Questions tagged [organelle]

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How to distinguish Golgi apparatus from endoplasmic reticulum in an electron micrograph

How could we tell whether in the electron micrograph the Golgi apparatus or endoplasmic reticulum is shown? Is for example the endoplasmic reticulum larger? Closer to the nucleus? For example, in the ...
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What are the small white dots in an onion cell seen under an electron microscope?

We had to use an electron microscope in class for an assignment and used onion cells. On the 40x and 100x magnification there are tiny white dots and I was wondering if someone could tell me what they ...
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4 answers
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Does the cytoplasm include the organelles?

I am a student in middle school. My textbook says that Cytoplasm is the gelatinous liquid part of the cell excluding organelles. However my teacher said this is wrong. According to her, the correct ...
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How do peroxisomes work?

I have this question from my book: A child is diagnosed with an enzyme deficiency that prevents the production of hydrogen peroxide. What would the likely outcome be of such deficiency? H2O2 is ...
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Is centrosome one of the structures that red blood cells lose during maturation process?

Centrosomes are microtubule organising centres- their function is to facilitate cell division. RBCs don't undergo division. They are produced via hematopoeisis in the bone marrow. It doesn't even have ...
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What is the difference between apoptosis caused by the release of enzymes from the electron transport chain vs that from the lysosome?

I know that the mitochondria is responsible for regulating apoptosis via release of enzymes from the electron transport chain. I believe that the release of hydrolytic enzymes from a lysosome is how ...
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Are all organelle lumens a reducing environment like the cytosol, or nonreducing like the extracellular space and the ER lumen?

I am interested to know if cysteine can form disulphide bridges in proteins within organelles. Typically cysteine will not form disulphide bonds in the reducing environment of the cytosol, but will in ...
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7 votes
1 answer
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How does the Endoplasmic Reticulum scale with Cell Volume in Epithelial Cells?

I am working on a mathematical model of a biological tissue (drosophila pupal notum; an epithelial tissue) where the tissue is built up from cells all described by the same cellular-model. The tissue ...
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Why don't the cell organelles settle down in the cell under the influence of gravity? [closed]

In cuboidal or columnar cells or cells of any other shape the nucleus and the other organelles and inclusions remain suspended in the cytoplasm. Why doesn't gravity affect them ? Could this be because ...
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-3 votes
1 answer
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Primary function of cell wall is [closed]

A. Controlling volume B. Providing shape C. It's selective permeability D. Protection against bursting To me, all the given options seem correct except C. A and D are correct when the cell is placed ...
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"Bacteria don't have membrane-bound organelles." Are sulfur bacteria or Cyanobacteria exceptions?

Can bacteria have membrane-bound organelles? I read this many textbooks: Bacteria cells are simple cells that do not contain a nucleus or other membrane-bound organelles. However, they do contain ...
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Do larger unicellular eukaryotic organisms have larger organelles?

It seems that many of the giant unicellular eukaryotic organisms (size 1mm and above) are multinucleate but there are some with a single nucleus as well (the genus of Acetabularia). My question is: do ...
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Does Rough ER (RER) produce phospholipids?

I have found out that rough endoplasmic reticulum (RER) produces membranes. Therefore it has to produce phospholipids, but I thought that the smooth ER was where the synthesis of lipids occurs. What ...
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2 votes
2 answers
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Why is sedimentation rate significant for a ribsome

When we take a look at biology textbooks (Campbell, Pearson etc), they will only mention the difference between eukaryotic and prokaryotic ribosome sedimentation rates. Why is sedimentation rate ...
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Where is catalase produced?

I am doing a research project on the peroxisomes, and in it I referenced the enzyme catalase, which breaks down hydrogen peroxide into water and oxygen. However, the assignment asks me to specify the ...
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2 votes
1 answer
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What will happen if mitochondria had a structure like lysosomes?

I wanted to know an explanation how the structure of mitochondria affects its function. Therefore, how would it turn out if its structure is like the structure of lysosomes, what is going to happen?
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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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4 votes
1 answer
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Are there any viruses that integrate their DNA into organellar DNA?

It is known that many viruses (e.g. retroviridae) integrate in the nuclear genome of their host as part of their cycle. However, I'd like to know if integration can happen in organellar DNA (cpDNA and ...
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Is this sentence about RER correct on Wikipedia?

While studying about Endoplasmic Reticulum on Wikipedia, I came across this sentence A ribosome only binds to the RER once a specific protein-nucleic acid complex forms in the cytosol. This special ...
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Why is the rough ER necessary to make extracellular proteins? [closed]

It is my current understanding that free ribosomes synthesise proteins to be used inside the cell, and the rough endoplasmic reticulum is necessary to make proteins that are to be secreted by the cell....
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1 vote
1 answer
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Why is the outer circle of human mitochondrial DNA ‘heavy’, whereas the inner circle is ‘light’?

Why is the outer circle of human mitochondrial DNA "heavy" whereas the inner circle is "light"?
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1 vote
1 answer
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How do plant cell vacuoles form?

Does the plant cell vacuole form by the invagination of the cell membrane?
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1 vote
1 answer
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Do Archaea have membrane-bound organelles?

From Campbell Ch. 6 Intro to the Cell, Which of the following statements concerning bacteria and archaea cells is correct? A) Archaea cells contain small membrane-enclosed organelles; bacteria do ...
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2 votes
1 answer
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Which two organelles absorb acid? [closed]

I stain an unknown acid with purple dye. Later, you find the cell in two organelles. What are they? I am guessing that one of them is lysosomes, because they break down unwanted elements. What would ...
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1 answer
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Which organelle is the easiest to see in a cell? [closed]

I was asked a question in class: "Which organelles are easiest to see in any cells while using a microscope?" This seems a little bit like a trick question, and since I'm not an expert in cellular ...
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1 vote
2 answers
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Why is it said that bacteria have no membrane-bound organelles, when they often have one or more flagella?

Why is it said that bacteria have no membrane-bound organelles, when they often have one or more flagella? https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3386205/ "Cilia and flagella .. are membrane-...
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Why do ribosomes associate with rough endoplasmic reticulum but not other membranes?

As far as I am aware, all eukaryotic membranes consist of a lipid bilayer. Smooth endoplasmic reticulum (ER) and rough ER are distinguished by the presence of ribosome on the rough ER surface, but are ...
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2 votes
2 answers
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How does the peptidoglycan layer of a bacterial cell wall help prevent osmotic lysis? [duplicate]

I recently read that penicillin works by damaging the peptidoglycan layers of a bacterial cell wall causing osmotic lysis, which is when the bacteria cell bursts due to osmotic pressure. I just ...
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