03 Processes Involving the Genetic Material Flashcards
is the process where DNA duplicates itself.
Replication
is the process where DNA is converted into mRNA.
and is sequentially divided into 3 parts:
Transcription
i. Initiation
ii. Elongation
iii. Termination
is the process where the genetic information in the mRNA is used to make proteins
and is sequentially divided into 3 parts:
Translation
i. Initiation
ii. Elongation
iii. Termination
_____ are enzymes that catalyze the synthesis of DNA or RNA polymers whose sequence is complementary to the original template, as defined by Watson–Crick base pairing.
Polymerases
RNA polymerases
● _____ utilize one RNA polymerase for all transcription of types of RNA.
● ____ utilize three slightly different RNA polymerases: RNA polymerase I, RNA polymerase II, and RNA polymerase III.
- (RNA Polymerases I, which transcribes ____; II, which transcribes ____; and III, which transcribes ____).
Prokaryotes
Eukaryotes
rRNA
mRNA
tRNA
____is responsible for the process of DNA replication by making the new strand of DNA by adding DNA bases in one direction from the 5’ prime end to the 3’ prime end.
DNA polymerase
In eukaryotes, a major function of DNA polymerases is to accurately replicate the _____ that constitute the human genome to replicate the genome and thus to allow transmission of genetic information from one generation to the next, or simply making the new strand of DNA by adding DNA bases in one direction from the 5’ prime end to the 3’prime end.
six billion nucleotides
In prokaryotes, three main types of polymerases are known: _________. It is now known that ____ is the enzyme required for DNA synthesis or responsible for replication; DNA pol I and DNA pol II are primarily required for repair.
DNA pol I, DNA pol II, and DNA pol III
DNA pol III
The general process of transcription can be applied to both prokaryotic cells and eukaryotic cells. The basic biochemistry for each is the same; however, the specific mechanisms and regulation of transcription differ between prokaryotes and eukaryotes
While specific aspects of transcription differ between prokaryotes and eukaryotes, the basic chemistry behind the process is the same. Both utilize ____ to catalyze the synthesis of RNA, and while regulation may differ, the ultimate product of transcription in prokaryotes and eukaryotes is ____.
RNA polymerase
RNA
Stages of Transcription
1. Initiation
• RNA polymerase binds to a sequence of DNA called the ____, found near the beginning of a gene.
• Each gene (or group of co-transcribed genes, in bacteria) has its own promoter.
• Once bound, RNA polymerase ____ the DNA strands, providing the single-stranded template needed for transcription.
promoter
separates
Stages of Transcription
- Elongation
• One strand of DNA, the _____, acts as a template for RNA polymerase.
• As it “reads” this template one base at a time, the polymerase builds and RNA molecule out of complementary nucleotides, making a chain that grows from 5’ to 3’.
• RNA transcript carries the same information as the non-template (coding) strand of DNA, but it contains the base uracil (U) instead of thymine (T).
template strand
Stages of Transcription
3. Termination
• Sequences called terminators signal that the RNA transcript is complete.
• Once they are transcribed, they cause the transcript to be released from the RNA polymerase
• Example mechanism is the ____. ___ is an unpaired loop of messenger RNA (mRNA) that is created when an mRNA strand folds and forms base pairs with another section of the same strand.
hairpin
Process of making complementary DNA, cDNA, from single stranded RNA and • Allows scientists to work backward.
Reverse Transcription
RNA processing
Both prokaryotes and eukaryotes process their ribosomal and transfer RNAs. The major difference in RNA processing between them is in the processing of _____ In prokaryotes, RNA transcripts are ready to act as messenger RNAs and get translated into proteins right away. In eukaryotes, RNA transcripts (called pre-mRNA) undergoes extensive processing before it is ready to be translated.
messenger RNAs (mRNAs).
Process of post-transcriptional modifications
- Capping at the 5’ end
- Addition of a polyA tail at the 3’ end; and
- Splicing for intron removal
Capping
• While the pre-mRNA is still being synthesized, a ____ is added to the 5′ end of the growing transcript by a 5′-to-5′ phosphate linkage.
• First, at the 5’ end of the mRNA, one phosphate is removed.
• Next, guanyl transferase attaches a guanosine monophosphate (GMP) molecule to the end of the mRNA.
• Then the newly transferred guanine is methylated by a guanine-7-methyltransferase.
7-methylguanosine cap
The cap protects the 5’ end of the mRNA from degradation by nucleases and also helps to position the mRNA correctly on the ribosomes during protein synthesis.
polyA tail addition
Polyadenylation of the 3’ end of eukaryotic mRNAs begins with an _____ of the mRNA, usually between a conserved ____ sequence and a downstream U- orGU-rich region. CA nucleotide near the AAUAAA sequence marks the cleavage point for precursor mRNA. Then, a tail of approximately ______ is added by poly(A) polymerase, thus the name “polyA tail”. The tail makes the transcript more stable and helps it get exported from the nucleus to the cytosol.
initial cleavage
AAUAAA
200 adenine nucleotides
RNA splicing
Eukaryotic genes are composed of _____, which correspond to protein-coding sequences and intervening sequences called ____, which may be involved in gene regulation, but are removed from the pre-mRNA during processing. Intron sequences in mRNA do not encode functional proteins, thus they are spliced out. The process of mRNA splicing is carried out by the ____, a dynamic complex of RNA and protein subunits that removes introns from precursor mRNA.
exons
introns
spliceosome
_______ recognize sequences at the 5′ end of the intron because introns always start with the nucleotides ___ and they recognize sequences at the 3′ end of the intron because they always end with the nucleotides ____
Spliceosomes
GU
AG
The spliceosome cleaves the pre-mRNA’s sugar phosphate backbone at the G that starts the intron and then covalently attaches that G to an internal A nucleotide within the intron. Then the spliceosome connects the 3′ end of the first exon to the 5′ end of the following exon, cleaving the 3′ end of the intron in the process. This results in the splicing together of the two exons and the release of the intron in a lariat form.
Major Components of translational machinery:
_____ = came from transcription; provides the information that must be interpreted by the translation machinery and is the template for translation
mRNA
Major Components of translational machinery:
_____ = binds to mRNA; composed of both RNA and protein. It coordinates the correct recognition of the mRNA by each tRNA and catalyzes peptide-bond formation between the growing polypeptide chain and the amino acid attached to the selected tRNA.
Ribosomes
