BIO-205 Chapter 11 F24 RMB Revisions PDF

Ryan Bockoven z Chapter 11  Our genetic information is stored in our DNA. But how does DNA actually affect organisms on a practical level?  Information Flows from Genes to Proteins Gene expression occurs in two steps: Transcription: DNA sequenc...

Ryan Bockoven z Chapter 11  Our genetic information is stored in our DNA. But how does DNA actually affect organisms on a practical level?  Information Flows from Genes to Proteins Gene expression occurs in two steps: Transcription: DNA sequence is copied to a complementary RNA sequence. Translation: The RNA sequence is the template for an amino acid sequence. The “central dogma of molecular biology” describes the ways in which information flows in a cell. Dotted lines are non- Polypeptides = traditional. Seen in Proteins (the things in some viruses. the cell that DO STUFF)  Question What occurs during the process of transcription? a. RNA is used as a template to make DNA b. RNA is used as a template to make proteins c. DNA is used as a template to make RNA d. DNA is used as a template to make proteins e. Proteins are used as a template to make RNA f. Proteins are used as a template to make DNA  Question What occurs during the process of transcription? a. RNA is used as a template to make DNA b. RNA is used as a template to make proteins c. DNA is used as a template to make RNA d. DNA is used as a template to make proteins e. Proteins are used as a template to make RNA f. Proteins are used as a template to make DNA Rewrite from one Nucleic Acid to another Translate from Nucleic Acid to Protein Overview of how DNA Affects Organisms Genetic Protein Protein information mRNA Sequence folding / in gene sequence (as amino shape (DNA) acids) Organismal Cellular Protein process process function Information Flows from Genes to Proteins (1) Gene expression occurs in two steps: Transcription: DNA sequence is copied to a complementary RNA sequence. Translation: The RNA sequence is the template for an amino acid sequence. The “central dogma of molecular biology” describes the ways in which information flows in a cell.  Characteristics of DNA DNA is a nucleic acid polymer made of nucleotide monomers, arranged in a double-helix There are four types of nucleotides: Adenine (A), Cytosine (C), Guanine (G), and Thymine (T). Adenine base-pairs across the helix with Thymine. Cytosine pairs with Guanine The two strands of DNA are antiparallel The 3’ end of one strand is opposite the 5’ end of the other strand  DNA is Replicated Semi- conservatively DNA replication is semi-conservative: new DNA molecules have both a new and an old strand DNA replication occurs in the 5’ to 3’ direction. Three steps in DNA replication: 1. Initiation: double helix is unwound, making two template strands 2. Elongation: addition of complementary base pairs linked by phosphodiester bonds 3. Termination: DNA synthesis ends when all DNA regions have been replicated  Initiation - The Origin of DNA Replication Origin of Replication = Where replication starts. Prokaryotes have one origin. Eukaryotes have multiple.  Three proteins involved in DNA Replication Initiation Various proteins have roles in replication initiation: Topoisomerase (DNA gyrase) reduces supercoiling DNA helicase uses energy from ATP hydrolysis to unwind the DNA (pulls the strands apart). Single-strand binding proteins (SSBs) keep the strands from getting back together. SSBs Helicase  Primase The protein primase performs the crucial step of synthesizing primers for DNA Primers are short RNA starter strands required for DNA Replication initiation DNA Polymerase cannot add DNA nucleotides directly “across the rung” of the DNA ladder. It needs something to the side to attach the nucleotides to. In the long run, the RNA primer will be degraded and replaced with DNA.  DNA Polymerase (and Elongation) DNA polymerase (DNAP): the main protein complexes that catalyze elongation of DNA The enzyme is shaped like open right hand—the “palm” brings the active site and the substrates into contact. The “fingers” recognize the nucleotide bases. They bind to bases by hydrogen bonding and rotate inward.  Question Which of the following proteins is involved with removing supercoils from DNA? a. DNA Polymerase b. Primase c. Topoisomerase d. Helicase e. SSBs  Question Which of the following proteins is involved with removing supercoils from DNA? a. DNA Polymerase b. Primase c. Topoisomerase d. Helicase e. SSBs  Elongation: New DNA Strands Grow ONLY in 5’ to 3’ Direction If this was transcription and we were adding an “A” to the sequence, the “incoming dC Incoming dNTPs “bring nucleoside TP their own energy” in terms triphosphate” of phosphates that get  Leading vs Lagging Strand Synthesis At the replication fork, DNA opens up like a zipper in one direction. The leading strand grows in the 5’ to 3’ direction, in the same direction the DNA is unwound by helicase Replicated continuously The lagging strand also grows 5’ to 3’, but in the opposite direction from the unwinding of the DNA. Thus, an unreplicated gap forms. Replicated non-continuously in Okazaki fragments Named after Japanese scientist Reiji Okazaki  Replacing Primer Fragments DNA polymerase III adds nucleotides to the 3′ end of the new primer, until reaching the primer of the previous fragment. DNA polymerase I then replaces the primer with DNA. The final phosphodiester linkage between fragments is catalyzed by DNA ligase.  Termination Less is known about Replication termination. In prokaryotes, Topoisomerase IV is involved with “decatenating” the newly replicated DNA from the old DNA  Mutations Mutations: heritable changes in DNA sequences, sometimes (but not always) affecting protein gene products Mutations can have beneficial, harmful, OR neutral effects on the protein (and thus on the cell as a whole) Recipe bad = meal tastes bad. Recipe good = meal tastes good. Image: https://evolution.berkeley.edu/dna-and-mutations/a-case-study-of-the-effects-of-mutation-sickle-cell-anemia/  Spontaneous Mutations Spontaneous mutations occur with no outside influence Various internal chemical reactions can alter bases. Example: Loss of an amino group (deamination) from cytosine converts it to uracil. If not repaired, DNA polymerase will add an A instead of G. (For comparison) If the altered base is not repaired prior to replication, or if it is repaired incorrectly, a (spontaneous) mutation will result For that matter, DNA Replication itself will have errors  Induced Mutations Induced mutation: agent from outside the cell (a mutagen) causes a change in DNA. Chemical mutagens can alter or add groups to bases Radiation can directly damage DNA or indirectly damage it through the formation of reactive oxygen species (ROS) Example: UV radiation (from the sun) is absorbed by thymine, causing it to form covalent bonds with adjacent bases (thymine dimers) and disrupt DNA replication. Ionizing radiation (like X-rays) damage Image: https://en.wikipedia.org/wiki/Pyrimidine_dimer DNA even more than typical radiation  DNA Repair While not all mutations are bad, you still do not want them to occur more often than necessary Cells have three repair mechanisms: 1. Proofreading: DNA polymerase recognizes mismatched pairs and removes incorrectly paired bases. After proofreading, only 1 error per 107 new nucleotides  Mismatch Repair 2. Mismatch repair (MMR): Newly replicated DNA is scanned by other proteins for mismatches (areas where opposite nucleotides are not complementary), so they can be corrected. After MMR, only 1 mistake per 109 new nucleotides.  Excision Repair 3. Excision repair: Enzymes scan DNA for bulky lesions (such as thymine dimers)—they are excised and undamaged nucleotides are added back. Uses a different set of proteins than mismatch repair.  Ames Test Uses bacteria to screen carcinogenic potential of new chemical compounds A Salmonella strain has a mutation that prevents it from making its own histidine, an amino acid required for life. It is placed in a medium without histidine. If the compound is mutagenic, reversion mutations will occur.  A Systematic Approach (16 of 24) Horizontal gene transfer (HGT) ─ when a gene of one species is absorbed into another pre-existing organism’s genome. Peer-to-peer instead of parent-to-child Especially common in microorganisms Not very common in eukaryotes like humans Can make it difficult to determine how organisms are evolutionarily related. Sometimes we refer to “webs” of life instead of “trees” Image: https://en.wikipedia.org/wiki/Horizontal_gene_transf er#/media/File:Tree_Of_Life_(with_horizontal_gene_t ransfer).svg Four Main Types of Horizontal Gene Transfer 1. Transformati on 2. Conjugation 3. Transductio n  HGT: Transformation In nature, prokaryote takes up naked DNA found in its environment Only a few cells are naturally competent (can bring in DNA this way) Researchers can use this method to introduce designed DNA plasmids into bacteria Artificial competence must be induced for most species, usually using heat or an electric current Image: https://www.sigmaaldrich.com/US/en/technical-documents/technical-article/genomics/advanced-gene-editing/transf  HGT: Conjugation DNA copied and sent from one prokaryote to another by a conjugation (sex) pilus that forms a cytoplasmic bridge Makes use of rolling circle replication This technique is occasionally used for research, but not as often as transformation Typically, the material moved from one cell to another cell is a plasmid and not an entire chromosome What types of genes on plasmids are commonly transferred by Transformation / Conjugation? Usually, you move genes that are useful, but not absolutely vital! Many plasmid genes fall into these categories: Unusual metabolic functions (e.g., breaking down hydrocarbons) Antibiotic resistance genes (R factors) Genes for making a sex pilus Image:  HGT: Transduction Viruses move short pieces of chromosomal DNA from one bacterium to another Can occur because of incorrect packaging or incorrect excision of prophage This technique is also sometimes used for research, although not as often as transformation Image: https://en.wikipedia.org/wiki/Transduction_(genetics)  Question Which of the following types of horizontal gene transfer is most frequently used by researchers to manipulate bacterial genomes? a. Transformation b. Transduction c. Conjugation d. Transposition  Question Which of the following types of horizontal gene transfer is most frequently used by researchers to manipulate bacterial genomes? a. Transformation b. Transduction c. Conjugation d. Transposition Information Flows from Genes to Proteins (1) Gene expression occurs in two steps: Transcription: DNA sequence is copied to a complementary RNA sequence. Translation: The RNA sequence is the template for an amino acid sequence. The “central dogma of molecular biology” describes the ways in which information flows in a cell.  Transcription Very similar to DNA replication, except RNA is made instead of DNA Like DNA Replication, mRNA strands are made in the 5’ to 3’ direction Like DNA Replication, transcription occurs in 3 steps: 1. Initiation 2. Elongation 3. Termination  RNA Polymerase Different cellular machinery is needed for transcription. An RNA Polymerase is needed as the main catalyst of elongation instead of a DNA Polymerase The RNA Polymerase needs the help of a sigma factor to bind to the DNA Other key differences between Transcription and DNA Replication 1. Use up NTPs instead of dNTPs 2. Only synthesize a single strand 3. Many different small mRNAs made, instead of a single, large DNA genome 4. Do not need primers  Reminder: Ribosomes Read ONE mRNA Strand During Translation If you give the ribosome the complementary (opposite) strand, it will NOT make a correct protein! You MUST transcribe the CORRECT strand!  Template vs. Non-template Strands Template / Antisense / Non-coding Strand: Involved in transcription (used as a base to build mRNA across from). Complementary (NOT identical) sequence to the mRNA. Non-template / Sense / Coding Strand: identical (NOT complementary) sequence to the mRNA (but has T’s instead of U’s). Not actually involved in transcription What would the simplest system for gene expression be? To always express (transcribe and translate) everything all the time! This is called constitutive expression. Some specific genes, like the genes needed to make energy SHOULD be expressed / transcribed all the time. But not ALL genes. Image: https://en.wikipedia.org/wiki/Glyceraldehyde_3-phosphate_dehydrogenase It is not ideal for a cell to always express every gene Expression consumes energy ATP is literally a building block of mRNA Some gene products outright harmful to the cell As an extreme example, some genes cause the cell to intentionally commit suicide when expressed Image: https://cdn.kastatic.org/ka-perseus-images/6c2102f5a13afe3b1a9f93e285393594bb594732.png  When is it ideal to express proteins that help digest lactose? When lactose is present – otherwise is wasteful of energy When a better energy source (especially glucose) is NOT present – otherwise would ALSO be wasteful of energy Don’t use until necessary Image: http://www.clipartbest.com/clipart- Image: https://cliparting.com/free-milk-clipart- How do we ensure we express all the enzymes needed to di8Xn6k8T 36627/ digest lactose at the same time? All of them are encoded for An extra Glycolysis step is needed to digest lactose Galactose compared to glucose. Thus, digesting lactose when both are available would waste energy. Image: Takenaka Y, Seno S, Matsuda H. Detecting shifts in gene regulatory networks during time- course experiments at single-time-point temporal resolution. J Bioinform Comput Biol.  What Proteins are Needed to Digest Lactose? Three enzymes are needed for the uptake and metabolism of lactose. 1. LacZ: Beta-galactosidase that cleaves lactose 2. LacY: Beta-galactoside permease that allows lactose to enter the cell 3. LacA: Beta-galactoside transacetylase (role less clear) In most cases, if the cell wants LacZ, it will also want LacY, and vice versa. Image: https://cliparting.com/free-milk- Image: https://en.wikipedia.org/wiki/Beta-galactoside_permease clipart-36627/  How does a cell ensure it expresses all the enzymes needed to digest lactose at the same time? All of them are encoded for by the same operon! Transcription Initiation Occurs at Specific Sequences RNA polymerase (RNAP) binds to a DNA promoter sequence, called a promoter. This sequence tells the enzyme where to start and which strand to transcribe. Prokaryotic Gene Expression Is Regulated in Operons Operon: prokaryotic gene cluster with a single promoter consisting of: A promoter (where RNA Polymerase binds) Two or more structural genes (the parts that directly encode the proteins) An operator—a short sequence between promoter and structural genes Binds to regulatory proteins called transcription factors. Transcription factors either increase transcription (activators) or decrease transcription (repressors).  Question What does RNA Polymerase bind to in order to catalyze transcription?  Question What does RNA Polymerase bind to in order to catalyze transcription? A promoter. How the lac Operon is Only Turns On When Lactose is Present When lactose is absent, repressor (a constitutive protein expressed from a nearby gene) binds to operator, prevents transcription When lactose is present, the inducer lactose binds to the repressor and changes its shape (and thus function). Inducers ultimately cause transcription to be turned on by binding to a transcription factor This prevents the repressor from binding to the operator; then RNA polymerase can bind to the promoter, and all three genes are Negative Regulation in Inducible System: Two Possibilities Lactose Repressor Repressor not acts binds to present normally operator Repressor Transcripti disrupts Lactose on falls to RNA not utilized nearly zero polymeras e Represso Lactose Inducer Lactose r converted binds to present to inducer repressor changes shape RNA polymeras Repressor Lactose e falls off utilized performs operator transcripti on  True or False? When lactose is present, the lac repressor is not transcribed.  True or False? When lactose is present, the lac repressor is not transcribed. FALSE. The lac repressor is ALWAYS transcribed. When lactose is present, the lac repressor stops binding to DNA.  What happens (in terms of growth) if glucose and lactose are both available? 1. Cell uses only glucose – growth is fast 2. Glucose depleted – growth slows down Machinery in place to use glucose but not lactose as energy source 3. Cell produces machinery for lactose (activates the lac operon) Lactose Growth remains slow in the meantime operon activated 4. Cell uses lactose – growth speeds here up 5. Lactose depleted – growth slows down This is called diauxic or diphasic growth Image: https://openstax.org/books/microbiology/pages/11-7-gene-regulation-operon-theory How the lac Operon Only Turns On When Glucose is Absent If glucose is low, the co-activator cAMP increases. A co-activator helps to activate an activator, which in turn helps to activate transcription cAMP binds to cAMP receptor protein (CRP); CRP-cAMP complex then binds to the lac promoter. CRP is an activator; it results in more efficient binding of RNA polymerase and thus increased transcription.  Positive Regulation in Inducible System: Two Possibilities cAMP CRP cAMP Lactose Glucose does not does not Transcripti levels poorly present bind to bind to on is poor low utilized CRP DNA CRP- Glucose cAMP cAMP Transcripti cAMP Lactose not levels binds to on is binds to utilized present rise CRP activated DNA When is the Lac Operon transcribed? https://openstax.org/books/microbiology/pages/11-7-gene-regulation-operon-theory When is the Lac Operon transcribed? Ideal conditions for transcription https://openstax.org/books/microbiology/pages/11-7-gene-regulation-operon-theory When is the Lac Operon transcribed? Not enough Lactose https://openstax.org/books/microbiology/pages/11-7-gene-regulation-operon-theory When is the Lac Operon transcribed? Too much glucose https://openstax.org/books/microbiology/pages/11-7-gene-regulation-operon-theory What happens if we mix and match regulatory regions with structural genes? Example: what if we put the structural genes needed to digest sucrose downstream of the lac promoter / operator / etc. in E. coli? What happens if we mix and match regulatory regions with structural genes? Example: what if we put the structural genes needed to digest sucrose downstream of the lac promoter / operator / etc. in E. coli? Hint: remember that the regulatory region decides WHETHER something gets transcribed. The structural genes are the THINGS THAT ACTUALLY GET TRANSCRIBED. What happens if we mix and match regulatory regions with structural genes? Example: what if we put the structural genes needed to digest sucrose downstream of the lac promoter / operator / etc. in E. coli? The genes needed to digest sucrose would be transcribed when lactose is present and glucose is absent! Researchers know how to manipulate genomes, so that means they can create their OWN inducible systems!  Reporter Genes Researchers can learn more about a regulatory region by using a “reporter gene” that performs a known function when expressed. Note: Usually, these reporter genes are designed to monitor transcription and are called “transcriptional fusions” or “operon fusions.” Ex: Green Fluorescent Protein causes cell to fluoresce green when expressed LacZ, Luciferase (generates light), and Red Fluorescent Protein are also famous reporter genes Image: https://en.wikipedia.org/wiki/Reporter_gene  Eukaryotic Pre-mRNA Transcripts Are Processed prior to Translation The overall Central Dogma works the same in prokaryotes and eukaryotes. But there are differences in gene structure and whether the nucleus separates transcription and translation.  Splicing, Introns, and Exons Primarily in eukaryotes, noncoding regions (introns) get transcribed, but sliced out of pre-mRNA in the nucleus. Only the coding sequences (exons) reach the ribosome. Splicing out introns is a step in RNA processing. Information Flows from Genes to Proteins (1) Gene expression occurs in two steps: Transcription: DNA sequence is copied to a complementary RNA sequence. Translation: The RNA sequence is the template for an amino acid sequence. The “central dogma of molecular biology” describes the ways in which information flows in a cell.  Codons provide the information for translation Three nucleotides (1 codon) provide the information on which amino acid to translate Start codon defines reading frame 5’ –AUAAGGAGGUUACG(AUG)(CAG)(CAG)(GGC)(UUU)(ACC) – 3’ Met –Gln -Gln -Gly -Phe -Thr Addition of a U shifts the reading frame and changes the codons and amino acids specified 5’ –AUAAGGAGGUUACG(AUG)(UCA)(GCA)(GGG)(CUU)(UAC)C – 3’ Met –Ser -Ala -Gly -Leu -Tyr The big red dog can run and hop. One letter missing - Thb igr edd ogc anr una ndh op. 2 letters missing - Tbi gre ddo gca nru nan dho p. Three letters missing - The red dog can run and hop. The big red dog can run and hop. Insert letters- The big kre ddo gca nru nan dho  True or False? A deletion of one nucleotide from a sequence will have a greater effect on the resulting protein than a deletion of three nucleotides.  True or False? A deletion of one nucleotide from a sequence will have a greater effect on the resulting protein than a deletion of three nucleotides. TRUE Genetic Code Redundant but NOT ambiguous  Types of Mutations (in Terms of Their Effects on Proteins) Silent mutation: substitution that results in a codon that codes for the same amino acid. Missense mutation: substitution resulting in a codon for a different amino acid. In sickle-cell anemia, the sickle allele differs from normal by one base pair, which alters one subunit of hemoglobin.  Nonsense Mutations Nonsense mutations: base substitution results in a stop codon somewhere in the mRNA. Results in a shortened protein, usually not functional. If near the 3' end, it may have no effect.  Frame-shift Mutations Loss of stop (stop-loss) mutation: base pair substitution that changes a stop codon to a sense codon; extra amino acids are added to the polypeptide. Can also get start-loss mutations. Frame-shift mutation: insertion or deletion of a base pair. Alters the mRNA reading frame (consecutive triplets) during translation; produces nonfunctional proteins. This could also lead to stop-loss  Question Which of the following types of mutations involves a stop codon existing where it is not supposed to? a. Silent mutation b. Nonsense mutation c. Missense mutation d. Frameshift mutation e. Loss-of-stop mutation  Question Which of the following types of mutations involves a stop codon existing where it is not supposed to? a. Silent mutation b. Nonsense mutation c. Missense mutation d. Frameshift mutation e. Loss-of-stop mutation  Frame-shift Mutations Frame-shift mutation: insertion or deletion of a base pair. Alters the mRNA reading frame (consecutive triplets) during translation; produces nonfunctional proteins. This could also lead to stop-loss  Different Types of RNA (3 main ones) mRNA (messenger) An RNA copy of a gene that is read by a ribosome and translated into the amino acid sequence of a protein. tRNA (transfer) RNA molecules that bind and transport individual amino acids to the ribosome for protein assembly. rRNA (ribosomal) RNA molecules that form part of the structure of a ribosome. Are involved in catalyzing peptide bond formation  Question Which of the following types of RNA is present as a structural component of the ribosome? a. mRNA b. rRNA c. tRNA d. Ribosomes are composed of proteins, not RNA  Question Which of the following types of RNA is present as a structural component of the ribosome? a. mRNA b. rRNA c. tRNA d. Ribosomes are composed of proteins, not RNA  tRNA Structure tRNA is the “translation book” of the cell It can convert the information of mRNA codons to the information of specific amino acids due to its structure On one end, it has an anticodon that can base pair with specific codons On the other end, it binds to an amino acid There are many specific tRNAs. Each of them only ever binds to one specific amino acid Image: Need to Charge tRNA to Perform Translation Carried out by an enzyme called Aminoacyl tRNA synthetase No other amino acid can get into this space No other tRNA can get into this space  The Coding Sequence in mRNA Is Translated into Proteins by Ribosomes The ribosomal large subunit has three binding sites: A (aminoacyl tRNA) site —binds with the anticodon of charged tRNA. P (peptidyl tRNA) site— where tRNA holding the growing chain resides (until the growing chain is transferred). E (exit) site—where  Translation Three steps: 1. Initiation 2. Elongation 3. Termination  Translation Initiation A charged tRNA and a small ribosomal subunit, both bound to mRNA, form an initiation complex. In prokaryotes, rRNA binds to the Shine-Dalgarno sequence on the mRNA. In eukaryotes, it binds to the 5′ cap. Process is guided by various proteins called initiation factors Start codon is AUG First amino acid always methionine, but can be removed First tRNA ends up in P site  Translation Elongation 1. Another charged tRNA enters A site Requires energy  Translation Elongation 1. Another charged tRNA enters A site Requires energy 2. The rRNA of large subunit catalyzes the transfer of the growing amino acid chain from the tRNA in the P site to the amino acid in the A site Does not require energy  Translation Elongation 1. Another charged tRNA enters A site Requires energy 2. The rRNA of large subunit catalyzes the transfer of the growing amino acid chain from the tRNA in the P site to the amino acid in the A site Does not require energy 3. Newly-uncharged tRNA translocates to the E site while the tRNA that now has the growing chain transfers to the P site Requires energy  Translation Elongation 1. Another charged tRNA enters A site Requires energy 2. The rRNA of large subunit catalyzes the transfer of the growing amino acid chain from the tRNA in the P site to the amino acid in the A site Does not require energy 3. Newly-uncharged tRNA translocates to the E site while the tRNA that now has the growing chain transfers to the P site Requires energy 4. E site tRNA dissociates from the ribosome. It can be charged again.  Translation Elongation 1. Another charged tRNA enters A site Requires energy 2. The rRNA of large subunit catalyzes the transfer of the growing amino acid chain from the tRNA in the P site to the amino acid in the A site Does not require energy 3. Newly-uncharged tRNA translocates to the E site while the tRNA that now has the growing chain transfers to the P site Requires energy 4. E site tRNA dissociates from the ribosome. It can be charged again. Elongation occurs as the steps are repeated. It is a very complex process with many components  Amino end of polypeptide E mRNA 3 Ribosome ready for P A sitesite next aminoacyl tRNA 5 GTP GDP  P i E E P A P A GDP  P i GTP E P A Translation Termination Translation ends when a stop codon enters the A site. A protein release factor hydrolyzes the bond between the polypeptide and the tRNA in the P site. The polypeptide then separates from the ribosome. Peptide released through exit tunnel of ribosome  Polypeptides Can Be Modified and Transported during or after Translation Most polypeptides are modified after translation (by various post-translational modifications):  Polypeptides Can Be Modified and Transported during or after Translation Proteolysis: Polypeptide is cut by proteases, (e.g., signal sequence is removed).  Polypeptides Can Be Modified and Transported during or after Translation Glycosylation: Addition of sugars to form glycoproteins. The sugars can act as signals; others form membrane receptors. Polypeptides Can Be Modified and Transported during or after Translation Phosphorylation: Addition of phosphate groups, catalyzed by protein kinases. The charged phosphate groups change the conformation and may expose active sites or binding sites.  True or False? Once a protein has been translated, it is a completely static entity that can never be altered for any reason.  True or False? Once a protein has been translated, it is a completely static entity that can never be altered for any reason. FALSE