Biology 1406- Chapter 5 Objectives

List the four major classes of macromolecules.

-Carbohydrates. -Lipids -Proteins. -Nucleic Acids

Explain how weak interactions and disulfide bridges contribute to tertiary protein structure

1. Hydrophobic side chains clump together in the center of the protein by Van Der Waals reactions away from water. 2. Hydrogen bonds between ppolar side chain form weak bonds. 3. Ionic bonds form between charged side chains. 4. Disulfiude bridges form between the sulfur in 2 cysteines. The bridges stabalize the weak interactions.

Identify an ester linkage and describe how it is formed

A bond formed by dehydration synthesis between a hydroxyl group of glycerol and a carboxyl group of a fatty acid.

Describe the formation of a glycosidic linkage

A covalent bond between two monosacharides by a dehydration reaction.

List the major components of a nucleotide, and describe how these monomers are linked to form a nucleic acid.

A nucleotide includes a Phosphate group, a 5 carbon sugar, and a nitrogenous base. The phosphate group links two sugars together with a phosphodiester linkage.

Distinguish between a nucleotide and nucleoside.

A nucleotide is the entire monomer consisting of all three parts (Nucleo*T*ide = *T*otal). A nucleoside only contains two parts, the sugar and nitrogenous base (Nucleo*S*ide = *S*ome)

Explain how a peptide bond forms between two amino acids.

A peptide bond forms when a dehydration synthesis reaction happens between the carboxyl group at the end of one amino acid and the amino group at the end of an adjacent amino acid.

Distinguish between monomers and polymers.

A polymer is a long molecule consisting of many similar or identical building blocks linked by covalent bonds. (like a train consists of a chain of cars.) Monomers are the smaller, repeated molecule units that serve as the building blocks of a polymer

Distinguish between a protein and a polypeptide.

A polypeptide is a polymer of amino acids. A protein is a functional molecule made of one or more polypeptide each folded and coiled into a 3D shape.

Distinguish between pyrimidine and purine.

A pyrimidine has one six-membered ring of carbon and nitrogen atoms. (Cytosine, Thymine, Uracil). A purine has a six-membered ring fused to a five-membered ring of carbon and nitrogen atoms (Adenine, Guanine)

List and describe the four major components of an amino acid. Explain how amino acids may be grouped according to the physical and chemical properties of the R group.

An amino acid is made up of a central carbon(alpha carbon) with a hydrogen atom, an amino group, a carboxyl group, and a variable group referred to as the "R Group". Amino acids are grouped based on their R groups which can be Polar, Nonpolar, Hydrophyllic, or Hydrophobic.

Disaccharides

Consists of two monosacharides joined together by a glycosidic linkage.

Polysaccharides

Consists of two or more (typically a few hundred to a few thousand) joined by glycosidic linkages. Used for energy storage and building material.

Name the principal energy storage molecules of plants and animals.

Fat

Describe the building-block molecules, structure, and biological importance of fats (triglyceride).

Fats are constructed from glycerol and fatty acids. They a formed by three fatty acid chains joined to glycerol by an ester linkage. Fats are utilized mostly for energy storage as one gram of fat stores more than twice as much energy as a polysacharide.

List four conditions under which proteins may be denatured.

Heat, High salt content, pH levels,nonpolar solvents.

Monosaccharides

Monosaccharides are the building blocks of carbohydrates. They are simple sugars (usually multiple of CH2O). Made up of a carbonyl group and many hydroxyl groups. If the carbonyl group is in the middle it is a ketone sugar(Fructose), if it is at the end it is an aldehyde sugar (Glucose).

Describe the building-block molecules, structure, and biological importance of phospholipids.

Phospholipids are constructed form glycerol, fatty acids, and a phosphate group. They are formed by two fatty acid chains connected with an ester linkage to glycerol and a phosphate group taking the third connection. Phospholipids have a hydrophobic tail with a hydrophyllic head. Phospholipids form the membrane of a cell.

List the Four Levels of protein structure with their main properties.

Primary is the order of amino acids. Secondary is when the chains begin coiling (alpha helix) and folding (Beta pleated sheets) by hydrogen bonds in the backbones. Tertiary is when the side chains bond to form the overall 3D shape. Quaternary is the shape that forms when two or more polypeptide units aggregate together.

Saturated Fats.

Saturated fats have no double bonded carbons thus is "saturated" with hydrogen. The straight form of the fatty acids allow them to pack together tightly. They are solid at room temperature. Examples include butter and lard.

Distinguish between the glycosidic linkages found in starch and cellulose. Explain why the difference is biologically important.

Starch and cellulose are both polymers of glucose. However, when the glucose forms a ring, the hydroxyl group is positioned either below (alpha) or above (beta) the plane of the ring. Starch has the Alpha configuration making it helical and easier to break down. Cellulose has the Beta configuration making it more straight and able to bend back on itself forming cable-like microfibrils making it strong building material.

Describe the building-block molecules, structure, and biological importance of steroids.

Steroids are characterized by a carbon skeleton consisting of four fused rings. Different chemical groups attach to the ensemble of rings giving them different functions. An example of a common steroid is cholesterol.

Describe the role of symbiosis in cellulose digestion by animals.

Symbiosis is when two organisms live together in direst and intimate contact. This seen in cows and termites. Both have cellulose-digesting prokaryotes in their guts.

Distinguish between 5' end and 3' end of a nucleotide

The 5' end is where a phosphate group is attached to a 5' carbon. The 3' end is where a hydroxyl group is attached to a 3' carbon. All Polynucleotides have a built in directionality from the 5' end to the 3' end.

Explain how chaperonins may assist in proper folding of proteins.

The chaperonins keep the new polypeptide segregated from disruptive chemical conditions in the cytoplasmic environment while the protein folds spontaneously.

Why is the difference in glycosidic linkages of starch and cellulose biologically important?

The enzymes that break up the Alpha configurations of glucose are unable to break up the Beta configurations due to the different shapes. Cellulose is not able to be digested by animals or humans. Instead, it stimulates the cell walls as it passes through our system to secrete mucus, which aids in smooth passage of food through the tract.

Distinguish between ribose and deoxyribose.

The only differnece between the two sugars is that Deoxyribose lacks an oxygen atom on the 2nd carbon in the ring. (*DEOXY*ribose means it loses one oxygen)

Explain what determines the primary structure of a protein.

The primary structure is determined by the order of the amino acids.

Name two types of secondary protein structure. Explain the role of hydrogen bonds in maintaining secondary structure.

The two types of secondary structure include Alpha Helix's and Beta pleated sheets. The hydrogen bonds form between the backbones of polypeptides not the R groups. The bonds are between the partially negative oxygen on the carboxyl end and the partially positive hydrogen on the amino end.

Briefly describe the three-dimensional structure of DNA.

Two strands of DNA that are anti-parallel [run opposite directions form 5' to 3'(like a divided highway)] form a double helix structure around an imaginary axis.

Unsaturated Fats

Unsaturated fats contain one or more double bonds between carbons. These double bonds typically cause a kink in the chain. These kinks make it so that they can't pack tightly together to solidify at room temperature. Examples include oils (olive oil and vegetable oil).

Explain how DNA or protein comparisons may allow us to assess evolutionary relationships between species.

We can observe the protein sequence(amino acid sequence) of one species and compare it to the protein sequence of another species to compare how similar they are.

List and briefly describe three complementary approaches to determining protein structure.

X-Ray crystallography, Nuclear magnetic resonance spectroscopy, and Bioinformatics.