Molecular Genetics
Operon
This acts as a unit of transcription, and functions to produce by transcription a single mRNA molecule which codes for more than one protein with related metabolic functions Ex: Arc Opeorn
Replication
1st Tenet of the Central Dogma All of DNA is copied during the s (synthesis) subphase of interphase. This occurs in two opposite directions simultaneously. This process is semi-conservative because there is a double separation of helices, the nucleotides in both being the same 1. DNA molecule uncoils during the S Phase from a highly condensed state (within a chromosome, protected by a histone protein), assisted by DNA Helicase. The "unzipping" of the double helix of DNA occurs at the replication fork via the enzyme DNA Helicase. 2. Hydrogen bonds between complementary nitrogenous bases break (Adenine w/ Thymine, Guanine w/ Cytosine) 3. The breaking of the complementary nitrogenous bases expose a "half-rung" ladder-like structure called a template, by which a new DNA molecule will be produced from 4. A free DNA nucleotide from the nucleus is brought into place by DNA Polymerase, which proofreads the strand for misplaced nucleotides 5. An enzyme, ligase, ligates the template with the formerly free DNA nucleotide. 5. The DNA fork is recoiled
Replication vs. Transcription
1st Tenet of the Central Dogma All of DNA is copied during the s (synthesis) subphase of interphase. This occurs in two opposite directions simultaneously. This process is semi-conservative because there is a double separation of helices, the nucleotides in both being the same 1. DNA molecule uncoils during the S Phase from a highly condensed state (within a chromosome, protected by a histone protein), assisted by DNA Helicase. The "unzipping" of the double helix of DNA occurs at the replication fork via the enzyme DNA Helicase. 2. Hydrogen bonds between complementary nitrogenous bases break (Adenine w/ Thymine, Guanine w/ Cytosine) 3. The breaking of the complementary nitrogenous bases expose a "half-rung" ladder-like structure called a template, by which a new DNA molecule will be produced from 4. A free DNA nucleotide from the nucleus is brought into place by DNA Polymerase, which proofreads the strand for misplaced nucleotides 5. An enzyme, ligase, ligates the template with the formerly free DNA nucleotide. 5. The DNA fork is recoiled vs. 2nd Tenet of the Central Dogma 1. A single strand within the double helix of a DNA molecule unzips (only one template is transcribed 5>3) 2. Uracil pairs with adenine (instead of thymine) 3. The resulting mRNA strand leaves the nucleus and goes to the ribosomes, the site of protein synthesis, to be translated 4. DNA zips back up Both RNA and DNA are nucleic acids, which use base pairs of nucleotides as a complementary language that can be converted back and forth from DNA to RNA by the action of the correct enzymes. During transcription, a DNA sequence is read by an RNA polymerase, which produces a complementary, antiparallel RNA strand called a primary transcript. As opposed to DNA replication, this process results in an RNA complement that includes the nucleotide uracil (U) in all instances where thymine (T) would have occurred in a DNA complement.
Transcription
2nd Tenet of the Central Dogma 1. A single strand within the double helix of a DNA molecule unzips (only one template is transcribed 5>3) 2. Uracil pairs with adenine (instead of thymine) 3. The resulting mRNA strand leaves the nucleus and goes to the ribosomes, the site of protein synthesis, to be translated 4. DNA zips back up Both RNA and DNA are nucleic acids, which use base pairs of nucleotides as a complementary language that can be converted back and forth from DNA to RNA by the action of the correct enzymes. During transcription, a DNA sequence is read by an RNA polymerase, which produces a complementary, antiparallel RNA strand called a primary transcript. As opposed to DNA replication, this process results in an RNA complement that includes the nucleotide uracil (U) in all instances where thymine (T) would have occurred in a DNA complement.
Transcription vs. Translation
2nd Tenet of the Central Dogma 1. A single strand within the double helix of a DNA molecule unzips (only one template is transcribed 5>3) 2. Uracil pairs with adenine (instead of thymine) 3. The resulting mRNA strand leaves the nucleus and goes to the ribosomes, the site of protein synthesis, to be translated 4. DNA zips back up Both RNA and DNA are nucleic acids, which use base pairs of nucleotides as a complementary language that can be converted back and forth from DNA to RNA by the action of the correct enzymes. During transcription, a DNA sequence is read by an RNA polymerase, which produces a complementary, antiparallel RNA strand called a primary transcript. As opposed to DNA replication, this process results in an RNA complement that includes the nucleotide uracil (U) in all instances where thymine (T) would have occurred in a DNA complement. vs. 3rd Tenet of the Central Dogma "The decoding of an mRNA message into a protein" The sequence of nitrogenous bases in an mRNA molecule is a set of instructions that arrange amino acids on ribosomes so that they are joined in a fastidious polypeptide. This begins when a ribosome attaches to an mRNA molecule in a cytoplasm. As each codon passes through the ribosome, tRNAs bring proper amino acids into the ribosome. The ribosome then attaches amino acids to what will become a polypeptide chain. Each tRNA molecule carries a specific amino acid in its anticodon that is complementary to the nitrogenous bases in mRNA's codons. The ribosome helps form a peptide bond between amino acids and simultaneously the bond likning a tRNA molecule with its amino acid is broken. This process continues until the polypeptide chain reaches a stop codon, releasing the newly formed polypeptide and mRNA molecule. ALT: mRNA carries coded message that directs ________ tRNA delivers specific amino acids (anticodons) per the codon on mRNA rRNA molecules help hold ribosomal proteins in place and locate the beginning of an mRNA message (start codon)
Codon
A sequence of three nucleotides in mRNA that complementary base pair with the corresponding aniticodon of tRNA molecule carrying a particular amino acid, indicating the type and sequence of amino acids for protein synthesis. Ex: CUA, AUG, GAU
Translation
3rd Tenet of the Central Dogma "The decoding of an mRNA message into a protein" The sequence of nitrogenous bases in an mRNA molecule is a set of instructions that arrange amino acids on ribosomes so that they are joined in a fastidious polypeptide. This begins when a ribosome attaches to an mRNA molecule in a cytoplasm. As each codon passes through the ribosome, tRNAs bring proper amino acids into the ribosome. The ribosome then attaches amino acids to what will become a polypeptide chain. Each tRNA molecule carries a specific amino acid in its anticodon that is complementary to the nitrogenous bases in mRNA's codons. The ribosome helps form a peptide bond between amino acids and simultaneously the bond likning a tRNA molecule with its amino acid is broken. This process continues until the polypeptide chain reaches a stop codon, releasing the newly formed polypeptide and mRNA molecule. ALT: mRNA carries coded message that directs ________ tRNA delivers specific amino acids (anticodons) per the codon on mRNA rRNA molecules help hold ribosomal proteins in place and locate the beginning of an mRNA message (start codon)
Translation vs. Replication
3rd Tenet of the Central Dogma "The decoding of an mRNA message into a protein" The sequence of nitrogenous bases in an mRNA molecule is a set of instructions that arrange amino acids on ribosomes so that they are joined in a fastidious polypeptide. This begins when a ribosome attaches to an mRNA molecule in a cytoplasm. As each codon passes through the ribosome, tRNAs bring proper amino acids into the ribosome. The ribosome then attaches amino acids to what will become a polypeptide chain. Each tRNA molecule carries a specific amino acid in its anticodon that is complementary to the nitrogenous bases in mRNA's codons. The ribosome helps form a peptide bond between amino acids and simultaneously the bond likning a tRNA molecule with its amino acid is broken. This process continues until the polypeptide chain reaches a stop codon, releasing the newly formed polypeptide and mRNA molecule. ALT: mRNA carries coded message that directs ________ tRNA delivers specific amino acids (anticodons) per the codon on mRNA rRNA molecules help hold ribosomal proteins in place and locate the beginning of an mRNA message (start codon) vs. 1st Tenet of the Central Dogma All of DNA is copied during the s (synthesis) subphase of interphase. This occurs in two opposite directions simultaneously. This process is semi-conservative because there is a double separation of helices, the nucleotides in both being the same 1. DNA molecule uncoils during the S Phase from a highly condensed state (within a chromosome, protected by a histone protein), assisted by DNA Helicase. The "unzipping" of the double helix of DNA occurs at the replication fork via the enzyme DNA Helicase. 2. Hydrogen bonds between complementary nitrogenous bases break (Adenine w/ Thymine, Guanine w/ Cytosine) 3. The breaking of the complementary nitrogenous bases expose a "half-rung" ladder-like structure called a template, by which a new DNA molecule will be produced from 4. A free DNA nucleotide from the nucleus is brought into place by DNA Polymerase, which proofreads the strand for misplaced nucleotides 5. An enzyme, ligase, ligates the template with the formerly free DNA nucleotide. 5. The DNA fork is recoiled
Single Nucleotide Polymorphisms
A DNA sequence variation occurring commonly within a population in which a single nucleotide — A, T, C or G — in a species' genetic code (genome) differs among individuals. Ex: Two sequenced DNA fragments from different individuals, AAGCCTA to AAGCTTA, contain a difference in a single nucleotide.
Deoxyribose
A pentose sugar present within the side chains of DNA. This lacks an oxygen that ribose (in RNA, e.g.) has. This monosaccharide is linked to phosphoric acid via a phosphodiester bond.
Mutagen
A physical or chemical agent that a mutation arises from. Ex: Tobacco Smoke (chemical) UV light (physical)
Adenine
A purine, this is a relatively large nitrogenous base that forms two hydrogen bonds and pairs with Thymine in DNA and Uracil in RNA (both pyrimidines)
Guanine
A purine, this relatively larger nitrogenous base pairs with cytosine in both DNA and RNA, forming three hydrogen bonds (weak).
Thymine
A pyrimidine, this relatively small nitrogenous base pairs with Adenine in ONLY DNA (it is replaced by Uracil in RNA).
Cytosine
A pyrmidine, this relatively smaller nitrogenous base pairs with guanine in both DNA and in RNA, forming three hydrogen bonds (weak).
Anticodon
A sequence of three nucleotides in tRNA that complementary base pairs with the corresponding codon of mRNA molecule. The molecule that complementary base pairs carries a particular amino acid, thus indicating the type and sequence of amino acids for protein synthesis. Ex: GAU, UAC, CUA
Ribonucleic Acid
A single-stranded nucleic acid comprised of ribose (an additional oxygen when compared to deoxyribose in DNA), phosphoric acid, and four nitrogenous bases, Adenine, URACIL, cytosine, and guanine. Uracil replaces thymine; uracil and thymine are not isomers. Ex: Three varieties of interest/concentration: mRNA (messenger RNA) tRNA (transfer RNA) rRNA (ribosomal RNA)
Hydrogen Bond
A weak type of chemical bond formed when the slightly positive hydrogen atom of a polar covalent bond is attracted to the slightly negative atom of a polar covalent bond in another molecule. Ex: These types of bonds are present between Adenine and Thymine in DNA (which forms two of these), Adenine and Uracil in RNA (which forms two of these), and Guanine and Cytosine in DNA and RNA (which forms three of these).
Central Dogma
All life has a common "language" for the synthesis of proteins. Information is transmitted from DNA (replication) to RNA (transcription) to proteins (translation). There are tenets: 1) DNA Replication (S subphase of interphase) 2) Transcription (formation of RNA from DNA) 3) Translation (using RNA formed from DNA to make proteins during Go, G1, and G2 during the interphase)
DNA Helicase
An enzyme involved in the replication of DNA during the S subphase of interphase that disentangles the double helix of DNA by breaking up the hydrogen bonds, allowing complementary nitrogenous base pairing that will be expedited by Ligase. (Adenine=Thymine (two hydrogen bonds) & Cytosine with Guanine (three hydrogen bonds))
DNA Polymerase
An enzyme that catalyzes DNA replication by joining nucleotides to produce a new strand of DNA. This enzyme also produces phosphodiester bonds by joining congealing phosphoric acid and deoxyribose. This enzyme also "proofreads" each new DNA strand, so that each molecule is a near-perfect copy of the original (template).
Stem Cells
An unspecialized cell that has the prospect to become what it needs to become. These are "kept in check" by niche cells that prevent differentiation, or the specialization of a cell to later enact a certain function. Ex: Embryonic, Hematopoietic (blood marrow ____ ____)
Deoxyribonucleic Acid
DNA The master "blueprint" that delineates the construction of proteins This nucleic acid is composed of deoxyribose (pentose carbohydrate/sugar), phosphoric acid, and nitrogenous bases. Regarding nitrogenous bases, there are two kinds in DNA: purines (adenine, guanine) and pyrimidines (cytosine, thymine). Adenine and thymine bond to each other via feeble (in order for them to be broken during DNA replication) two hydrogen bonds. Guanine and cytosine also have weak hydrogen bonds, but they form three hydrogen bonds. The bonding of like hydrogen bonds among nitrogenous bases in DNA (and RNA) is called complementary base pairing. The phosphoric acid and the deoxyribose are on the sides of DNA and are arranged by phosphodiester bonds. Both the phosphodiester and hydrogen bonds collectively compose the double helical structure of DNA (proposed by Chargaff's rule, validated by Watson and Crick). DNA as other nucleotides is good at absorbing ultraviolet radiation. Also, DNA is slightly acidic.
RNA Polymerase
During transcription (when segments of DNA serve as templates to produce complementary DNA molecules because DNA is valuable, RNA not as much), this enzyme uses one strand of DNA as a template to assemble complementary nucleotides into a strand of RNA.
Point Mutation
Gene mutations that involve changes in one or a few nucleotides because they occur at a single point in the DNA sequence, usually occurring during the DNA Replication (S subphase of interphase). Ex: Frameshift Mutations (Insertion and Deletion) and Substitution
Mutation
Heritable changes in genetic information produced by errors in genetic process (e.g., during DNA Replication). Stressful environmental conditions increase the rate of this. Ex: Gene Mutations (Heritable changes produced in single gene) Substitution Deletion Insertion Chromosomal Mutation (Heritable changes produced in chromosomes) Deletion Duplication Inversion Translocation
Frameshift Mutation
Mutations like genetic insertions and deletions that shift the "reading frame" of the genetic message (not left to right per usual). By shifting the reading frame, these types of mutations can change every amino acid after the point of mutation, perhaps rendering the entirety of the protein dysfunctional.
Phosphoric Acid
P04 Both present in DNA and RNA, bonding to deoxyribose and ribose respectively in each molecule's side chain via a phosphodiester bond.
rRNA
Ribosomal Ribonucleic Acid This helps hold ribosomal proteins in place and locates the beginning of an mRNA message (three nitrogenous bases in a sequence, a start codon) This decodes the mRNA into various amino acids, assisting translation of transcribed genetic information from DNA into mRNA so that tRNA may assemble polypeptides. This type of ribonucleic acid comprises 60% of ribosomes (the other 40% comprised of proteins), the site of protein synthesis where mRNA attaches.
rRNA vs. tRNA
Ribosomal Ribonucleic Acid This helps hold ribosomal proteins in place and locates the beginning of an mRNA message (three nitrogenous bases in a sequence, a start codon) This decodes the mRNA into various amino acids, assisting translation of transcribed genetic information from DNA into mRNA so that tRNA may assemble polypeptides. This type of ribonucleic acid comprises 60% of ribosomes (the other 40% comprised of proteins), the site of protein synthesis where mRNA attaches. vs. Transfer Ribonucleic Acid This carries an amino acid to a ribosome (60% rRNA, 40% protein), pairing the codon on the mRNA with a complementary anticodon that it will accordingly administer. Ex: If mRNA is coding for CUA, then tRNA responds with an anticodon of GAU.
Splicosomes
Small nuclear organelles in which the splicing and excision reactions that remove introns and amalgamate exons from a nascent messenger RNA molecules occur. These organelles enable the development of an mRNA molecule.
Junk DNA
That portion of DNA which is not transcribed and expressed because of no palpable function. There will probably be a day, however. Ex: 98% of the human genome is noncoding DNA,while only about 2% of a typical bacterial genome is noncoding DNA
Phosphodiester Bond
The bond present both within the DNA and RNA in their side chains, linking together phosphoric acid with deoxyribose in DNA and phosphoric acid with ribose in RNA. This a relatively strong bond because it is the part of DNA or RNA that remains regardless of other interactions. It is the hydrogen bonds between the nitrogenous bonds that are weak because these are the bonds that are broken during replication, transcription, translation.
Peptide Bonds
The bonds between amino acids within a protein/polypeptide. These linkages are strong covalent bonds that have intricate primary, secondary, tertiary, and quaternary complexities.
Stop Codon
The codon at which translation (i.e., protein synthesis) is signaled to end. Ex: The three complementary bases on mRNA that indicate of translation are UGA,UAA, and UAG, as no amino acids can pair up with these codons.
mRNA
The messenger ribonucleic acid carries instructions for polypeptide synthesis from the nucleus to ribosomes in the cytoplasm during translation. It is formed via nitrogenous base pairing (A=U, C=G) during transcription. A messenger RNA molecule only has a transcribed gene from DNA because not every protein has to have the capability to do everything, everyone's a role player.
Amino Acid
The monomer of proteins that is formed during translation (protein synthesis) in which tRNA complementary base pairs with mRNA on ribosomes comprised of rRNA and protein (60/40). The bonds among amino acids are peptide bonds, which are strong covalent bonds. Ex: Methionine, Lysine, Theonine
Nucleotide
The monomers of the group of biopolymers categorized as nucleic acids, which subsumes DNA as well as RNA. All nucleic acids are composed of a phosphoric acid, sugar, and a nitrogenous base. DNA consists of deoxyribose (pentose carbohydrate), phosphoric acid (P04), and nitrogenous bases (adenine with thymine; cytosine with guanine). RNA consists of ribose (sugar), phosphoric acid (P04), and nitrogenous bases (adenine with uracil; cytosine with guanine).
Watson & Crick
The pair of scientists determined that DNA must have a double helical structure as a result of the complementary base pairing (Adenine with Thymine, Guanine with Cytosine). The scientists "provided an explanation for how all the components of DNA could be arranged in a manner that would allow the molecule to replicate itself. They espoused, developed, formalized the 1st Part of Central Dogma.
Exon
The portions of nascent mRNA that are kept by mRNA. These are spread out throughout the mRNA molecule to reduce the likelihood of decimation by ultraviolet radiation (e.g.). When the introns are cut out, the ____ are spliced together.
Differentiation
The process by which unspecialized cell becomes special. When stem cells are attributed to perform a certain function, they must first specialize so that they are able.
Start Codon
The sequence of three nitrogenous bases in a mRNA molecule that indicates the beginning of the formation of a protein (i.e., translation). There is only one, AUG. Ex: AUG, which codes for the amino acid methionine
Ancient Code
There are still genes that are shared among organisms, however diverse.
Purine
These are relatively large (as opposed to Pyrmidines) nitrogenous bases within nucleotides. Adenine and Guanine are ______. Ex: Adenine (forms two hydrogen bonds with Thymine in DNA and Uracil in RNA), Guanine (forms three hydrogen bonds with Cytosine in DNA and RNA)
Purines vs. Pyrmidines
These are relatively large (as opposed to Pyrmidines) nitrogenous bases within nucleotides. Adenine and Guanine are ______. Ex: Adenine (forms two hydrogen bonds with Thymine in DNA and Uracil in RNA), Guanine (forms three hydrogen bonds with Cytosine in DNA and RNA) vs. These are relatively small (as opposed to purines) nitrogenous bases within nucleotides. Thymine, Uracil, and Cytosine are all examples of a _________. Ex: Thymine (forms two hydrogen bonds with Adenine in DNA), Uracil (forms two hydrogen bonds with Adenine in RNA), and Cytosine (forms three hydrogen bonds with Guanine in both DNA and RNA).
Pyrmidine
These are relatively small (as opposed to purines) nitrogenous bases within nucleotides. Thymine, Uracil, and Cytosine are all examples of a _________. Ex: Thymine (forms two hydrogen bonds with Adenine in DNA), Uracil (forms two hydrogen bonds with Adenine in RNA), and Cytosine (forms three hydrogen bonds with Guanine in both DNA and RNA).
Wilkins & Franklin
These scientists inundated DNA with X-Rays, one of them took a picture which would later be interpreted by Watson & Crick as the cornerstone of the DNA, the double helical structure. The picture of the double helical structure was #51, and its taker later died from exposure to the X-Rays.
Deoxyribonucleic Acid vs. Ribonucleic Acid
This nucleic acid is composed of deoxyribose (pentose carbohydrate/sugar), phosphoric acid, and nitrogenous bases. Regarding nitrogenous bases, there are two kinds in DNA: purines (adenine, guanine) and pyrimidines (cytosine, thymine). Adenine and thymine bond to each other via feeble (in order for them to be broken during DNA replication) two hydrogen bonds. Guanine and cytosine also have weak hydrogen bonds, but they form three hydrogen bonds. The bonding of like hydrogen bonds among nitrogenous bases in DNA (and RNA) is called complementary base pairing. The phosphoric acid and the deoxyribose are on the sides of DNA and are arranged by phosphodiester bonds. Both the phosphodiester and hydrogen bonds collectively compose the double helical structure of DNA (proposed by Chargaff's rule, validated by Watson and Crick). DNA as other nucleotides is good at absorbing ultraviolet radiation. Also, DNA is slightly acidic. vs. A single-stranded nucleic acid comprised of ribose (an additional oxygen when compared to deoxyribose in DNA), phosphoric acid, and four nitrogenous bases, Adenine, URACIL, cytosine, and guanine. Uracil replaces thymine; uracil and thymine are not isomers. Three varieties of interest/concentration: mRNA (messenger RNA) tRNA (transfer RNA) rRNA (ribosomal RNA)
Translocation (Translocational Chromosomal Mutation)
This variety of chromosomal mutation (involving the changes in the structure or number of chromosomes) occurs when part of one chromosome breaks off and attaches to another chromosome. Ex: Schizophrenia is caused by this type of chromosomal mutation
tRNA
Transfer Ribonucleic Acid This carries an amino acid to a ribosome (60% rRNA, 40% protein), pairing the codon on the mRNA with a complementary anticodon that it will accordingly administer. Ex: If mRNA is coding for CUA, then tRNA responds with an anticodon of GAU.
Base Substitution
When one nitrogenous base in DNA or RNA is changed to another, then that which would have not usually have been there, is there This usually only affects a single amino acid, or none at all. (type of a point mutation) Ex: Neurofibromatosis, Sickle Cell Anemia
Base Deletion
When one nitrogenous base is removed from a sequence DNA molecule. The entire reading of the codons are affected though, however, because mRNA reads three bases at a time. If a nucleotide is added or deleted, bases still read in codons, but the grouping of the codons change after the mutation. For this reason, they are called frameshift mutations. Ex: If base A, B, C existed, and then C is removed, the sequence mRNA will read will be A,B,D. Now, the next sequence that mRNA will not be D,E,F as in a healthy gene, but rather, E,F,G.
Inversion (Inverse Chromosomal Mutation)
When the direction of parts of a chromosome are reversed. A type of chromosomal mutation (involving changes in the number or structure of chromosomes)
Promoter
Where RNA polymerase binds, in regions of DNA that have specific base sequences. These are signals in DNA molecules that show RNA polymerase exactly where to begin making RNA to initiate transcription.
Intron
Within nascent mRNA before DNA transcription to decrease the likelihood of the decimation of contiguous genes before excision. Exons are kept, ______ are taken out, and an RNA cap and tail are added to form the final mRNA molecule. Portions of pre-mRNA molecules that are extracted and discarded.