Sorry, I am kind of in a hurry, so I cannot individually answer your questions, but I will copy some information for you. Which may help you on your test.
Carbs, also known as saccharides, are organic molecules that are used as energy sources, structural molecules and as components of other biological molecules.
Inorganic and Organic Molecules
Even the experts don’t agree on how to define the difference between organic and inorganic substances, but a good, broad definition is as follows.
Inorganic molecules are essentially substances that don’t have carbon-hydrogen (C-H) bonds, whereas organic molecules are substances that contain carbon-hydrogen bonds, are found in living things.
The major classes of organic molecule include carbohydrates, proteins, lipids and nucleic acids.
Carbohydrates
The term carbohydrate is actually a descriptor of what these molecules are composed of. They are “carbon hydrates,” in a ratio of one carbon molecule to one water molecule (CH2O)n.
You may y recognize carbohydrates as source of energy (starch, glycogen), but they fulfill a wide range of roles, including the structural materials of plants (cellulose in plant cell walls) and of some animals chitin of an insect’s exoskeleton.
Carbohydrates can also be components of other molecules such as DNA, RNA, glycolipids, glycoproteins, and adenosine tri phosphate (ATP)
Saccharides
The word saccharide is a synonym for carbohydrate and is generally preceded with a prefix indicating the size of the molecule (mono-, di-, tri- poly-).
Monosaccharides
single sugars (one molecule)
simplest
examples are glucose and fructose
Disaccharides
double sugars
combination of two monosaccharides
sucrose = glucose + fructose
lactose = glucose + galactose
Polysaccharides
polymers composed of several sugars
can be same monomer (many of same monosaccharide) or mixture of monomers
glycogen is the major stored carbohydrate in animals
starch is storage polysaccharide of plants. It is a long chain of glucose molecules.
chitin is a structural carb in some animals
cellulose is the major structural carbohydrate in plants
Building and Breaking Down Sugars
Dehydration and hydrolysis are chemical reactions that make bigger (dehydration) and smaller (hydrolysis).
Dehydration Reactions
Dehydration is when one molecule contributes a hydrogen (H) and the other a hydroxyl group (OH), therefore the removal of a water molecule (H2O) results in the joining of two smaller molecules. With respect to carbohydrates, dehydration reactions make bigger carbohydrate molecules from smaller sugars.
Hydrolysis Reactions
Hydrolysis is the reverse of dehydration and is when the addition of a water molecule breaks (lyses) a larger molecule into two smaller molecules. With respect to carbohydrates hydrolysis, the bonds on the larger carbohydrate are broken through the addition of water. One of the smaller molecules receives a hydrogen (H) and the other received a hydroxyl group (OH)
Living organisms are complex systems. Hundreds of thousands of proteins exist inside each one of us to help carry out our daily functions (see the Fats and Proteins lesson for more information). These proteins are produced locally, assembled piece-by-piece to exact specifications. An enormous amount of information is required to manage this complex system correctly. This information, detailing the specific structure of the proteins inside of our bodies, is stored in a set of molecules called nucleic acids.
The nucleic acids are very large molecules that have two main parts. The backbone of a nucleic acid is made of alternating sugar and phosphate molecules bonded together in a long chain, represented below:
sugar phosphate sugar phosphate ...
Each of the sugar groups in the backbone is attached (via the bond shown in red) to a third type of molecule called a nucleotide base:
nucleotide
base nucleotide
base
| |
sugar phosphate sugar phosphate ...
Though only four different nucleotide bases can occur in a nucleic acid, each nucleic acid contains millions of bases bonded to it. The order in which these nucleotide bases appear in the nucleic acid is the coding for the information carried in the molecule. In other words, the nucleotide bases serve as a sort of genetic alphabet on which the structure of each protein in our bodies is encoded.
DNA
In most living organisms (except for viruses), genetic information is stored in the molecule deoxyribonucleic acid, or DNA. DNA is made and resides in the nucleus of living cells. DNA gets its name from the sugar molecule contained in its backbone(deoxyribose); however, it gets its significance from its unique structure. Four different nucleotide bases occur in DNA: adenine (A), cytosine (C), guanine (G), and thymine (T).
Chemical Structure of the DNA Nucleotides
These nucleotides bind to the sugar backbone of the molecule as follows:
A T G C
sugar phosphate sugar phosphate sugar phosphate sugar ...
The versatility of DNA comes from the fact that the molecule is actually double-stranded. The nucleotide bases of the DNA molecule form complementary pairs: The nucleotides hydrogen bond to another nucleotide base in a strand of DNA opposite to the original. This bonding is specific, and adenine always bonds to thymine (and vice versa) and guanine always bonds to cytosine (and vice versa). This bonding occurs across the molecule, leading to a double-stranded system as pictured below:
sugar phosphate sugar phosphate sugar phosphate sugar ...
T A C G
¦ ¦ ¦ ¦
A T G C
sugar phosphate sugar phosphate sugar phosphate sugar ...
In the early 1950s, four scientists, James Watson and Francis Crick at Cambridge University and Maurice Wilkins and Rosalind Franklin at King's College, determined the true structure of DNA from data and X-ray pictures of the molecule that Franklin had taken. In 1953, Watson and Crick published a paper in the scientific journal Nature describing this research. Watson, Crick, Wilkins and Franklin had shown that not only is the DNA molecule double-stranded, but the two strands wrap around each other forming a coil, or helix. The true structure of the DNA molecule is a double helix, as shown at right.
The double-stranded DNA molecule has the unique ability that it can make exact copies of itself, or self-replicate. When more DNA is required by an organism (such as during reproduction or cell growth) the hydrogen bonds between the nucleotide bases break and the two single strands of DNA separate. New complementary bases are brought in by the cell and paired up with each of the two separate strands, thus forming two new, identical, double-stranded DNA molecules. This concept is illustrated in the animation below.
The Replication of DNA
Concept simulation - Reenacts replication of DNA.
(Flash required)
RNA
Ribonucleic acid, or RNA, gets its name from the sugar group in the molecule's backbone - ribose. Several important similarities and differences exist between RNA and DNA. Like DNA, RNA has a sugar-phosphate backbone with nucleotide bases attached to it. Like DNA, RNA contains the bases adenine (A), cytosine (C), and guanine (G); however, RNA does not contain thymine, instead, RNA's fourth nucleotide is the base uracil (U). Unlike the double-stranded DNA molecule, RNA is a single-stranded molecule. RNA is the main genetic material used in the organisms called viruses, and RNA is also important in the production of proteins in other living organisms. RNA can move around the cells of living organisms and thus serves as a sort of genetic messenger, relaying the information stored in the cell's DNA out from the nucleus to other parts of the cell where it is used to help make proteins.
A U G C
sugar phosphate sugar phosphate sugar phosphate sugar ...
RNA
The active site of an enzyme contains the catalytic and binding sites. The structure and chemical properties of the active site allow the recognition and binding of the substrate.
The active site is usually a small pocket at the surface of the enzyme that contains residues responsible for the substrate specificity (charge, hydrophobicity, steric hindrance) and catalytic residues which often act as proton donors or acceptors or are responsible for binding a cofactor such as PLP, TPP or NAD. The active site is also the site of inhibition of enzymes
There are two proposed models of how enzymes work: the lock-and-key model and the induced fit model. The lock-and-key model assumes that the active site is a perfect fit for a specific substrate and that once the substate binds to the enzyme no further modification is necessary, this is simplistic. The induced fit model is a devlopment of the lock and key model and instead assumes that an active site is more flexible and that the presence of certain residues (amino acids) in the active site will encourage the enzyme to locate the correct substrate. After which conformational changes may occur as the substrate is bound.
Substrates bind to the active site of the enzyme or a specificity pocket through hydrogen bonds, hydrophobic interactions, temporary covalent bonds (van der waals) or a combination of all of these to form the enzyme-substrate complex. Residues of the active site will act as donors or acceptors of protons or other groups on the substrate to facilitate the reaction. In other words, the active site modifies the reaction mechanism in order to decrease the activation energy of the reaction. The product is usually unstable in the active site due to steric hindrances that force it to be released and return the enzyme to its initial unbound state.
Kinds of nucleic acids
The term nucleic acid refers to a whole class of compounds that includes dozens of different examples. The phosphate (P) group in all nucleic acids is exactly alike. However, two different kinds of sugars are found in nucleic acids. One kind of sugar is called deoxyribose. The other kind is called ribose. The difference between the two compounds is that deoxyribose contains one oxygen less (deoxy means "without oxygen") than does ribose. Nucleic acids that contain the sugar deoxyribose are called deoxyribonucleic acid, or DNA; those that contain ribose are called ribonucleic acid, or RNA.
Nucleic acids also contain five different kinds of nitrogen bases. The names of those bases and the abbreviations used for them are adenine (A), cytosine (C), guanine (G), thymine (T), and uracil (U). Deoxyribonucleic acids all contain the first four of these nitrogen bases: A, C, G, and T. Ribonucleic acids all contain the first three (A, C, G) and uracil, but not thymine.
DNA and RNA molecules differ from each other, therefore, with regard to the sugar they contain and with regard to the nitrogen bases they contain. They differ in two other important ways: their physical structure and the role they play in living organisms.
Deoxyribonucleic acids (DNA). A single molecule of DNA consists of two very long strands of nucleotides, similar to the structure of all nucleic acids. The two strands are lined up so that the nitrogen bases extending from the sugar-phosphate backbone face each other. Finally, the two strands are twisted around each other, like a pair of coiled telephone cords wrapped around each other. The twisted molecule is known as a double helix.
The function of DNA. One of the greatest discoveries of modern biology occurred in 1953 when the American biologist James Watson (1928– ) and the English chemist Francis Crick (1916– ) uncovered the role of DNA in living organisms. DNA, Watson and Crick announced, is the "genetic material," the chemical substance in all living cells that passes on genetic characteristics from one generation to the next. How does DNA perform this function?
When a biologist says that genetic characteristics are passed from one generation to the next, one way to understand that statement is to say that offspring know how to produce the same kinds of chemicals they need in their bodies as do their parents. In particular, they know how to produce the most important of all chemicals in living organisms: proteins. Proteins are essential to the function and structure of all living cells.
Watson and Crick said that the way nitrogen bases are lined up in a DNA molecule constitute a kind of "code." The code is not all that different from codes you may use with your friends: A = 1, B = 2, C = 3, and so on. In DNA, however, it takes three nitrogen bases to form a code. For example, the combination CGA means one thing to a cell, the combination GTC another, the combination CCC a third, and so on.
Each possible combination of three nitrogen bases in a DNA molecule stands for one amino acid. Amino acids are the chemical compounds from which proteins are formed. For example, the protein that tells a body to make blue eyes might consist of a thousand amino acids arranged in the sequence A15-A4-A11-A8-A5- and so on. What Watson and Crick said was that every different sequence of nitrogen bases in a DNA molecule stands for a specific sequence of amino acid molecules and, thus, for a specific protein. In the example above, the sequence N4-N1-N2-N3-N4-N3-N3-N1-N4 might conceivably stand for the amino acid sequence A15-A4-A11-A8-A5- which, in turn, might stand for the protein for blue eyes.
When any cell sets about the task of making specific chemicals for which it is responsible, then, it "looks" at the DNA molecules in its nucleus. The code contained in those molecules tells the cell which chemicals to make and how to go about making them.
Ribonucleic acid. So what role do ribonucleic acid (RNA) molecules play in cells? Actually that question is a bit complicated because there are at least three important kinds of RNA: messenger RNA (mRNA); transfer RNA (tRNA); and ribosomal RNA (rRNA). In this discussion, we focus on only the first two kinds of RNA: mRNA and tRNA.
DNA is typically found only in the nuclei of cells. But proteins are not made there. They are made outside the cell in small particles called ribosomes. The primary role of mRNA and tRNA is to read the genetic message stored in DNA molecules in the nucleus, carry that message out of the nucleus and to the ribosomes in the cytoplasm of the cell, and then use that message to make proteins.
The first step in the process takes place in the nucleus of a cell. A DNA molecule in the nucleus is used to create a brand new mRNA molecule that looks almost identical to the DNA molecule. The main difference is that the mRNA molecule is a single long strand, like a long piece of spaghetti. The nitrogen bases on this long strand are a mirror image of the nitrogen bases in the DNA. Thus, they carry exactly the same genetic message as that stored in the DNA molecule.
Once formed, the mRNA molecule passes out of the nucleus and into the cytoplasm, where it attaches itself to a ribosome. The mRNA now simply waits for protein production to begin.
In order for that step to take place, amino acid molecules located throughout the cytoplasm have to be "rounded up" and delivered to the ribosome. There they have to be assembled in exactly the correct order, as determined by the genetic message in the mRNA molecule.
The "carriers" for the amino acid molecules are molecules of transfer RNA (tRNA). Each different tRNA molecule has two distinct ends. One end is designed to seek out and attach itself to some specific amino acid. The other end is designed to seek out and attach itself to some specific sequence of nitrogen bases. Thus, each tRNA molecule circulating in the cell finds the specific amino acid for which it is designed. It attaches itself to that molecule and then transfers the molecule to a ribosome. At the ribosome, the opposite end of the tRNA molecule attaches itself to the mRNA molecule in just the right position. This process is repeated over and over again until every position on the mRNA
A computer-generated model of RNA. (Reproduced by permission of Photo Researchers, Inc.)
molecule holds some specific tRNA molecule. When all tRNA molecules are in place, the amino acids positioned next to each other at the opposite ends of the tRNA molecules join with each other, and a new protein is formed.
Lipids are broadly defined as any fat-soluble (lipophilic), naturally-occurring molecules, such as fats, oils, waxes, cholesterol, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The main biological functions of lipids include energy storage, acting as structural components of cell membranes, and participating as important signaling molecules.
According to my memory, the other people who answered your question do have the right answers. Good luck on your test.