Podcast
Questions and Answers
Proteins are _____ made up of _____ _____.
Proteins are _____ made up of _____ _____.
polypeptides, amino acids
What are bonds between amino acids called?
What are bonds between amino acids called?
peptide bonds
Define gene expression.
Define gene expression.
the process by which DNA directs the synthesis of proteins
What are the two stages of gene expression?
What are the two stages of gene expression?
Define transcription.
Define transcription.
What does transcription allow for?
What does transcription allow for?
Where does transcription occur?
Where does transcription occur?
Messenger RNA is synthesized during _____ using a _____ template.
Messenger RNA is synthesized during _____ using a _____ template.
MRNA carries information from the _____ (at the _____) to the _____ in the _____.
MRNA carries information from the _____ (at the _____) to the _____ in the _____.
In what process are transfer RNA molecules important?
In what process are transfer RNA molecules important?
What does each tRNA carry?
What does each tRNA carry?
How does tRNA attach to mRNA?
How does tRNA attach to mRNA?
Define anticodon.
Define anticodon.
What do tRNA allow information to be translated into?
What do tRNA allow information to be translated into?
What do rRNA help form?
What do rRNA help form?
What does rRNA help link?
What does rRNA help link?
DNA contains the sequence of _____ that codes for _____.
DNA contains the sequence of _____ that codes for _____.
The sequence of nucleotides is read in groups of _____ called the _____ code.
The sequence of nucleotides is read in groups of _____ called the _____ code.
How many DNA strands are transcribed during transcription?
How many DNA strands are transcribed during transcription?
What is the DNA strand that is transcribed during transcription called?
What is the DNA strand that is transcribed during transcription called?
How are mRNA molecules related to DNA nucleotides?
How are mRNA molecules related to DNA nucleotides?
How many codon combinations are there?
How many codon combinations are there?
How many codon combinations code for amino acids?
How many codon combinations code for amino acids?
How many stop codons are there?
How many stop codons are there?
Define redundancy.
Define redundancy.
Define no ambiguity.
Define no ambiguity.
Define reading frame.
Define reading frame.
What are the three steps in transcription?
What are the three steps in transcription?
When does transcription begin?
When does transcription begin?
Does RNA polymerase need a primer to attach to a promoter region of DNA?
Does RNA polymerase need a primer to attach to a promoter region of DNA?
Where are promoter regions located?
Where are promoter regions located?
What is the promoter region in Eukaryotes?
What is the promoter region in Eukaryotes?
What helps RNA polymerase bond in Eukaryotes?
What helps RNA polymerase bond in Eukaryotes?
How can RNA polymerase bind to the promoter in Prokaryotes?
How can RNA polymerase bind to the promoter in Prokaryotes?
As elongation begins, _____ _____ opens the DNA and reads the _____ code of the _____ strand.
As elongation begins, _____ _____ opens the DNA and reads the _____ code of the _____ strand.
RNA polymerase moves in what direction?
RNA polymerase moves in what direction?
MRNA transcript elongates in what direction?
MRNA transcript elongates in what direction?
What does RNA polymerase pairs?
What does RNA polymerase pairs?
The growing _____ strand peels away from the _____ template strand; DNA double helix then _____.
The growing _____ strand peels away from the _____ template strand; DNA double helix then _____.
A single _____ can be transcribed simultaneously by several _____ _____ molecules; this helps increase the amount of mRNA synthesized, which increases protein production
A single _____ can be transcribed simultaneously by several _____ _____ molecules; this helps increase the amount of mRNA synthesized, which increases protein production
Describe Termination in prokaryotes.
Describe Termination in prokaryotes.
Define polyadenylation signal sequence.
Define polyadenylation signal sequence.
What are the three modifications that must occur in eukaryotic pre-mRNA before it is ready for translation?
What are the three modifications that must occur in eukaryotic pre-mRNA before it is ready for translation?
Define 5' cap (GTP).
Define 5' cap (GTP).
Define Poly-A tail.
Define Poly-A tail.
What are 5' cap and poly-A tail functions?
What are 5' cap and poly-A tail functions?
Define RNA splicing.
Define RNA splicing.
Define introns.
Define introns.
Define alternative splicing.
Define alternative splicing.
Define mature mRNA.
Define mature mRNA.
What can mature mRNA do?
What can mature mRNA do?
TRNA has an _____ region which i complementary and _____ to mRNA.
TRNA has an _____ region which i complementary and _____ to mRNA.
TRNA carries that _____ _____ that the mRNA _____ codes for
TRNA carries that _____ _____ that the mRNA _____ codes for
The _____ aminoacyl-tRNA synthase is responsible for attaching _____ _____ to _____; when tRNA carries an amino acid it is "charged"
The _____ aminoacyl-tRNA synthase is responsible for attaching _____ _____ to _____; when tRNA carries an amino acid it is "charged"
What are the sizes of prokaryotes small subunits and large subunits?
What are the sizes of prokaryotes small subunits and large subunits?
Define A site.
Define A site.
What are the three translation stages?
What are the three translation stages?
TRNA carries _____.
TRNA carries _____.
After the start codon, the _____ subunit binds.
After the start codon, the _____ subunit binds.
When does elongation start in translation?
When does elongation start in translation?
Describe codon charts.
Describe codon charts.
What does common ancestory mean?
What does common ancestory mean?
Define code recognition.
Define code recognition.
Define peptide bond formation.
Define peptide bond formation.
When does termination occur in translation?
When does termination occur in translation?
Define release factor.
Define release factor.
As translation takes place, what happens to the growing polypeptide chain?
As translation takes place, what happens to the growing polypeptide chain?
_____ determine the _____ _____, which determine the final shape.
_____ determine the _____ _____, which determine the final shape.
Some polypeptides require _____ proteins to _____ correctly and some require _____ before it can be _____ in the cell.
Some polypeptides require _____ proteins to _____ correctly and some require _____ before it can be _____ in the cell.
Define retroviruses.
Define retroviruses.
Proteins are __________ made up of __________ __________.
Proteins are __________ made up of __________ __________.
What is gene expression?
What is gene expression?
What is transcription?
What is transcription?
Messenger RNA is synthesized during __________ using a __________ template.
Messenger RNA is synthesized during __________ using a __________ template.
MRNA carries information from the __________ (at the __________) to the __________ in the __________.
MRNA carries information from the __________ (at the __________) to the __________ in the __________.
What process are transfer RNA molecules important in?
What process are transfer RNA molecules important in?
What is an anticodon?
What is an anticodon?
What do rRNA help link together?
What do rRNA help link together?
DNA contains the sequence of __________ that codes for __________.
DNA contains the sequence of __________ that codes for __________.
The sequence of nucleotides is read in groups of __________ called the __________ code.
The sequence of nucleotides is read in groups of __________ called the __________ code.
MRNA molecules formed are __________ and __________ to the DNA nucleotides.
MRNA molecules formed are __________ and __________ to the DNA nucleotides.
What are mRNA nucleotide triplets called?
What are mRNA nucleotide triplets called?
What is redundancy?
What is redundancy?
What is no ambiguity?
What is no ambiguity?
What is a reading frame?
What is a reading frame?
What do RNA polymerase molecules not need to attach to a promoter region of DNA?
What do RNA polymerase molecules not need to attach to a promoter region of DNA?
In Eukaryotes, what helps RNA polymerase bond?
In Eukaryotes, what helps RNA polymerase bond?
In Prokaryotes, how can RNA polymerase bind to the promoter?
In Prokaryotes, how can RNA polymerase bind to the promoter?
As elongation begins, __________ __________ opens the DNA and reads the __________ code of the __________ strand
As elongation begins, __________ __________ opens the DNA and reads the __________ code of the __________ strand
RNA polymerase pairs complementary what?
RNA polymerase pairs complementary what?
The growing __________ strand peels away from the __________ template strand; DNA double helix then __________
The growing __________ strand peels away from the __________ template strand; DNA double helix then __________
A single __________ can be transcribed simultaneously by several __________ __________ molecules; this helps increase the amount of mRNA synthesized, which increases protein production
A single __________ can be transcribed simultaneously by several __________ __________ molecules; this helps increase the amount of mRNA synthesized, which increases protein production
What are the three steps to Termination in prokaryotes?
What are the three steps to Termination in prokaryotes?
What codes for polyadenylation signal (AAUAAA); releases pre-mRNA from the DNA; most undergo modifications before translation (eukaryotes)
What codes for polyadenylation signal (AAUAAA); releases pre-mRNA from the DNA; most undergo modifications before translation (eukaryotes)
What is the 5' cap (GTP)?
What is the 5' cap (GTP)?
What is the Poly-A tail?
What is the Poly-A tail?
What is RNA splicing?
What is RNA splicing?
What are introns?
What are introns?
What is alternative splicing?
What is alternative splicing?
What is mature mRNA?
What is mature mRNA?
TRNA has an __________ region which is complementary and __________ to mRNA.
TRNA has an __________ region which is complementary and __________ to mRNA.
TRNA carries that __________ __________ that the mRNA __________ codes for.
TRNA carries that __________ __________ that the mRNA __________ codes for.
The __________ aminoacyl-tRNA synthase is responsible for attaching __________ __________ to __________; when tRNA carries an amino acid it is "charged"
The __________ aminoacyl-tRNA synthase is responsible for attaching __________ __________ to __________; when tRNA carries an amino acid it is "charged"
Prokaryotes small subunits __________ and large subunits __________
Prokaryotes small subunits __________ and large subunits __________
What is A site?
What is A site?
After the start codon, the __________ subunit binds
After the start codon, the __________ subunit binds
What are used to determine the amino acid?
What are used to determine the amino acid?
What is common ancestry?
What is common ancestry?
What is code recognition?
What is code recognition?
What is peptide bond formation?
What is peptide bond formation?
What is a release factor?
What is a release factor?
As translation takes place, the growing polypeptide chain begins to __________ and __________
As translation takes place, the growing polypeptide chain begins to __________ and __________
__________ determine the __________ __________, which determine the final shape
__________ determine the __________ __________, which determine the final shape
Some polypeptides require __________ proteins to __________ correctly and some require __________ before it can be __________ in the cell
Some polypeptides require __________ proteins to __________ correctly and some require __________ before it can be __________ in the cell
What are retroviruses?
What are retroviruses?
TRNA allow information to be translated into a __________ __________
TRNA allow information to be translated into a __________ __________
Define redundancy in the genetic code.
Define redundancy in the genetic code.
Define "no ambiguity" in the genetic code.
Define "no ambiguity" in the genetic code.
RNA polymerase moves __________ and opens small sections of DNA at a time
RNA polymerase moves __________ and opens small sections of DNA at a time
RNA polymerase pairs complementary __________ __________
RNA polymerase pairs complementary __________ __________
What does polyadenylation signal sequence code for?
What does polyadenylation signal sequence code for?
What are the functions of 5' cap and poly-A tail?
What are the functions of 5' cap and poly-A tail?
How is pre-mRNA considered mature mRNA?
How is pre-mRNA considered mature mRNA?
What are the prokaryotes small and large subunits?
What are the prokaryotes small and large subunits?
What are codon charts used for?
What are codon charts used for?
What type of ancestory do all organisms use the same genetic code?
What type of ancestory do all organisms use the same genetic code?
Explain code recognition.
Explain code recognition.
Explain peptide bond formation.
Explain peptide bond formation.
Explain translocation.
Explain translocation.
What does stop codons code for?
What does stop codons code for?
Flashcards
Polypeptides & Amino Acids
Polypeptides & Amino Acids
Proteins are chains of amino acids linked by peptide bonds.
Peptide Bonds
Peptide Bonds
Bonds that link amino acids in a polypeptide chain.
Gene Expression
Gene Expression
The process by which DNA directs protein synthesis.
Two Stages of Gene Expression
Two Stages of Gene Expression
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Transcription
Transcription
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Purpose of Transcription
Purpose of Transcription
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Location of Transcription
Location of Transcription
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Translation
Translation
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Location of Translation
Location of Translation
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mRNA Synthesis
mRNA Synthesis
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mRNA Function
mRNA Function
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tRNA Importance
tRNA Importance
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tRNA Cargo
tRNA Cargo
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tRNA Attachment
tRNA Attachment
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Anticodon Definition
Anticodon Definition
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tRNA and Peptide Sequence
tRNA and Peptide Sequence
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rRNA Function
rRNA Function
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rRNA and Amino Acids
rRNA and Amino Acids
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DNA's Role in Proteins
DNA's Role in Proteins
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Triplet Code
Triplet Code
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Strand Transcribed
Strand Transcribed
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Template Strand
Template Strand
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mRNA Relationship to DNA
mRNA Relationship to DNA
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Codons
Codons
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Total Codon Combinations
Total Codon Combinations
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Amino Acid Coding Codons
Amino Acid Coding Codons
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Number of Stop Codons
Number of Stop Codons
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Redundancy in Genetic Code
Redundancy in Genetic Code
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No Ambiguity
No Ambiguity
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Reading Frame
Reading Frame
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Three Steps in Transcription
Three Steps in Transcription
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Transcription Start
Transcription Start
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No Primer required
No Primer required
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Promoter Regions
Promoter Regions
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Promoter region in Eukaryotes.
Promoter region in Eukaryotes.
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Eukaryotes, transcription factors.
Eukaryotes, transcription factors.
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Prokaryotes, RNA polymerase
Prokaryotes, RNA polymerase
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Elongation Process
Elongation Process
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RNA polymerase direction.
RNA polymerase direction.
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mRNA Transcript Elongation
mRNA Transcript Elongation
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RNA polymerase to DNA.
RNA polymerase to DNA.
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RNA polymerase pairs.
RNA polymerase pairs.
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Growing mRNA strand
Growing mRNA strand
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Simultaneous Gene Transcription
Simultaneous Gene Transcription
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Termination in Prokaryotes
Termination in Prokaryotes
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polyadenylation signal
polyadenylation signal
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Study Notes
- Proteins consist of polypeptides, which are made up of amino acids.
- Peptide bonds link amino acids together.
- Gene expression is the process where DNA directs protein synthesis.
- Transcription and translation are the two main stages of gene expression.
Transcription
- The synthesis of RNA using DNA information.
- Allows the message of DNA to be transcribed.
- Occurs in the nucleus.
Translation
- Uses RNA information to synthesize polypeptides; a nucleotide sequence turns into an amino acid sequence.
- Takes place in the ribosome.
mRNA
- Messenger RNA is synthesized using a DNA template during transcription.
- Carries information from DNA (in the nucleus) to ribosomes in the cytoplasm.
tRNA
- Transfer RNA molecules are important in translation.
- Each tRNA carries a specific amino acid.
- tRNA attaches to mRNA via its anticodon, which is complementary to mRNA codons.
- Allows information to be translated into a peptide sequence.
rRNA
- Ribosomal RNA helps form ribosomes.
- rRNA helps link amino acids together.
DNA and the Triplet Code
- DNA has nucleotide sequences that code for proteins.
- Nucleotide sequences are read in groups of three, known as the triplet code.
- During transcription, only one DNA strand is transcribed which is called the template strand (or noncoding, minus, antisense strand).
- mRNA molecules formed are antiparallel and complementary to the DNA nucleotides.
- mRNA nucleotide triplets called codons, code for amino acids.
- There are 64 codon combinations; 61 code for amino acids and 3 are stop codons.
- The genetic code exhibits redundancy, where multiple codons can code for the same amino acid, but there is no ambiguity, as each codon specifies only one amino acid.
- During translation, mRNA codons must be read in the correct groupings, known as the reading frame, to synthesize the correct proteins.
Transcription Stages
- Initiation, Elongation, and Termination.
Transcription: Initiation
- Begins when RNA polymerase molecules attach to a promoter region of DNA, located upstream of the desired gene.
- RNA polymerase molecules do not need a primer to attach to a promoter region of DNA.
- In eukaryotes, the promoter region includes the TATA box, and transcription factors help RNA polymerase bind.
- In prokaryotes, RNA polymerase can bind directly to the promoter.
Transcription: Elongation
- RNA polymerase opens the DNA and reads the triplet code of the template strand, moving in the 3' to 5' direction.
- The mRNA transcript elongates in the 5' to 3' direction as RNA polymerase moves downstream and opens small sections of DNA at a time.
- RNA polymerase pairs complementary RNA nucleotides.
- The growing mRNA strand peels away from the DNA template strand, and the DNA double helix reforms.
- Multiple RNA polymerase molecules can transcribe a single gene simultaneously, increasing mRNA synthesis and protein production.
Transcription: Termination
- Prokaryotes: A termination sequence causes a termination signal, RNA polymerase detaches, and the mRNA transcript is released without needing modifications.
- Eukaryotes: A polyadenylation signal sequence codes for the polyadenylation signal (AAUAAA), releasing pre-mRNA from the DNA; it typically undergoes modifications before translation.
Eukaryotic pre-mRNA Modifications
- 5' cap, Poly-A tail, and RNA splicing.
- 5' Cap: The 5' end receives a modified guanine nucleotide "cap" (GTP).
- Poly-A Tail: The 3' end receives 50-250 adenine nucleotides.
Functions of 5' Cap and Poly-A Tail
- Help mature mRNA leave the nucleus.
- Protect the mRNA from degradation.
- Help ribosomes attach to the 5' end of the mRNA when it reaches the cytoplasm.
- RNA Splicing: Introns (non-coding sequences) are removed, and exons (coding sequences) are joined together.
- Alternative splicing allows a single gene to code for more than one kind of polypeptide.
- Once all modifications occur, pre-mRNA becomes mature mRNA.
- Mature mRNA can leave the nucleus for translation at the ribosomes.
tRNA in Translation
- tRNA has an anticodon region complementary and antiparallel to mRNA.
- tRNA carries the amino acid that the mRNA codon codes for.
- The enzyme aminoacyl-tRNA synthase attaches amino acids to tRNA, "charging" it.
Ribosome Subunits
- Prokaryotes: small subunit 30S, large subunit 40S.
- Eukaryotes: small subunit 40S, large subunit 60S.
Ribosome Sites
- A Site: Amino acid site; holds the next tRNA carrying an amino acid.
- P Site: Polypeptide site; holds the tRNA carrying the growing peptide chain.
- E Site: Exit site.
Translation Stages
- Initiation, Elongation, and Termination.
Translation: Initiation
- Occurs when the small ribosomal subunit binds to the mRNA, and a charged tRNA binds to the start codon, AUG, on the mRNA, carrying methionine.
- After the start codon, the large subunit binds.
Translation: Elongation
- Begins when the next tRNA comes into the A site, mRNA is moved through the ribosomes which allows for the codons to be read; each mRNA codon codes for a specific amino acid.
- Codon charts are used to determine the amino acid.
- All organisms use same genetic code suggesting a common ancestry.
- The appropriate anticodon of the next tRNA goes to the A-site for code recognition.
- Peptide bonds form, transferring the polypeptide to the A-site tRNA for peptide bond formation.
- Translocation occurs: the tRNA in the A site moves to the P site, the tRNA in the P site moves to the E site, and the A site is open for the next tRNA.
Translation: Termination
- Happens when a stop codon in the mRNA reaches the A site of the ribosomes (stop codons do not code for amino acids).
- Stop codons code for a release factor, which hydrolyzes the bond that holds the polypeptide to the P site, releasing the polypeptide and disassembling all translational units.
Post-Translation
- As translation takes place, the growing polypeptide chain begins to coil and fold.
- Genes determine the primary structure, which dictates the final shape.
- Some polypeptides need chaperone proteins to fold correctly and some require modifications before becoming functional in the cell.
Retroviruses
- Information flows from RNA to DNA using reverse transcriptase.
- Viral RNA couples to DNA, and this DNA becomes part of the RNA.
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