Unit 5: Central Dogma of Molecular Biology Flashcards
Enumerate the sequence:
encoding of genetic information
- replication
- transcription
- translation
Identify the process:
process of duplication of DNA (requires RNA)
replication
Identify the process:
process of formation of RNA on a DNA template
transcription
Identify the process:
process of protein synthesis
translation
T/F:
During transcription, base sequence of DNA is reflected in the base sequence of RNA
true
T/F:
During translation, amino acid sequence of the protein reflects the sequence of bases in the gene that codes for that protein
true
Identify the term:
viruses in which RNA is the genetic material rather than DNA
retroviruses
Identify the enzyme:
catalyzes retroviruses and directs the synthesis of DNA on an RNA template
reverse transcriptase
Identify the type of organisms:
where most of the details of the replication process were first investigated
prokaryotes (E. coli)
Identify the process:
involves separation of the 2 original strands and production of 2 new daughter strands using the original strands as templates
DNA replication
T/F:
each daughter strand contains 1 template strand and 1 newly synthesized strand
true
Identify the point:
where DNA double helix unwinds
origin of replication
T/F:
polynucleotide chains are synthesized in one direction only from the origin of replication
false;
in either both or in one direction
(DNA replication is bidirectional in most organisms.)
T/F:
at each origin of replication there are 4 replication forks
false;
2 replication forks
Identify the points:
at which new polynucleotide chains are formes
replication forks
Differentiate prokaryotes and eukaryotes:
based on numbers of origin of replication and bubble
prokaryotes: 1 origin of replication, 1 bubble
eukaryotes: several origins of replication, several bubbles
Identify the enzyme:
acts as a nucleophile by attacking the phosphorus adjacent to the sugar in the incoming nucleotide, which has a 5’-triphosphate on its sugar
DNA polymerase
Enumerate:
2 types of strands
- leading strand
- lagging strand
Identify strand based on polymerization mode:
synthesized continuously from its 5’ end to its 3’ end at the replication fork on the exposed 3’ to 5’ template strand
leading strand
Identify strand based on polymerization mode:
synthesized semidiscontinuously in small fragments or Okazaki fragments
lagging strand
T/F:
in the lagging strand, 3’ end of each fragment is closer to the replication fork than the 5’ end
false;
5’ end is closer
T/F:
DNA polymerase catalyze de novo synthesis
false;
cannot catalyze
Enumerate:
requirements of DNA polymerase reactions
- presence of primer
- all 4 deoxyribonucleoside triphosphates
- Mg2+
- DNA template
- all 4 ribonucleoside triphosphates
Identify the class of DNA polymerase:
reparing and patching DNA
DNA Pol I
Identify the class of DNA polymerase:
polymerization of the newly formed DNA strand
DNA Pol III
Identify the class of DNA polymerase:
repairing enzymes
DNA Pol II, IV, V
Identify the term:
removing incorrect nucleotides during DNA replication
proofreading
Identify the term:
removing incorrect nucleotides from DNA and replacing them with correct ones
repair
Identify the term:
complex of DNA polymerase, the RNA primer, primase, and helicase at the replication fork
replisomes
Identify the complex:
carry out DNA replication
replisomes
Identify the enzyme:
class II topoisomerase
DNA gyrase
Identify the enzyme:
catalyzes reactions involving relaxed, circular DNA with a nick in one strand to the supercoiled form with the nick sealed
DNA gyrase
T/F:
Prokaryotic DNA is positively supercoiled.
false; negatively
(opening the helix during replication introduces positive supercoils ahead of the replication fork)
Identify the enzyme:
fights positive supercoils and places negative supercoils ahead of the replication fork
DNA gyrase
Identify the enzyme:
ensures that the newly synthesized DNA automatically assumes the supercoiled shape
DNA gyrase
Identify the enzyme:
helix-destabilizing protein that promotes unwinding by binding at the replication fork
helicase
Identify the protein:
stabilizes single-stranded regions by binding tightly to them
single-strand binding protein (SSB)
Identify the NA:
serves as a primer in DNA replication
RNA
Identify the enzyme:
makes a short section of RNA to act as a primer for DNA synthesis
primase
Identify the complex:
located at the replication fork; consists of the RNA primer, primase, and helicase
primosome
Identify the enzyme:
commences synthesis of DNA
DNA polymerase III
Identify the enzyme:
As the replication fork moves away, the RNA primer is removed by this enzyme and then replaced by deoxynucleotides and this enzyme
DNA Pol I
Identify the enzyme:
responsible for the final linking of the new strand
DNA ligase
Identify the protein:
part of the Pol III enzyme that opens the sliding clamp and inserts the DNA chain
clamp loader
Identify the term:
errors in replication that occur spontaneously only once in every 109-1010 base pairs and can be lethal to organisms
mutations
Identify the process:
where cut-and-patch process catalyzed by Pol I takes place
replication
Identify the process:
removal of the RNA primer by the 5’ exonuclease function of the polymerase
cutting
Identify the process:
the incorporation of the required deoxynucleotides by the polymerase function of the same enzyme
patching
Identify the process:
removal of RNA primer or DNA mistakes by Pol I using its 5’ to 3’ exonuclease activity as it moves along the DNA and then filling in behind it with its polymerase activity
Nick translation
Identify the agents:
bring about a mutation
mutagens
Enumerate:
inclusions of mutagens
- ultraviolet light
- ionizing radiation
- various chemical agents or free radicals
Enumerate:
DNA damage types
- endogenous
- exogenous
Enumerate:
endogenous DNA damage types
- cellular metabolic processes
- mismatch of DNA bases
- hydrolysis
- oxidation
- alkylation
Enumerate:
exogenous DNA damage types
- environmental factors
- UV radiation
- ionizing radiation
- chemical agents
Enumerate:
4 repair mechanisms
- mismatch repair
- base-excision repair
- nucleotide-excision repair
- nonhomologous DNA end-joining (NHEJ)
Identify the repair mechanism:
enzymes recognize that 2 bases are incorrectly paired
mismatch repair
Identify the enzyme:
In mismatch repair, area of mismatch is removed, and area is replicated again by?
DNA polymerases
Identify the repair mechanism:
damaged base is removed by DNA glycosylase leaving an AP site (apurinic or apyridiminic)
base-excision repair
Identify the enzymes:
In base-excision repair, sugar and phosphate are removed from the nucleotide by an ____ _____________, and several more bases are removed by an excision ____________.
AP endonuclease
exonuclease
Identify the repair mechanism:
common for DNA lesions caused by UV or chemical means
nucleotide-excision repair
Identify the enzyme:
In nucleotide-excision repair, section containing the lesion is removed by?
ABC exinuclease
Identify the repair mechanism:
breakage of both strands of a DNA molecule; pose a big threat to the stability of the genome
double-stranded breaks (DSB)
Enumerate:
double-stranded breaks (DSB) repair mechanisms
- nonhomologous DNA end-joining (NHEJ)
- recombination
Identify the repair mechanism:
for mismatch of DNA bases
mismatched repair system (MMR)
Identify the repair mechanism:
for hydrolysis, oxidation, and alkylation
base excision repair (BER)
Identify the repair mechanism:
for UV radiation
nucleotide excision repair (NER)
Identify the repair mechanism:
for ionizing radiation and chemical agents
double-strand breaks
Identify the process:
natural process in which genetic information is rearranged to form new associations
genetic recombination
Identify the type of recombination:
involves a reaction between homologous sequences
homologous recombination
Identify the type of recombination:
involves combination of different nucleotide sequences
nonhomologous recombination
Identify the zone:
DNA recombination occurs in specific zones of chromosome called?
hot spots
Identify the model:
describes how recombination occurs by the breakage and reunion of DNA strands so that physical exchange of DNA parts takes place
holiday model
T/F:
Prokaryotic DNA replication is more complicated than eukaryotic DNA replication.
false;
eukaryotic - more complicated
Enumerate reasons:
why eukaryotic DNA replication is more complicated
- multiple origins of replication
- need to control the timing to that pf cell divisions
- involvement of more proteins and enzymes
Enumerate:
In eukaryotic DNA replication, cell growth and division are divided into what phases
M
G1
S
G2
T/F:
eukaryotic replication can be initiated only by chromosomes from cells that have reached the G1 phase
true
Identify the protein:
bound to the DNA throughout the cell cycle but serves as an attachment site for several proteins that help control replication
origin recognition complex (ORC)
Identify the protein:
protein whose binding prepares for the start of DNA replication
replication activator protein (RAP)
Identify the protein:
proteins that are essential for DNA replication; some are cytosolic
replication licensing factors (RLFs)
Identify the term:
combination of the DNA, ORC, RAP, and RLFs that makes DNA competent for replication
pre-replication complex (pre-RC)
Identify the protein:
produced in one part of the cell cycle and degraded in another
cyclins
Identify the enzyme:
cyclins combine with?
cyclin-dependent protein kinases (CDKs)
Identify the phase in eukaryotic replication:
where DNA has been replicated
G2 phase
Identify the process:
1. where DNA is separated into daughter cells
2. dissolved nuclear membrane permits entrance of RLFs that are produced in the cytosol
mitosis
Enumerate 5 eukaryotic DNA polymerases
- polymerase α
- polymerase δ
- polymerase ε
- polymerase β
- polymerase γ
Identify the type of eukaryotic DNA polymerase:
makes primers
polymerase α
Identify the type of eukaryotic DNA polymerase:
principal DNA polymerase in eukaryotes
polymerase δ
Identify the type of eukaryotic DNA polymerase:
involved in leading strand replication
polymerase ε
Identify the type of eukaryotic DNA polymerase:
a repair enzyme
polymerase β
Identify the type of eukaryotic DNA polymerase:
carries out DNA replication in mitochondria
polymerase γ
Identify the term:
eukaryotic equivalent of the part of Pol III that functions as a sliding clamp (β)
PCNA
Identify the term:
trimer of 3 identical proteins that surround the DNA
PCNA
Identify the term:
special structures found in the ends of eukaryotic chromosomes
telomeres
Identify the enzyme:
ribonuclear protein that contains a section of RNA that is the complement of the telomere
telomerase