DNA Translation, Replication, and Transcription
Terms in this set (69)
What does DNA stand for?
What is the technical term for the shape of DNA?
Draw a nucleotide and label the following parts: nitrogen base, deoxyribose, phosphate, 5' end, 3' end, Hydrogen bond, covalent bond.
If given a picture of a nucleotide, be able to identify which is the 3' carbon and which is the 5' carbon. If shown a strand of DNA, be able to identify the 3' and 5' ends.
List the full names of the four bases of DNA.
What type of chemical reaction links nucleotides?
What type of bond holds the nucleotides together?
How many bases are on each "rung" of the ladder?
1 purine and 1 pyrimidine connected by a hydrogen bond
Which bases pair with which?
-Cytosine (pyrimidine) pairs with Guanine (purine)
-Thymine (pyrimidine) pairs with Adenine (purine)
How do purines differ from pyrimidines? Which bases are which?
-Adenine and Guanine are purines which are 2 ring structures.
-Thymine and Cytosine are pyrimidines which are 1 ring structures
In what direction does replication occur with regard to the original DNA strand?
ALWAYS in the 5'- 3' direction
In what direction does DNA replication occur on the newly synthesized strand?
Differentiate between a lead strand and a lag strand?
-The leading strand is the new strand that is synthesized continuously and follows the replication fork. (3'-5')
-The lagging strand is the new strand that is synthesized in short fragments in the opposite direction to the movement of the replication fork (5'-3')
Where are Okazaki fragments found?
Short fragments of a DNA strand formed on the lagging strand
Why is DNA considered "semi-conservative"?
DNA is considered semi-conservative because each original strand acts as a template to build up a new strand.
What happens during excision repair?
base excision repair (BER) is a cellular mechanism that repairs damaged DNA throughout the cell cycle. It is responsible primarily for removing small, non-helix-distorting bases from the genome.
What does helicase do?
Helicase is an enzyme found at the replication fork, with two functions- to unwind the two DNA strands, and to separate them by breaking the hydrogen bonds
What does RNA primase do?
RNA primase adds a short length of RNA, attached by complementary base pairing, to the template DNA strand. This acts as a primer, allowing the enzyme DNA polymerase III to bind.
Is deoxynucleoside triphosphate an enzyme? What does it do?
No, deoxynucleoside triphosphate is NOT an enzyme but it is an important molecule. It contains the base, sugar and three phosphates. It is also the precursor to a nucleotide.
What does DNA polymerase III do?
DNA polymerase III adds deoxynucleoside triphosphates (dNTPs) to the 3' end of the primer and then to the forming strand of DNA.
What does DNA polymerase I do?
DNA polymerase I later removes the RNA primer.
What does DNA ligase do?
DNA ligase joins the Okazaki Fragments together
Differentiate between genotype and phenotype.
-Genotype is the exact genetic constitution of an individual feature of an organism; the alleles of an organism.
-Phenotype is the characteristic or appearance or an organism which may be physical or biochemical.
Be able to identify if a strand of nucleic acid as being either DNA or RNA.
What type of molecule is RNA polymerase? What does it do?
RNA polymerase is an enzyme that adds the nucleoside triphosphates (NTPs) using base pairing to the antisense strand- special proteins allow this binding to occur. This enzyme both unwinds and separates the DNA in the front and joins and rewinds in the back. The middle section is where the mRNA strand is being made.
What "new" base is found in RNA? Which base does it replace?
The "new" base that is found in RNA is Uracil (U) which replaces Thymine (T)
What is the purpose of transcription?
The purpose of transcription is to transfer sections of the genetic code from DNA to an mRNA molecule.
In what direction (prime) is mRNA formed?
mRNA is formed in the 5'-3' direction.
How many base pairs long is each DNA "word"? What is this word called on the DNA?
Each "word" in DNA is ALWAYS 3 base pairs long. Each word is called a triplet.
What are these words called on RNA?
On RNA these words are called codons.
Codon- genetic code made of one triplet of bases.
What does mRNA create a mirror image of? (Except for one base).
mRNA create a mirror image of a "mirror image" of the triplets found on DNA is created.
Once mRNA is created, where does it go?
mRNA then travels out of the nucleus and toward a ribosome.
What process occurs at the organelle mentioned above?
What is the purpose of translation?
The purpose of translation is to decode the mRNA at a ribosome to produce an amino acid sequence.
What role does tRNA play?
tRNA is made of a single strand of nucleotides that is folded and held in place by base pairing and hydrogen bonds. tRNA has a 'clover leaf' appearance. tRNA has an anticodon on one
end and a CCA on the other end, where amino acid will bind. tRNA brings matching anticodon to codon.
Be able to determine which amino acid is made from which codon, using the chart. You will be allowed to use the chart on the exam.
What is a polypeptide?
A polypeptide is a chain of amino acids linked by peptide bonds.
Write-out a polypeptide that has five amino acids on it.
Met Leu Ile Arg Ser
What role do proteins play in your body?
Proteins make up most tissue in your body - skin, all organs, muscles, etc. Proteins make you who you are.
What is meant by the statement "genetic code is degenerate"?
It means that each amino acid can be synthesized by more than one codon
Ex: both UUU and UUC make phenylalanine
What is meant by the statement "genetic code is universal"?
It means that the same codons are found in all living organisms.
Each polypeptide can draw its origin back to one _________.
Where are the promoter and terminator found? What role does each of them play?
A specific sequence of DNA bases at the start of a gene to which RNA polymerase binds. Promoter is an example of non-coding DNA with a function. The terminator region marks the end of a gene. A specific sequence of DNA marking the end of transcription.
Draw a simple diagram of transcription, and label the sense strand, anti-sense strand, and mRNA, as well as the 5' and 3' ends of all strands.
Which strand is mRNA complementary to?
Due to complementary base pairing, the sequence of bases along the mRNA molecule corresponds to the sequence on the original DNA molecule. Each sequence of three bases (triplet) corresponds to a specific amino acid.
Which strand is mRNA similar to?
mRNA is similar to the sense strand.
In between transcription and translation is a "middle step" called _____________.
What does "post-transcriptional" mean?
Post-transcriptional means regulation mechanisms that control or regulate mRNA after it has been produced. After the process of transcription.
Differentiate between introns and exons.
-Introns: non-coding sequences of DNA that are transcribed but not translated. After the transcription of a gene, the introns are removed in a process called post-transcriptional modification.
-Exons: Coding sequences of DNA that are spliced together to form mature mRNA that is then translated.
What are the two distinct parts to a tRNA (found at opposite ends)?
The two distinct parts to a tRNA is the anticodon and the CCA on the other end, where amino acid will bind (amino acid attachment site).
What is required for hooking the appropriate amino acid onto a tRNA molecule?
Requires a tRNA activating enzyme, and uses ATP for energy.
Draw a rough sketch of a ribosome and label the large subunit and the small subunit.
How many tRNA binding sites are there on a ribosome at any one time?
On the large subunit, which is made up of two molecules of rRNA and some proteins, there are 3 binding sites for tRNA (A site, P site and E site-- exit site).
How many mRNA binding sites are there on a ribosome at any one time?
On the small subunit, which made up of one molecule of rRNA and some proteins, there is one binding site for mRNA.
In what direction (prime) does translation take place?
Occurs in 5'→3' direction with regard to the mRNA. Because start codon is found on the 5' end
What is a polysome?
A polysome are ribosomes that are clustered together on the mRNA, creating several copies of the same polypeptide at the same time.
What is the role of a start codon?
The start codon (AUG) is located at the 5' end of the mRNA sequence and the ribosome moves along it in the 3' direction.
What is the role of a stop codon?
Translation stops- A site is not copied, signal for translation to stop (UAG, UAA, UGA).
What is the destination for proteins synthesized by free ribosomes?
Free ribosomes synthesize proteins for use within the cell.
What is the destination for proteins synthesized by bound ribosomes?
Bound ribosomes synthesise proteins primarily for secretion or inclusion in lysosomes
Identify the parts of a nucleotide.
Know the position of the hydrogen bond
Know and recognize the difference between conservative, semi-conservative and dispersive models of DNA replication.
Be able to identify all components during the replication process: parent DNA, lead strand, lag strand, Okazaki fragment, 3' end, 5' end, sequence of formation of Okazaki fragments, DNA polymerase, ligase, RNA primase, RNA primer.
Be able to label diagrams of transcription and translation.
Be able to label diagrams of transcription and translation.
Explain the process of translation. 
Translation is a process that decodes the information of mRNA into the sequence of amino acids that eventually form a protein. This process occurs after transcription. Translation occurs in the 5'-3' direction. Once the mRNA is at the ribosome, translation starts. In both eukaryotes and prokaryotes, translation occurs in 3 stages: initiation, elongation, and termination.
Before initiation can occur, specific tRNA-activating enzymes catalyze the attachment of amino acids to tRNA molecules, using ATP for energy. Then initiation begins and the small ribosomal subunit binds to the 5' end of mRNA and moves along it until it reaches the start codon (AUG). mRNA is used as a template and is read as 3 bases (triplets) at a time. Three bases pairs is called a codon. Each codon specifies which amino acid is added to the growing polypeptide. tRNA has a specific amino acid attached. The appropriate tRNA molecule binds to the codon via its anticodon (according to complementary base pairing). Finally, the large ribosomal subunit aligns itself to the tRNA molecule at its P-site and forms a complex with the small ribosomal subunit.
The next stage is elongation, the second tRNA molecule pairs with the next codon in the ribosomal A-site. The amino acid in the P-site is covalently attached by a peptide bond to the amino acid in the A-site. In translation, a process called translocation occurs. Basically, just the moving from one spot to the other.
The ribosome moves along the mRNA sequence in a 5' - 3' direction, synthesizing a polypeptide chain. Multiple ribosomes can translate a single mRNA sequence simultaneously (forming polysomes). The last stage of translation is termination. Elongation and translocation continue until the ribosome reaches a stop codon. These codons do not code for any amino acids and instead signal for translation to stop. The polypeptide is released and the ribosome disassembles back into subunits.
Explain the process of transcription leading to the formation of mRNA. 
Transcription is the first process by which the DNA code is used to build polypeptides. Transcription transfers sections of the genetic code from DNA to an mRNA molecule. Transcription happens in the nucleus and occurs in the 5'-3' direction.
At the start of transcription, the DNA molecule is separated into two strands by the enzyme RNA polymerase, which binds to the DNA near the beginning of a gene. Hydrogen bonds between the bases are broken and the double helix unwinds.
Transcription begins at a specific point on the DNA molecule called the promoter region, which is a short sequence of non-coding DNA just before the start of the gene. Only one of the strands is used a template for transcription which is called the antisense strand. The other DNA strand is called the sense strand. RNA polymerase uses free nucleoside triphosphate (NTPs) to build the RNA molecule, using complementary base pairing to the DNA and condensation reactions between the nucleotides. This produces a primary mRNA molecule that is complementary to the antisense strand being transcribed, and has the same base sequence as the sense strand (except it has the base Uracil instead of Thymine). RNA polymerase moves along the antisense strand in a 3' to 5' direction. As it does so, the 5' end of a nucleotide is added to the 3' end of the mRNA molecule so that the construction of the mRNA proceeds in a 5' to 3' direction. Eventually, the RNA polymerase reaches the terminator region, which indicates the end of the gene and stops the RNA polymerase and ultimately transcription. The RNA polymerase releases the completed mRNA and finishes rewinding the DNA before breaking free.
Explain the process of DNA replication. 
Explain the process of DNA replication. 
DNA replication is semi conservative, occurs in the 5'-3' direction and occurs during the S phase of mitosis. The first stage of DNA replication is the uncoiling of the DNA double helix by the enzyme helicase. Helicase separates the DNA into two template strands by breaking the hydrogen bonds between base pairs. RNA primase then adds a short sequence of RNA to the template strands. This short sequence of RNA is a primer which allows DNA polymerase III to bind to the strands and start the replication process. Once this is done, DNA polymerase III adds deoxynucleoside triphosphates (dNTPs) to the 3' end of the primer and then to the forming strand of DNA. Deoxynucleoside triphosphates contain the base, sugar and three phosphates and are the precursors to a nucleotide. Two of the three phosphates groups break off during the replication process to release energy. The dNTPs pair up opposite their complementary base partner (adenine pairs with thymine ; guanine pairs with cytosine). Since the strands are anti-parallel (the two strands have their 5' end and 3' end on opposite ends) and the DNA opens in one direction one strand can be replicated continuously (leading strand- 3') but the other must be built is small sections (lagging strand- 5'). These fragments are called Okazaki fragments. DNA polymerase I will remove the RNA primers and replace these with DNA. The enzyme DNA ligase then joins the Okazaki fragments together to form a continuous new strand of DNA.
YOU MIGHT ALSO LIKE...
MCAT Biochemistry | Kaplan Guide
AP Biology- DNA Structure and Replication, Transcription, and Translation
Ch. 8 Microbiology
OTHER SETS BY THIS CREATOR
Option A Review Packet
Topic 5 Quiz- Evolution
THIS SET IS OFTEN IN FOLDERS WITH...
IB biology topic 5
Mitochondria (The powerhouse of the cell)
IB Bio 2.1 Molecules to Metabolism
44 biology terms