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Questions tagged [cell-biology]

The study of cells, their physiological properties, structure, environmental interaction, division, life cycle, and death, as well as the organelles they contain. Also known as cytology.

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Why do -ssRNA viruses need to do intermediate positive strand (antigenome) instead of just replicate it negative strands?

I was reading about RSV replication here https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3185921/, but i cannot understand what is the reason for making a antigenome instead of just replicate it negative ...
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Cell cycle arrest and apoptosis

Is cell cycle arrest needed for apoptosis to occur? I note that some of the factors that mediate cell cycle arrest induction (e.g. DNA damage) happen to be responsible for initiating apoptosis as well....
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How does hydrophilic and/or hydrophobic components of polysaccharides influence their 3 dimensional conformation?

It is my understanding that polysaccharides are insoluble in water. Does this mean they are hydrophobic? Beyond being insoluble in water how does this affect their 3D structure? Thanks!
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do platelets cytoplasm contains DNA?

I'm a 12th-grade student and I have an entrance exam this year. I have a question in biology. I would appreciate you if you help me <3 as we thoroughly know platelets are multiple pieces of a big ...
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73 views

Why biologic systems tends to become more complex?

From elements, chemical compounds, cells, multicellular organisms, society evolves and with each step possibilities increase and things get complex. We are builing structures like ribosome builds ...
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1answer
30 views

Can Phosphogycolate buildup in a plant kill it?

I'm trying to think of some things for the science fair, for part of my experiment I need to know if Phosphogycolate build up in a plant can kill it. Also, are there any chemicals that may disrupt the ...
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RNA Molecule folding

For a Single Stranded RNA Molecule : A) Adenine Content Always Equals to Thymine Content B) Cytosine content Equals to Guanine content C) Adenine content Always Equal to Uracil D) Guanine content ...
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41 views

Is it possible to fuse DNA from two sperms into one sperm?

Is it possible to fuse the DNA of two genetically different sperms into one singular sperm? In theory, half of the number of chromosomes in a normal sperm would come from one sperm and the other half ...
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Why sperms don't forms follicles

As all of us know that in meiosis oocyte forms follicles and egg cells, so my question is that if an oocyte can form follicles then why sperm cells do not forms the follicles? And in evolutionary ...
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stem cells divisions and normal cells division

I'm a beginner in biology, but I've read that stem cells replace the "worn out" cells or the dead cells. Well, I'm a bit confused - why do they do this? Aren't there any cells nearby which are the ...
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1answer
58 views

Fertilization of the human egg- where does our centrosome come from?

Is there a centrosome in a human egg cell? Is the reason why the egg cell remains paused before meiosis 2 because there isn't a centrosome, and it only divides when the sperm fertilizes it thus it can ...
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Is there a specific suffix for “within a cell”? i.e. in a similar manner to how -aemia refers to within the blood

Words like hyperglycemia and hyponatremia refer to the relative level of each component in the blood, not in the cell. Is there a suffix for within the cell? For reference I would like one word as an ...
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What does “PDPN+ cells” means?

Are they podoplanin positive cells (cells that tested positive for podoplanin)? "...though it has been shown that podoplanin (PDPN+) cells analogous to mouse FRCs are found in human secondary ...
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Time spent in phases of cell cycle

I am looking for references to papers containing the time intervals spent in different phases of the cell cycle (ej., G0, G1, S, G2, M for eukaryotes) for different cells. In particular, I am ...
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21 views

How many cells should be seeded for passaging?

Do you count cells when you passage them? I found that many people will according to a ratio (maybe 1:2 or 1:3,etc.) to subpackage. It is so indistinct! What is the optimal seedling density or ...
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What exactly is a reducing equivalent and what does it do? [migrated]

I've encountered this term in the context of cellular metabolism, but I can't seem to find an explanation of what a reducing equivalent is or why it is named this way. Wikipedia was not really helpful,...
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Is callus totipotent or pluripotent?

Is callus (in the context of plant tissue culture) totipotent or pluripotent? As I understand, the difference between totipotency and pluripotency is an ability to differentiate into extraembryonic ...
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How is AMP “recharged” to become ATP in a cell?

I understand that after the translation stage of ribosomal protein synthesis, tRNA molecules are floating in the cytoplasm without attached amino acids until they find the correct aminoacyl tRNA ...
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2answers
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Why do stomata close in salt water?

Why do the guard cells of the stomata close when they come in contact with salt water? I recognize it has something to do with osmosis and the fact that osmosis makes the water drain in some sort, ...
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73 views

What determines the metabolic pathways that a biological cell is able to carry?

For example: human cells (eukaryotes) can utilize the Kreb's cycle pathway to generate more ATP after glycolysis, but most bacteria cannot utilise the Kreb's cycle plant cells can utilise the ...
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4k views

How does water buffer a sudden drop in temperature?

A property of water is that it is slow to heat and cool. According to my biology book, some energy from an increase in temperature would spent breaking hydrogen bonds, so that temperature does not ...
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352 views

What is the weight of a single human sperm (spermatozoon) compared to a single human egg

While the difference in dimension is well covered, I have been unable to find the mass measurements of each.
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3answers
9k views

Do we consume dna, proteins of other organisms?

When we eat raw meat, e.g. chicken or fish, we are actually consuming the DNA, proteins etc. which are present in their cells. Wouldn't this affect our cell functions as this DNA might enter our ...
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1answer
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Why is inhibition of inhibition (reciprocal inhibition) such a common motif in cell signalling?

In transcriptional regulation, you often find that positive signals proceed by inhibiting or destroying a protein that is in turn inhibiting or destroying the effector protein. This can be seen in the ...
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1answer
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What is the difference between a signal peptide and a transit peptide?

From what I know, the two names are used interchangeably and I haven't found any resource which says otherwise either. Is there at all any difference, is there a transit peptide that is not a signal ...
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2answers
652 views

How will changing the concentration of a Tris buffer affect amylase enzyme activity?

For instance if you increase the amount of Tris but pH still does not change then will the enzyme activity still proceed normally? If it does change the pH will it change enzyme structure and why?
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How does cholesterol affect the fluidity of a plasma membrane?

I was previously taught that cholesterol affects the fluidity of a plasma membrane. At high temperatures, cholesterol decreases fluidity and at low temperatures cholesterol increases fluidity. The ...
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Why does a lightsource postpone the time it takes for the leaves falling from a birch?

It is autumn and the leaves have already left their trees on all birch and other trees that has leaves, except one. This birch has a spotlight pointed to the tree and it is on 24/7. I have recognized ...
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Why are sex abnormalities more likely to survive than autosomal abnormalities?

I found that it is because of dosage compensation mechanism to counteract genetic imbalance between males and females , but i didn't understand it , please can you explain it
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1answer
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can magnesium bicarbonate be absorbed in the mouth?

Can Magnesium Bicarbonate be absorbed in the mouth?" Magnesium Bicarbonate occurs naturally in some mineral waters.
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3answers
228 views

Problems with housekeeping genes

I have tried several housekeeping genes to analyze the relative expression of a cytokine for measure the inflammatory local response in mice ears, all the housekeeping genes I have tried are not ...
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1answer
39 views

Do epigenetics determine the proteins a cell produces and therefore it's function?

I'm having trouble understanding what epigenetics is in a simple sense. How I imagine it is that if we had 2 twins with identical DNA and we let them live we will see that they'll develop differently....
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1answer
161 views

Does depolymerisation take place at the minus end of microtubule?

Wikipedia says that Dynamic instability refers to the coexistence of assembly and disassembly at the 'ends' of a microtubule. but Karp's Cell Biology, 7th edition says Dynamic instability is ...
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RDW values in teenagers

What is the normal range for RDW( Red blood cell Distribution Width) in athletes. Is 16-17% values high or normal for national team athletes(ages around 12-14years)?
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When muscles contract is the process similar to how non-newtonian fluids react?

I'm trying to understand how muscles contraction/tension works but getting loss in on the cellular level. From my understanding, when muscle tissue need to contract, the cells are flooded with calcium?...
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Osmotic Pressure Clarification

My textbook states that the higher concentration of solutes, the greater the osmotic pressure will be and the greater the pull of water in will be. However, osmotic pressure is defined "as the ...
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Glycolysis of respiration

What process provides directly ATP for the cell? It is glycolysis because it generates 2 ATP in cytoplasm. How many times ΑΤP are available from glycolysis when compared to ΑΤP of cellular ...
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1answer
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James Allison's T-cell discovery technique

The excerpt on Wired magazine of The Breakthrough by Charles Graeber has the following description of how James Allison found the T-cell receptor. Suddenly it seemed so obvious: If Allision could ...
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How to take precise/low number of cells from cell lysate? [closed]

I would like to know that how can we take low or precise number of cells from a cell lysate? (without using any protein quantification assay). Let say, If I have a cell line having cell density 5x10^...
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2answers
12k views

Does endo- and (or) exocytosis require energy? Do they belong to active / passive transport?

I expect vesicle formation and fusion to require energy input; however, I'm not sure about which of endocytosis and exocytosis require energy and how they use the energy input. Do they belong to ...
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1answer
46k views

Chromosome and chromatid numbers during cell cycle phases

A diploid cell in G1 has 6 chromosomes. How many chromosomes and how many chromatids are present in each of the following stages? Here is what I am guessing G1: 6 chromosomes ; 6 chromatids G2: 6 ...
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1answer
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What is the meaning of the following: “ completion of open rounds of DNA replication”?

I am studying a paper about the relation between polyP granule and cell cycle exit. As the author explained the four general steps for cell cycle exit, the second step is" the completion of open ...
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1answer
308 views

Cell biology - Resting membrane potentials

Why do we say there is an overall negative charge on the intracellular side of the plasma membrane at rest, and an overall positive charge on the extracellular side when both potassium and sodium are ...
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3answers
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Does trypsin strip flask coating?

Mammalian cell/tissue cultures sometimes require flasks coated with proteins. My uneducated guess is that these proteins mimic the ECM, perhaps the basal lamina, so finicky contact-dependent cells can ...
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1answer
2k views

Why does ATP contain ribose rather than deoxyribose?

I read in a textbook that ATP is made from ribose and not deoxyribose. Originally, I thought that the pentose sugar didn’t have functional importance. Is there a functional reason why the ATP used ...
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3answers
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Multi-nucleated cells: advantages and examples?

This question arises because I saw that monocytes and leukocytes are commonly called 'mononuclear cells' in the scientific literature. The implication of course being that other immune sub-types are ...
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3answers
161 views

Knockout and knockdown of gene

Out of curiosity, I got this question whether knocking out (deletion) of a gene on one side and knocking down (RNAi) of the same gene on the other side will affect the cell in a similar manner or not. ...
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1answer
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Why don't the heads of phospholipid bilayers repel hydrophobic molecules?

What I Think I Know: Hydrophilic and hydrophobic things repel each other. Since the cell membrane contains hydrophobic tails, it is difficult for hydrophilic molecules to pass through the cell ...
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1answer
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Univocal identifying of a plant cell

We yesterday got our biology-exams back and there's one exercise where I don't agree with my teacher. However, since he is the expert and not me, I need the support of external sources, i.e. experts ...
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Do all animal cells have lysosomes?

I know that white blood cells have lysosomes but what about other body cells? I mean, any other cell such as cells in the respiratory system.