Ch.17 APBIO (The Central Dogma - From Gene to Protein)
Thiol Group
SH
Termination
The last stage of trranscription, stop of mRNA synthesis (i.e., transcription) at the terminator site, in Eukaryotes it involves the use of a polyadenton sequence.
Complete Growth Medium
This is a minimal medium that is supplemented with all 20 amino acids and a few other nutrients, usually required by the mutated species.
p53
This tumor suppressor gene causes cell cycle arrest in G1, providing time for DNA repair. If repair is successful, cells re-enter the cycle. If unsuccessful, apoptosis
GTP
Two molecules of _______ are required for Codon recognition, and it also increases the accuracy and efficency, one more _____ is hydrolyzed to provide energy fro the translocation step.
Free Ribosomes
ribosomes that float in the cytosol to make the proteins that are used there
Signal Recognition Particle
(SRP), a protein-RNA complex that recognizes a signal peptide as it emerges from a ribosome and helps direct the ribosome to the endoplasmic reticulum (ER) by binding to a receptor protein on the ER
miRNA
(microRNA) about 20 nucleotides long, a small, single-stranded RNA molecule, generated from a hairpin structure on a precursor RNA transcribed from a particular gene, it associates with one or more proteins in a complex that can degrade or prevent translation of an mRNA with a complementary sequence, up to 1/3 of all human genes may be regulated by ______
Small Nuclear Ribonucleoproteins
(snRNPs) recognize splice sites; are composed of RNA, protein molecules at the end of introns, they are located in the cell nucleus, the RNA within it is called a (snRNA) or small nuclear RNA, forms part of spliceosomes
The Central Dogma
1. DNA is the genetic material, containing the genes that are responsible for the physical traits (phenotye) observed in all living organisms 2. DNA is replicated from existing DNA to produce new genomes 3. RNA is produced by reading DNA in a process called transcription 4. this RNA serves as the message used to decode and transmit the genetic information and synthesize proteins according to the encoded information. This process of protein synthesis is called translation.
Elongation
2nd stage where amino acids brought by tRNAs are joined together by the ribosome in the order determined by the mRNA
TATA Box
A DNA sequence in eukaryotic promoters crucial in forming the transcription initiation complex
Gene
A _______ is a region of DNA whose final product is either a polypeptide or an RNA molecule.
Ribosomes
A cell organelle constructed in the nucleolus and functioning as the site of protein synthesis in the cytoplasm; consists of rRNA and protein molecules, which make up two subunits, act as the sites of translation, and facilitate the orderly linking of amino acids into polypeptides.
Phosphate Group
A chemical group consisting of a phosphorus atom covalently bonded to four oxygen atoms; important in energy transfer., , -OPO3^-2; contributes neg charge to molecule of which it is a part ; has potential to react with water releasing NRG
Exons
A coding region of a eukaryotic gene. Exons, which are expressed except for the UTR, are separated from each other by introns.
Release Factor
A cytoplasmic protein that binds to a stop codon where it appears in the A-site of the ribosome. modify the peptidyl transferase activity of the ribosome, so that a water molecule is added to the end of the completed protein. This releases the finished protein from the final tRNA, and allows the ribosome subunits and mRNA to disassociate.
Hydroxyl Group
A functional group consisting of a hydrogen atom joined to an oxygen atom by a polar covalent bond. Molecules possessing this group are soluble in water and are called alcohols.
Carboxyl Group
A functional group present in organic acids and consisting of a single carbon atom double-bonded to an oxygen atom and also bonded to a hydroxyl group.
Amino Group
A functional group that consists of a nitrogen atom bonded to two hydrogen atoms; can act as a base in solution, accepting a hydrogen ion and acquiring a charge of +1., -NH2
Gibberellins
A growth hormone that causes a wide variety of effects. One role is to stimulate growth of stems by promoting cell division. Farmers use it to make fruit grow larger.
Sickle Cell Disease
A human genetic disease caused by a recessive allele that results in the substitution of a single amino acid in the hemoglobin protein; characterized by deformed red blood cells that can lead to numerous symptoms.
Insertions
A mutation involving the addition of one or more nucleotide pairs to a gene.
Frameshift Mutation
A mutation occurring when the number of nucleotides inserted or deleted is not a multiple of three, resulting in the improper grouping of the following nucleotides into codons.
Nonsense Mutation
A mutation that changes an amino acid codon to one of the three stop codons, resulting in a shorter and usually nonfunctional protein.
Complementary Strand
A newly synthesized strand of RNA or DNA that has a base sequence complementary to that of the template strand
GTP
A nucleotide composed of guanine, ribose, and three linked phosphate groups. It is incorporated into the growing RNA chain during synthesis of RNA and used as a source of energy during synthesis of proteins
Missense Mutation
A point mutation in which a codon that specifies an amino acid is mutated into a codon that specifies a different amino acid.
Silent Mutation
A point mutation in which a codon that specifies an amino acid is mutated into a new codon that specifies the same amion acid.
Polypeptide
A polymer (chain) of many amino acids linked together by peptide bonds.
Signal Peptide
A sequence of about 20 amino acids at or near the leading (amino) end of a polypeptide that targets it to the endoplasmic reticulum or other organelles in a eukaryotic cell.
Anticodon
A sequence of three bases of a tRNA molecule that pairs with the complementary three-nucleotide codon of an mRNA molecule during protein synthesis.
Triplet Code
A set of three-nucleotide-long words that specify the amino acids for polypeptide chains.
Terminator
A special sequence of nucleotides in DNA that marks the end of a gene. It signals RNA polymerase to release the newly made RNA molecule, which then departs from the gene
Spliceosomes
A spliceosome is a complex of specialized RNA (snRNPs) and protein subunits that removes introns from a transcribed pre-mRNA (segment. This process is generally referred to as splicing.
Aminoacyl tRNA
A tRNA with an amino acid attached. This is made by an animoacyl-tRNA synthetase specific to the amino acid being attache.d
Codons
A three-nucleotide sequence of DNA or mRNA that specifies a particular amino acid or termination signal; the basic unit of the genetic code. Written in 5` to 3` direction.
RNA
A type of nucleic acid consisting of nucleotide monomers with a ribose sugar and the nitrogenous bases adenine (A), cytosine (C), guanine (G), and uracil (U); usually single-stranded; functions in protein synthesis and as the genome of some viruses.
Base Pair Substitution
A type of point mutation; the replacement of one nucleotide and its partner in the complementary DNA strand by another pair of nucleotides. Some are called silent mutations
Tetrahymena
A type of protists called ciliates; small, unicellular organisms that can be found in pond water, and object of self splicing rRNA
Wobble
A violation of the base-pairing rules in that the third nucleotide (5' end) of a tRNA anticodon can form hydrogen bonds with more than one kind of base in the third position (3' end) of a codon.
Ribozymes
An RNA molecule that functions as an enzyme, catalyzing reactions during RNA splicing
Retroviruses
An RNA virus that reproduces by transcribing its RNA into DNA and then inserting the DNA into a cellular chromosome; an important class of cancer-causing viruses.
Streptomycin
An antibiotic produced by the actinomycete Streptomyces griseus and used to treat tuberculosis, works because of the differential sizes of rRNA in bacteria and humans.
Human Genome Project
An international effort to map the complete human genetic code. This effort was essentially completed in 2001, though analysis is ongoing.
Nuclei
Because bacteria lack _____, their DNA is not segregrated from ribosomes and the other protein synthesizing equipment.
The 5` Cap
Contains a modified inverted nucleotide (7-methyl guanosine) which confers stability against nucleases and provides a mechanism to be recognized by the translation machinery. elps protect the pre mRNA from hydrolytic enzymes, and facilitate the export of mature mRNA from the nucleus.
Alkaptonuria
Defect in homogentisate oxidase, resulting in accumulation of homogentisic acid (Alkapton) which results in black urine, and Polymerized forms results in damage to joints, calfications in CV and UT, red skin
Translocation
During protein synthesis, the third stage in the elongation cycle when the RNA carrying the growing polypeptide moves from the A site to the P site on the ribosome
RNA Polymerase
Enzyme similar to DNA polymerase that binds to DNA and separates the DNA strands during transcription, can only assemble in 5` to 3` ends.
aminoacyl- tRNA synthetase
Enzyme which joins amino acids to the correct tRNA
Polyribosomes
Found in eukaryotic and prokaryotic cells, enable a cell to make many copies of a polypeptide very quickly during translation; multiple ribosomes attached to an MRNA strand
RNA Pol 2
In Eukaryotes it is the RNA polymerase that transcribes DNA template strand when signaled by promoter
Tertiary Structure
Irregular contortions of a protein molecule due to interactions of side chains involved in hydrophobic interactions, ionic bonds, hydrogen bonds, and disulfide bridges. (Making Up the 3-D Structure)
George Beadle
Man who hypothesis that each of the various mutations affecting eye color in Drosophila blocks pigment synthesis at a specific step by preventing production of the enzyme that catalyzes that step Along with Tatum he mutated bread mold (Neurospora Crassa) using x-rays and observed difference in food requirements by providing different enzymes at differnt steps in the catabolic pathway and discovered that each class was blocked at different steps in the pathway because mutations in the class lacked the enzyme that catalyzes the blocked step this lead to the one gne one enzyme hypothesis - which then lead to the one gene one polypedptide hypothesis
RNA processing
Modification of RNA transcripts(pre mRNA), including splicing out of introns, joining together of exons, and alteration of the 5' and 3' ends
Spontaneous Mutations
Natural changes in the DNA caused by unidentified environmental factors
Elongation Factors
One of a group of nonribosomal proteins required for continued translation of mRNA (protein synthesis) following initiation
A Site
One of a ribosome's three binding sites for tRNA during translation. This site in the ribosome holds the tRNA carrying the next amino acid to be added to the polypeptide chain.
E Site
One of a ribosome's three binding sites for tRNA during translation. This site is the place where discharged tRNAs leave the ribosome.
pre- mRNA
Precursor mRNA; the first strand of mRNA produced by the gene transcription that contains both introns and exons
Messenger RNA
RNA that copies the coded message from DNA in the nucleus and carries to the protein synthesizing machinery of a cell into the cytoplasm
Mutations
Random errors in gene replication that lead to a change in the sequence of nucleotides; the source of all genetic diversity
Redundancy
Repetition of messages to reduce the probability of errors in transmission, found in mRNA base sequences
Hermann Muller
Scientist(s) who demonstrated that mutations and hereditary changes can be caused via radiation.
Transfer RNA
Short-chain RNA molecules (L Shaped) present in the cell (in at least 20 varieties, each variety capable of combining with a specific amino acid) that attach the correct amino acid to the protein chain that is being synthesized at the ribosome of the cell, at 3` end it has amino acid.
AUG
Start codon for protein synthesis(METHIONINE)
Ribosomal RNA
The MOST abundant type of RNA, which together with proteins, forms the structure of ribosomes. Ribosomes coordinate the sequential coupling of tRNA molecules to mRNA codons. Made in the nucleolus
N Terminus
The amino end of the methionine(START) in an RNA. The amino end
64
The amount of possible base code words( 4 ^3), enough to code for the 20 amino acids known. 61 code for things while 3 are either start or stop codons.
C Terminus
The end of a polypeptide chain that contains the last amino acid to be incorporated during mRNA translation; usually retains a free carboxyl group
Primary Structure
The first level of protein structure; the specific sequence of amino acids making up a polypeptide chain.
Archibald Garrod
The first to suggest that genes dictate phenotypes through enzymes that catalyze specific chemical reactions in the cell., Reported Alkaptonuria as the first human example of what is now known as Mendelian inheritance.
Quaternary Structure
The fourth level of protein structure; the complex shape resulting from the association and aggregation of two or more polypeptide subunits.
One gene One polypeptide hypothesis
The hypothesis that every gene directs the synthesis of a particular polypeptide chain; originally called the one geneone enzyme hypothesis.
Secondary Structure
The localized, repetitive coiling or folding of the polypeptide backbone of a protein due to hydrogen bond formation between constituents of the backbone.Alpha helices and beta pleated sheets describe this
Poly A Tail
The modified end of the 3' end of an mRNA molecule consisting of the addition of some 50 to 250 adenine nucleotides. Helps protect the pre mRNA from hydrolytic enzymes, and facilitate the export of mature mRNA from the nucleus.
Nucleolus
The organelle where ribosomes are made, synthesized and partially assembled, located in the nucleus
UTR
Untranslated regions at the 5 and 3 primed ends; are part of the mRNA that will not be translated into protein but promote ribosome binding
Minimal medium
a defined medium that contains the minimal ingredients needed by genetically normal (wild type) strains of a particular species.
Keratin
a fibrous scleroprotein that occurs in the outer layer of the skin(epidermis) and in horny tissues such as hair feathers nails and hooves, lead to the revison of the one gene- one enzyme hypothesis.
Introns
a non-coding, intervening sequence within a eukaryotic gene removed during RNA splicing
Deletions
a nucleotide is deleted, which changes the amino acid sequence.
Promoter
a nucleotide sequence on a DNA molecule to which an RNA polymerase molecule binds, which initiates the transcription of a specific gene, upstream from the terminator, determines which DNA strand is used as the template.
Alternative RNA splicing
a type of eukaryotic gene regulation at the RNA-processing level in which different mRNA molecules are produced from the same primary transcript, depending on which RNA segments are treated as exons and which as introns, also explains why humans can get along with a relatively small amount of genes.
Mutagens
agents, such as chemicals or radiation, that damage or alter genetic material in cells
Tetracycline
an antibiotic (trade name Achromycin) derived from microorganisms of the genus Streptomyces and used broadly to treat infections,orks because of the differential sizes of rRNA in bacteria and humans.
Carbonyl Group
an organic molecule, a functional group consisting of a carbon atom linked to a double bond to an oxygen atom, C=O
siRNA
class of double-stranded RNAs about 23 nucleotides in length that silence gene expression; act by either promoting the degradation of mRNAs with precisely complementary sequences or by inhibiting the transcription of genes containing precisely complementary sequences, also called small interfering RNA
Domains
discrete structural and functional regions of proteins
Primary Transcript
in eukaryotes, the initial RNA product containing introns and exons produced by transcription of DNA; must be processed to form proteins
Polyadenylation
last step of splicing, adds poly-a to the tail with the AUAAA code with poly-A-polymerase, then 10 to 35 nucletides the pre-mRNA is released
Marshall Nirenberg
made poly-U mRNA (UUUUU); when mixed with amino acids, ribosomes, & proper enzymes, a polypeptide containing only one amino acid (phenylalanine)(AAA) was produced
Point Mutation
mutation that affects a single nucleotide, usually by substituting one nucleotide for another
proto oncogenes
normal cellular genes that are important regulators of normal cellular processes, they promote growth. alterations in the expression of these cells resulr in oncogenes
Post Translation Modification
occurs mainly in Golgi includes addition of sugars, lipids, etc. to complete polypeptide also have polypeptides that are cleaved or several different polypeptides that come together to form final protein (ex.- hemoglobin)
P Site
one of a ribosome's three binding sites for tRNA during translation. It holds the tRNA carrying the growing polypeptide chain.
Initiation Factors
proteins that bind to ribosomal subunits and mRNA that bring components together in the correct positions to start translation
Oncogenes
research on tumor viruses led to the discovery of cancer-causing genes called ___________ in certain retroviruses
Bound Ribosomes
ribosomes that are attached to the endoplasmic reticulum to make proteins to be exported, to be embedded in membranes, and to be shipped elsewhere within the cell
snRNA
short for small nuclear RNA and found within snRNPs. It can remove introns during the process: RNA splicing
snoRNA
small nucleolar RNA that form snoRNPs that modify rRNA and other snRNAs
Neurospora crassa
studied by Beadle and Tatum using X-Ray , a common bread mold that grows on a very simple medium containing sugar and simple inorganic salts
Template Strand
the DNA strand that provides the pattern, or template, for ordering the sequence of nucleotides in an RNA transcript using DNA Polymerase.
Transcription Initiation Complex
the completed assembly of transcription factors and RNA polymerase bound to the promoter
Initiation
the first phase of transcription; RNA polymerase binds to DNA @ the promoter, and unwinds the double helix
Exon shuffling
the presence of introns in a gene may facilitate the evolution of new and potentially useful proteins as a result of a process known as _______ _________, by increasing the probability of a crossover (like recombinant DNA by increasing distances between exons)
Gene Expression
the process by which DNA directs the synthesis of proteins, Has two stages transcription and translation.
Translation
the process whereby genetic information coded in messenger RNA directs the formation of a specific polypeptide at a ribosome in the CYTOPLASM
RNA Splicing
the removal of introns and joining of exons in eukaryotic RNA, forming an mRNA molecule with a continuous coding sequence; occurs before mRNA leaves the nucleus.
Transcription
the synthesis of RNA on a DNA template, the information is copied from one molecule to another, resulting in a faithful copy the gene's protein coding genes(mRNA), occurs in the NUCLEUS.
Reading Frame
the way in which a cell's mRNA-translating machinery groups the mRNA nucleotides into codons.
Transcription Factors
to initiate transcription, eukaryotic RNA polymerase requires the assistance of proteins called _________ _________, which usually contains a TATA box
Transcription Unit
unit, a region of a DNA molecule that is transcribed into an RNA molecule
