Flashcards in Chapter 5 - Test Review Deck (51):
What are macromolecules?
Giant molecules formed by the joining of smaller molecules (usually by a dehydration reaction). Composed of thousands of covalently connected atoms.
What are monomers? How are they used to build polymers?
Small building block molecules. Repeating units that serve as the building blocks of a polymer. A polymer is a long chain of molecules consisting of many similar or identical building blocks linked by covalent bonds. A polymer is a chain of monomers.
What are the 4 classes of macromolecules? Name their monomers (M), polymers (P) and the types of linkages (L) between the monomers.
1. Sugars (Carbohydrates) - M; monosaccharide - P; polysaccharide - L; glycosidic
2. Lipids - M; fatty acids - P; triacylglycerols - L; ester linkage
3. Proteins - M; amino acids - P; polypeptides - L; peptide bond
4. Nucleic Acids - M; nucleotides - P; polynucleotides - L; phosphodiester
What is a dehydration reaction?
Monomers are connected by a reaction in which two molecules are covalently bonded to each other, with the loss of a water molecule. When this bond forms, each monomer contributes part of the water molecule. One monomer provides the hydroxyl group (-OH) and the other provides a hydrogen (-H). These reactions are repeated as monomers are added to the chain, 1 by 1, creating a polymer.
What is a hydrolysis reaction? Give an example.
Essentially the reverse of the dehydration reaction. Hydrolysis means water breakage. The bond between monomers is broken as polymers are disassembled. The bond is broken by the addition of a water molecule with the hydroxyl attaching to one group and the hydrogen to another. Example - digestion.
What are carbohydrates?
Sugars and the polymers of sugars.
What are monosaccharides, disaccharides, and polysaccharides?
1. The simplest of sugars are monosaccharides or simple sugars. Monosaccharides generally have molecular formulas that are some multiple of the unit CH2O. Glucose (C6H12O6) is the most common monosaccharide.
2. Disaccharides are double sugars joined by covalent bonds; or two monosaccharides joined by a glycosidic linkage (a covalent bond formed by a dehydration reaction). The most common disaccharide is sucrose (table sugar) and is composed of glucose + fructose.
3. Polysaccharides are macromolecules; or polymers with a few hundred to a few thousand monosaccharides joined by glycosidic linkages.
How are monosaccharides classified?
1. The location of the carbonyl group. Monosaccharides have a carbonyl group (CO) and multiple hydroxyl groups (-H). Sugars vary in their location of the carbonyl group. When the carbonyl group is at the end of the carbon skeleton, that sugar is known as an aldehyde sugar (ALDOSES). When the carbonyl group is within the carbon skeleton, that sugar is known as a ketone sugar (KETOSES).
2. Another criteria for classifying sugars is the size of the carbon skeleton (from 3-7 carbons long). Skeletons with 6 carbons are called HEXOSES; i.e. glucose, galactose, and fructose. Skeletons with 5 carbon sugars are called PENTOSES; i.e. ribose and ribulose. Skeletons with 3 carbons are called TRIOSES; i.e. glyceraldehyde and dihydroxyacetone.
What is an aldehyde?
An aldehyde sugar is when the carbonyl group is at the end of the carbon skeleton.
What is a ketone?
A ketone sugar is when the carbonyl group is within (in the middle) of the carbon skeleton.
What is a glycosidic bond? What are the different glycosidic bonds?
A covalent bond formed by a dehydration reaction.
1. Maltose - 2 glucose molecules
2. Sucrose - glucose and fructose (most present disaccharide)
3. Lactose - glucose and galactose
Distinguish between the glycosidic bonds of starch and cellulose.
1. Starch; most glucose monomers are joined by a 1-4 linkage of alpha glucose monomers. All of the glucose monomers are in the a (alpha) configuration. The monomers are in the same orientation (pointing down).
2. Cellulose - consist of glucose monomers joined by 1-4 B (beta) glycosidic linkages. Every B glucose monomer is upside down with respect to its neighbors (every other; up, down, up, down, etc.)
What are the functions of carbohydrates?
Fuel; building material; energy storage; biosynthesis; structure; cell recognition / adhesion
What are the 3 polysaccharides of plants and animals? What are their functions?
1. Starch - stored energy in plants; stored in structures called plastids. Two kinds of starch; amylose (unbranched) and amylopectin (somewhat branched)
2. Glycogen - stored energy in muscle cells; branched
3. Cellulose - fibers in plant cell walls; all polysaccharides composed entirely of glucose monomers. Always unbranched; hydrogen bonds between parallel cellulose molecules hold them together
*In starch and glycogen, the polymer chains tend to form helices in unbranched regions because of the angle of the linkages between glucose molecues
What are lipids?
A diverse group of hydrophobic molecules; soluble in fat, but insoluble in water.
What are some functions of lipids?
Energy storage; major component of cell membranes; cell signaling; insulation and cushioning
What distinguishes lipids from other macromolecules?
The one class of biological molecules that does not include true polymers, and they are generally not big enough to be considered macromolecules. They share one important trait, which is their hydrophobic nature. Because lipids consist of mostly hydrocarbon regions, they mix poorly with water.
What are the three types of lipids? And what are their building blocks?
1. Fats - fatty acids
2. Phospholipids - phosphate group + 2 fatty acids
3. Steroids - a carbon skeleton consisting of four fused rings
What are fats? What are fatty acids? What are their building blocks, properties, and importance?
Fats are constructed of two kinds of smaller molecules; glycerol + fatty acids, which are their building blocks.
Fatty acids are composed of a long hydrocarbon chain, usually 16-18 carbons with a carboxyl (-COOH) group at one end.
In order to form triacylglycerols, 3 fatty acids are joined to glycerol by an ester linkage (a bond formed by a dehydration reaction) between a hydroxyl group (-OH) and a carboxyl group (-COOH).
The resulting fat, a triacylglycerol is an important energy source.
What is an ester linkage?
A covalent bond formed by a dehydration reaction between a hydroxyl group (-OH) and a carboxyl group (-COOH). A linkage between fatty acids.
What is the difference between a saturated fat and an unsaturated fat?
1. Saturated fatty acid - no double bonds between carbon atoms; such a structure is saturated with hydrogen; solid at room temperature (i.e. butter); most animal fats are saturated
2. Unsaturated fatty acid - one or more double bonds with one fewer hydrogen atom on each double bonded carbon; liquid at room temperature (i.e. vegetable oils); plant fats and fish fats are usually unsaturated
What is a trans fat?
An unsaturated fat formed artificially during hydrogenation of oils and contains one or more trans double bonds
Where to humans and animals store their fats?
In adipose cells, which swell and shrink as fat is deposited or withdrawn; adipose tissue also cushions vital organs
What are phospholipids? What are their building blocks, properties, and importance?
Essential for cells because they are the major component of cell membranes.
BB; Phospholipids are similar to a fat but have only 2 fatty acids attached to a glycerol, as well as a phosphate group with a charged organic molecule.
P; When phospholipids are added to water, they self assemble into double layered structures called bilayers, with the hydrophobic tails pointing toward the interior, shielding their hydrophobic tails from water
What are steroids? What are their building blocks, properties, and importance?
Steroids are lipids characterized by a carbon skeleton consisting of four fused rings with attached chemical groups. Different steroids are characterized by the particular chemical group attached to the ensemble of rings.
Steroid hormones contain 4 hydrocarbon rings with distinct functional groups and act as signaling molecules.
Cholesterol is an example of one type of steroid and is a crucial molecule in animals. It is a common component of animal cell membranes and is also the precursor from which other steroids, such as the vertebrate sex hormones are synthesized.
What are proteins?
The most diverse of all the macromolecules in cells as cells contain thousands of different proteins which perform a variety of functions. Proteins account for more than 50% of the dry mass of most cells.
*A protein is a biologically functional molecule made up of one or more polypeptides, each folded and coiled into a specific 3D shape and each have a unique and specific function.
What are the building blocks of a protein? What kind of bonds do amino acids form?
Amino acids. A peptide bond is the bond between amino acids.
What is the basic structure of an amino acid? What are the 4 components?
An organic molecule with both an amino group (-NH2) and a carboxyl group (-COOH)
The center of the amino acid is an asymmetric carbon atom called the alpha carbon. Its four different partners are;
1. Amino group
2. Carboxyl group
3. Hydrogen atom
4. R group (side chain)
What is a polymer of amino acids called?
How does a peptide bond form?
When 2 amino acids are positioned so that the carboxyl (-COOH) group of one is adjacent to the amino (-NH2) group of the other, they can become joined by a dehydration reaction, with the removal of a water molecule. The resulting bond is called a peptide bond.
Describe the linkage between amino acids.
Amino acids form peptide links when the carboxyl group (-COOH) links with the amino group (-NH2). Amino acids are also grouped according to the properties of their side chains. Some groups consist of non polar side chains, which are hydrophobic. Another group consists of amino acids with polar side chains, which are hydrophilic. Amino acids can be acidic or basic. Amino acids with side chains that are positively charged are basic and amino acids with side chains that are negatively charged are acidic. Both of these are hydrophilic.
Describe a protein vs. a polypeptide vs. a peptide.
A functional protein is not just a polypeptide chain, but one or more polypeptides precisely twisted, folded, and coiled into a molecule of unique shape. It is the amino acid sequence of each polypeptide that determines what 3D structure the protein with have under normal cellular conditions, and thus the function it will perform.
What are the 8 types of proteins and their functions?
1. Enzymatic proteins - selective acceleration of chemical reactions; i.e. digestive enzymes catalyze the hydrolysis of bonds in food molecules for energy.
2. Storage proteins - store amino acids; i.e. casein, the protein of milk, is the major source of amino acids for baby mammals. Plants have storage proteins in their seeds.
3. Hormonal proteins - coordinate an organism's activities and responses; i.e. insulin causes other tissues to take up glucose, thus regulating blood sugar concentration.
4. Motor proteins - function in cell movement; i.e. responsible for the undulations of cilia and flagella. Actin and myosin proteins are responsible for the contraction of muscles.
5. Defensive proteins - protect against disease; i.e. antibodies inactivate and help destroy viruses and bacteria.
6. Transport proteins - transport substances; i.e. hemoglobin, the iron containing protein of vertebrate blood, transports oxygen from the lungs to other parts of the body. Other proteins transport molecules across membranes.
7. Receptor proteins - receives signals from chemical stimuli outside of the cell; i.e. receptors built into the membrane of a nerve cell detect signaling molecules released by other nerve cells.
8. Structural proteins - provide structural support; i.e. keratin is the protein of hair, horns, feathers, and other skin appendages. Collagen and elastin proteins provide a fibrous framework in animal connective tissue.
What are the 20 amino acids of proteins? How are they grouped? What are the bonds that form?
Nonpolar side chains; hydrophobic;
1. Glycine (G)
2. Alanine (A)
3. Valine (V)
4. Leucine (L)
5. Isoleucine (I)
6. Methionine (M)
7. Phenylalanine (F/Phe)
8. Tryptophan (W/Trp)
9. Proline (P)
Polar side chains; hydrophilic;
10. Serine (S)
11. Threonine (T)
12. Cysteine (C)
13. Tyrosine (Y/Try)
14. Asparagine (N/Asn)
15. Glutamine (Q/Gln)
Electrically charged side chains; hydrophilic;
Acidic (negatively charged)
16. Aspartic acid (D/Asp)
17. Glutamic acid (E/Glu)
Basic (positively charged)
18. Lysine (K/Lys)
19. Arginine (R/Arg)
20. Histidine (H/His)
*Bonds; Peptide bonds are formed between amino acids by a dehydration reaction when the carboxyl group (-COOH) of one amino acid links to the amino group (-NH2) of another amino acid. Th peptide bonds are formed one at a time, starting with the amino acid at the amino end (N-terminus). The polypeptide has a repetitive backbone to which the amino acid side chains are attached.
What are the 4 levels of protein structure? What are the key molecular interactions needed to maintain each?
1. Primary - the sequence of amino acids in a protein; the primary structure is determined by inherited genetic information; i.e. like the order of letters in a long word;
+H3N (amino end) + G+P+T+G...+ -COOH (carboxyl end)
2. Secondary - coils and folds due to the result of hydrogen bonds between the repeating components of the polypeptide backbone; i.e.
Alpha (a) helix - a delicate coil held together by hudrogen bonding between every 4th amino
B (Beta) pleated sheet - 2 or more segments of the polypeptide chain lying side by side (B strands) and connected by hydrogen bonds between parts of the two parallel segments of the polypeptide backbone
3. Tertiary - the final 3D shape stabilized by interactions between side chains; i.e.
a. Hydrophobic exclusion and van der Walls
b. Ionic bonds between side groups
c. Disulfide bonds between cysteine side groups
d. Hydrogen bonds between side groups
4. Quaternary - forms when two or more polypeptide chains associate for form a functional protein; i.e.
a. Collagen - three helical polypeptides intertwined (collagen accounts for 40% of the protein in the human body)
b. Hemoglobin - four polypeptide subunits
What is denaturation?
The loss of a protein's native structure. This can happen when the pH, salt concentration, temperature, or other aspects of a protein's environment are altered. The weak chemical bonds and interactions within a protein may be destroyed, causing the protein to unravel and lose its shape. Once it is misshapen, the denatured protein is now biologically inactive.
What are chaperonins? What are their functions?
Protein molecules that assist in the proper folding of other proteins. They are crucial to the folding process of proteins as they keep polypeptides segregated from disruptive chemical conditions in the cytoplasmic environment by creating a cylinder with a hydrophilic environment for the polypeptide to fold.
What are nucleic acids?
Polymers made of monomers called nucleotides. Macromolecules that exist as polymers called polynucleotides.
What are the building blocks of a nucleic acids?
What are the two types of nucleic acids?
1. Deoxyribonucleicacid; DNA
2. Ribonucleicacid; RNA
What are genes?
Consist of DNA and are responsible for programming the amino acid sequence of a polypeptide
What are the basic components of a nucleotide? Draw it.
1. A 5 carbon sugar
2. A nitrogenous base
3. One or more phosphate groups
What are the functions of DNA?
Provides directions for its own replication and directs the synthesis of messenger RNA (mRNA). Through mRNA, DNA controls protein synthesis, which occurs in ribosomes.
What is the process of gene expression?
DNA ---> RNA ---> Protein
What are the functions of DNA and RNA (nucleic acids)?
Store and transmit hereditary information;
DNA - stores all hereditary information
RNA - carries protein-coding instructions from DNA to protein synthesizing machinery
What are the differences between DNA and RNA?
a. Sugar - deoxyribose (lacks an oxygen atom)
b. Nitrogenous base - C (cytosine), G (guanine), A (adenine), T (thymine)
c. Usually double stranded helix
a. Sugar - ribose
b. Nitrogenous base - C (cytosine), G (guanine), A (adenine), U (uracil); adenine pairs with uracil as thymine is not present in RNA
c. Usually single stranded and more variable in shape
What are the 2 families of nitrogenous bases found in DNA and RNA?
1. Pyrimidines - one six membered ring of carbon and nitrogen atoms
a. Cytosine (C)
b. Thymine (T) - only DNA
c. Uracil (U) - only RNA
2. Purines - larger, a six membered ring fused to a fine membered ring
a. Adenine (A)
b. Guanine (G)
What is deoxyribose?
The sugar component in DNA, which is attached with the nitrogenous base. Lacks an oxygen atom.
What is ribose?
The sugar component in RNA.
What are disulfide bonds?
A strong covalent bond (disulfide bridge) formed when the sulfur of one cysteine monomer bonds to the sulfur of another cysteine monomer.