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Intro to cell and molec. bio
Chapter 5
54
Biology
Undergraduate 1
01/28/2007

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Term
Polymer
Definition
long molecule conssiting of many similar or identical building blocks linked by covalent bonds.
Term
Monomers
Definition
small molecules that are the repeating units that serve as the building blocks of a polymer.
Term
Condensation Reaction
Definition
Monomers are connected by a reaction in which two molecules are covalently bonded to each other through loss of a water molecule. Specifically, it is a DEHYDRATION REACTION because a water molecule is lost.
Term
Hydrolysis
Definition
(polymers are disassembled to monomers in this way) a process that is essentially the reverse of the dehydration reaction. Means to break with water. Bonds between monomers are broken by the addition of water molecules. (ex. digestion)
Term
Carbohydrates
Definition
include both sugars and their polymers.
Term
Monosaccharides
Definition
the simplest carbohyrates, single/simple sugars. Generally have molecular formula that are multiples of CH2O. Glucose (C6H12O6) is the most common monosaccharide.
Term
Disaccharide
Definition
consists of two monosaccharides joined by a GLYCOSIDIC LINKAGE (a covalent bond formed between two monosaccharides by a dehydration reaction).
Term
What does 2 glucose units form when they are bonded?
Definition
The glycosidic link joins the #1 carbon of one glucose to the #4 carbon of the second glucose...this is the dehydration synthesis of MALTOSE.
Term
What does glucose and fructose form?
Definition
sucrose 1-2 gly. link.
Term
Polysaccharides
Definition
macromolecules, polymers with a few hundred to a few thousand monosaccharides joined by glycosidic linkages. Some polysac. serve as storage material and other serve as building material for structures.
Term
Starch
Definition
a storage polysac. of plants, it is a polymer consisting entirely of glucose monomers. (AMYLOSE=unbranched; AMYLOPECTIN=branched) joined by 1-4 linkages.
Term
Glycogen
Definition
the storage polyac. of animals, a polymer of glucose that is similar to amylopectin, but MORE extensively branced. Humans and vertebrates store glycogen in liver and muscle cells. Hydrolysis of glycogen in these cells releases glucose when the demand for sugar increases.
Term
Cellulose
Definition
STRUCTURAL polysac. that is a major component of the tough walls taht enclose plant cells.(never branched)
Term
alpha and beta forms for glucose
Definition
alpha: when hydroxyl group attached to the #1 carbon is BELOW the ring. Beta: when the hydroxyl is ABOVE the ring.
Term
Chitin
Definition
(structural polysac.) used by anthropods to build exoskeletons.
Term
What are the four major classes of organic compounds in cells?
Definition
carbohydrates, lipids, proteins, and nucleic acids. Some of these compounds are very large and are called MACROMOLECULES. Most macro. are polymers.
Term
how does LIPID differ from the other biological molecules?
Definition
it does not include polymers.
Term
LIPIDS
Definition
compounds that are grouped together because they have LITTLE or NO AFFINITY for water (hydrophobic). Important families of lipids include fats, phospholipids, and steroids.
Term
Fat
Definition
Although fats are not polymers, they are made by dehydration reactions. It is constructed from two kinds of smaller molecules: glycerol and fatty acids.
Term
what is glycerol?
Definition
an alcohol wiht three carbons, each bearing a hydroxyl group.
Term
Fatty acid
Definition
include a long carbon skeleton , usually 16 or 18 carbon atoms in length. At one end is a carboxyl group (i.e. acid). Attached to the carboxyl is a long hydrocarbon chain. It is these nonpolar hydrocarbon chains that make fats hydrophobic.
Term
Triacylglycerol (TAG)
Definition
consists of three fatty acids ("tails") linked to one glycerol molecule ("head").
Term
How is TAG formed?
Definition
three fatty acids each join to glycerol by an ESTER LINKAGE, a bond between a hydroxyl grp and a carboxyl grp.
Term
Saturated fatty acid
Definition
at room temp., the molecules of a saturated fat are PACKED closely together, forming a SOLID. (there are no double bonds between carbon atoms)
Term
Unsaturated fatty acid
Definition
(has one or more double bonds) formd by the removal of hydrogen atoms from the carbon skeleton. It will have a kink in its talil wherever a double bond occurs. At room temp., the molecules CANNOT pack together closely enough to solidify becuase of the kinks.
Term
Are animal fats saturated or unsaturated? And plants?
Definition
animals=saturated ex. lard and butter. Plant and fish fats are oils.
Term
Phospholipids
Definition
similar to fats, but they have only TWO fatty acid tails rather than 3. The 3rd hydroxyl grp of glycerol is joined to a phosphate grp.(- charge). Tails=hydrophobic because of hydrocarbons. Phosphate gpr form a hydroPHILIC head.
Term
Steroids
Definition
lipids characterized by a carbon skeleton consisting of 4 fused rings.
Term
Cholesterol
Definition
(a steroid) a common component of animal cell membranes and is also the molecule from which other steroids (include sex hormones) are synthsized.
Term
Polypeptide
Definition
Polymers of amino acids
Term
Protein
Definition
consists of one ore more polypeptides folded and coiled into specific conformations. Proteins are all polymers made up of a same set of 20 amino acids.
Term
Amino Acids
Definition
organic molecules possessing both carboxyl and amino groups.
Term
Physical and chemical properties of R (side chains) of amino acids.
Definition
Amino acids with nonpolar side chains are hydrophobic. Polar is hydrophilic.
Term
Acidic and Basic amino acids
Definition
Acidic amino acids are those with side chains that are (-charge) becuase of a carboxyl grp, which is usually dissociated (IONIZED) at a cellular pH. Basic amino acids have amino grps in their side chain that is (+charge) Both acid and basic side chains are hydroPHILIC because they are charged.
Term
N-terminus and C-terminus
Definition
N=amino end...C=carboxyl end
Term
Primary structure
Definition
a protein's unique sequence of amino acids.
Term
Secondary Structure
Definition
the coiled or folded polypetide chain in patterns that contribute to the protein's overall conformation. These folds and coils are the result of hydrogen bonds at regular intervals along hte polypeptide backbone.
Term
Secondary structure (continued)...ALPHA helix...BETA pleated sheet
Definition
Only the atoms of the backbone are involved,not the amino acid side chains. Nitrogen and oxygen atoms are hydrogen bonded to a nearby peptide bond. The ALPHA helix is a coil held together by hydrogen bonding between every 4th amino acid. The BETA pleated sheet is when 2 or more regions of the polypeptide chain lie parallel to each other.
Term
Tertiary Structure
Definition
Consists of irregular contortions from interactions between side chains (R grps) of the various amino acids.
Term
Tertiary structure (continued) HYDROPHOBIC INTERACTION, DISULFIDE BRIDGES
Definition
Hydrophobic side chains usually end up in the interior of a protein, away from water. Along with this clustering of hydrophobic gropus, misleadingly called hydrophobic interactions, hydrogen bonds, ionic bonds, and van der Waals interactions are all weak interactions (weak bonds) between side chains that hold the protein in a specific conformation. HOWEVER, MUCH STRONGER, are the disulfide bridges, covalent bonds between the side chains of 2 cysteine amino acids.
Term
Quarternary Structure
Definition
The overall structure that results from the aggregation (2 or more) of these polypeptide subunit to form a functional protein.
Term
What determines protein conformation?
Definition
Depends on the physical and chemical conditions of the protein's environment.
Term
Denaturation
Definition
If the pH, salt concentration, temperature, or other aspects of its envrionment are altered, the protein may unravel and lose its native conformation.
Term
Chaperonins (chaperone proteins)
Definition
protein molecules that assist the proper folding of other proteins.
Term
Gene
Definition
the amino acid sequence of a polypeptide is programmed by this unit of inheritance.
Term
Nucleic acids
Definition
Genes consist of DNA, which is a polymer belonging to this class of compounds.-->Nucleic acids store and transmit hereditary information
Term
Deoxyribonucleic Acid (DNA)
Definition
(type of nucleic acid) Provides directions for its own replication. Also directs RNA synthesis, and through RNA, controls protein synthesis. DNA is the genetic material that organisms inherit from their parents.
Term
Flow of genetic information?
Definition
DNA -> RNA -> Protein
Term
Nucleotides
Definition
Nucleic acids are polymers of monomers. It is composed of : an organic molecule called a nitrogenous base, a pentose (5-carbon sugar), and a phosphate group.
Term
The 2 families of nitrogenous bases: PYRIMIDINES, and PURINES
Definition
A PYRIMINIDINE has a 6-membered ring of carbon and nitrogen atoms. Members of this family are cytosine (C), thymine (T), and uracil (U)...PURINES are larger , with the 6-member ring fused to a 5-membered ring. Include adenine (A) and guanine (G).***THYMINE is found only in DNA, and URACIL is found only in RNA*** the others are found in BOTH.
Term
Ribose and Deoxyribose
Definition
The pentose connected to the nitrogenous base is RIBOSE in the nucleotides of RNA and DEOXYRIBOSE(it lacks and oxygen atom on its #2 carbon) in DNA.
Term
POLYNUCLEOTIDE
Definition
A nucleic acid polymer; nucleotides are joined by covalent bonds called PHOSPHODIESTER LINKAGES between teh phosphate of 1 nucleotide and the sugar of the next.
Term
Base pairing in the double helix
Definition
Adenine(A)-with-Thymine(T); and Guanine(G)-with-Cytosine(C). The 2 strands of the double helix are COMPLEMENTARY, each predicts its counterpart. Each of the 2 stands of DNA serves as a template...results in 2 identical copies.
Term
Importance of DNA
Definition
The linear sequences of nucleotides in DNA molecules are passes from parents to offspring, and these DNA sequences determine the amino acid sequences of proteins.
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