103 terms

biology 3

biology 3
The diversity of life is staggering. Yet the molecular logic of life is simple and elegant: Small molecules common to all organisms are ordered into unique macromolecules. Explain why carbon is central to this diversity of organic molecules. How do carbon skeletons, chemical groups, monomers, and polymers relate to this molecular logic of life?
Carbon forms four covalent bonds, either with other carbon atoms, producing chains or rings of various lengths and shapes, or with other atoms, such as characteristic chemical groups that confer specific properties on a molecule. This is the basis for the incredible diversity of organic compounds. Organisms can link a small number of monomers into different arrangements to produce a huge variety of polymers
There are four classes of organic molecules that are essential to all living organisms. Name the classes;their components; their functions and examples of each
1-carbohydrates- Components: monosaccharides Functions: energy for cell, raw material, energy storage, and plant cell support Ex: glucose, starch, glycogen, cellulose
2- lipids (dont form polymers) Components: glycerol, fatty acid, components of a fat molecule Functions: energy storage, cell membrane components, and hormones Ex: fats, phospholipids, and steroids
3- Proteins- Components: amino group, carboxil group, R group, and amino acid Function: enzyme, structural protein, movement, transport, communication, defense, storage, receive signals Ex: lactose, hair, tendons, muscles, hemoglobin, signal proteins, antibodies, egg albumin, receptor protein
4- Nucleic acids- Components: phosphate group, nitrogeneous base, ribose or deoxyribose, nucleotide Functions: heredity, DNA Ex: code for proteins, DNA and RNA
A glucose molecule is to starch as __________ is to _________.
nucleotide; nucleic acid
What makes a fatty acid an acid?
It has a carboxyl group that dontates an H+ ion to a solution
Where in the tertiary structure of a water soluble protein would you most likely find an amino acid with a hydrophobic R group?
on the inside, away from water
Cows can derive nutrients from cellulose because
one of their stomachs contains prokaryotes that can hydrolyze the bonds of cellulose
A shortage of phosphorus in the soil would make it especially difficult for a plant to manufacture
Lipids differ from other macromolecules in that they
are not truly polymers
Which functional group (or groups) is polar and tends to make organic compounds hydrophilic?
carbonyl, amino, hydroxyl, carboxyl
Unsaturated fats have
double bonds in their fatty acid chains
List three different kinds of lipids and describe their functions
fats (triglycerides) -store energy. Phospholipids-are major components of membranes. Steroids--one kind, cholesterol, is a component of cell membranes; other kinds function as hormones
Explain why heat, ph changes, and other environmental changes can interfere with a protein's function
Weak bonds that stabilize the three dimensional structure of a protein are disrupted, and the protein unfolds. Function depends on shape, so if the protein is the wrong shape, it wont function properly
How can a cell make many different kinds of protein out of only 20 amino acids? of the myriad possibilities, how does the cell "know" which proteins to make?
Proteins are made of 20 amino acids arranged in many different sequences into chains of many different lengths. Genes, defined stretches of DNA, dictate the amino acid sequences of proteins in the cell
Briefly describe the various functions performed by proteins in a cell
Proteins function as enzymes to catalyze chemical reactions. they also function in structure, contraction, transport,defense, signaling signal reception, and storage of amino acids (module 3.11)
Explain how DNA controls the functions of a cell
The sequence of nucleotides in DNA is transcribed into a sequence of nucleotides in RNA, which determines the sequence of amino acids that will be used to build a polypeptide. Proteins mediate all the activities of a cell; thus, by coding for proteins, DNA controls the functions of a cell
Sucrose is broken down in your intestine to the monosaccharides glucose and fructose, which are then absorbed into your blood. Draw a diagram showing how this would occur
This is a hydrolysis reaction, which consumes water. It is essentially the reverse of the diagram in figure 3.5 except note that fructose has a different shape than glucose
(draw the diagram on pg 40 #17.) List and name the functional groups in this organic molecule. What type of compound is this? Fro which class of macromolecules is it a monomer?
Circle NH 2, an amino group; COOH, a carboxyl group; and OH a hydroxyl group on the R group. This is an amino acid, a monomer of proteins. The OH group makes it a polar amino acid
Enzymes usually function best at an optimal ph and temperature. The following graph shows the effectiveness of two enzymes at various temperatures (draw out diagram) From what you know about enzyme structure, explain why the rate of the reaction catalyzed by enzyme A slows down at temperatures above 40 degrees celcius
Above 40 degrees celcius, the human enzyme denatures and loses its shape and thus its function. The increased thermal energy disrupts the weak bonds that maintain secondary and tertiary structure in an enzyme
Some scientists hypothesize that life elsewhere in the universe might be based on the element silicon rather than on carbon. Look at the electron shell diagrams in Figure 2.6. What properties does silicon share with carbon that would make silicon based life more likely than, for example, neonbased or sulfur based life?
Silicon has four electrons in its outer electron shell, as does carbon. One would predict that silicon could thus form complex molecules by binding with four partners. Neon has a filled outer shell and is nonreactive. Sulfur can only form two covalent bonds and thus would not have the versatility of carbon or silicon.
Almost all the molecules a cell makes are composed of _________________ atoms bonded to one another and to atoms of other elements.
What is the foundation for the myriad of molecules and chemical processes required for life?
Carbon compounds
Define organic compounds
carbon based molecules
Describe the structure of a carbon atom
a carbon atom has four outer electrons in a shell that holds eight. Carbon completes its outer shell by sharing electrons with other atoms in four covalent bonds. Thus, each carbon atom is a connecting point from which a molecule can branch in up to four directions
Define hydrocarbons
methane and other compounds composed of only carbon and hydrogen ex ethane and propane
Define carbon skeleton
the chain of carbon atoms in an organic molecule ex butane and isobutane
Define isomers
compounds with the same formula but different structures; their different shapes result in unique properties.
Why do isomers, which have the same formula (same number of atoms), have different properties?
isomers have different structures, or shapes, and the shape of a molecule usually helps determine the way it functions; how it interacts with other molecules
The unique properties of an _____________________ depend on the size and shape of its carbon skeleton and on the groups of atoms that are attached to that skeleton
organic compound
Define functional groups
an assemblage of atoms commonly attached to the carbon skeletons of organic molecules and usually involved in chemical reactions; polar
Define hydrophilic
water loving; pertaining to polar, or charged, molecules, or parts of molecules, that are soluble in water
Define hydroxyl group
in an organic molecule, a functional group consisting of a hydrogen atom bonded to an oxygen atom
Define carbonyl group
in an organic molecule, a functional group consisting of a carbon atom linked by a double bond to an oxygen atom
Define carboxyl group
in an organic molecule, a functional group consisting of an oxygen atom double bonded to a carbon atom that is also bonded to a hydroxyl group
Define amino group
in an organic molecule, a functional group consisting of a nitrogen atom bonded to two hydrogen atoms
Define phosphate group
a functional group consisting of a phosphorus atom covalently bonded to four oxygen atoms
Define methyl group
in an organic molecule, a carbon bonded to three hydrogens
identify the chemical groups that do not contain carbon
the amino, hydroxyl, and phosphate groups
The four main classes of large biological molecules are
carbohydrates, lipids, proteins, and nucleic acids
Define macromolecules
a giant molecule in a living organism formed by the joining of smaller molecules a protein, carbohydrate, or nucleic acid
Define polymers
a large molecule consisting of many identical or similar molecular units, called monomers, covalently joined together in a chain
Define monomers
a chemical subunit that serves as a building block of a polymer
The varieties in ____________ accounts for the uniqueness of each organism
Define dehydration reaction
a reaction that removes a molecule of water
Dehydration reactions are the same regardless of...
the type of polymer the cell is producing
Define hydrolysis
a chemical process in which polymers are broken down by the chemical addition of water molecules to the bonds linking their monomers; an essential part of digestion
Both dehydration reactions and hydrolysis require the help of ___________ to make and break bonds
Define enzymes
specialized macromolecules that speed up chemical reactions in cells
Suppose you eat some cheese. What reactions must occur for the amino acid monomers in the protein of the cheese to be converted to proteins in your body?
In digestion, the amino acids are released by hydrolysis. New proteins are formed in your body from these monomers in dehydration reactions
Define carbohydrate
member of the classof biological molecules consisting of simple single monomer sugars(monosaccharides), two monomer sugars (disaccharides, and other multiunit sugars (polysaccharides)
Define monosaccharides
the simplest carbohydrate; a simple sugar with a molecular formula that is generally some multiple of CH2O. Monosaccharides are the building blocks of disaccharides and polysaccharides
________________, particularly glucose, are the main fuel molecules for cellular work
How is high frutose corn syrup made from corn?
Corn starch is hydrolyzed to glucose then enzymes convert glucose to frutose. This frutose is combined with corn syryp to produce HFCS
Define polysacharides
polymers of monosaccharides linked together by dehydration reactions; may function as storage molecules or as structural compounds
Define starch
a storage polysaccharide in plants, consists entirely of glucose monomers. Starch molecules coil into a helical shabe because of the angles of the bonds joining their glucose units. A starch helix may be unbranched or branched. Plant cells, like animal cells, need sugar for energy and as raw material for building other molecules. Plant cells often contain starch granules from which they can withdraw glucose by hydrolysis. humans and most other animals also have enzymes that can hydrolyze plant starch to provide a source of glucose. Potatoes and grains, such as wheat, corn, and rice, are the major sources of starch in the human diet
Define glycogen
an extensively branched polysaccharide of many glucose monomers; serves as an energy storage molecule in liver and muscle cells; the animal equivalent of starch
Define cellulose
the most abundant organic compound on earth, forms cable like fibrils in the tough walls that enclose plant cells. Cellulose is also a polymer of glucose, but its glucose monomers are linked together in a different orientation; joined by hydrogen bonds; not a nutrient for humans but does contribute to digestive system health.
Define insoluble fiber
cellulose that passes unchanged through our digestive tract
Define chitin
a structural polysaccharide found in many fungal cell walls and in the exoskeletons of arthropods
Compare and contrast starch and cellulose, two plant polysaccharides
Both are polymers of glucose, but the bonds between glucose monomers have different shapes. Starch functions mmainly for sugar storage. Cellulose is a structural polysaccharide that is the main material of cell walls
Define lipids
divierse compounds that are grouped together because they share one trait: they mix poorly, if at all, with water; consist mainly of carbon and hydrogen atoms linked by nonpolar covalent bonds; hydrophobic
Define hydrophobic
water fearing
Define fat
a large lipid made from two kinds of smaller molecules: glycerol and 3 fatty acids; consists of carboxyl group (the functional group that gives these molecules the name fatty acid) and a hydrocarbon chain, usually 16 or 18 carbon atoms in length. The carbons in the chain are linked to each other and to hydrogen atoms by nonpolar covalent bonds, making the hydrocarbon chain hydrophobic; main function is energy storage
Define unsaturated fats
fatty acids and fats with double bonds in the carbon chain; have less than the maximum number of hydrogens;kinks prevent the molecules from packing tightly together and solidifying at room temperature; oils; found in most plant fats
Define saturated fats
fats with the maximum number of hydrogens; found in most animals
On a food package, what does :unsaturated fats" mean?
Unsaturated fats are fats with some double bonds in the carbon chain of their fatty acids. These fats have fewer hydrogen atoms than they would without the double bonds
Define phospholipids
a lipid made up of glycerol joined to two fatty acids and a phosphate group, giving the molecule a nonpolar hydrophobic tail and a polar hydrophilic head. Phospholipids form bilayers that function as biological membranes
Define steroids
lipids whose carbon skeleton contains four fused rings
Define cholesterol
a common component in animal cell membranes, and animal cell membranes, and animal cells also use it as a starting material for making other steroids, including sex hormones
Why are human sex hormones considered lipids?
They are steroids, one of the hydrophobic compounds grounded as lipids
Define anabolic steroids
synthetic variants of male hormone testosterone.
_____________ causes a general buildup of muscle and bone mass in males during puberty and maintains masculine traits throughout live.
What kind of carbon ring structure would you find in an anabolic steroid?
four fused carbon rings; three six sided and one five sided as in all steroids
Define protein
a polymer constructed from amino acid monomers.
__________ are important to the structures of cells and organisms and participate in everything they do
Probably the most important role for proteins is as ________, the chemical catalysts that speed and regulate virtually all chemical reactions in cells
Name 7 types of proteins
1-Structural: found in hair and the fibers that make up connective tissues such as tendons and ligaments 2-Contractile: found in muscles 3-Defensive proteins such as the antibodies of the immune system 4- Signal proteins such as many of the hormones and other messengers that help coordinate body activities by communicating between cells 5- Receptor proteins may be built into cell membranes and transmit signals into cells 6- Transport protein found in hemoglobin in red blood cells and delivers O2 to working muscles 7- Storage proteins such as ovalbumin, the protein of egg white which serves as a source of amino acids for developing embryos
Which of the following is not a protein: hemoglobin, cholesterol, ovalbumin, an enzyme, an antibody?
Define amino acid
an organic molecule containing a carboxyl group and an amino group; serves as the monomer of proteins
________________ with polar and charged R groups help proteins dissolve in the aqueus solutions inside cells
amino acids
Define peptide bond
the covalent linkage between two amino acid units in a polypeptide; formed by a dehydration reaction
Define polypeptide
a polymer (chain) of amino acids linked by peptide bonds
In what way is the production of a dipeptide similar to the production of a disaccharide?
In both cases, the monomers are joined by a dehydration reaction
_______________ consists of one long polypeptide and is globular
Most ____________ and _____________ are globular. ______________ such as those making up hair and tendons are typically long and thin--fibrous
enzymes; other proteins; structural proteins
Define denaturation
a process in which a protein unravels, losing its specific structure and hence function; can be caused by changes in ph or salt concentration or by high temperature. Also refers to the separation of the two strands of the DNA double helix, caused by similar factors
Why does a denatured protein no longer function normally
The function of each protein is a consequence of its specific shape, which is lost when a protein denatures
Define primary structure
a proteins unique sequence of amino acids
Define secondary structure
the second level of protein structure, parts of the polypeptide coil or fold into local patterns; results in alpha helix; a certain kind of folding leads to a pleated sheet.
Define alpha helix
the spiral shape resulting from the coiling of a polypeptide in a proteins secondary structure
Define pleated sheet
the folded arrangement of a polypeptide in a proteins secondary structure
Define tertiary structure (get from back too)
refers to the overall three dimensional shape of a polypeptide; most cab be described as either globular or fibrous------(glossary def) The third level of protein structure; the overall, three dimensional shape of a polypeptide due to interactions of the R groups of the amino acids making up the chain
Define quaternary structure
The fourth level of protein structure; the shape resulting from the association of two or more polypeptide subunits
Name the four levels of structure of proteins
primary; secondary; tertiary; quaternary
In a genetic mutation changes the primary structure of a protein, how might this destroy the proteins function
Primary structure, the amino acid sequence, affects the secondary structure, which affects the tertiary structure, which affects the quaternary structure(if any). Thus primary structure affects the shape of the protein, and the function of a protein depends on its shape
___________________--- are information rich polymers of nucleotides
nucleic acids
Define gene
a discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA (or RNA, in some viruses). Most of the genes of a eukaryote are located in its chromosomal DNA; a few are carried by the DNA of mitochondria and chloroplasts
Define DNA
(deoxyribonucleic acid) A double stranded helical nucleic acid molecule consisting of nucleotide monomers with deoxyribose sugar and the nitrogenous bases adenine (A), cytosine (C), guanine (G), and thymine (T). Capable of replicating is an organisms genetic material
Define nucleic acids
a polymer consisting of many nucleotide monomers; serves as a blueprint for proteins and through the actions of proteins, for all cellular structures and activities. The two types of nucleic acids are DNA and RNA
Define ribonucleic acid
(RNA) a type of nucleic acid consisting of nucleotide monomers with a ribose sugar and the nitrogenous bases adenin (A), cytosine (C) guanine (G), and uracil (U); usually single stranded; functions in protein synthesis and as the genome of some viruses
Define nucleotides
an organic monomer consisting of a five carbon sugar covalently bonded to a nitrogenous base and a phosphate group. Nucleotides are the building blocks of nucleic acids
Define double helix
the form of native DNA, referring to its two adjacent polynucleotide strands wound into a spiral shape
how are the two types of nucleic acids functionally related?
the hereditary material of DNA contains the instructions for the primary structure of polypeptides. RNA is the intermediary that translates those instructions into the order of amino acids
Explain how lactose intolerance involves three of the four major classes of biological macromolecules
Lactose, milk sugar, is a carbohydrate that is hydrolyzed by the enzyme lactase, a protein. The ability to make this enzyme and the regulation of when it is made is coded for in DNA, a nucleic acid