Chapter 2- Chemistry of Life Carbon Compounds in Cells

Molecules of Life Organic Compounds- Only living cells can synthesize carbohydrates, lipids, proteins, and nucleic acids These molecules consist of carbon and one or more additional elements covalently bonded O 2, H 2, C are the most abundant elements in living matter

Carbon bonding Carbons can share up to 4 electron pairs allowing for different configurations Functional groups-atoms or groups of atoms that bond to a carbon backbone with distinct properties Hydroxyl, methyl, carbonyl, carboxyl, amino, phosphate, sulfhydryl

Organic Compounds 4 families of building blocks –Simple sugars, fatty acids, amino acids, nucleotides 5 categories of reactions –Enzymes are special groups that mediate the following- functional group transfer, electron transfer, rearrangement, condensation, cleavage Condensation vs Hydrolysis

Carbohydrates Simple sugars- –Monosaccharides- simplest, soluble,sweet, several OH groups –Ribose and Deoxyribose –Glucose and fructose- used to build larger carbs –Important monomers include glycerol and vitamin C

Carbohydrates

Short chain carbs- –Oligosaccharide- short chain of two or more monomers –Disaccharides- simplest- two monomers Lactose- glucose + galactose Sucrose- glucose + fructose Maltose- glucose + glucose –Oligosaccharides with 3 or more monomers are attached as short chains to proteins involved in membrane function

Carbohydrates Complex carbohydrates- polysaccharides- straight or branched chain of hundreds or thousands of monomers –Starch- unbranched coiled chains- easily hydrolized –Cellulose- insoluble, used in plant cell walls –Glycogen- highly branched, used to store energy in animal cells –Chitin- contains nitrogen attached to glucose, used in arthropod exoskeletons to add strength

Complex carbohydrates

Lipids Greasy, oily, insoluble Can be broken down by hydrolysis Energy storage, membrane structure, coatings

Lipids Fats and Fatty acids –A fatty acid is a long chain of C & H with –COOH at the end –When they are part of complex lipids they resemble long, flexible tails –UNSATURATED- liquid at room temp, one or more double bonds between C –SATURATED- (triglycerides)- have a single C-C bond, solid at room temp –Fats are formed by fatty acids attaching to a glycerol –Rich in energy-2x carbs energy & provide insulation

Fatty acids

Lipids Phospholipids- fatty acids plus a phosphate group attached to glycerol –Main structural material of cellular membranes Sterols- 4-carbon ring backbone but no fatty acid tail –Cholesterol- component of cell membranes and can be changed into sex hormones Waxes- long-chain fatty acids attach to long-chain alcohols or carbon rings –Serve as coatings for plant parts and animal coverings

Lipids

AMINO ACIDS Proteins functions- storage, movement, transport, hormones, antibodies, structural materials Formed by chains of amino acids Amino acids- small organic molecules with an amino group, carboxyl group, and one of twenty R groups Covalently bonded to a central C atom

Amino acids Polypeptide chain formation- –Primary structure is a chain of amino acids held together by peptide bonds There are 20 amino acids available Sequence of amino acids is determined by DNA and unique for each protein –Fibrous proteins are organized as strands or sheets- contribute to shape, internal org. and movement of cells –Globular proteins, including most enzymes, have folded chains in rounded shapes

Amino Acids

Protein Structure 2 nd level refers to the helical coil or sheet- like array resulting from H-bonding of side groups on amino acid 3 rd level is a result of folding due to R groups along the polypeptide chain

Protein Structure 4 th level describes the complexing of two or more polypeptide chains Hemoglobbin- 4 interacting chains that forma globular protein Glycoproteins- oligosaccharides covalently bonded to proteins Denaturation- how to break a protein- changes in pH, or high temps. Often irreversible- you can’t uncook an egg

Protein Structure Alteration of a cell’s DNA can result in the wrong amino acid being inserted into a protein. This can result in various mutations such as sickle cell anemia or other genetic disorders

Proteins

Protein Structure

Nucleic Acids and Nucleotides Nucleotides consist of a 5-carbon sugar (RNA or DNA), a nitrogen-containing base, and a phosphate group. Adenosine phosphates are chemical messengers (cAMP) or energy carriers (ATP) Nucleotide coenzymes transport hydrogen atoms and electrons Nucleotides are the building blocks for nucleic acids

Nucleotides

DNA and RNA Nucleic acids are polymers of nucleotides 4 different kinds of nucleotides are strung together to form single or double stranded molecules Each strands backbone consists of joined sugars and phosphates with nucleotides attached to them.

DNA and RNA The two most important nucleic acids are RNA and DNA DNA is a double stranded molecule containing hereditary instructions RNA is a single stranded molecule and functions in translating DNA to build proteins

DNA vs. RNA