Chapter 7 - DNA Replication and Gene Expression Flashcards
The biological process of producing two replicas of DNA from an original copy.
DNA replication
Turning DNA into multiple “working copies” in the form of RNA to provide instructions to produce enzymes/structural proteins.
transcription
RNA molecules are read and decoded to form the enzymes/structural proteins of the cell.
translation
The systems ability to deal with damage to the core DNA molecules of the cell.
DNA repair
The ________ experiment was one of the earliest experiments that pointed out that DNA could contribute to hereditary information in bacteria.
Griffith
Griffith found that when ______ (_) strains of S. pneumoniae were injected into mice, the virus killed them.
smooth (S)
Griffith found that when ______ (_) strains of S. pneumoniae were injected into mice, the virus did not kill them.
rough (R)
Griffith found that when the _____________ R strain and heat killed ___________ S strain were both injected into the mice, the mice were killed. This suggests that…
nonpathogenic, pathogenic
a transformation occurred
The ________________________ experiment used mixtures obtained from S strains but digested away one component at a time to show that the mixture with ___ left over could still transform. This suggests that…
Avery, MacLeod and McCarty, DNA
DNA was the molecule responsible for transformation
What 3 scientists are responsible for the discovery of the double-stranded double helix structure of DNA?
Rosalind Franklin
James Watson
Francis Crick
Each nucleotide consists of a ____-______ _____ (2-deoxyribose), a _________ group attatched to the 5’ carbon of the sugar, and a ___________ base attached to the 1’ carbon of the sugar.
five-carbon sugar, phosphate, nitrogenous
One strand of DNA is _______________ to the other strand.
complementary
Adenine pairs with _______, and cytosine pairs with _______ by hydrogen bonds.
thymine, guanine
______________ covalent bonds form the sugar/phosphate backbone of each strand.
phospodiester
While the overall structure of DNA is the ____ across all three domains, the way it is _________ is not.
same, packaged
________ DNA is a single circular chromosome.
Bacteria
_______ DNA is a singular circular chromosome packaged around histone proteins.
Archaea
_______ DNA is multiple linear chromosomes packed around histone proteins.
Eukarya
DNA replication is a ________________ process, meaning that each time the DNA is copied, each copy carries one strand of the original molecule and one newly made strand.
semiconservative
DNA replication begins at a specific site on the chromosome, the origin of replication, or ____
oriC
A _______ aids in the unwinding of DNA during DNA replication.
helicase
A ______ is recruited to lay down initial RNA primers needed for DNA polymerases to work.
primase
______-________ ___ _______ ________ (____) are recruited to help keep the DNA unwound.
Single-stranded DNA binding proteins (SSB)
Eukaryal replication initiates ________ origins of replication on each chromosome.
multiple
Once the replication fork forms, ___ _________ adds nucleotides to the intial RNA primers.
DNA polymerase
A continuous _______ stand and a discontinuous _______ strand are formed.
leading, lagging
The lagging strands form ______ fragments.
Okazaki
On the lagging strand, ___ _________ _ removes the RNA primers and fills in the gaps with new nucleotides.
DNA polymerase I
DNA ______ seals the sugar/phosphate backbone of the fragments, making the lagging strand continuous.
ligase
A region of repetitive DNA sequences at the end of a chromosome.
Telomere
__________ extends the ends of chromosomes so sequences arent lost after rounds of replication.
Telomerase
A ____ is a segment of DNA that gets transcribed (copied) into ssRNA.
gene
DNA is __________ into RNA. (initiation, elongation, and termination)
transcribed
_________ RNA (____) is approximately 500-10,000 nucleotides and codes molecules translated into proteins.
Messenger (mRNA)
_________ RNA (____) is approximately 75-100 nucleotides and is involved in translation & charged with amino acids.
Transfer (tRNA)
_________ RNA (____) is made up of a small and large subunit.
Ribosomal (rRNA)
_________ RNA (____) is approximately <100 nucleotides and serves various regulatory functions.
Micro (miRNA)
The basic process of transcription starts at a ________ (the region of DNA where RNA polymerase binds to begin transcription).
promoter
In bacteria, _____ _______ bound to RNA polymerase care enzyme direct the combined holoenzyme to a promoter.
sigma factors
Transcription in archaea resemble __________ transcription (transcription factors).
eukaryal
Termination in bacteria can occur in two processes: Rho-_________ or Rho-____________.
dependent, independent
A rho protein follows RNA polymerase and pops it off the DNA when it reaches a termination sequence=
rho-dependent
The DNA sequence transcribed forms an RNA hairpin loop structure that causes the RNA polymerase to dissociate from the DNA=
rho-independent
How is eukaryal RNA is modified after transcription:
- 5’ cap added
- poly(A) tail added
- intorns spliced out, exons joined together
During ___________, the information contained in the mRNA molecules is decoded to form proteins.
translation
During translation, ribosomes interact with the mRNA and _____ charged with particular _____ _____ are delivered to the system.
tRNAs, amino acids
Each nucleotide triplet (_____) matches a complementary _________ on each tRNA molecule.
codon, anticodon
_______ bonds are formed between the amino acids that are delivered.
peptide
The codon on the mRNA doesn’t need to be an exact match to the _________ (“wobble” phenomenon)
anticodon
Segment of mRNA that binds to the 16S rRNA of the small ribosomal subunit and properly aligns mRNA on the ribosome in bacteria.
Shine-Dalgarno sequence
Because of multiple Shine‒Dalgarno sequences, bacterial mRNA can be ______________ (coding for more than one protein) while eukaryal mRNA is usually ____________.
polycistronic, monocistronic
When ribosomes reach a ____ _____, release factors cause the complex to come apart, releasing the new protein for folding and modification.
stop codon
Proteins must fold into their _________/________ forms.
Some proteins require assembly of multiple subunits to form a ___________ structure.
primary/tertiary, quaternary
_________ __________ (___________) assist in correct folding/refolding of polypeptide sequences.
Molecular chaperones (chaperonins)
Molecular chaperones (chaperonins) were originally referred to as “____-_____ ________” because they appear after exposure of cells to heat.
heat-shock proteins
Because of the lack of a nuclear membrane in bacteria, transcription and translation can be _______.
coupled
In general, DNA replication occurs without much error—but mistakes (________) can occur.
mutations
This mutation is usually in the third position of a codon; results in no change in the amino acid sequence of the protein.
silent
This mutation is a change in a codon that results in coding for a different amino acid at that position in the eventual protein.
missense
This mutation is a change that forms a stop codon where one shouldn’t be found.
nonsense
Insertions or deletions of nucleotides can also result in a mutation known as a “___________” that change how a ribosome reads an mRNA molecule.
frameshift
Mutation where a section of DNA is inverted and reinserted into the genome.
inversion
Mutation where a segment of a chromosome breaks off and reattaches to a different location.
translocation
_________ (such as nitrous acid on the right) can induce mutations at a higher rate than is found spontaneously.
Chemicals
___________ _____can also cause a higher than expected mutation rate in DNA by forming _______ ______.
ultraviolet light, thymine dimers
Complex mechanisms for repairing DNA:
- Mismatch repair systems
- Photolyase (for thymine dimers)
- DNA polymerase 3’ to 5’ exonuclease proofreading activity
Process that corrects errors in DNA replication by excising several bases around the mismatched base, filling in the resulting gap with the correct bases, and linking together the adjoining fragments
mismatch repair system
Action of DNA polymerase that identifies and removes an incorrect base that has been incorporated into a growing chain.
DNA polymerase 3’ to 5’ exonuclease proofreading activity
Enzyme that repairs thymine dimers by cleaving the covalent bonds linking adjacent thymine bases
photolyase
