Cell Structure and Function
What cell structure determines what enters/exits the cell and maintains homeostasis?
The cell membrane
Water is polar. What does this mean?
Unequal sharing of electrons leads to partial charges.
What is the main goal of cellular respiration?
To make ATP
What is the purpose of mitosis?
Growth, repair, and asexual reproduction.
Why do muscle cells have many mitochondria?
High ATP demand
Why do cells remain small rather than growing very large?
Surface-area-to-volume ratio limits diffusion and efficiency.
Why does enzyme activity depend on precise structure?
The shape of the active site determines substrate binding and catalysis.
Where does glycolysis occur?
the cytoplasm
Why is DNA condensed into chromosomes before mitosis?
Prevents tangling and ensures accurate separation.
What happens if a cell membrane becomes too fluid?
Cell can become "leaky", and transport and signaling proteins can lose their structure and function.
How does the structure of the rough ER directly support protein secretion?
Ribosomes make proteins, then the ER folds/processes/modifies the proteins, and they are sent to the Golgi Apparatus via vesicles.
Will accept that they have RIBOSOMES in their membrane which is used for PROTEIN SYNTHESIS/MODIFICATION.
Explain why dehydration synthesis and hydrolysis are essential for biology.
Build polymers (dehydration) and break them down (hydrolysis) for metabolism and energy use.
Why does the ETC require oxygen?
Oxygen is the final electron acceptor allowing electrons to keep flowing through the ETC.
How does RB regulate the G1 checkpoint?
RB blocks S-phase genes until phosphorylated.
A patient with a defective ETC can still perform glycolysis. Why?
NAD+ regenerated via fermentation
Compare prokaryotic binary fission to eukaryotic mitosis in terms of chromosome handling
Prokaryotes do not degrade their nucleus, and they copy a single circular chromosome without spindle fibers, while eukaryotes degrade their nuclei and use spindle fibers to separate multiple linear chromosomes.
Predict how a noncompetitive inhibitor will affect an enzyme.
It will bind allosterically to the enzyme, ultimately changing the shape of the active site, and therefore inhibiting the reaction from taking place.
Explain how photosystem II and I work together to produce NADPH and ATP.
PSII generates electrons, used to establish hydrogen/proton gradient, which is used to make ATP...PSI re-excites that electron that is used to generate NADPH.
Explain how loss of function in p53 promotes cancer.
Damaged DNA is not paused for repair and therefore mutations accumulate.
A cell placed in a solution shrivels, what does that mean about the tonicity of the solution?
It means the solution is hypertonic to the cell.
Two cells, one from the liver and one from a rapidly dividing skin tissue, are examined under a microscope. Both contain the same organelles, yet the liver cell has far more smooth ER and peroxisomes, while the skin cell has far more ribosomes and mitochondria.
Explain how these differences in organelle abundance reflect the unique functional demands of each cell type, and why this does not require differences in their DNA.
Liver cells perform detoxification and lipid metabolism, so they require more extensive smooth ER for lipid synthesis and drug detoxification, in addition to more peroxisomes to break down harmful metabolic byproducts.
Skin cells must divid rapidly and frequently to replace lost tissue, so they require many ribosomes to synthesize large quantities of proteins for growth and many mitochondria to generate ATP needed for mitosis and biosynthesis.
These differences arise from differential gene expression, not differences in DNA. Both cells contain the same genome but activate different sets of genes to match their specialized roles.
A patient's bloodstream becomes more acidic. How might this affect protein structure and cellular function?
pH shifts outside of certain threshold tolerances can DENATURE enzymes, ultimately changing the way in which they are structured, affecting the enzymes ability to catalyze the reaction they were meant to catalyze.
DNP collapses the proton gradient in mitochondria. Predict the effects on ATP and heat production
ATP decreases..energy releases as heat since chemiosmosis cannot occur.
Why can cancer cells tolerate DNA damage that would normally trigger apoptosis?
Mutations disable checkpoints, apoptosis pathways, and immune detection.
cells in the stomach divide much more frequently than nerve cells. What does this difference tell you about how these tissues use the cell cycle?
Stomach cells move through the cell cycle rapidly for constant repair and replacement, while nerve cells stay in Go and rarely divide.