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During which phase of the cell cycle are chromosomes not condensed?
Interphase (G1-G2).
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During which phase of mitosis does the nuclear envelope break down?
Metaphase.
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What occurs during prophase 1 of meiosis?
- 1.) Homologous chromosome pairs congregate
- 2.) Crossing over occurs between homologous pairs (recombination)
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During which phase of meiosis do homologous pairs separate?
Anaphase 1. Sister chromatids remain connected at this step.
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True or False?
DNA synthesis occurs during interphase II.
- False.
- In meoisis, DNA synthesis only occurs once, during the S phase of interphase I.
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True or False?
Autosomal and sex chromosomes occur in pairs.
True.
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What is the basic tool by which all genes are mapped?
A three point cross.
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True or False?
Multiple recombination events may occur between distant genes. Genes are linked if an odd # of recombinations occurred.
- False.
- They are linked if an even # of recombinations occurred.
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What does it mean if two genes, with respect to one another, have a very low recombination frequency?
They are close in proximity on the chromosome. For ex. a value of 0.010 means that 1% of the time, these two genes were recombined.
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If a specific characteristic in a group of offspring is determined solely by that same characteristic in the mother, what can be said of that gene?
It is located in the circular DNA of the chloroplast/mitochondria of the mother.
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True or False?
The same motif in different RNA molecules will often fill a role unique to that molecule.
- False.
- The same motif in different RNA molecules often serves a similar role.
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True or False?
Proteins can recognize DNA and RNA sequences, but must momentarily disrupt their secondary structure.
False.
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True or False?
Induced fits involving "reading" proteins and DNA utilize nonspecific sequence deformability of the nucleic acid.
- False.
- Deformability relies almost solely on particular nucleic acid sequences.
- Example: Eco RV and the GATATC
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In a relaxed circle, what is the relationship between LK and the number of twists?
They are equal. There are no writhes in a relaxed circle, therefore only twists determine the LK.
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True or False?
Unwinding negatively supercoiled DNA facilitates strand separation, which is essential for replication and transcription.
True.
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Which base is a purine structure and has only an oxygen group facing the major groove off of carbon-6?
Hypoxanthine.
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Which base is a precursor to adenine and guanine?
Hypoxanthine.
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Which base is a methylated version of uracil?
Thymine.
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Ribonucleosides end in the suffix ______, while ribonucleotides end in the suffix ______.
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What prevents RNA from forming the B-type helix?
The hydroxyl group on C-2 of ribose causes steric hindrance.
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Which type of helix is described as having a "donut hole?"
Type-A. This allows the C-2 hydroxyl of RNA's ribose to avoid steric hindrance.
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Which type of nucleic acid-helices has its bases pushed out toward the side?
A-form.
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What can a protein "read" to determine a nucleic acid sequence?
- 1.) Hydrogen (electron) donors and acceptors on bases
- 2.) Hydrophobic patches
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True or False?
If a piece of double stranded DNA is unwound (but not broken), its linking number will change.
- False.
- Since neither strand was broken while unwinding, the linking number will remain unchanged, while writhes will compensate.
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What are the components (DNA and enzymatic) of a type II topoisomerase?
- 1.) Gate segment of DNA
- 2.) Transport segment of DNA
- 3.) 2 ATP binding domains
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