypeptide: 10-100 amino acids. Protein: more than 100 amino acids.

Protein structure: Proteins fold into unique 3-dimensional structures. The shape into which a protein naturally folds is known as its native state, which is determined by its sequence of amino acids. Thus, proteins are their own polymers, with amino acids being the monomers. Biochemists refer to four distinct aspects of a protein's structure:

Primary structure: the primary structure of an unbranched biopolymer, such as a molecule of DNA, RNA or protein, is the specific nucleotide or peptide sequence from the beginning to the end of the molecule. The primary structure, in other words, identifies a biopolymer's exact chemical composition and the sequence of its monomeric subunits. determine and essential to proper function.

Secondary structure :highly patterned sub-structures — alpha helix and beta sheet — or segments of chain that assume no stable shape and are formed by hydrogen bonding. Secondary structures are locally defined, meaning that there can be many different secondary motifs present in one single protein molecule.

Tertiary structure: the 3-D shape of an amino acid chain. some long protein chains fold up into a ball or other compact shape when the R groups of amino acids in the a-helix are attracted to each other. the attraction may be between adjacent amino acids or between amino acids that are at different ends of the molecules.

In some proteins, the tertiary structure is held in place by hydrogen bonds. in other proteins, sulfur atoms in two different cysteine molecules bond covalently to each other in a disulfide bong(s-s).

Globular proteins: have amino acid chains that are folded into a ball-like shapes.comprising globelike proteins that are more or less soluble in aqueous solutions (where they form colloidal solutions). This main characteristic helps distinguishing them from fibrous proteins (the other class), which are pratically insoluble. 1, They act as carriers for insoluble lipids in the blood, binding to them and making them soluble. 2, they serve as enzymes that increase the rate of chemical reactions. 3, the also act as cell-to-cell messengers in the form of hormones and neurotransmitters and 4, as defense molecules to help fight foreign invaders.

Fibrous proteins, also called scleroproteins, are long filamentous protein molecules that form one of the two main classes of tertiary structure protein (the other being globular proteins). Fibrous proteins are only found in animals and are practically water-insoluble. This is due to hydrophobic R-groups which stick out of the molecule. They are usually used to construct connective tissues, tendons, bone matrix and muscle fibre.

Examples of fibrous proteins include keratins(hari and nail), collagens(coonective tissue) and elastins.

Quaternary structure: assemblies of more than one protein (polypeptide) molecule, which in the context of the larger assemblage are known as protein subunits. In addition to the tertiary structure of the subunits, multiple-subunit proteins possess a quaternary structure, which is the arrangement into which the subunits assemble. Enzymes composed of subunits with diverse functions are sometimes called holoenzymes, in which some parts may be known as regulatory subunits and the core is often called the catalytic subunit. Examples of proteins with quaternary structure include hemoglobin, DNA polymerase, and ion channels.

Conjugated proteins: are proteins molecules combined with another kind of biomolecule. Proteins combine with lipids to form lipiproteins which are found mostly in cell membranes.Proteins combine with carbohydrates to form glycoproteins: are important components of cell membranes. The carbohydrate portions of these molecules are usually found on the external surface of the cell, where they can form hydrogen bonds with water and other molecules in body fluids.

glycoproteins:The sugar group can assist in protein folding or improve its stability. Glycoproteins are often used in proteins that are at least in part located in extracellular space (that is, outside the cell). Glycoproteins are important for immune cell recognition, especially in mammals. Examples of glycoproteins in the immune system are:

• molecules such as antibodies (immunoglobulins), which interact directly with antigens
• molecules of the major histocompatibility complex (or MHC), which are expressed on the surface of cells and interact with T-cells as part of the adaptive immune response.

Other examples of glycoproteins include:

• components of the zona pellucida, which surrounds the oocyte, and is important for sperm-egg interaction.

Soluble glycoproteins often show a high viscosity, for example, in egg white and blood plasma.

Glycolipids :are believed to contribute to the stability of the cell membrane. are carbohydrate-attached lipids. Their role is to provide energy and also serve as markers for cellular recognition.They occur where a carbohydrate chain is associated with phospholipids in the cell surface membrane. The carbohydrates are found on the outer surface of all eukaryotic cell membranes.They extend from the phospholipid bilayer into the aqueous environment outside the cell where it acts as a recognition site for specific chemicals as well as helping to maintain the stability of the membrane and attaching cells to one another to form tissues.

Membrane receptor: bind to molecules outside the cell.

Cell marker: identify cells, like a label, so that the defense cells of the body can tell the difference between "self" and foreign invaders.

Nucleotides:Transmit and store energy and information

Nucleotides: play an important role in many of the processes of the cell, including the storage and transmission of genetic information and the transfer of energy.

Nucleotide: three part molecule: 1, one or more phosphate groups 2, a five-carbon sugar 3, a carbon-nitrogen ring structure called base.

What are the two possible sugars? (five carbon) : 1, ribose or deoxyribose

What are the two types of bases? 1, Purines and 2, pyrimidines. Pruines have a double ring structure: adenine and guanine. the pyrimidines have a single ring, three different pyrimidines: cytosine, thymine and uracil.

Examples of nucleotides: the smallest nucleotides includes the energy-transferring compounds ATP and ADP contain the base adnine, the sugar ribose and two or three phophate groups. cAMP(cyclic adenosine monophosphate) a molecule important in the transfer of aignals between the ECF and the cell. NAD (nicotinamide adenine dinucleotide) and FAD (flavin adenine dinucleotide)

What are nucleotides polymers?

DNA and RNA. they store genetic information within the cell and transmit it to future generations of cells. one complete DNA molecule with its associated proteins forms a chromosome.

What is DNA and RNA?

DNA stands for deoxyribonucleic acid. RNA is for ribonucleiacid. DNA contains the base AGCT. RNA AGCU. Both polymers are formed by linking nucleotides into long chains, similar to the long amino acid chains of proteins. The sugar of one nucleotide links to the phophate of the next, creating a chain or a backbone.

posted by C-T @ 6:24 PM