Questions and Answers
What is the primary requirement for active transport mechanisms in cells?
Which of the following substances requires a channel for facilitated diffusion across the cell membrane?
During osmosis, what is the usual consequence of placing a cell in a hypertonic solution?
Which stage of cellular respiration occurs in the cytoplasm and does not require oxygen?
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What role does oxygen play in the electron transport chain?
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What structure is primarily responsible for protein synthesis in a cell?
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Which process generates the most ATP during cellular respiration?
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What is the main function of the smooth endoplasmic reticulum?
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Study Notes
Types of Particle Movement
- Simple and facilitated diffusion allow substances to move from high to low concentration along their concentration gradient without ATP.
- Simple diffusion involves fat-soluble substances passing directly through the lipid bilayer of the cell membrane.
- Facilitated diffusion requires channels for water-soluble substances, such as Na+ channels, to move across the hydrophobic cell membrane.
- Active transport moves substances against their concentration gradient, from low to high concentration, and requires ATP; an example is the sodium/potassium pump.
- Osmosis specifically refers to the diffusion of water molecules.
- Water tends to move towards charged particles like Na+. In a hypertonic solution, water exits the cell causing it to shrivel, while in a hypotonic solution, water enters the cell causing it to swell.
ATP Production
- ATP is generated through cellular respiration, which consists of three main stages:
- Glycolysis occurs in the cytoplasm, converting one glucose molecule into two pyruvate molecules with a net gain of 2 ATP, functioning anaerobically (without oxygen).
- The Krebs cycle, or citric acid cycle, takes place in the mitochondria and produces 2 ATP, requiring oxygen (aerobic).
- Oxidative phosphorylation creates 34 ATP and utilizes a set of proteins known as the electron transport chain embedded in the inner mitochondrial membrane.
- Cyanide is lethal as it disrupts oxidative phosphorylation, preventing sufficient ATP production for cell function.
- Oxygen serves as the final electron acceptor in the electron transport chain, essential for completing the ATP generation process.
Parts of the Cell
- The cell membrane is a phospholipid bilayer composed of lipids and proteins.
- Ribosomes, made of RNA and protein, synthesize proteins and can be found on the rough endoplasmic reticulum or freely in the cytoplasm.
- Smooth endoplasmic reticulum is involved in lipid synthesis and lacks ribosomes.
- The nucleus houses DNA and is the site for transcription of messenger RNA (mRNA) from DNA templates before mRNA exits the nucleus through nuclear envelope pores for translation into proteins.
- Mitochondria, known as the powerhouse of the cell, generate the majority of ATP and have their own DNA, allowing for independent replication from nuclear DNA.
- The Golgi apparatus packages cellular products into vesicles for distribution.
- Peroxisomes function to detoxify hydrogen peroxide (H2O2).
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Description
Explore the mechanisms of particle movement across cell membranes, including diffusion, osmosis, and active transport. Learn how ATP production occurs through cellular respiration and its significance in maintaining cellular functions.
