Term
| why is hemoglobin a bad example of 1 gene = 1 protein? |
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Definition
| because hemoglobin is one protein, but made of multiple polypeptide chains. |
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Term
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Definition
| the creation of mRNA from a DNA template strand |
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Term
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Definition
| ribosomes turning mRNA molecules into polypeptide chains (proteins) |
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Term
| what are two differences between the transcription/translation process in prokaryotes and in eukaryotes? |
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Definition
1. in prokaryotes there is no nucleus, so both transcription and translation take place in the cytoplasm; transcription takes place in the nucleus of the eukaryotic cell.
2. in eukaryotic cells there is a step in between transcription and translation called RNA processing; in prokaryotic cells the progression is immediate. |
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Term
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Definition
| mRNA before mRNA processing but after transciption in a eukaryotic cell. |
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Term
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Definition
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Term
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Definition
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Term
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Definition
| you can have more than triplet coding for the same amino acid |
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Term
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Definition
| the third place in a triplet can change and still code for the same amino acid |
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Term
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Definition
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Term
| what is the major different between RNA polymerase and DNA polymerase? |
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Definition
| RNA polymerase doesn't need a primer to start its chain |
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Term
| ribonucleoside triphosphates |
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Definition
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Term
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Definition
| the DNA sequence to which the RNA attaches and begins transcription |
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Term
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Definition
| the piece of DNA that's transcribed by the mRNA |
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Term
| three stages of transcription |
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Definition
| initiation, elongation, termination |
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Term
| what is the difference between how RNA binds to a promotor in eukaryotes and in prokaryotes? |
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Definition
| in prokaryotes, the mRNA binds directly. in eukaryotes, it needs proteins called TRANSCRIPTION FACTORS. |
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Term
| transcription initiation complex |
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Definition
| the transcription factors and the RNA polymerase II bound to the promotor together |
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Term
| transcription unit vs. transcript |
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Definition
| the transcription unit is the DNA being transcribed; the transcript is the RNA onto which it is transcribed. |
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Term
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Definition
| sequence common in eukaryotic promoters |
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Term
| what are three things that can happen during RNA processing before translation? |
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Definition
1. capping
2. polyadenylation
3. splicing |
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Term
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Definition
| happens during RNA modification in all eukaryotic cells; adds a GTP cap onto the 5' end |
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Term
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Definition
| adding a poly-A tail (AAAA...AAAA) to the 3' end of the pre-mRNA before translation |
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Term
| what roles do the caps and the poly-A tails play regarding the RNA? (3) |
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Definition
1. helps to transport the mRNA out of the nucleus and into the cytoplasm
2. increases the stability of the transcript - keeps it from being degraded while being translated over and over again
3. helps bind the ribosomes to the transcript |
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Term
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Definition
| certain units of the mRNA are cut out during RNA processing and the ends are spliced together; introns are not expressed; extrons are expressed. |
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Term
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Definition
| depending on the sections of mRNA that are cut out or left in, a single gene can code for multiple polypeptide chains. |
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Term
| describe how alpha myosin and beta myosin can be coded for by the same gene |
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Definition
| two different ways of splicing the myosin gene will give rise to each variation, respectively |
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Term
| what determines sex in dresophola? |
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Definition
| the same gene, spliced in different ways |
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Term
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Definition
| brings amino acids to the ribosomes |
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Term
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Definition
| the secondary structure of the tRNA molecule; there are three "hairpins" that stick together with hydrogen bonding. |
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Term
aminoacyl-tRNA synthetase
endo-exo? |
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Definition
| binds the tRNA to the appropriate amino acid - this is endergonic and requires energy from ATP |
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Term
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Definition
| the sequence of nucleotides on a loop of tRNA that matches the codon on the mRNA molecule; read 3'-5' (because the codon is read 5'-3') |
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Term
| each ribosome subunit is made of: (2) |
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Definition
1. proteins
2. ribosomal RNA (rRNA) |
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Term
| in eukaryotes, what are the large and small ribosomal subunits? in prokaryotes? |
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Definition
EUKARYOTES
large: 50s
small: 30s
PROKARYOTES
large: 60s
small: 30s |
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Term
| what is an example of a gene that doesn't have a final product as a protein? |
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Definition
| ribosomal RNA (stays as RNA) |
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Term
| describe the synthesis/assembly of ribosomes |
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Definition
| ribosomal proteins are synthesized in the cytoplasm and then brought back into the nucleus, into the nucleolus, where the rRNA is made. These work together to assemble the two separate halves of the ribosomes, which then exit through the pores, still separate. |
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Term
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Definition
| they target the ribosomes of prokaryotes, but not eukaryotes (they're made differently) |
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Term
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Definition
| aminoacyl-tRNA binding site in the ribosome - holds the tRNA with the next amino acid that will be added to the chain |
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Term
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Definition
| peptidyl-tRNA site on the ribosome - holds the tRNA which has the growing polypeptide chain |
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Term
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Definition
| exit site on the ribosome - the place from where the polypeptide leaves when it's complete |
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Term
| messenger RNA binding site |
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Definition
| the sequence that is upstream from the UAG start codon |
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Term
| in what direction is a polypeptide chain synthesized? |
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Definition
| from the N-terminus to the C-terminus |
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Term
| why can transcription and translation take place at the time in prokaryotic cells? |
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Definition
| because there's (a) no compartmentalization and (b) no RNA processing - so they can happen at the same time. |
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Term
| how does polypeptide synthesis end? (describe termination) |
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Definition
| a stop codon in the mRNA reaches the A site of the ribosome; a release factor (protein) binds to this stop codon and hydrolyzes the bond between the tRNA and the polypeptide chain in the P-site |
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Term
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Definition
| this is a sequence that tells the ribosomes that it needs to end up in the ER |
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Term
| how does a protein that needs to end up in the ER get there? |
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Definition
| has a polypeptide sequence called a signal peptide; this is grabbed by a signal-recognition particle (SRP) which binds to an SRP receptor protein in the lumen of the ER |
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Term
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Definition
| begins every protein that needs to end up in the ER; grabbed by SRP |
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Term
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Definition
| signal recognition particle; binds with signal peptide; made of proteins and RNA |
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Term
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Definition
| complex of proteins associated with the membrane of the ER; binds with the signal peptide and the ribosome starts translating again, feeding the polypeptide chain into the ER |
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Term
| what are the three main proteins associated with the translocation complex? |
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Definition
1. receptor protein (binds to the SRP)
2. pore protein (lets the polypeptide chain in through it)
3. cleaving enzyme (removes the signal peptide from the polypeptide chain after it attaches) |
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Term
| the translation of a protein that needs to end up in the ER starts in the ___________ and ends in the ___________ |
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Definition
| starts in the CYTOPLASM and ends in the ER |
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Term
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Definition
| mass of proteins and snRNPs, which recognizes introns and extrons and splices them |
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Term
| point mutation (what is it; what are the two kinds?) |
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Definition
a single base-pair change
1) base-pair substitution
2) frameshift mutation |
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Term
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Definition
| a form of point mutation wherein one base pair is changed to another (AT becomes CG, for example.) |
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Term
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Definition
| when an amino acid has been changed as the result of a base-pair change. |
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Term
| if a base pair change resulted in a the change of a polar amino acid into a nonpolar amino acid, which in turn affects the secondary and tertiary structures of the protein, this is an example of a _______________ |
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Definition
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Term
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Definition
| when there is a mutation but it has no practical effect - gene sequence changes but it ends up coding for the same protein |
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Term
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Definition
| when a gene sequence is changed to a stop codon |
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Term
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Definition
| usually off until it gets outside stimulus - then is turned on |
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Term
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Definition
| gene is usually on unless it gets outside stimulus, then it turns off |
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Term
| how many enzymes do you need to make tryptophan? |
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Definition
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Term
| coordinate vs. differential gene expression |
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Definition
coordinate: a bunch of genes are expressed as a single unit
differential: the genes are expressed individually |
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Term
| structural genes of trp operon |
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Definition
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Term
| what are the two sequences of the control region of an operon? |
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Definition
promotor (RNA polymerase binds to this)
operator (regulates the expression of the structural genes - repressor binds to this.) |
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Term
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Definition
| regulatory gene of the trp operon; makes the repressor protein |
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Term
| polygenic transcription occurs in _______ |
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Definition
| eukaryotes (this is where each gene has its own promotor). in prokaryotes, there is one promotor for multiple genes. |
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Term
| how does the tryptophan repressor work? |
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Definition
| the repressor protein is always being synthesized; but it is inactive until tryptophan binds to it, in which case it binds to the operator and blocks RNA polymerase |
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Term
| trp operon is a model of a ___________ system |
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Definition
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Term
| lac operon is a _____________ system |
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Definition
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Term
| what are the three lac structural genes? |
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Definition
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Term
| what are the two parts of the control region? |
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Definition
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Term
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Definition
| the regulatory gene of the lac operon |
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Term
| the three proteins produced by the lac operon |
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Definition
beta-galactosidase
permease
trans-acetelase |
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Term
| what happens in an environment that contains both lactose and glucose? (nonspecifically) |
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Definition
| while glucose is available, lactose isn't needed; so the lac operon is switched off. |
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Term
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Definition
| is produced in environments with low glucose; binds to the CAP protein to activate it |
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Term
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Definition
| activated by cyclic AMP; binds to the CAP binding site and enables the production of beta-galactosidase |
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Term
| differential gene expression |
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Definition
| the expression of different genes by cells with the same genome |
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Term
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Definition
| loosens the fiber by making the histone tails nonpolar - they don't stick to each other and therefore don't bind tightly. |
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Term
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Definition
| attaching -CH3 (methyl) groups to the histone tails; promotes condensation of the chromatin |
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Term
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Definition
| all members of a given species occupying a given area at a given time |
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Term
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Definition
| when the frequency of alleles changes, but the species and population haven't changed |
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Term
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Definition
| when there is change over a species - one species goes extinct and another arises |
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Term
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Definition
| any self-contained population undergoing random sexual reproduction will retain the same allele/genotype frequency |
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Term
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Definition
| when a phenotype bell curve shifts over time in one direction - favors one extreme |
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Term
| bacteria become more resistent to antibiotics over time (as more antibiotics are used.) What is this an example of? |
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Definition
| directional selection (one extreme is favored - everything else dies out) |
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Term
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Definition
| when the extremes of a phenotype bell-curve are favored |
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Term
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Definition
| neither extreme of a phenotypical bell curve is favored; the intermediate is favored |
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Term
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Definition
| when individuals with certain characteristics are more likely than others to obtain mates |
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Term
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Definition
| when having a heterozygous genotype serves you better than having either monozygote; having a heterozygous genotype for sickle cell anemia PROTECTS you against malaria! |
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Term
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Definition
| when natural selection favors two or more forms |
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Term
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Definition
| a group of which all members can mate and produce viable, fertile offspring |
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Term
| what are the two categories of reproductive barriers? |
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Definition
| prezygotic and postzygotic |
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Term
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Definition
| two species can't breed because their habitats don't coincide |
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Term
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Definition
| two species can't breed because they have different fertile cycles |
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Term
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Definition
| two species can't breed because they have different courting rituals, and each only respond to their own courting rituals |
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Term
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Definition
| two species can't mate because thier reproductive organs don't fit together |
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Term
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Definition
| two species can't mate because thier zygotes can't fertilize each other |
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Term
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Definition
| two species are physically separated and a new species arises in one of the environments |
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Term
| ribonocleoprotein particles |
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Definition
| another word for ribosomes - because they contain proteins and ribosomal RNA molecules (rRNA) |
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Term
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Definition
| tRNA in the P-site that holds the RNA that has been translated already |
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Term
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Definition
| the mRNA getting dragged through the ribosome, in turn dragging the tRNA from A site to P site to E site to out of the ribosome (uncharged, having deposited its amino acid on the P-site chain.) |
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Term
| what is the anticodon for a stop codon? |
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Definition
| there is none - it attracts a release factor instead |
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Term
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Definition
| a lot of ribosomes simultaneously translating the same RNA molecule (you see this in both prokaryotes and eukaryotes) |
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Term
| natural selection works on (phenotype/genotype) |
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Definition
| phenotype (survival of the fittest - those with traits that will enable them to produce offspring.) |
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Term
| what are the three postzygotic barriers to reproduction? |
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Definition
1. reduced hybrid viability (zygote will be aborted or offspring will die)
2. reduced hybrid fertility
3. hybrid breakdown (the GRANDCHILDREN can't produce viable offspring) |
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