Search found 23 matches

by poobear
Fri Apr 11, 2014 9:58 pm
Forum: Molecular Biology
Topic: Help: Confused with primers in a PCR of a vector?
Replies: 2
Views: 9122

1) positive control (T7-gene-T3). 2) if your gene is inserted into the vector so the beginning of the gene is right next to T7: T7-gene. If your gene is inserted into the vector so that the beginning of the gene is next to T3: Nothing since both primers bind in the same direction. 3) if your gene is...
by poobear
Fri Apr 11, 2014 9:40 pm
Forum: Molecular Biology
Topic: No "beginning-replication problem" on leading strand?
Replies: 1
Views: 4654

No "beginning-replication problem" on leading strand?

Whenever I read why we have telomers, the answer is always so that we can replicate the end of the lagging strand. This is because the extreme end have a RNA primer to make the last Okazaki fragment, and after the removal of this primer it needs to somehow be replaced with DNA. I have the latest ver...
by poobear
Fri Sep 23, 2011 6:30 pm
Forum: Cell Biology
Topic: Does cancer cells origin from stem cells?
Replies: 2
Views: 3281

Does cancer cells origin from stem cells?

Hi everyone From what I know cancer cells are cells with uncontrolled cell divisions. Also, in our bodies only the stem cells divide. The other cells are differentiated and do not undergo cell division. From that I conclude that cancer cells origin from stem cells, but that the stem cells have uncon...
by poobear
Fri Jul 29, 2011 1:06 pm
Forum: Molecular Biology
Topic: Why use trypsin in cell cultures?
Replies: 1
Views: 17943

Why use trypsin in cell cultures?

Hello everyone! I've heard that trypsin is used in cell cultures, to make the cells stop adhere to the bottom. So it is cleaving some cell-matrix bond I guess. But does anyone have more details on this? What is this bond and why does it form? Does it also cleave cell-cell bonds? I get the big pictur...
by poobear
Mon May 16, 2011 9:11 pm
Forum: Cell Biology
Topic: How do gram-positive build proton gradient? No periplasm..
Replies: 1
Views: 3489

How do gram-positive build proton gradient? No periplasm..

Hi The proton gradient in bacteria are mostly used to create ATP and to drive the flagella as far as I know. In gram-negative bacteria such as E. coli this is easy for me to understand, just send the protons out to the periplasm and then let them come back. But in gram-positive bacteria there is no ...
by poobear
Thu Apr 21, 2011 2:16 pm
Forum: Cell Biology
Topic: Why do we need to eat so much protein? A.a. can be reused
Replies: 5
Views: 6609

Why do we need to eat so much protein? A.a. can be reused

Hi There is a high turn-over of proteins in all cells, but as far as I know the proteins are broken down into amino acids and then all amino acids can be used again in the next round of protein synthesis. So we shouldn't need much new proteins, since we can reuse what we have (compared to sugar that...
by poobear
Thu Apr 14, 2011 3:38 pm
Forum: General Discussion
Topic: Explanation of sugar crash?
Replies: 2
Views: 2427

Explanation of sugar crash?

Hi You always here that you shouldn't eat a lot of sugar. They are broken down very quickly, inducing much insulin production which leads to high cell intake of sugar which in turn leads to lower blood sugar levels. I hear that the final blood sugar level in the end is actually Lower than before tak...
by poobear
Sun Mar 20, 2011 1:00 pm
Forum: Cell Biology
Topic: Why is bovine pancreas used so much?
Replies: 1
Views: 2682

Why is bovine pancreas used so much?

Hi everyone I recently had a lab in school and we used a cell lysate from bovine pancreas. Today I read about Anfinsens classic experiment [http://en.wikipedia.org/wiki/Anfinsen%27s_dogma], and apparently they took the enzyme (Ribonuclease A) from bovine pancreas.. I have heard of bovine pancreas be...
by poobear
Wed Mar 16, 2011 11:35 am
Forum: Cell Biology
Topic: How can so many signals use the same second messenger?
Replies: 0
Views: 1712

How can so many signals use the same second messenger?

Hi everyone, So often when I read about signal transduction in my textbooks they talk about cAMP that acts as second messenger. Only in a very few instances have I read about other second messenger, such as DAG, IP3 and Ca2+. But how can so many different signals use the same second messenger? It wo...
by poobear
Wed Mar 02, 2011 9:06 pm
Forum: Molecular Biology
Topic: Difference between amino acid "termini" and "terminal"?
Replies: 1
Views: 1328

Difference between amino acid "termini" and "terminal"?

Hi, I see some papers use the term "termini" and some people use the term "terminal". Such as in "C-terminal" or "N-termini" of a amino acid chain. Is there a distinction of these two words? Any difference at all? If not, why is there no convention on what to ...
by poobear
Thu Feb 17, 2011 3:35 pm
Forum: Molecular Biology
Topic: Why is 1 absorbance of proteins ~ 1 mg/ml?
Replies: 1
Views: 7299

Why is 1 absorbance of proteins ~ 1 mg/ml?

Hi, An absorbance of 1 of proteins at 280 nm (absorbance of tryptophane and tyrosin) equals around 1 mg/ml. This is true for a heterogenic mixture of proteins, of course this will differ between different proteins. I just tested this with an enzyme (glutathione reductase in yeast) and if I did the c...
by poobear
Fri Jan 28, 2011 1:29 pm
Forum: Human Biology
Topic: What makes us feel full when we eat? (energy, volume, mass)
Replies: 2
Views: 6962

Re:

This is controlled by the nervous system, in the ‘Satiety’ and ‘feeding’ centres of the lateral hypothalamus . The actions of these t wo nerve centers have opposite effects. If the feeding center is stimulated, we feel the sensation of hunger, and we will eat. Many of the stimuli that tell the hypo...