Chapter 8&9 Bio Flashcards
Purine
Adenine and Guanine.
They have DOUBLE carbon rings.
Pyrimidine
Thymine and cytosine
They have SINGLE carbon rings.
What 2 bases have 2 hydrogen bonds?
Adenine and thymine
What 2 bases have 3 hydrogen bonds?
Guanine and cytosine
Adenine will always pair with?
Thymine
Guanine will always pair with?
Cytosine
Topoisomerase function
This is the first step in DNA replication.
This enzyme untwists the double helix of DNA, relives the supercooling ahead of the helicase.
DNA helicase function
This is the second step in DNA replication.
This enzyme breaks hydrogen bonds between the DNA strands.
Primase function
This is the third step in DNA replication.
This enzyme makes primers.
Primer function
This is the fourth step in DNA replication.
A primer is a single strand of DNA or RNA that’s complementary to a targeted sequence [DNA polymerase needs primers]
A primer serves to prime and lay a foundation for DNA synthesis.
DNA polymerase function
This is the fifth step in DNA replication.
This enzyme joins free nucleotides into a new strand of DNA, synthesize DNA in the 5’—>3’ prime direction of the new DNA.
Carries out DNA replication. Uses a DNA template to assemble a complementary strand of DNA.
What is the leading strand?
6) The new CONTINUOUS complementary DNA strand synthesized along the template in the 5’—>3’ direction, moving toward the replication fork.
What is the lagging strand?
6) A DISCONTINUOUSLY synthesized DNA strand that is created in fragments/segments called Okazaki fragments. Runs in the 5’—>3’ direction AWAY from the replication fork.
Okazaki fragments
6) Segments/fragments of the lagging strand.
DNA ligase
7) This enzyme connects the sugar phosphate backbone of the okazaki fragments.
What is the initial substrate of DNA replication?
DNA
What is the final product of DNA replication
2 DNA
Where in the cell does DNA replication occur?
Nucleus
What is the initial substrate of transcription
DNA
What is the final product of transcription?
MRNA
Where in the cell does transcription occur?
Nucleus
What is the function of RNA polymerase?
First step in transcription
Acts as a helicase, unwinding the DNA and also copies the DNA [carries out transcription] once it attaches to a promoter.
What is the function of a promoter?
Second step in transcription
The promoter tells the RNA polymerase where to “sit down” on the DNA and begin transcribing.
What is the third step in transcription?
RNA polymerase attaches to the start codon [after attaching to the promoter].
What is the start codons nucleotide bases? What is the chemical name?
“AUG”
Methionine
Where is the start codon located?
MRNA
What is the fourth step in transcription?
RNA polymerase reaches TERMINATION [which means it has finished making the copy of mRNA]
What kind of nucleic acid is TERMINATION?
DNA nucleic acid
Think of it like this, RNA polymerase is copying DNA off of a DNA strand to make mRNA. When RNA polymerase reaches the end [done copying off the DNA strand] it stops. It was copying off of a DNA strand, which means TERMINATION is a DNA nucleic acid.
What is RNA processing?
What is another name for RNA processing?
This is the fifth step in transcription
Removing introns
Keeping exons
ALTERNATIVE SPLICING
What is the sixth step in transcription?
- A modified GUANINE nucleotide is added at the beginning of the mRNA as a “cap”.
- Extra adenine [poly-A] nucleotides are added to the end of the mRNA strand, forming a “tail”.
What is the eighth step in transcription?
After the mRNA has been matured, it can leave the nucleus through a nuclear pore and move on to TRANSLATION.
Where in the cell does translation occur?
Ribosomes/cytoplasm
What is the initial substrate for translation?
MRNA
What is the final product of translation?
Protein
What is the first step in translation?
mRNA binds to a ribosome.
What happens in initiation in translation?
A tRNA show up with the anticodon [UAC] complementary to the start codon of mRNA [AUG, methionine]
This is called INITIATION
What is the second step in translation?
Elongation
This is where the process repeats. A tRNA will come deliver amino acids/anticodons mRNA the codon, the amino acids will be linked by peptide bonds. Remember that it takes energy to create peptide bonds between amino acids.
What kind of reaction would translation be?
Endergonic [positive change of G, not spontaneous].
What is the final step in translation?
Termination. This means that tRNA as reached mRNAs STOP CODON which means end of translation.
A tRNA does not have an anticodon complementary to the mRNAs stop codon.
What kind of reaction would DNA replication be?
Endergonic [positive change of G, not spontaneous]
What kind of reaction would transcription be?
Endergonic [positive change of G, not spontaneous]
