Biochemistry Courses - SOS I Flashcards
Most cells in the body are in which cell phase?
G0 - RESTING CELLS.
Cells in G1 phase:
- GI epithelial cells.
2. Nucleated RBCs.
DNA replication occurs only in which cell phase?
S phase.
Transcription takes place during which phase of the cell cycle?
During the ENTIRE INTERPHASE.
Signals for the G1 –> S step:
Growth factors –> GH, IGF-1 etc.
Purines:
- Adenine.
2. Guanine.
Pyrimidines:
- Cytosine.
- Uracil.
- Thymine.
“CUT”
Purines have 1 or 2 rings?
2 rings.
Pyrimidines –> 1 ring.
Difference between the adenine and guanine:
12 o clock position –> Adenine has NH2.
Guanine has O.
Difference between the pyrimidines:
12 o clock –> Cytosine has NH2.
Uracil –> O.
Thymine –> O + a methyl group (CH3) in 2 o clock.
Nucleoside = …?
BASE + SUGAR (ribose or deoxyribose).
Nucleotide = …?
BASE + SUGAR + P (1, 2 or 3 P, eg AMP, ADP, ATP).
Base –> Nucleoside:
Adenine --> Adenosine. Guanine --> Guanosine. Cytosine --> Cytidine. Uracil --> Uridine. Thymine --> (Deoxythymidine).
Difference between RNA and DNA:
- Pyrimidine base.
2. Ribose type –> 2’ carbon has OH in RNA ribose - DNA is DEoxyribonucleic acid.
Histones are + or - charged?
+ charged, because they have too many ARGININES + LYSINES.
DNA is - charged due to …?
PHOSPHATES.
10nm chromatin refers to …?
NUCLEOSOME.
H1 is …?
NOT FOUND WITHIN THE NUCLEOSOME - Found out of it.
Difference between a 10nm chromatin and a 30nm chromatin?
30nm chromatin has H1 (condense nucleosomes together).
DNA packaging:
DNA double helix –> 10nm chromatin –> 30nm chromatin –> 30nm fibers forms loops attached to scaffolding proteins –> Higher order packaging (heterochromatin).
Euchromatin is light or dark-staining:
Light –> Euchromatin –> ACTIVE genes.
Dark –> Heterochromatin –> INACTIVE genes - If FEMALE, then the right answer might be a BARR BODY.
Euchromatin - When DNA is exposed (light staining spots) …?
If there is no option “active genes”, APOPTOSIS may also be correct!
Nucleases can take care of the DNA during apoptosis.
DNA pauses and checks:
Has 3’ –> 5’ EXONUCLEASE ACTIVITY.
RNA polymerase DOES NOT require a …?
PRIMER.
How many genes do we have?
20.000-25.000 genes.
Why proofreading during DNA replication?
TO AVOID INHERITABLE MUTATIONS.
Why do we don’t care about the NON-Proofreading ability of the RNA polymerase?
- NOT INHERITED.
- SHORT half life of protein.
- Only happening in 1 cell.
Does reverse transcriptase require a primer?
YES - Because it is a RNA-dependent DNA DNA DNA polymerase.
ALL DNA POLYMERASES REQUIRE A PRIMER.
Why do we need to fragment DNA and not RNA in order to analyze it?
Because DNA is MUCH longer than RNA.
