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Define cell organelle.
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Define cell organelle.
Organelles are discrete subunits of cells that are adapted to perform specific functions.
True or False?
The cell membrane is not an organelle.
False.
The cell membrane is an organelle.
Name three components of the cell that are not considered organelles.
Three components of the cell that are not considered organelles are the cell wall, cytoskeleton and cytoplasm.
What are three organelles in a typical animal cell?
Organelles in a typical animal cell include:
the nucleus
vesicles
ribosomes
the plasma membrane
Which new techniques allowed the study of the function of individual organelles? (NOS)
The invention of ultracentrifuges methods for cell fractionation allowed the study of the function of individual organelles.
Which organelle allows the separation of the processes of transcription and translation?
The nucleus allows the separation of the processes of transcription and translation.
What is the advantage of separating the nucleus and cytoplasm into separate compartments, with reference to transcription and translation?
The advantage of separating the nucleus and cytoplasm is that post-transcriptional modification of mRNA can happen before the mRNA meets ribosomes in the cytoplasm.
True or False?
Prokaryotes do not have a membrane-bound nucleus.
True.
Prokaryotes do not have a membrane-bound nucleus. Instead, their genetic material is free in the cytoplasm. This means that mRNA may immediately meet ribosomes during transcription and translation, instead of being separated by the nuclear membrane.
What are the advantages of compartmentalisation in the cytoplasm of cells?
The advantages of compartmentalisation in the cytoplasm of cells are:
the separation of incompatible biochemical processes, such as lysosomes and phagocytic vacuoles
the correct concentrations of enzymes and metabolites to be present within specific regions for specific metabolic processes and reactions
What is the role of the double membrane in the mitochondrion for ATP production?
The double membrane creates a small intermembrane space where a high concentration of protons can quickly accumulate, aiding the production of ATP by chemiosmosis.
True or False?
The large surface area of the cristae in mitochondria provides more space for ATP synthesis.
True.
The cristae increase the surface area for the electron transport chain and ATP synthase enzymes, enhancing ATP production.
The enzymes and substrates for the are compartmentalised in the mitochondrial matrix, allowing efficient ATP production.
The enzymes and substrates for the Krebs cycle are compartmentalised in the mitochondrial matrix, allowing efficient ATP production.
What advantage does the large surface area of thylakoid membranes provide for photosynthesis?
The large surface area allows for a greater number of photosystems and electron transport chain proteins, enhancing light absorption and ATP production.
True or False?
The small volume inside the thylakoids allows for a faster buildup of hydrogen ions, which is essential for ATP production in photosynthesis.
True.
The small volume facilitates a rapid increase in proton concentration, which drives ATP synthesis in the chloroplast.
The enzymes and substrates for the are compartmentalised in the stroma of the chloroplast, facilitating the synthesis of carbohydrates.
The enzymes and substrates for the Calvin cycle are compartmentalised in the stroma of the chloroplast, facilitating the synthesis of carbohydrates.
Why is compartmentalisation of Calvin cycle enzymes in the chloroplast stroma beneficial?
Compartmentalisation in the stroma keeps Calvin cycle enzymes and substrates localised, optimising the efficiency of carbohydrate synthesis during photosynthesis.
How does thylakoid structure in chloroplasts support ATP production?
The thylakoids have a large surface area for light absorption and a small internal volume for rapid proton accumulation, both of which facilitate efficient ATP synthesis.
What is the main function of the double membrane surrounding the nucleus?
The double membrane of the nucleus, or nuclear envelope, protects the DNA and separates it from the cytoplasm, allowing regulated exchange of materials.
Why are pores necessary in the nuclear membrane?
Nuclear pores allow the selective passage of molecules such as RNA and ribosomal subunits out of the nucleus and regulatory proteins and nucleotides into the nucleus.
During cell division, the nuclear membrane breaks into to facilitate chromosome segregation.
During cell division, the nuclear membrane breaks into vesicles to facilitate chromosome segregation.
What is the primary function of free ribosomes in the cell?
Free ribosomes synthesise proteins that remain in the cell, such as enzymes used in the cytoplasm and structural proteins.
How does protein synthesis differ between free ribosomes and ribosomes on the rough endoplasmic reticulum (RER)?
Free ribosomes produce proteins for use within the cell, while ribosomes on the RER synthesise proteins destined for transport, insertion into membranes, or secretion from the cell.
True or False?
Ribosomes consist of a large and a small subunit composed of protein and ribosomal RNA (rRNA).
True.
Ribosomes consist of a large and a small subunit composed of protein and ribosomal RNA (rRNA).
What is the primary role of the Golgi apparatus in protein processing?
The Golgi apparatus modifies, sorts, and packages proteins for transport to their target destinations or for secretion outside the cell.
How does the Golgi apparatus prepare proteins for secretion?
The Golgi apparatus adds chemical modifications, sorts proteins, and packages them into vesicles, directing them to specific destinations within or outside the cell.
What is the structure of the Golgi apparatus?
The Golgi apparatus consists of flattened sacs of membrane called cisternae (like the rough endoplasmic reticulum).
True or False?
The Golgi apparatus' trans side faces the endoplasmic reticulum.
False.
The cis side side of Golgi sacs face the endoplasmic reticulum. The other faces the plasma membrane and is called the trans side.
What is a vesicle in a cell?
A vesicle is a small, membrane-bound sac that transports, stores, or digests cellular substances within the cell.
What are the primary functions of vesicles in cells?
Vesicles transport molecules within the cell, help in the secretion of substances outside the cell, store materials, and play a role in digestion and waste removal.
What is clathrin, and what role does it play in vesicle formation?
Clathrin is a protein that helps in forming vesicles by creating a lattice-like coating on the membrane, which helps in shaping and budding off the vesicle.
Why is clathrin important for endocytosis?
Clathrin provides structural support for forming vesicles during endocytosis, allowing the membrane to pinch inward and carry substances into the cell.