organization of cells Flashcards
How is mitochondrial DNA inherited?
Mitochondrial DNA is inherited only from the mother through maternal inheritance.
What are the two main stages of cellular respiration that occur in mitochondria?
The Krebs cycle (in the matrix) and the electron transport chain (on the inner membrane).
Why is the plasma membrane called a “fluid” mosaic?
It is called “fluid” because the molecules, such as lipids and proteins, can move freely past one another within the membrane.
What role do vacuoles play in plant cells?
Vacuoles maintain proper internal pressure to provide support and structure for growing plant cells
What process involves the breakdown of damaged organelles by lysosomes?
This process is called autophagy.
How is illumination provided in Transmission Electron Microscopy (TEM)?
Illumination is provided by an electron beam produced by a heated tungsten filament.
What is the key structural difference between the smooth ER and the rough ER?
The smooth ER lacks ribosomes on its surface, while the rough ER has ribosomes attached to its membrane
What is the primary function of chloroplasts?
Chloroplasts are responsible for photosynthesis, converting light energy into chemical energy stored in glucose.
What does the ribosome do with mRNA?
The ribosome moves along the mRNA, translating the genetic message into a protein.
How does the smooth ER help in detoxification?
the smooth ER helps liver cells detoxify circulating drugs by modifying harmful substances, making them easier for the body to eliminate.
What roles do proteins play in the plasma membrane?
Proteins in the plasma membrane regulate traffic (e.g., transport proteins), assist in signal reception (receptor proteins), and provide structural support and cell recognition.
What are the two main parts of a mitochondrion?
The outer membrane and the inner membrane, which is folded into structures called cristae.
What is the tonoplast?
The tonoplast is the membrane surrounding the vacuole in plant cells, regulating the movement of materials in and out of the vacuole.
How do vacuoles contribute to cellular function?
Vacuoles store water, nutrients, and waste products, and help maintain turgor pressure in plant cells.
What advantage does the Scanning Electron Microscope (SEM) have over TEM?
SEM provides great depth of focus and creates 3D images of specimens’ surfaces.
What are the two stages of photosynthesis that occur in chloroplasts?
The light-dependent reactions (produce ATP and NADPH) and the light-independent reactions (Calvin cycle, convert CO2 into glucose).
What pigment is found in chloroplasts that helps with photosynthesis?
Chlorophyll is the pigment that absorbs light for photosynthesis.
How does a Light Microscope (LM) achieve magnification?
Magnification is achieved by the objective lens and ocular (eyepiece) lenses, with illumination provided by light
Why do plants appear green?
Plants appear green because chlorophyll reflects green light and absorbs other wavelengths, especially blue and red.
How do proteins from the rough ER reach other parts of the cell?
Transport vesicles bud off from the rough ER and carry proteins to other locations, such as the Golgi apparatus.
What are the three main types of RNA involved in protein synthesis?
mRNA, tRNA, and rRNA.
What is the function of the nuclear envelope?
It separates the nucleus from the cytoplasm and contains pores to regulate material exchange.
What is the structure of microtubules and their role?
Microtubules are hollow tubes made of tubulin proteins that help guide the movement of organelles and chromosomes during cell division.
What is the extracellular matrix (ECM) of animal cells made up of?
The ECM is composed of glycoproteins such as collagen, proteoglycans, and fibronectin.
What is the role of mRNA in protein synthesis?
mRNA carries the genetic code from DNA to the ribosome for protein synthesis
What is the function of lysosomes in eukaryotic cells?
Lysosomes break down waste and foreign material within the cell.
What is the function of the vacuole in plant cells related to waste?
Vacuoles in plant cells store waste and help break it down, protecting the rest of the plant from harm.
What is the primary function of peroxisomes regarding organic molecules?
Peroxisomes use molecular oxygen to oxidize organic molecules.
What is the primary energy currency of the cell?
ATP (adenosine triphosphate) is the primary energy carrier in cells.
What does “mosaic” refer to in the fluid mosaic model?
“Mosaic” refers to the diverse collection of proteins embedded in the lipid bilayer of the plasma membrane, each performing different functions.
What are glycoproteins?
recognition proteins
How do vacuoles function in animal cells?
Vacuoles in animal cells are relatively small and primarily involved in storage and waste removal.
How does mRNA exit the nucleus?
mRNA exits the nucleus through pores in the nuclear envelope.
What components make up ribosomes?
Ribosomes are made up of 4 rRNAs and approximately 80 ribosomal proteins.
What is a key characteristic of prokaryotic cells?
They lack membrane-enclosed organelles and a nucleus.
What are the two major categories of cells?
Prokaryotic cells and Eukaryotic cells.
What is a nucleosome?
A nucleosome is the basic unit of chromatin, consisting of DNA wrapped around 8 histone proteins.
What separates the nucleus from the cytoplasm in a eukaryotic cell?
The nuclear envelope, a double membrane that serves as a barrier.
What byproducts are produced during mitochondrial cellular respiration?
The byproducts are carbon dioxide (CO2) and water (H2O).
How does the Golgi apparatus work with the endoplasmic reticulum?
the Golgi receives products from the ER, modifies them, and then packages them for distribution or secretion
What role do peroxisomes play in inflammation?
Peroxisomes assist in the regulation of inflammation, important for immune and tissue repair responses.
What is the structure of a peroxisome?
Peroxisomes are bounded by a single bi-lipid layer membrane and do not contain genetic material.
What process do chloroplasts perform to generate energy?
Chloroplasts perform photosynthesis, converting light energy into glucose.
What molecule is the final electron acceptor in the mitochondrion’s electron transport chain?
Oxygen is the final electron acceptor, forming water when combined with electrons and protons.
What role does collagen play in the ECM?
Collagen provides structural strength and resilience to tissues, contributing to the overall integrity of the ECM.
What are the two main parts of chloroplasts involved in photosynthesis?
The thylakoid membranes (where light-dependent reactions occur) and the stroma (where the Calvin cycle takes place).
What structure inside the mitochondria increases surface area for energy production?
The inner membrane is highly folded into cristae, increasing the surface area for cellular respiration
What is a unique feature of animal cells that is not present in plant cells?
Animal cells may have channels between cells that allow for communication and material exchange.
What types of proteins are synthesized in the rough ER?
The rough ER synthesizes membrane proteins and secretory proteins.
Does the number of chromosomes vary between species?
Yes, the number of chromosomes varies between species. For example, humans have 46 chromosomes.
Where are ribosomes partially assembled?
Ribosomes are partially assembled in the nucleolus.
What is the function of the nucleolus inside the nucleus?
The nucleolus is where ribosome precursors are assembled, which include rRNA and ribosomal proteins.
What is the cis face and trans face of the Golgi apparatus?
The cis face faces the ER and receives materials from it, while the trans face faces away from the ER and ships out processed products.
Can lysosomes digest foreign particles?
Yes, lysosomes can digest foreign particles or invading microorganisms, contributing to the cell’s immune defense
What is the function of phospholipids in the plasma membrane?
Phospholipids form the phospholipid bilayer, creating a barrier with hydrophilic heads facing outward and hydrophobic tails facing inward to separate the cell’s internal and external environments.
What types of chemical modifications occur in the Golgi apparatus?
The Golgi adds carbohydrate chains to proteins and lipids, forming glycoproteins and glycolipids.
What is the role of integrins in the ECM?
Integrins are receptor proteins in the plasma membrane that bind to ECM proteins and help mediate communication between the ECM and the cytoskeleton.
What byproducts are produced in mitochondria during cellular respiration?
The byproducts of cellular respiration in mitochondria are carbon dioxide and water.
What forms the chromatin in the nucleus?
Long DNA molecules wrapped around proteins, specifically histones, form chromatin.
What is the difference between rough ER and smooth ER?
Rough ER has ribosomes and synthesizes proteins, while smooth ER lacks ribosomes and is involved in lipid synthesis and detoxification.
What are food vacuoles in the context of lysosome function?
Food vacuoles are tiny cytoplasmic sacs that engulf nutrients for digestion by lysosomes.
What do mitochondria do to produce energy?
Mitochondria perform cellular respiration, converting glucose and oxygen into ATP.
Name two key membranous organelles in eukaryotic cells.
Mitochondria (energy production) and Golgi Apparatus (modifies and packages proteins).
What is the main role of the Golgi apparatus in the cell?
The Golgi apparatus receives, refines, stores, and distributes chemical products of the cell.
Where are chloroplasts mainly found in plants?
Chloroplasts are primarily found in the leaves and other green or colored organs of plants and in algae
What are the main functions of the extracellular matrix (ECM)?
The ECM provides structural support, helps adhere cells together, and allows cell communication to regulate processes like growth and differentiation.
What is a key modification that occurs in the rough ER for some proteins?
Some proteins undergo glycosylation, where carbohydrates are added to form glycoproteins.
Which organisms are made up of eukaryotic cells?
Protists, plants, fungi, and animals.
What happens when a food vacuole fuses with a lysosome?
The enzymes in the lysosome break down the food inside the vacuole, allowing digestion to occur.
How do vacuoles in plant cells differ from those in animal cells?
Plant cells have large vacuoles that store materials, waste, and help maintain internal pressure for structural support. Animal cells have smaller vacuoles.
In which types of cells are mitochondria found?
Mitochondria are found in almost all eukaryotic cells (both plant and animal cells).
What is the function of the nucleus in eukaryotic cells?
The nucleus contains the cell’s DNA and controls cellular activities.
How do lysosomes contribute to cell nutrition?
Lysosomes digest food engulfed in food vacuoles, providing essential nutrients to the cell after breaking down large molecules.
What is the resolution of a Transmission Electron Microscope (TEM)?
TEM provides very high resolution (2 to 4 Å), allowing for observation at a molecular level.
What is the function of chloroplasts in plant cells?
Chloroplasts convert light energy into chemical energy through photosynthesis to produce food for the plant.
What do intermediate filaments provide for the cell?
Intermediate filaments provide structural support and help maintain cell shape, but they do not participate in cell movement.
Which organisms are made up of prokaryotic cells?
Bacteria and Archaea.
What is the function of proteoglycans in the ECM?
Proteoglycans help retain water in the ECM and provide structural support to tissues, aiding in their flexibility and cushioning.
What happens to the small molecules produced from digestion inside lysosomes?
The small molecules are released from the lysosome and are used to nourish the cell.
What type of lipids does the smooth ER produce?
The smooth ER produces steroids and phospholipids, essential for cell membranes.
What are the two key characteristics of the plasma membrane described in the fluid mosaic model?
The two key characteristics are fluidity (molecules can move freely) and mosaic (the membrane has a variety of proteins).
What are the digestive enzymes in lysosomes used for?
The enzymes break down macromolecules such as proteins, fats, polysaccharides, nucleic acids, and damaged organelles.
What organelle is formed in the Golgi apparatus?
The Golgi apparatus is responsible for the formation of lysosomes, which digest cellular material.
What is the function of ribosomes?
Ribosomes are the protein-synthesizing machines of the cell.
What is the primary function of lysosomes?
Lysosomes break down large molecules (proteins, fats, polysaccharides, nucleic acids) and damaged organelles in the cell.
Does the amount of DNA vary across species?
Yes, the amount of DNA in a cell depends on the species and can differ significantly.
How does a Light Microscope (LM) achieve magnification?
Magnification is achieved by the objective lens and ocular (eyepiece) lenses, with illumination provided by light.
What is the primary composition of the plasma membrane?
The plasma membrane is composed of lipids (mainly phospholipids) and proteins.
What theory explains the origin of mitochondria and chloroplasts?
The endosymbiont theory suggests that mitochondria and chloroplasts were once free-living prokaryotes that became incorporated into eukaryotic cells.
What are the main functions of the smooth ER?
The smooth ER is involved in lipid synthesis, detoxification of drugs, calcium storage, and carbohydrate metabolism.
What is the role of the plasma membrane?
The plasma membrane controls the entry and exit of materials and helps maintain communication with the environment.
What are microfilaments made of and what is their role in muscle contraction?
Microfilaments are made of actin proteins and play a key role in muscle contraction by interacting with myosin
What role does the Golgi apparatus play in the cell?
The Golgi apparatus modifies, sorts, and packages proteins and lipids for transport.
What types of molecules do peroxisomes break down?
Peroxisomes break down fatty acids, amino acids, and toxins (e.g., alcohol, drugs).
What does the cytoskeleton in eukaryotic cells do?
Provides structure and helps with cellular movement using microtubules, intermediate filaments, and microfilaments.
What is the primary function of mitochondria?
Mitochondria convert the energy in food molecules into ATP through cellular respiration.
What role do the pores in the nuclear envelope play?
They regulate the selective movement of materials between the nucleus and the cytoplasm.
What is the composition of eukaryotic ribosomes?
Eukaryotic ribosomes are made of 4 rRNA molecules and about 80 ribosomal proteins.
What are lysosomes and their function?
Lysosomes contain digestive enzymes that break down waste materials, cellular debris, and foreign substances.
What is the purpose of the cell wall in plant cells?
The cell wall provides protection, structural support, and helps prevent the plant cell from absorbing too much water. It is made of cellulose.
Which cytoskeletal component is involved in cytokinesis?
Microfilaments (actin filaments) are involved in cytokinesis, helping to pinch the cell membrane during cell division.
What does each chromatin fiber constitute?
Each long chromatin fiber constitutes one chromosome.
Where are ribosomes completely assembled?
Ribosomes are completely assembled in the cytoplasm
What are the main functions of the cytoskeleton?
The cytoskeleton provides mechanical support, maintains cell shape, and facilitates movement.
What does DNA do to direct protein production?
DNA transfers its coded information into messenger RNA (mRNA), which directs protein production.
What is the main difference between TEM and SEM?
TEM passes an electron beam through the specimen for internal details, while SEM scans the surface of the specimen, providing a 3D image with great depth of focus.
What types of substances can vacuoles store in plant cells?
Vacuoles can store organic nutrients, waste, pigments (e.g., autumn colors), and poisons (e.g., nicotine).
What are the two main energy-producing organelles in cells?
Chloroplasts (in plant cells) and mitochondria.
What is the role of vacuoles in plant cell structure?
Vacuoles absorb water to develop hydrostatic pressure, helping to keep the plant turgid and maintain its shape.
What is the matrix of a mitochondrion?
The matrix is the innermost part of the mitochondrion, where the Citric Acid Cycle occurs and contains enzymes for cellular respiration.
Why does a Transmission Electron Microscope (TEM) operate under a vacuum?
The vacuum prevents electrons from being absorbed or deflected by air, ensuring clear imaging.
What is meant by the fluid mosaic model of the plasma membrane?
The fluid mosaic model describes the membrane as a flexible, dynamic structure with lipids and proteins that can move fluidly, creating a “mosaic” pattern of various components.
Which type of cells contain lysosomes?
Animal cells contain lysosomes, while they are usually absent in plant cells.
Why do mitochondria have their own DNA?
Mitochondria have their own DNA because of their evolutionary history as free-living prokaryotes, as suggested by the endosymbiont theory.
