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bio exam 3
| Question | Answer |
|---|---|
| in eukaryotes DNA is in the ________ and in prokaryotes DNA is in the _________ | nucleus; nucleoid |
| each polypeptide is coded for by a single ________. ________ is all of the DNA in your body and DNA codes for genes which codes for polypeptides | gene . genome |
| A _________ is a single DNA molecule | chromosome |
| in eukaryotes DNA is arranged ________ and in prokaryotes DNA is arranged ________ | linearly; circular |
| DNA wraps itself around ________ (protein) to make ________ | histones; chromatin |
| why do histones and DNA wrap around so well? | because histones are positively charged and DNA is negatively charged |
| what does it mean when DNA is condensed? | DNA and histones are really wrapped tight around each other and are really organized and that is when you get the "X" shape |
| the only time DNA is in the X shape is after ________ | replication |
| when DNA is in the X form, you have _____ chromosomes and _____ molecules of DNA (this is after replication) | 1; 2 |
| ______ ________ code for biological "information." | Nucleic acids |
| how are nucleotides linked? | by a condensation reaction between the hydroxyl groups that forms a phosphodiester bond |
| biological information that is used to make polypeptides is held in the _________ of ________ | sequence of bases |
| DNA carries information in a _______ _______ (structure) | double helix |
| what aspect of DNA gives us the ability to create new identical strands of DNA using a template strand? | complementary base pairing |
| when you go through DNA replication, the entire _______ is replicated | genome |
| do you need to perform DNA replication when you go through transcription? | no, DNA replication is not necessary to go through transcription or translation, replication is only used before cell division |
| what 4 features define DNA structure? | double helix with uniform diameter, right handed (chirality), antiparallel, major and minor grooves |
| double helix structure was determined with ________ _____________ | x-ray crystallography |
| what scientist played a large role in x-ray crystallography and discovering DNA's double helix structure | rosalyn franklin |
| how does complementary base pairing make DNA diameter uniform? | because of the fact that purines go with pyrimidines and that single rings bond with double rings; if there were two single rings or two double rings the diameter would vary |
| _______ _________ relates uniform diameter to complementary base pairing | charger's rule |
| purines are ______ ringed and pyrimidines are ______ ringed | double; singled |
| ________ and ________ summarized pre-existing data to make the first model of DNA | • Watson and Crick |
| why are the grooves important in DNA? | the exposed base pairs' surfaces differ and that allows for protein DNA interaction |
| DNA structure is essential to its __________ | function |
| _________ have many genes and _______ are part of chromosomes | Chromosomes; genes |
| Which of the following best represents the relationship between a nitrogenous base and a phosphate? | In a nucleotide they are both connected to a 5 carbon sugar They are connected to a 1’ carbon and a 5’ carbon |
| The complement of 5’ ATCCGTA 3’ must be _______ and have the sequence _______ | 3' to 5'; TAGGCAT |
| if a DNA sequence is made up of 10% A then you know there must be how much of C? | 40% C |
| What is the relationship between a gene and a phenotype | A gene determines a phenotype bc your proteins determine phenotype and genes code for proteins |
| new nucleotides are added onto the __________ group | 3' OH |
| antiparallel refers to the ________ orientation | nucleotide |
| _______ of bases and _______ bonds formed in the grooves differ | polarity; hydrogen |
| _______ _______ are where enzymes and other proteins interact with the DNA molecule | major grooves |
| the major groves are more _______ and have more _______ | reactive; space |
| in order to keep DNA's functions of replication, storage of genetic information, and expression of genotype, we have to have _______ replication of DNA | precise |
| in living things, _______ is the hereditary material | DNA |
| what experiment solved the problem of whether protein or DNA was the hereditary materials? | hershey-chase experiment |
| what did hershey-chase experiment use in their experiment? | injected bacteriophage with radioactive sulfur to see if the hereditary material was protein and injected bacteriophage with radioactive phosphorus to see if the hereditary material was DNA |
| what did hershey-chase find? | radioactive phosphorus was in the pellet with the bacterial cells so DNA was passed on and it was found to be the hereditary material and not protein because radioactive sulfur was in fluid with viruses |
| what are DNA's 2 primary functions? | replicate genetic information for new cells and transcribe genetic info to make polypeptides |
| replication is important before ______ _______ and transcription and translation is important for _______ ________ | cell division; phenotypic expression |
| what were the 2 hypotheses for how DNA replicated | semiconservative and conservative |
| hypothesis of replicating DNA by saving half of the original strand and synthesizing one new strand to go with it | semiconservative |
| hypothesis of replicating DNA by somehow replicating by saving original molecule and synthesizing 2 brand new strands | conservative |
| Meselsohn and Stahl used isotopes of ________ to test the 2 hypotheses of semiconservative replication and conservative replication | nitrogen |
| Meselsohn and Stahl showed that DNA replicates __________ because there was an intermediate strand | semi-conservatively |
| what are the 2 main steps that DNA replication involves? | strand separation and elongation or extension |
| where does replication start? | the "origin of replication" |
| in prokaryotes, there are _______ origins of replication and eukaryotes there are ________ origins of replication | one, multiple |
| specific DNA sequence that specific enzymes recognize and know to start replication | "ori" sequence |
| Strand separation opens the helix with specific ________ | enzymes |
| certain enzyme that unwinds the helix and breaks apart the hydrogen bonds between bases; kind of twists DNA molecule to prevent it from being tangled | helicase |
| proteins that prevent the strands from coming back together after helicase opens the helix up | single stranded binding proteins |
| strand separation exposes the ________ _______ | nucleotide bases |
| why is the exposing of nucleotide bases in strand separation important? | because then we can use it as a template and find the complementary bases and form a new strand |
| DNA extension adds nucleotides to a free ____________ | 3’-OH (hydroxyl) |
| a phosphodiester bond is formed where in a strand of DNA | between 3’-OH (hydroxyl) and phosphate |
| where does DNA polymerase III get the energy to make phosphodiester bonds between nucleotides on a strand of DNA? | from breaking off 2 phosphates off of a dNTP |
| why do we need that free 3’-OH (hydroxyl) to synthesize new nucleotides on a strand of DNA | because DNA polymerase only recognizes 3’-OH (hydroxyl) in order to link together new nucleotides |
| _________ are substrates for DNA polymerase | dNTPs |
| what 3 things does DNA extension need | free 3'OH, DNA polymerase, dNTP |
| the fact that the dNTP phosphate hydrolysis is used to fuel the synthesis of a phosphodiester is a ______ _______ reaction | energy coupled |
| the synthesis of a new DNA strand is ________ | endergonic |
| ________ ________ is a large enzyme that wraps itself around the DNA and synthesizes a new DNA strand using a free 3'OH group and dNTP | DNA polymerase |
| DNA extension starts with a ________ | primer |
| the primer in DNA synthesis provides a _______________ for DNA polymerase | free 3'OH group |
| an enzyme that can synthesize a nucleic acid without the aid of a free 3'OH group; can just start building a new strand of RNA | primase |
| the ________ strand replicates continuously | leading |
| DNA is always read in what direction? | 3' to 5' |
| DNA is synthesized in what direction? | 5' to 3' |
| in the leading strand, the template strand is in what orientation? | 3' to 5' |
| the _______ _______ replicates in fragments | lagging strand |
| in the lagging strand, the template strand is in what orientation? | 5' to 3' |
| fragments of newly synthesized molecule in the lagging strand | okazaki fragments |
| ________ __________ removes RNA primers | DNA polymerase 1 |
| _______ _________ patches new DNA fragments together | DNA ligase |
| LOOK AT ENZYMES CAN MAKE MISTAKES LECTURE 22 | |
| ________ is a controlled method of replicating DNA | PCR - polymerase chain reaction |
| LOOK AT PCR IN BOOK | |
| ________ _________ is responsible for reproduction, growth, and regeneration | Cell division |
| cell division can be triggered by _______ or ________ cues | internal or external |
| Prokaryotic cells divide by _______ _________ | binary fission |
| mitosis involves nuclear division, and since prokaryotes do not have a nucleus they divide differently | |
| how does binary fission work | there is 1 ori, the DNA is replicated then segregated, then the cell splits in half. there is no rebuilding of the nucleus or any other organelles bc they don't have them |
| eukaryotic cells divide by ________ or ________ and then _________ | mitosis, meiosis, cytokinesis |
| when is mitosis used for cell division? | growth, cell replacement, healing, development |
| when is meiosis used for cell division? | to generate gametes |
| the ______ ________ is the life of the cell and its the process that goes into cell division | cell cycle |
| the cell cycle has ______ phases | 4 |
| what are the 4 phases of the cell cycle | G1, S, G2, AND M |
| phase of the cycle that includes: growth, normal function (cell resp, photosynthesis), chromosomes are a single molecule of DNA | G1 |
| phase of the cell cycle that includes: DNA replication, 2 sister chromatids (X) | S |
| phase of the cell cycle that includes: preparation for mitosis, building of microtubules | G2 |
| ________ are essential to pulling apart the chromosomes and segregating them for cells, they use motor proteins to do this also | microtubules |
| phase of the cell cycle that includes: mitosis (nuclear division) and cytokinesis (cytoplasmic division) | M |
| Before DNA replication, a frog has 24 chromosomes. How many chromosomes does it have after DNA replication? | 24 |
| before DNA replication a frog cell has 24 chromosomes. How many DNA molecules does it have after DNA replication? | 48 |
| before DNA replication, a frog cell has 24 chromosomes. How many sister chromatids does it have after DNA replication? | 48 |
| sister chromatids and DNA molecules can kind of be kept as the same term!!!!! | |
| Progress through the cell cycle depends on ___________ | kinases (CDKs). |
| out of control cell division is _______ | cancer |
| when _____ is present, your cells will NOT go through cell division | RB |
| what does RB inhibit? | DNA synthesis |
| what happens if RB is NOT present? | your cell divides |
| how do we take away RB so our cells can divide when needed? | we phosphorylate RB in the cyclin CDK complex and the phosphorylation changes its shape so it can no longer inhibit DNA synthesis |
| kinases are involved with the transferring of __________ | phosphates; phosphorylation |
| CDK is operated by ________ regulation | allosteric |
| ________ and ________ bind together to form a protein complex | CDK and cyclin |
| if cyclin or cdk is absent, you can't phosphorylate RB which means what? | your cells can't divide |
| when cyclin and cdk bind together, CDK forms an active site for ______ | RB |
| cyclin and cdk produce ATP when bound together and when RB binds to CDK's active site, it is _______ and _________ | phosphorylated and inactivated |
| to turn on cell division, what can your cells do? | either produce cyclin and CDK or stop making RB |
| In order to move beyond the S phase or into the S phase, you have to have _______ and ________ and then __________ | cyclin and CDK and then RB |
| Cyclin binding to CDK changes CDK’s shape and provides an active site for RB – ________ regulation | allosteric |
| If cyclin is absent from a cell, what happens to CDK | its inactive and inhibits cell division |
| • CDKs work at cell cycle _______ | checkpoints |
| programmed cell death | apoptosis |
| LOOK AT CDK CELL CYCLE CHECKPOINTS LECTURE 23 SLIDE 6 | |
| If CDKs are inhibited, the cell cycle _______ | stops |
| LOOK AT P53 STUFF lecture 23 | |
| ______ ________ can stimulate the cell cycle | growth factors |
| small peptides that bind to a receptor in the cell membrane and set off a signal cascade (signal transduction) | growth factors |
| When a cell passes through checkpoints, moves onto _______ | mitosis |
| the _________ segregates our chromosomes | cytoskeleton |
| protein structure that ends up at the poles of either end of the cell | centrosome |
| attahced to centrosomes are the _________ | microtubules |
| microtubules are made of ________, can easily break apart and reattach, can increase or shorten length by _______ or ________ tubulin, when microtubules are shortened the chromosomes pull _______ | tubulin, taking or adding, apart |
| microtubules are not only attached to centrosomes but also _______ | centriole |
| what are the 6 phases of mitosis | interphase, prophase, prometaphase, metaphase, anaphase, telophase |
| G1, S, and G2 are all apart of the ________ stage of mitosis - you don't see condensed DNA in this phase | interphase |
| phase of mitosis - chromosomes condense, cytoskeleton organizes into the spindle apparatus, microtubules start to attach to chromosomes, start to have centrosomes move to opposite ends of cell | prophase |
| what do you have at the end of prophase | completely condensed chromosomes and developed spindles |
| phase of mitosis - complete attachment of spindle to chromosomes | prometaphase |
| phase of mitosis - chromosomes line up on the equatorial line, spindle is still attached to chromosomes | metaphase |
| phase of mitosis - start to shorten microtubules, pulling apart of sister chromatids, | anaphase |
| phase of mitosis - rebuilding of nuclear envelope, 2 separate nuclei, getting rid of spindle | telophase |
| mitosis is the division of the ________ | nucleus |
| what completes cell division? | cytokinesis |
| how do animals perform cytokinesis | building a furrow, or dent, in cytoskeleton and pinching cytoplasm in half |
| how do plants perform cytokinesis | take a bunch of vesicles of cellulose between nucleuses and dump them and make a cell plate |
| the vesicles used to carry the cellulose to form a cell wall in plant cytokinesis use what to carry them? | microtubules and kinesin (motor protein) |
| ________ occurs when cells divide uncontrollably | cancer |
| _______ is a cluster of uncontrollably dividing cells | tumor |
| ________ _________ are not really too harmful dividing cells, that are encapsulated and usually stay in online one place | benign tumors |
| ________ __________ are harmful dividing cells and can be sent to other places in the body | malignant tumors |
| the process in cancer when uncontrollably dividing cells break out of their encapsulation and are sent to other areas of the body | metastasis |
| in cancer, the ________ _________ _________ fails | cell cycle regulation fails |
| what is the cancer gene that is a growth factor that stimulates cell division? | oncogene |
| how does oncogene work? | binds to receptor and stimulates signal transduction that produces cyclin. cyclin binds to CDK and they phosphorylate RB stimulating cell division |
| in cancer, cell division is stimulated either by too many ________ _______ or ___________ | growth factors or receptors |
| tumor suppressors _________ cell division | inhibit |
| a gene that has the potential to go wrong and if mutated it can over stimulate cell division | proto-oncogene |
| how is cancer stimulated in breast cancer cells? | it has too many receptors caused by mutation in DNA so it is very sensitive and easily stimulated to divide by growth factors |
| how is cancer stimulated in cancerous cervical cells? | a virus (HPV) infects the cells and makes a protein that blocks RB and that prevents inhibition of division so the cell divides |
| cancer treatments target the ______ ________ | cell cycle |
| when cancer treatments target mitosis, you inhibit the ______ ______. | mitotic spindle |
| if the mitotic spindle is inhibited, what happens to the cell? | the chromosomes don't attach and the cell is signaled for cell death |
| _________ damages DNA and causes apoptosis at the S and G2 checkpoints | radiation |
| some drugs, such as etoposide, inhibit _______ _______ _______ at the restriction point | growth factor stimulation |
| some drugs, such as 5-fluoracil block _______ __________ | DNA replication |
| breast cancer cells often have more growth factor receptors than normal cells. Cells with more receptors are | more sensitive to stimulation to divide |
| when a cell is going to express a gene, which of the following is the correct order of process | transcription then translation |
| genes code for _________ | proteins |
| _______ determine phenotype | proteins |
| transcription takes place in the _________ | nucleus |
| translation takes place in the ___________ or __________ | cytoplasm/ ribosome |
| how many polypeptides can a single gene code for? | 1 |
| what is the sequence of bases called that tell us where to start transcription of a gene? | promoter site |
| what is the sequence of bases on DNA that tell us where to end transcription of a gene? | termination site |
| if hemoglobin requires 4 polypeptides to make it, how many genes are used? | 4 |
| why does transcription need to use DNA to make RNA? | to use the DNA as a template |
| what are the 3 main types of RNA used in transcription and translation | rRNA, tRNA, and mRNA |
| template RNA used in translation | mRNA |
| RNA used to build ribosomes | rRNA |
| RNA that is mostly in the nucleus but can break down mRNA | microRNA |
| RNA that is small and nuclear; its job is to edit mRNA; not found in prokaryote | snRNA |
| what is the difference in bases for RNA and DNA | RNA - uracil DNA - thymine |
| whats the difference in ribose sugars and deoxyribose sugars | ribose - hydroxyl group on 2' carbon deoxyribose - hydrogen on 2' carbon |
| in transcription, nucleic acids are always synthesized in what direction? | 5' - 3' |
| RNA polymerase does not require what in order to start synthesizing a strand of RNA? | a free 3'OH group |
| _________ is a RNA polymerase | primase |
| RNA polymerase reads in what direction and synthesizes in what direction | reads 3' --> 5', synthesizes 5' --> 3' |
| what are the 3 main steps in which transcription occurs | initiation, elongation, and termination |
| nucleotides are added to RNA in which direction in transcription | 5' --> 3' |
| the initiator and terminator sequences are on the ________ | DNA |
| _______ ________ recognizes a promoter in transcription | RNA polymerase |
| an example of a promoter would be a ________ box | TATA |
| is the promoter transcribed by RNA polymerase? | no |
| upstream refers to the _____ side of a nucleotide and downstream refers to the _____ side of a nucleotide | 3'/ 5' |
| ________ and _________ finish making RNA in transcription | elongation, termination |
| GO WATCH TRANSCRIPTION TUTORIAL ON LAUNCHPAD | |
| __________ is the RNA used to make a protein | mRNA |
| ________ is modified after transcription in eukaryotes | mRNA |
| when mRNA is modified, _______ are kept and code for proteins while _______ are cut out | exons; introns |
| what 2 things are added to mRNA that let it get out of the nucleus? | 5' cap and a poly-A tail on 3' |
| long strand of A nucleotides added to mRNA | poly-A tail |
| _________ removes introns in eukaryotes | splicing |
| splicing uses what type of RNA to form _________ to form a spliceosome | snRNA to form snRNP |
| _________ come together to form a spliceosome | snRNPs |
| what does mature mRNA consist of (3 things) | exons, 5' cap, 3' poly A tail |
| • where do the tRNA and rRNA molecules used for translation come from | there are genes that code for tRNA and rRNA |
| the genetic code is captured in _________ | mRNA |
| unit we use to tell our cells what amino acid to add to the polypeptide and it is 3 bases | codon |
| _______ ________ is made up of codons | genetic code |
| the genetic code is _________ and _________, but not ___________ | redundant and universal but not ambiguous |
| what does it mean when we say the genetic code is redundant | some codons code for the same amino acids |
| what does it mean when we say the genetic code is not ambiguous | because UUU will always code for phenylalanine and nothing else |
| why is the genetic code generally universal, but not always for all living things | prokaryotes mess it up a bit |
| mRNA is read from in what direction | 5' to 3' |
| __________ converts mRNA to proteins | translation |
| for every single codon that exists, you have a different _________ | tRNA |
| the site of protein synthesis | ribosomes (rRNA) |
| each tRNA is linked to how many amino acids | 1 |
| tRNA carry not only the corresponding amino acids, but also the __________ | anticodon |
| complement and the antiparallel of a codon | anticodon |
| what does it mean when tRNA is charged? | it has an amino acid attached |
| the ribosome consists of what 2 unites | large and small subunit |
| how does translation initation work? | small subunit recognizes 5' cap and attaches and finds start codon and corresponding tRNA attaches to small subunit then large subunit attaches |
| what are the start codons | 5' AUG |
| what are the stop codons | 5' UAA, UAG, UGA |
| how does termination work in translation | protein release factor comes in and binds to complex when a stop codon enters the A site, the release factor disconnects the polypeptide from the tRNA in the P site, the complex and factor separate |
| is there an amino acid for stop codons | no |
| how are the amino acids bonded | peptide bonds |
| how are proteins modified | cut so their shape is different, added sugars, added phosphates |
| protein with sugars on it | glycoprotein |
| when are proteins modified | after translation |
| _____ __________ are changes in nucleotide sequences | DNA mutations |
| DNA mutations can be passed on or ___________ | inherited |
| how are DNA mutations passed onto other cells? | through mitosis |
| mutations that you have to deal with as an individual, but won't get passed onto offspring; skin cell mutation | somatic mutation |
| mutations that happen in cells that produce sperm and egg and are passed down to offspring | germ line mutation |
| mutation where the protein loses its function. ex: no longer has an active site | loss of function mutation |
| mutation where the protein gains a function. ex: gets 2 binding sites | gain of function mutation |
| mutations are _________ or __________ | beneficial; costly |
| mutation that is sensitive to the environment; ex: hotter - lighter fur, colder - darker fur | conditional mutation |
| ________ __________ have no effect on translation; protein comes out exactly the same as if we didn't mutate the DNA | silent mutations |
| __________ _________ cause an amino acid change; can be loss or gain of function, but usually loss | missense mutations |
| _______ _________ produce a stop codon; screws up translation the most; proteins can never be made | Nonsense mutations |
| why are nonsense mutations usually huge loss of function | because the protein can never fully be made |
| __________ __________ shift entire “reading frame” | frame-shift mutations |
| when does reading frame shift? | when a nucleotide gets added or removed |
| what can frame shfit mutations cause? | nonsense mutations or too long of proteins |
| mutations can occur _________ or be ___________ | spontaneously, induced |
| what are examples of spontaneous mutations? | tautomers, deamination, errors in replication |
| what does the tautomer of cytosine look like and do? | instead of having an amino group, it has a N-H and then a separate H; this makes cytosine bind to adenine not guanine |
| what does deamination do to cytosine? | gets rid of amino group and makes it an oxygen and changes it to uracil; so it binds with A and not G |
| what are mutagens? | environmental mutations like UV radiation and chemicals and you can pass these mutations on |
| _________ are raw material for evolution | mutations |
| ________ _______ and ________ ________ can cause harm | germline and somatic |
| what is wrong with sickle cells | can't carry oxygen as well as normal red blood cells |
| what kind of mutation creates sickle cell disease | mutation from T to an A - missense |
| why is sickle cell disease good in some environments | having sickled cells prevents malaria from getting in your cell; malaria destroys red blood cells but can't destroy sickled cells |
| gene expression is _________ | regulated |
| term used for turning off a gene; lower number of transcripts produced | down regulation |
| term used for turning on a gene and expressing the number of mRNA transcripts produced | up regulate |
| gene expression respondes to changes in __________ | environment |
| expressing genes is _________ __________ so we can't have our cells expressing every gene all the time | energetically expensive |
| we can control how much protein is being made by _________ or __________ mRNA | blocking or exposing |
| Regulation can occur at the ________ or ________ level | gene; enzyme |
| __________ stimulate gene expression | inducers |
| gene that is expressed all the time at the same concentration | constitutive e |
| ____________, like E. coli, regulate gene expression | • Prokaryotes |
| ________ is easier for e. coli to metabolize | glucose |
| in e. coli, when lactose is mainly present, what does e. coli use to start to digest it | inducible genes |
| what are the inducible genes that e. coli uses when lactose is present | a carrier protein specific for lactose to bring lactose into the cell and enzymes specific for lactose to break it down |
| e. coli induces certain genes when ________ is present | lactose |
| in prokaryotes, transcription is regulated at the ___________ | operon |
| in prokaryotes, a single promoter that turns on a set of genes | operon |
| in prokaryotes, upstream from the promoter are additional genes and they are __________ genes | regulatory |
| in prokaryotes, they have some role in turning on or off the production of structural proteins and the turning on and off of transcription | regulatory sequences |
| if a ________ _________ is present, transcription is inhibited (prokaryotes) | repressor protein |
| in e. coli, if there is no lactose then there is _____ inducer and a repressor is ________. lac genes are _______ (prokaryotes) | no; present; off |
| repressor genes have ________ expression at all times (prokaryotes) | constitutive |
| repressor protein binds to the _________ (DNA) (prokaryotes) | operator |
| repressor proteins are coded for by a _________ ________ ________gene (prokaryotes) | regulatory upstream repressor gene |
| when repressor is active, ______ __________ can't unwind the DNA or do anything (prokaryotes) | RNA polymerase |
| where do repressor proteins bind on the DNA? (prokaryotes) | major grooves |
| _________ bind and alter the repressor protein. (prokaryotes) | Inducers |
| when lactose is present in e. coli, inducer is _______ and repressor is _______ lac genes are _______ (prokaryotes) | present; inactive; on |
| if an inducer is present, __________ is turned on (prokaryotes) | transcription |
| what do inducers bind to? (prokaryotes) | repressor proteins - changes their shape and they fall off |
| in e. coli, what is the inducer? (prokaryotes) | lactose |
| lactose in e. coli is an _________ inhibitor (prokaryotes) | allosteric |
| after lactose induces the repressor protein what happens? (prokaryotes) | the structural genes are transcribed and translated into lactose-metabolizing enzymes |
| _______ __________ enhance transcription (prokaryotes) | activator proteins |
| how do activator proteins work when there is low glucose and lactose present? (prokaryotes) | regulatory protein CRP binds to cAMP and the complex binds to promoter; RNA polymerase then binds more efficiently to promoter; lac operon (genes encoding lactose metabolizing enzymes) is transcribed |
| how do activator proteins respond when there is high glucose but lactose present (prokaryotes) | cAMP is low and CRP doesn't bind the promoter and RNA polymerase can't bind efficiently; transcription for structural genes for lac operon is redueced |
| _________ ___________ operate by negative feedback (prokaryotes) | Repressible operons |
| LOOK AT SLIDE 7 LECTURE 27 | |
| regulation of expression can be _______ or _________ (prokaryotes) | positive or negative |
| _________ regulate gene expression in many ways | • Eukaryotes |
| what are the 3 main ways eukaryotes regulate gene expression | transcriptional control, chromatin remodeling, mRNA modification |
| do eukaryotes have operons? | NO |
| physical modifications or changes to DNA | chromatin remodeling |
| ________ can bind to DNA | proteins |
| eukaryotes still have a promoter, but it is for how many genes? | a single gene |
| eukaryotes have a more _______ promoter than prokaryotes | complicated |
| upstream from promoters in eukaryotes there are ________ on the DNA where ________ ________ can bind | enhancer;activator proteins |
| what do transcription factors do in eukaryotes? | enhance transcription |
| what are transcription factors in eukaryotes? | proteins that bind to DNA and help RNA polymerase work |
| Transcription factors bind to _________ ______. | promoter DNA |
| place where the first transcription factor actually binds | recognition sequence/ TATA box |
| when a transcription factor recruits several other transcription factors and its a big blob that helps RNA polymerase and eukaryotic DNA get expressed | transcription complex |
| transcription factors may bind to many different __________ | promoters |
| LOOK AT LECTURE 27 SLIDE 12 | |
| altering _______ can alter transcription | DNA |
| what is methylation | adding a methyl group (CH3) to cytosine |
| when does methylation happen to cytosine | when it is next to guanine |
| what is the enzyme that adds methyls to cytosine | DNA methyltransferase |
| DNA methylation __________ transcription | prevents it from happening |
| DNA methylation prevents transcription by blocking ________ or attractiong __________ | block promoter or attract repressors |
| is DNA methylation a permanent change? | no can be demethylated |
| is DNA methylation heritable? | yes |
| methylation happens in response to ________ _________ | environmental conditions |
| how can methylation be passed onto kids | if you are a stress eater, stress can slow down your metabolism and it methylates your genes and your kids can have a slower metabolism |
| when DNA is wrapped tightly around histones, you can't do _________ | transcription |
| how do we loosen our chromatin so we can transcribe it? | add acetyl groups to make the histones negative so the DNA will want to get away from it and they will separate |
| _________ changes can be inherited | epigenetic |
| inherited external changes that aren't apart of base sequences, can be induced by environment | genomic imprinting |
| ________ can be modified after transcription | mRNA |
| how can mRNA be modified after transcription in eukaryotes and not prokaryotes? | due to the fact that eukaryotes have exons and introns and prokaryotes do not |
| in mRNA we can _________ the exons around which creates variety from the same transcript | shuffle |
| little bits of RNA that is complementary to a target mRNA and break it down | microRNA |
| _________ silence genes even if they are expressed | microRNA |
| mRNA can be inhibited by __________ | microRNA |
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