I. Summary
Proteins
Proteins are what allow a cell to carry out most of it's functions. Proteins play a structural role, they maintain cell shape and provide support. They are catalytic and this is why some proteins (enzymes) speed up reactions. Cells communicate with their environments by regulation through membrane proteins. Proteins also allow cells mobility. For example, sperm cells have flagellum (protein) that helps them move. Cells respond to their environment through regulatory and receptor proteins. They allow cells to respond to stimulus. Hormone proteins carry regulatory signals between cells. Antibody proteins defend against invading molecules and organisms. Storage proteins store substances for later use.
Proteins have four different levels of structure. Primary Structure is the sequence of amino acids that characterize a specific protein. The amino acids are joined together by peptide bonds (formed through dehydration synthesis). Proteins differ based on their primary structure, the sequence of their amino acids. Not all amino acids are hydrophilic. To protect the hydrophobic ones, the linear chain may fold, which leads us to the secondary structure. Secondary Structure is where amino acids interact with other amino acids around them. They might twist or bend, forming hydrogen bonds. It can form an alpha-helix or a beta-strand, which are essentially zig-zags in a flat plane. Beta-strands continue to form beta-sheets. Hydrogen bonds are what help stabilize secondary structures. Tertiary Structure is the overall conformation or three-dimensional shape of a protien. As the structures progress, they become more globular and compact. Now that the structure is more spherical and compact, we see that the hydrophobic regions can easily be protected from any aqueous solution because they can hide on the inside of the structure. Tertiary structures are stabilized by their R-groups. Of all the interactions (hydrogen, ionic, hydrophobic, and disulfide linkages) disulfide linkages are the strongest because they are covalent. Denaturation is the loss of protein structure and function. Folded proteins are functional and unfolded proteins are inactive. In this sense, primary and secondary structured proteins are not functional, only tertiary and quaternary are. Denaturation occurs at high heat, change in pH, and addition of salt. Quaternary Structure represents the interaction between two or more protein chains.
In sum, these structures are important because they determine the function and it is the sequence of the linear chains of amino acids that determine that function. Primary structures are stabilized by peptide bonds, secondary are stabilized by hydrogen bonds, tertiary are stabilized by ionic, hydrogen, hydrophobic interactions, and disulfide linkages. Of these, disulfide linkages are the most stable.
Nucleic Acids
Nucleic acids are long polymers of nucleotide building blocks. DNA (deoxyribose nucleic acid) stores all the information for proper cell function. DNA information is what determines the primary structures of proteins. RNA (ribose nucleic acids) is used in various forms to help assemble proteins. Nucleotides are made of a five-carbon sugar, nitrogenous base, and three phosphate groups. The general structure is numbered. One way to differentiate between DNA and RNA is that DNA has H on its 2' (that's why it's called deoxy... without oxygen). Meanwhile, RNA would have OH on its 2'. Nucleoside is the term used when referring to the sugar and nitrogenous base only. Nucleoside monophosphate is the sugar, nitrogenous base, and one phosphate. Diphosphate and triphosphate would have two or three phosphates respectively.
There are 20 amino acids used to make a protein. Of those, there are 4 nucleotides used to construct DNA and 4 to construct RNA. DNA uses A, T, C, G and RNA uses A, U, C, G. Nucleotides vary in sugar and nitrogenous bases. Two categories of nitrogenous bases are pyrimidines (one ring) and purines (two rings). DNA has a double helical structure because the partially negatively charged oxygen molecules form hydrogen bonds with the partially positively charged hydrogen molecules.
DNA and RNA polynucleotide chains are formed by linking the phosphate group of one nucleotide to the sugar of the next one. These are linked together by phosphodiester bonds which are covalent bonds specifically found in nucleic acids. Dehydration reactions link nucleotides. Just like how proteins have N and C termini, DNA has opposite ends, 5' and 3'. DNA is anti-parallel because one strand runs 5' to 3' and the other runs 3' to 5'. Two strands of DNA are joined by hydrogen bonds between the nitrogenous bases following base-pairing rules: A-T and C-G. A-T forms two hydrogen bonds and C-G forms three hydrogen bonds. Bonding of these purines-pyrimidines gives ideal spacing for hydrogen bonding.
RNA usually exists as a single strand. It uses a ribose sugar, instead of deoxyribose and Uracil instead of Thymine. The difference is just the Thymine has a methyl group and Uracil doesn't. It also follows same base-pairing rules as DNA.
II. Useful Materials
This website provides interactive flashcards and can help you memorize the 20 amino acids. It keeps track of how many you get correct and incorrect. Then, when you're ready you can take a test and the website will generate different kinds of questions to test your knowledge on the topic!
III. Article
This article is about thalidomide. Kevadon, which is known today by it's generic name thalidomide was meant to be a sedative. When William S. Merrell Co. applied for this drug to be approved by the FDA, they declined. Dr. Frances Kelsey was the one who was assigned to this drug, and she automatically declined it. She had always been very cautious about taking drugs while pregnant.
When articles began to pop up about women who took thalidomide during their pregnancy giving birth to severely deformed babies, America had Dr. Kelsey to thank. The only Americans who were exposed to the drug were travellers taking it while travelling the seas, and people who took part in experimental studies. This close encounter with thalidomide caused congress to pass the Kefauver Act, which required more in-depth documentation and careful review of drug safety.
Proteins
Proteins are what allow a cell to carry out most of it's functions. Proteins play a structural role, they maintain cell shape and provide support. They are catalytic and this is why some proteins (enzymes) speed up reactions. Cells communicate with their environments by regulation through membrane proteins. Proteins also allow cells mobility. For example, sperm cells have flagellum (protein) that helps them move. Cells respond to their environment through regulatory and receptor proteins. They allow cells to respond to stimulus. Hormone proteins carry regulatory signals between cells. Antibody proteins defend against invading molecules and organisms. Storage proteins store substances for later use.
Proteins have four different levels of structure. Primary Structure is the sequence of amino acids that characterize a specific protein. The amino acids are joined together by peptide bonds (formed through dehydration synthesis). Proteins differ based on their primary structure, the sequence of their amino acids. Not all amino acids are hydrophilic. To protect the hydrophobic ones, the linear chain may fold, which leads us to the secondary structure. Secondary Structure is where amino acids interact with other amino acids around them. They might twist or bend, forming hydrogen bonds. It can form an alpha-helix or a beta-strand, which are essentially zig-zags in a flat plane. Beta-strands continue to form beta-sheets. Hydrogen bonds are what help stabilize secondary structures. Tertiary Structure is the overall conformation or three-dimensional shape of a protien. As the structures progress, they become more globular and compact. Now that the structure is more spherical and compact, we see that the hydrophobic regions can easily be protected from any aqueous solution because they can hide on the inside of the structure. Tertiary structures are stabilized by their R-groups. Of all the interactions (hydrogen, ionic, hydrophobic, and disulfide linkages) disulfide linkages are the strongest because they are covalent. Denaturation is the loss of protein structure and function. Folded proteins are functional and unfolded proteins are inactive. In this sense, primary and secondary structured proteins are not functional, only tertiary and quaternary are. Denaturation occurs at high heat, change in pH, and addition of salt. Quaternary Structure represents the interaction between two or more protein chains.
In sum, these structures are important because they determine the function and it is the sequence of the linear chains of amino acids that determine that function. Primary structures are stabilized by peptide bonds, secondary are stabilized by hydrogen bonds, tertiary are stabilized by ionic, hydrogen, hydrophobic interactions, and disulfide linkages. Of these, disulfide linkages are the most stable.
Nucleic Acids
Nucleic acids are long polymers of nucleotide building blocks. DNA (deoxyribose nucleic acid) stores all the information for proper cell function. DNA information is what determines the primary structures of proteins. RNA (ribose nucleic acids) is used in various forms to help assemble proteins. Nucleotides are made of a five-carbon sugar, nitrogenous base, and three phosphate groups. The general structure is numbered. One way to differentiate between DNA and RNA is that DNA has H on its 2' (that's why it's called deoxy... without oxygen). Meanwhile, RNA would have OH on its 2'. Nucleoside is the term used when referring to the sugar and nitrogenous base only. Nucleoside monophosphate is the sugar, nitrogenous base, and one phosphate. Diphosphate and triphosphate would have two or three phosphates respectively.
There are 20 amino acids used to make a protein. Of those, there are 4 nucleotides used to construct DNA and 4 to construct RNA. DNA uses A, T, C, G and RNA uses A, U, C, G. Nucleotides vary in sugar and nitrogenous bases. Two categories of nitrogenous bases are pyrimidines (one ring) and purines (two rings). DNA has a double helical structure because the partially negatively charged oxygen molecules form hydrogen bonds with the partially positively charged hydrogen molecules.
DNA and RNA polynucleotide chains are formed by linking the phosphate group of one nucleotide to the sugar of the next one. These are linked together by phosphodiester bonds which are covalent bonds specifically found in nucleic acids. Dehydration reactions link nucleotides. Just like how proteins have N and C termini, DNA has opposite ends, 5' and 3'. DNA is anti-parallel because one strand runs 5' to 3' and the other runs 3' to 5'. Two strands of DNA are joined by hydrogen bonds between the nitrogenous bases following base-pairing rules: A-T and C-G. A-T forms two hydrogen bonds and C-G forms three hydrogen bonds. Bonding of these purines-pyrimidines gives ideal spacing for hydrogen bonding.
RNA usually exists as a single strand. It uses a ribose sugar, instead of deoxyribose and Uracil instead of Thymine. The difference is just the Thymine has a methyl group and Uracil doesn't. It also follows same base-pairing rules as DNA.
II. Useful Materials
This website provides interactive flashcards and can help you memorize the 20 amino acids. It keeps track of how many you get correct and incorrect. Then, when you're ready you can take a test and the website will generate different kinds of questions to test your knowledge on the topic!
This video shows DNA and RNA bonding. It explains the components of nucleotides, base pairing specificity, and the main differences between DNA and RNA.
III. Article
This article is about thalidomide. Kevadon, which is known today by it's generic name thalidomide was meant to be a sedative. When William S. Merrell Co. applied for this drug to be approved by the FDA, they declined. Dr. Frances Kelsey was the one who was assigned to this drug, and she automatically declined it. She had always been very cautious about taking drugs while pregnant.
When articles began to pop up about women who took thalidomide during their pregnancy giving birth to severely deformed babies, America had Dr. Kelsey to thank. The only Americans who were exposed to the drug were travellers taking it while travelling the seas, and people who took part in experimental studies. This close encounter with thalidomide caused congress to pass the Kefauver Act, which required more in-depth documentation and careful review of drug safety.
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