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48 Cards in this Set

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replisome
group of proteins that govern DNA replication
replication is a bidirectional process in (eukaryotes/prokaryotes)
prokaryotes
starting from the origin of replication
Does DNA replication require a primer? What kind?
Yes, RNA
What is the first step of transcription?
Initiation
- initiation factors find a promoter on DNA and assemble a transcription initiation complex, which includes RNA polymerase
What recognizes a promotor?
RNA polymerase
After initiation, what are the second and third steps of transcription?
2) elongation
3) termination
termination has a special termination sequence and requires special proteins
Most genetic regulation occurs at what level?
transcription level
occurs via activators and repressors, which are allosterically regulated by small molecules such as cAMP
What does it mean that prokaryotic mRNA is typically polycistronic?
several genes in a single transcript
operon
operator + promoter + genes that contribute to a single prokaryotic mRNA
explain the lac operon
- codes for enzymes that metabolize lactose
- low glucose --> high cAMP
- cAMP activates CAP protein which beinds upstream to the promoter on lac operon.
- promoter is now activated

- if lactose is present, the lac repressor protein is inactivated.
- it then does not bind to the operator which is located downstream of the operon.
What are three ways in which the primary transcript (pre-mRNA) can be processed?
1) addition of nucleotides
2) deletion of nucleotides
3) modification of nitrogenous bases
snRNPs
small nucleor ribonucleoproteins that recognize nucleotide sequences at the ends of introns. They associate with proteins and loop the introns to bring the exons together.
nucleic acid hybridization
a technique that allows scientists to identify nucleotide sequences by binding a known sequence with an unknown sequence.
- denature first and then allow separated strands to spontaneously associate with any other complementary nucleotide sequence.
recombinant DNA
artificially recombined DNA
restriction enzymes digest nucleic acid at _____ sites. These sites have a _____ sequence.
restriction
palindromic
How can recombinant DNA be used to produce a DNA library?
- recombinant DNA is placed in bacteria using a vector. The vector contains a gene for resistance to a certain antibiotic.
- The bacteria are then reproduced and an antibiotic is added to remove clones without the vector.
- also, the DNA is usually placed with an endonuclease that cuts the lacZ gene. When the lacZ gene is cleaved, the gene does not turn blue. If the lacZ gene is active it turns blue, meaning the DNA is not in that vector.
look at diagram on page 34
How is cDNA made?
mRNA is reverse transcribed to form DNA
What is the difference between DNA and cDNA?
cDNA does not contain the introns that DNA contains.
Explain PCR
- DNA is placed with primers (forward and reverse), heat resistant DNA polymerase, and nucleotides.
- Mixture is heated to denature DNA.
- Mixture is cooled to allow primers to anneal to complementary DNA strands.
- Mixture is heated to activate polymerase.
- Repeated many times to produce an exponential increase in DNA
Southern blotting vs Northern blotting?
same techniques. southern blot identifies specific sequences of DNA, northern blot identifies specific sequences of RNA.
Explain southern blotting
- used to identify target fragments of known DNA sequence in a large population of DNA
1) DNA is chopped up into restriction fragments
2) fragments are separated through gel electrophoresis.
3) DNA is denatured into single strands.
4) Membrane blots the gel causing the DNA fragments to be transferred to membrane.
5) A probe is added, which marks the target fragment.
6) the membrane is exposed to radiographic film which reveals the location of the target fragment.
Explain Western blot briefly.
It detects a protein using antibodies.
What is RFLP analysis
identifies individuals instead of specific genes. They are the DNA fingerprints used to identify criminals in court cases.
degenerative genetic code
more than one series of three nucleotides may code for any amino acid
unambiguous genetic code
any series of three nucleotides will only code for one single amino acid
A polypeptide contains 200 amino acids. How many possible amino acid sequences are there for this polypeptide?
20^200
there are 20 possible amino acids and 200 possible positions for each
What is the initiation complex?
What is initiation?
- The large subunit + mRNA + small subunit
- Initiation is when methionine attaches at the P-site and signals the large subunit to join and form the initiation complex
What occurs in post translational modification?
sugars, lipids, or phosphate groups may be added to amino acids
signal-recognition particle (SRP)
this protein-RNA structure recognizes the signal peptide on the growing amino acid sequence and directs the ribosome complex to a receptor protein on the ER.
What type of mutations result in a frameshift mutation?
insertion or deletion in multiples other than 3
explain transposons
transposons are DNA segments that can excise themselves from a chromosome and reinsert themselves at another location
- flanked by identical nucleotide sequences
- a portion of the flanking sequence is part of the transposon
forward mutation, backward mutation
mutation that changes the organism even more, mutation that tends to revert the organism back to its original state
nucleosome
eight histones wrapped in DNA
any cell that contains homologous pairs of chromosomes is said to be ______. if not, it is ________
diploid, haploid
What happens at the G1 stage in the life cycle of a cell?
cell begins to grow in size and produce new organelles and proteins.
passes G1 check point. If conditions are favorable for division, cells moves into S phase.
What happens in the G0 phase of a cell's life cycle?
non growing state
S phase?
replication of DNA
G2 phase of cell's life cycle?
cell prepares to divide. organelles continue to duplicate. G2 checkpoint checks for MPFF (mitosis promoting factor). When it is high enough, mitosis is triggered.
Prophase
chromosomes form, centrioles move to opposite ends, nucleolus and nucleus disappear, spindle apparatus begins to form
spindle apparatus
consists of aster (microtubules radiating from centrioles), microtubules growing from centromeres, and spindle microtubules connecting the two centrioles
kinetochore
structure of protein and DNA located at centromere of chromosomes
metaphase
chromosomes align along equator
anaphase
sister chromatids split, cytokinesis may start
telophase
nuclear membrane reforms, nucleolus reforms, chromosomes decondense, cytokinesis continues
primary spermatocyte or primary oocyte
spermatogonium or oogonium cell dafter replication occurs at the S phase of interphase
Which stage of meiosis is most similar to mitosis?
Meiosis II
What happens in meiosis I?
Prophase I - homologous chromosomes pair up, crossing over may occur
metaphase I - line up as tetrads
anaphase I - separation of homolgues
telophase I - nuc membrane may or may not reform, cytokinesis may or may not occur
nondisjunction
when the centromere of any chromosome does not split during anaphase I or II