Chapter 15-17 Biology Flashcards
The primer that is binding to a DNA sequence is made of ___.
RNA
DNA polymerase can/can’t start without a 3’ OH already there.
can’t
What part of DNA gives it a charge?
Phosphate
What is one molecule that is found in protein but NOT DNA?
Sulfur (disulfide bond in tertiary structure)
In the experiment with radioactive viruses, where was the radioactive DNA found? Where was the radioactive protein?
Radioactive DNA: inside cells, in pellet
—> confirms that genes are made of DNA
Radioactive protein: inside solution
—> confirms capsids are made of protein
Which of the following best describes the composition of DNA monomers?
a) All of the monomers contain ribose connected to one of four nitrogenous bases
b) All of the monomers contain a phosphate group connected to a nitrogenous base
c) All of the monomers contain a phosphate group and a nitrogenous base connected to a deoxyribose.
C
5 prime end is characterized by a ___ and the 3 prime is characterized by an ___ group.
phosphate, OH
In DNA, what type of bond is between the bases?
Van der Waals
DNA replication is semiconservative because replicated DNA molecules are composed of ___.
a) 2 strands of old DNA
b) 2 strands of new DNA
c) 1 strand of old DNA and 1 strand of new DNA
d) 1 strand of new DNA
C
What did the Meselson-Stahl Experiment prove?
DNA replication is semi-conservative
Meselson-Stahl Experiment results proving semi-conservative replication.
After two generations, 1/2 of DNA was low density and the other 1/2 was intermediate density.
DNA polymerase catalyzes DNA ___.
synthesis
Deoxyribonucleotides are only added to the __’ end of a growing DNA chain. Synthesis always from ___ to ___ prime
3’, 5 to 3
DNA synthesis requires energy, making it ___.
endergonic
Why is ATP a good source of energy?
Three phosphates that are all negatively charged want to repel and release a lot of energy.
How many origins of replication do bacterial chromosomes have?
1
How many origins of replication do eukaryotes have?
Many
What happens when origins of replication meet?
They make one big bubble.
What breaks the hydrogen bonds between DNA strands (think of secondary structure)?
DNA helicase
What attaches to separated strands to prevent them from closing?
Single-strand DNA-binding proteins (SSBPs)
What cuts and rejoins DNA to relieve tension caused by unwinding DNA?
Topoisomerase
Where is the origin of replication?
Replication fork
____ synthesizes RNA primer.
Primase
DNA polymerase synthesizes __ to ___
5’, 3’
DNA polymerase can only add on to existing 3’ __ groups, which is why we need RNA primer in ___ replication.
OH, DNA
What prevents the shortening of telomeres during replication?
Telomerase, has its own RNA template
True or False: Telomeres contain genes
False
Telomerase is primarily found in ___, ___cells, and ___ cells.
gametes, stem, cancer
List 3 outcomes of adding telomeres to cell cultures
- Allows them to continue to divide
- Cancer usually has active telomerase, passing checkpoints unregulated
- Allows for unlimited cell division
What proofreads in DNA synthesis?
DNA polymerase
When does mismatch repair occur?
When mismatched bases are corrected after DNA synthesis is complete.
Nucleotide excision repair
- Proteins detect irregularities in DNA structure
- An enzyme NICKS DNA on both sides of damage
When do the following happen?
Proofreading –>
Mismatch repair –>
Telomere repair –>
Nucleotide excision repair –>
synthesis, synthesis, extending telomeres, interphase
What is the One Gene, One Enzyme hypothesis? (Beadle and Tatum)
Each gene contains information to make an enzyme. IT IS SUPPORTED
What is the OGOE hypothesis also referred to as?
One Gene, One polypeptide
DNA –> ___ –> Protein
mRNA
What do the following RNAs stand for?
mRNA
tRNA
rRNA
mtRNA
messenger
transfer (seen in translation)
ribosomal (seen in translation)
mitochondrial
mRNA carries DNA info to ___, which takes place in the ___ during ___.
ribosomes, cytoplasm, transcription
RNA processing takes place in the ___.
nucleus
Translation takes place in the ___.
cytoplasm
RNA polymerase synthesizes ___ and can work without a ___.
RNA, primer
Match the phrase:
- Product of proteins
- Sequences of DNA bases
a) Genotype
b) Phenotype
b, a
Differences in DNA sequence may cause differences in ___.
phenotype
Modifications to central dogma
- RNA other functions
- RNA to DNA (reverse transcriptase)
What is the worst mutation?
addition OR deletion
What is the start codon?
AUG
___ starts transcription and ___ ends transcription.
Promoter, terminatior
All but two amino acids are encoded by more than one codon.
Redundant
One codon never codes for more than one amino acid
Unambiguous
Codons are read one at a time
Non-overlapping/Reading frame
All codons specify the same amino acids in all organisms (some exceptions)
Nearly universal
If several codons specify the same amino acid, the first two bases are usually identical
Conservative
If the mutation is on the third base of the codon, it is more/less detrimental.
less
Point mutation is when ___ nucleotide(s) are affected.
one
___ mutations change an amino acid in protein.
Missense
___ mutations do not change amino acid sequence due to redundancy in the code.
Silence (redundant… were you silent or were you silenced)
___ mutations shift reading frame, altering ALL subsequent codons.
Frameshift (addition and deletion)
___ mutation change codons that specify an amino acid into stop codon.
Nonsense (remember no more)
Beneficial mutations increase ___, the ability for an organism to survive and reproduce.
fitness
Segment of chromosome breaks off, flips around, and rejoins
Inversion
Section of chromosome breaks off and becomes attached to another chromosome
Translocation
Segment of a chromosome is lost
Deletion
Segment of chromosome is present in multiple copies
Duplication
Chromosome mutation can change what two things?
- chromosome number
- chromosome structure
Which of the following occurs during transcription?
a) protein synthesis
b) mRNA attaches to ribosomes
c) RNA synthesis
d) DNA replication
c
a, b –> refer to translation
Promoter is the ___ box, that signals where to start ___.
TATAA, transcription
Bonds between ribonucleotides
Phosphodiester
___ have one type of RNA polymerase and ___ have at least three RNA polymerase.
Bacteria, eukaryotes
Bacterial RNA polymerase
Holoenzyme
___ part of holoenzyme recognizes and binds to promoter.
Sigma
RNA forms a ___ structure that indicates transcription is coming to an end.
hairpin
Which of the following processes occurs in prokaryotes but not in eukaryotes?
a) gene splicing
b) translation and transcription occur simultaneously
c) post-transcriptional splicing
d) translation in the absence of a ribosome
b
Transcription in eukaryotes:
- Larger, more diverse ___, including TATA box
- General transcription factors recognize promoters rather than ___ proteins
- At termination a poly A signal is transcribed rather than a ___, and the RNA ___ is cut
- promoters
- sigma
- hairpin, downstream
How does the primary transcript in the nucleus of a eukaryotic cell compare to the functional RNA?
The primary transcript is larger than the mRNA.
The primary transcript has introns that get removed later on.
snRNPs form a complex known as ___
spliceosomes
What removes introns?
snRNPs, small nuclear ribonucleoproteins
In the primary RNA transcript, where do we add the 5’ cap and poly A tail?
5 ‘ end –> 5’ cap
3’ end –> poly A tail
Where does splicing occur?
Nucleus, during transcription
The 5’ cap consists of modified ___ nucleotides that enables ribosomes to bind and protect from ___.
guanine, degradation
The poly A tail consists of 100-250 ___ nucleotides that are needed for translation and protects again degradation.
adenine
Only the ___ RNA will be in the cytoplasm.
mature
___ has codons, ___ has anticodons, and ___ has amino acids.
mRNA, tRNA, proteins
___ tRNAs transfer amino acids to growing polypeptides, meaning tRNAs are an ___ molecule.
Aminoacyl, adapter
The anticodon of a particular tRNA molecule is complementary to the corresponding ___ codon
mRNA
Aminoacyl tRNA is tRNA linked to its ___.
amino acid
___ is required for tRNAs to attach to amino acids.
ATP
The anticodon’s third position can form a nonstandard base pair.
Wobble pairing
True of False: On tRNA is able to read more than one codon
True
Parts of a ribosome
A –> Accepting area where tRNA carries amino acid
P –> Peptidy, holds growing peptide chain
E –> Exit, tRNAs without amino acids exit ribosome
3 steps of translation
- Initiation
- Elongation
- Termination
Amino acids are always added to the ___ end, also known as C-terminus
carboxyl
Ribosome binding side is known as ___ in bacteria.
Shine-Delgarno site
- mRNA binds to small subunit
- Initiator aminoacyl tRNA binds to start codon
- Large subunit of ribosome binds
Initiation
What is the first amino acid added
Met
- Incoming aminoacyl tRNA
- Peptide-bond formation
- Translocation, tRNA exits
Elongation
___ factors bind to the stop codon in the A site in place of a tRNA. (eukaryotes)
Release
Which of the following processes occurs when termination of translation takes place?
a) The 5’ cap is reached
b) The end of the mRNA molecule is reached
c) A stop codon is reached
d) The poly-A tail is reached
c
If you are being asked to write the complementary primer strand for DNA polymerase, should you include adenine or uracil?
uracil
Which enzyme catalyzes the synthesis of DNA from its own RNA template?
telomerase
In bacteria, transcription normally stops when RNA ____ reaches a termination signal on the DNA. This leads to the formation of a ___ loop.
polymerase, hairpin
The sequence of three nucleotides in tRNA (transfer RNA) that matches a sequence in mRNA.
Anticodon
During elongation, what substrates are used for the polymerization reaction catalyzed by RNA polymerase?
Ribonucleoside triphosphates (NTPs)
What proteins are associated with promoters in bacteria during transcription?
Sigma proteins
What is the first step during the initiation of translation?
Ribosome binding site on the mRNA binds to a complementary sequence of rRNA on the ribosome small subunit.
