Chapter 5: Large Biological Molecules Structure And Function Flashcards
Condensation Reaction
A reaction in which two molecules are covalently bonded to each other with the loss of a small molecule
Dehydration Reaction
A chemical reaction in which two molecules become covalently bonded to each other with the removal of a water molecule
Functions in the assembly of monomers to polymers
Hydrolysis
A chemical reaction that breaks bonds between two molecules by the addition of water
Functions in the disassembly of polymers to monomers
Monosaccharide
The simplest carbohydrate, active alone or serving as a monomer for disaccharides and polysaccharides
Have a molecular formula that is some multiple of CH2O
Have a carbonyl group and multiple hydroxyl groups
Disaccharide
A double sugar, consisting of two monosaccharides joined by a glycosidic linkage formed by a dehydration reaction
Must be broken down by organisms to be used for energy
Maltose - 2 glucose
Sucrose - glucose+fructose
Lactose - glucose+galactose
Glycosidic linkage
A covalent bond formed between two monosaccharides by a dehydration reaction
Polysaccharides
A polymer of many monosaccharides, formed by dehydration reactions. The architecture and function of a polysaccharide is determined by its monosaccharides and the position of its glycosidic linkages
Starch
A storage polysaccharide in plants, consisting entirely of glucose monomers joined by glycosidic linkages.
Starch is largely helical which enables it to fit more glucose or energy into a denser area.
Glycogen
An extensively branched glucose polysaccharide found in the liver and muscle of animals; the animal equivalent of starch
Cellulose
A structural polysaccharide of plant cell walls, consisting of glucose monomers joined by beta glycosidic linkages.
Enzymes that digest starch by hydrolyzing its linkages are unable to break down the beta linkages in cellulose.
Lipid
Any of a group of large biological molecules, including fats, phospholipids, and steroids, that mix poorly, if at all, with water
Does not include true polymers
Fat
A lipid consisting of three fatty acids linked to one glycerol molecule
Glycerol
An alcohol with each of its three carbons having a hydroxyl group
Fatty Acid
A Carboxylic acid with a long carbon chain
The carbon at one end of the skeleton is part of a carboxyl group
The rest consists of a hydrocarbon chain which gives fat its hydrophobic properties
Making of a Fat Molecule
Each fatty acid molecule is joined to glycerol through a dehydration reaction which results in an ester linkage
Ester Linkage
A bond between a hydroxyl group and a carboxyl group
Unsaturated Fatty Acid
A fatty acid that has one or more double bonds between carbon in the hydrocarbon tail, which reduces the number of hydrogen atoms attached to the carbon skeleton
Cis double bonds cause kinks in the hydrocarbon chain
Saturated fat
A fat made from saturated fatty acids
Most saturated fats are solid at room temperature because their molecules can pack more tightly together
Unsaturated fat
Fats composed of one or more types of unsaturated fatty acids
The kinks from cis double bonds prevent the molecules from packing together closely, so unsaturated fats are normally liquid at room temperature
Trans fat
An unsaturated fat, formed artificially during hydrogenation of oils, containing one or more trans double bonds.
Trans double bonds do not kink
Phospholipids
A lipid made up of glycerol joined to two fatty acids and a phosphate group
The hydrocarbon chains of the fatty acids act as non polar, hydrophobic tails
The rest of the molecule acts as a polar, hydrophilic head
The phosphate group is often attached to a small charged or polar molecule
Phospholipid bilayer
Hydrocarbon tails are hydrophobic. The phosphate group and its attachment form a hydrophilic head. When phospholipids are put into water they self arrange into a double layered sheet with the tails pointing towards the interior.
Steroid
A type of lipid characterized by a carbon skeleton consisting of 4 fused rings with various chemical groups attached
Cholesterol
A steroid that forms an essential component of animal cell membranes and acts as a precursor molecule for the synthesis of other biologically important steroids, such as hormones
Protein
A biologically functional molecule consisting of one or more polypeptides folded and coiled into a specific three-dimensional structure
Amino acid
An organic molecule possessing both a carboxyl and an amino group.
Serve as the monomers of polypeptides
Structure of amino acids
Central carbon with an amino group, carboxyl group and hydrogen atom.
It is also attached to a side chain, which determine the unique characteristics of a particular amino acid.
Polypeptide
A polymer of many amino acids linked together by peptide bonds
Each specific polypeptide has a unique linear sequence of amino acids.
One side has a free amino group and the opposite side has a free carboxyl group
Peptide bond
The covalent bond between the carboxyl group on one amino acid and the amino group on another, formed by a dehydration reaction.
Polypeptide backbone
The repeating sequence of atoms in a polypeptide, everything buy the side chains.
Extending off of the backbone are the different side chains of the amino acids
Primary structure of proteins
The sequence of amino acids
Secondary Structure of Proteins
Regions stabilized by hydrogen bonds between atoms of the polypeptide backbone
Alpha helix - a delicate coil held together by hydrogen bonding between every fourth amino acid
Beta Pleated Sheet - Two or more segments of the polypeptide chain lying side by side, connected by hydrogen bonds.
Tertiary Structure of Proteins
Three dimensional shape stabilized by interactions between side chains
Overall shape of a polypeptide resulting from interaction between the side chains of the various amino acids.
Hydrophobic interactions - amino acids with non-polar hydrophobic side chains usually end up in clusters at the core of the protein
Disulfide bridges - covalent bonds between two sulfhydryl groups that reinforce the structure of the protein
Quaternary structure
Association of two or more polypeptides
Overall protein structure that results from the aggregation of these polypeptide subunits
Denaturation
A process in which proteins lose their native shape due to the disruption of weak chemical bonds and interactions, thereby becoming biologically inactive
Polynucleotide
A polymer consisting of many nucleotide monomers in a chain. The nucleotides can be those of DNA or RNA
Nucleotide
The building block of a nucleic acid, consisting of a five-carbon sugar covalently bonded to a nitrogenous base and one to three phosphate groups
Pyramidine
Six membered Ring
Cytosine, Uracil, Thymine
Purine
Six membered ring fused to a five membered ring
Adenine and Guanine
Deoxyribose
The sugar component of DNA nucleotides, having one fewer hydroxyl group than ribose
Ribose
The sugar component of RNA nucleotides
Nucleotide polymers
The linkage of nucleotides into a polynucleotide involves a condensation reaction
Adjacent nucleotides are joined by phosphodiester linkages
The linear order of bases in a gene specifies the amino acid sequence of a protein.
Phosphodiester Linkage
Consists of a phosphate group that covalently links the sugars of two nucleotides
DNA structure
Two polynucleotide strands that wind around an imaginary axis, forming a double helix
Double helix
The form of native DNA, referring to its two adjacent anti parallel polynucleotide strands wound around an imaginary acid into a spiral shape
The two strands are held together by hydrogen bonds
RNA structure
RNA molecules always exist as a single strand. Complementing base pairing can occur between regions of two RNA molecules.
RNA molecules are more versatile and variable in shape than DNA
