Podcast
Questions and Answers
If a cell were placed in a hypertonic solution, which of the following would occur?
If a cell were placed in a hypertonic solution, which of the following would occur?
- The cell would remain the same size as there is no net movement of water.
- The cell would burst due to excessive water intake.
- The cell would swell due to water moving into the cell.
- The cell would shrink due to water moving out of the cell. (correct)
What is the primary role of the glycocalyx in the plasma membrane?
What is the primary role of the glycocalyx in the plasma membrane?
- Anchoring the cytoskeleton to the extracellular matrix.
- Providing specific biological markers for cell recognition. (correct)
- Regulating the fluidity of the membrane.
- Facilitating the transport of ions across the membrane.
Which type of membrane junction forms an impermeable barrier, encircling the cell to prevent molecules from passing through the intracellular space?
Which type of membrane junction forms an impermeable barrier, encircling the cell to prevent molecules from passing through the intracellular space?
- Tight junctions (correct)
- Adherens junctions
- Gap junctions
- Desmosomes
How does the presence of cholesterol affect the plasma membrane?
How does the presence of cholesterol affect the plasma membrane?
Which of the following scenarios requires the cell to expend energy?
Which of the following scenarios requires the cell to expend energy?
What is the functional significance of membrane folds like microvilli?
What is the functional significance of membrane folds like microvilli?
In facilitated diffusion, what role do carrier proteins play?
In facilitated diffusion, what role do carrier proteins play?
What characteristics would favor a molecule's passage through the plasma membrane by simple diffusion?
What characteristics would favor a molecule's passage through the plasma membrane by simple diffusion?
Which of the following accurately describes the fluid mosaic model of the plasma membrane?
Which of the following accurately describes the fluid mosaic model of the plasma membrane?
A cell is placed in a solution and neither swells nor shrinks. What does this indicate about the solution?
A cell is placed in a solution and neither swells nor shrinks. What does this indicate about the solution?
What is the primary function of desmosomes?
What is the primary function of desmosomes?
In the context of membrane transport, what is filtration driven by?
In the context of membrane transport, what is filtration driven by?
How do gap junctions facilitate intercellular communication?
How do gap junctions facilitate intercellular communication?
How do glycolipids contribute to the structure and function of the plasma membrane?
How do glycolipids contribute to the structure and function of the plasma membrane?
What is the significance of the hydrophobic and hydrophilic regions of phospholipids in forming the plasma membrane?
What is the significance of the hydrophobic and hydrophilic regions of phospholipids in forming the plasma membrane?
Which of the following is NOT a typical function of membrane proteins?
Which of the following is NOT a typical function of membrane proteins?
How does the osmolarity of a solution affect the volume of a cell?
How does the osmolarity of a solution affect the volume of a cell?
What determines whether a transport process is active or passive?
What determines whether a transport process is active or passive?
A lab technician mistakenly uses a saline solution that is much more concentrated than normal (hypertonic) to prepare a slide of red blood cells. What would likely be observed under the microscope?
A lab technician mistakenly uses a saline solution that is much more concentrated than normal (hypertonic) to prepare a slide of red blood cells. What would likely be observed under the microscope?
If a researcher is studying how cells recognize each other, which plasma membrane component would be of MOST interest?
If a researcher is studying how cells recognize each other, which plasma membrane component would be of MOST interest?
Why do the different surfaces of the plasma membrane differ in lipid composition?
Why do the different surfaces of the plasma membrane differ in lipid composition?
In a scenario where a cell needs to rapidly transport a large quantity of glucose inside, which transport mechanism would likely be MOST efficient?
In a scenario where a cell needs to rapidly transport a large quantity of glucose inside, which transport mechanism would likely be MOST efficient?
How might a drug designed to block cell-cell communication via gap junctions function?
How might a drug designed to block cell-cell communication via gap junctions function?
What is the significance of having both enzymatic activity and receptor functions within membrane proteins?
What is the significance of having both enzymatic activity and receptor functions within membrane proteins?
Which of the following is the MOST accurate distinction between diffusion and osmosis?
Which of the following is the MOST accurate distinction between diffusion and osmosis?
If a researcher discovers a cell actively transporting glucose against its concentration gradient, which of the following energy sources would MOST likely be involved?
If a researcher discovers a cell actively transporting glucose against its concentration gradient, which of the following energy sources would MOST likely be involved?
Which of the following BEST describes the operational mechanism of the sodium-potassium pump?
Which of the following BEST describes the operational mechanism of the sodium-potassium pump?
A scientist is studying a cell that utilizes a symport system. Which of the following would be the MOST accurate observation?
A scientist is studying a cell that utilizes a symport system. Which of the following would be the MOST accurate observation?
In the context of active transport, what is the key distinction between primary and secondary active transport mechanisms?
In the context of active transport, what is the key distinction between primary and secondary active transport mechanisms?
If a pharmaceutical company wants to design a drug that selectively inhibits the Na+-glucose symport transporter in intestinal cells, what mechanism would be MOST effective?
If a pharmaceutical company wants to design a drug that selectively inhibits the Na+-glucose symport transporter in intestinal cells, what mechanism would be MOST effective?
A cell is observed engulfing a large, insoluble particle. Which of the following vesicular transport processes is MOST likely responsible for this observation?
A cell is observed engulfing a large, insoluble particle. Which of the following vesicular transport processes is MOST likely responsible for this observation?
How does receptor-mediated endocytosis differ fundamentally from fluid-phase endocytosis (pinocytosis)?
How does receptor-mediated endocytosis differ fundamentally from fluid-phase endocytosis (pinocytosis)?
A researcher discovers a cell type that actively transports a substance from the basolateral side to the apical side of the cell, effectively moving it across the cellular layer. Which transport process is MOST likely involved?
A researcher discovers a cell type that actively transports a substance from the basolateral side to the apical side of the cell, effectively moving it across the cellular layer. Which transport process is MOST likely involved?
What critical role do SNARE proteins play in the process of exocytosis?
What critical role do SNARE proteins play in the process of exocytosis?
Which of the following BEST describes the function of clathrin in receptor-mediated endocytosis?
Which of the following BEST describes the function of clathrin in receptor-mediated endocytosis?
After receptor-mediated endocytosis, what is the MOST likely fate of the internalized vesicle and its contents?
After receptor-mediated endocytosis, what is the MOST likely fate of the internalized vesicle and its contents?
Following clathrin-mediated endocytosis, what DIRECTLY enables the release of cargo from its receptor, allowing the receptor to be recycled back to the plasma membrane?
Following clathrin-mediated endocytosis, what DIRECTLY enables the release of cargo from its receptor, allowing the receptor to be recycled back to the plasma membrane?
A researcher observes that a particular cell type is deficient in producing vesicles. Which of the following organelles is MOST likely malfunctioning?
A researcher observes that a particular cell type is deficient in producing vesicles. Which of the following organelles is MOST likely malfunctioning?
How does the presence of ribosomes affect the functional specialization of the endoplasmic reticulum?
How does the presence of ribosomes affect the functional specialization of the endoplasmic reticulum?
What is the MOST direct role of a signal recognition particle (SRP) in protein synthesis?
What is the MOST direct role of a signal recognition particle (SRP) in protein synthesis?
What is the significance of the cis and trans faces of the Golgi apparatus?
What is the significance of the cis and trans faces of the Golgi apparatus?
Which of the following BEST describes the relationship between the endomembrane system's organelles?
Which of the following BEST describes the relationship between the endomembrane system's organelles?
If a cell were unable to produce functional lysosomes, what would be the MOST likely consequence?
If a cell were unable to produce functional lysosomes, what would be the MOST likely consequence?
How do peroxisomes neutralize harmful free radicals within the cell?
How do peroxisomes neutralize harmful free radicals within the cell?
A researcher disrupts the microtubule network within a cell. Which of the following processes would be MOST directly affected?
A researcher disrupts the microtubule network within a cell. Which of the following processes would be MOST directly affected?
Taxol, a drug used in chemotherapy, inhibits microtubule depolymerization. How does this affect mitosis?
Taxol, a drug used in chemotherapy, inhibits microtubule depolymerization. How does this affect mitosis?
How do centrioles contribute to cell division?
How do centrioles contribute to cell division?
What would be the MOST likely effect of a mutation that disrupts the function of dynein arms in cilia?
What would be the MOST likely effect of a mutation that disrupts the function of dynein arms in cilia?
Which of the following BEST describes the arrangement of microtubules within a cilium?
Which of the following BEST describes the arrangement of microtubules within a cilium?
What is the functional significance of the nucleolus?
What is the functional significance of the nucleolus?
How does the packaging of DNA into chromatin affect gene expression?
How does the packaging of DNA into chromatin affect gene expression?
During which phase of the cell cycle does DNA replication occur?
During which phase of the cell cycle does DNA replication occur?
What is the role of DNA polymerase III in DNA replication?
What is the role of DNA polymerase III in DNA replication?
A researcher discovers that a cell line is unable to complete cytokinesis. What is the MOST likely cause of this?
A researcher discovers that a cell line is unable to complete cytokinesis. What is the MOST likely cause of this?
During which phase of mitosis do sister chromatids separate and move toward opposite poles of the cell?
During which phase of mitosis do sister chromatids separate and move toward opposite poles of the cell?
What event characterizes the beginning of anaphase?
What event characterizes the beginning of anaphase?
What is the MAIN event that occurs during telophase?
What is the MAIN event that occurs during telophase?
How do the leading and lagging strands differ during DNA replication?
How do the leading and lagging strands differ during DNA replication?
What is the function of DNA ligase during DNA replication?
What is the function of DNA ligase during DNA replication?
Select the correct order of mitosis phases.
Select the correct order of mitosis phases.
In the sodium-potassium pump, what is the direct energy source that drives the conformational change of the protein to expel sodium ions (Na+) and bind potassium ions (K+)?
In the sodium-potassium pump, what is the direct energy source that drives the conformational change of the protein to expel sodium ions (Na+) and bind potassium ions (K+)?
A cell is engineered to have a malfunctioning Na+-K+ ATPase pump that can no longer maintain the normal electrochemical gradient. How would this MOST directly affect secondary active transport mechanisms in the cell?
A cell is engineered to have a malfunctioning Na+-K+ ATPase pump that can no longer maintain the normal electrochemical gradient. How would this MOST directly affect secondary active transport mechanisms in the cell?
If a cell is actively performing transcytosis, moving a protein from the basolateral to the apical side, what would MOST likely happen if clathrin-coated pits were unable to form?
If a cell is actively performing transcytosis, moving a protein from the basolateral to the apical side, what would MOST likely happen if clathrin-coated pits were unable to form?
A researcher is studying a novel cell line and observes that it has a significantly reduced capacity for exocytosis. Which organelle is MOST likely impaired in this cell line?
A researcher is studying a novel cell line and observes that it has a significantly reduced capacity for exocytosis. Which organelle is MOST likely impaired in this cell line?
If a cell is unable to add the appropriate signal sequence to a protein during its synthesis, where would the protein MOST likely end up?
If a cell is unable to add the appropriate signal sequence to a protein during its synthesis, where would the protein MOST likely end up?
A mutation causes the ribosomes of a cell to lose their ability to differentiate between mRNA molecules coding for integral membrane proteins and those coding for cytosolic enzymes. What is the MOST likely consequence of this mutation?
A mutation causes the ribosomes of a cell to lose their ability to differentiate between mRNA molecules coding for integral membrane proteins and those coding for cytosolic enzymes. What is the MOST likely consequence of this mutation?
After an immune cell phagocytoses a bacterium, the resulting vesicle fuses with which organelle to digest the bacterium?
After an immune cell phagocytoses a bacterium, the resulting vesicle fuses with which organelle to digest the bacterium?
Which of the following cellular responses would MOST directly counteract the effects of a sudden accumulation of free radicals within a cell?
Which of the following cellular responses would MOST directly counteract the effects of a sudden accumulation of free radicals within a cell?
A scientist treating cancer cells with a new drug observes that the mitotic spindle is unable to pull the chromosomes apart. Which component of the cytoskeleton is MOST likely being directly affected by this drug?
A scientist treating cancer cells with a new drug observes that the mitotic spindle is unable to pull the chromosomes apart. Which component of the cytoskeleton is MOST likely being directly affected by this drug?
If a mutation occurred that inhibited the function of the nucleolus, what cellular process would be MOST directly affected?
If a mutation occurred that inhibited the function of the nucleolus, what cellular process would be MOST directly affected?
What is the MOST critical function of ATP in primary active transport?
What is the MOST critical function of ATP in primary active transport?
How does the sodium-potassium pump contribute to the maintenance of cell volume?
How does the sodium-potassium pump contribute to the maintenance of cell volume?
In the context of secondary active transport, what would be the MOST immediate consequence of inhibiting the primary active transporter?
In the context of secondary active transport, what would be the MOST immediate consequence of inhibiting the primary active transporter?
If a cell suddenly lost its ability to phosphorylate proteins, how would this MOST directly impair the function of the sodium-potassium pump?
If a cell suddenly lost its ability to phosphorylate proteins, how would this MOST directly impair the function of the sodium-potassium pump?
How does the action of a symport transporter differ MOST significantly from that of an antiport transporter?
How does the action of a symport transporter differ MOST significantly from that of an antiport transporter?
What is the MOST immediate outcome if a cell's SNARE proteins were non-functional?
What is the MOST immediate outcome if a cell's SNARE proteins were non-functional?
What is the MOST critical role of clathrin in receptor-mediated endocytosis?
What is the MOST critical role of clathrin in receptor-mediated endocytosis?
Following receptor-mediated endocytosis, which of the following is the MOST likely sequence of events for an internalized vesicle?
Following receptor-mediated endocytosis, which of the following is the MOST likely sequence of events for an internalized vesicle?
How would a defect in COPII-coated vesicles production MOST directly affect a cell's function?
How would a defect in COPII-coated vesicles production MOST directly affect a cell's function?
What is the fundamental role of the signal recognition particle (SRP) in co-translational protein targeting?
What is the fundamental role of the signal recognition particle (SRP) in co-translational protein targeting?
In the Golgi apparatus, what chemical modification is MOST likely to occur?
In the Golgi apparatus, what chemical modification is MOST likely to occur?
How does the arrangement of the endomembrane system facilitate its complex functions in protein production and distribution?
How does the arrangement of the endomembrane system facilitate its complex functions in protein production and distribution?
What is the MOST critical consequence if a cell could not maintain an acidic environment within its lysosomes?
What is the MOST critical consequence if a cell could not maintain an acidic environment within its lysosomes?
How do peroxisomes use catalase to neutralize hydrogen peroxide ($H_2O_2$), a toxic byproduct of their oxidative reactions?
How do peroxisomes use catalase to neutralize hydrogen peroxide ($H_2O_2$), a toxic byproduct of their oxidative reactions?
How might inhibiting microtubule dynamics DIRECTLY affect the intracellular transport of vesicles?
How might inhibiting microtubule dynamics DIRECTLY affect the intracellular transport of vesicles?
What is the MOST immediate effect of a drug that inhibits the function of dynein, but NOT kinesin, on a ciliated cell?
What is the MOST immediate effect of a drug that inhibits the function of dynein, but NOT kinesin, on a ciliated cell?
Which cellular process would MOST directly be impaired if the nucleolus were non-functional?
Which cellular process would MOST directly be impaired if the nucleolus were non-functional?
How might histone acetylation affect gene expression within a cell?
How might histone acetylation affect gene expression within a cell?
During DNA replication, if a mutation occurred that inactivated primase, what would be the MOST immediate consequence?
During DNA replication, if a mutation occurred that inactivated primase, what would be the MOST immediate consequence?
How does telomerase address the issue of chromosome shortening during DNA replication in eukaryotic cells?
How does telomerase address the issue of chromosome shortening during DNA replication in eukaryotic cells?
What is the MOST direct role of the anaphase promoting complex/cyclosome (APC/C) in regulating the metaphase-anaphase transition?
What is the MOST direct role of the anaphase promoting complex/cyclosome (APC/C) in regulating the metaphase-anaphase transition?
How does the formation of the contractile ring during cytokinesis lead to cell division?
How does the formation of the contractile ring during cytokinesis lead to cell division?
What is the MOST immediate consequence of a mutation that disrupts the function of the Rb protein, a key regulator of the cell cycle?
What is the MOST immediate consequence of a mutation that disrupts the function of the Rb protein, a key regulator of the cell cycle?
What is the MOST critical distinction between the function of the rough endoplasmic reticulum (RER) and the smooth endoplasmic reticulum (SER)?
What is the MOST critical distinction between the function of the rough endoplasmic reticulum (RER) and the smooth endoplasmic reticulum (SER)?
If a signal sequence on a protein destined for the plasma membrane is mutated such that it's non-functional, where would the protein MOST likely end up?
If a signal sequence on a protein destined for the plasma membrane is mutated such that it's non-functional, where would the protein MOST likely end up?
How would a mutation affecting the trans face of the Golgi apparatus MOST directly affect cellular processes?
How would a mutation affecting the trans face of the Golgi apparatus MOST directly affect cellular processes?
Which outcome is MOST likely if a cell's lysosomes malfunction and release their contents into the cytoplasm?
Which outcome is MOST likely if a cell's lysosomes malfunction and release their contents into the cytoplasm?
What is the MOST direct effect on cellular function if the centrosomes fail to duplicate during interphase?
What is the MOST direct effect on cellular function if the centrosomes fail to duplicate during interphase?
How do intermediate filaments contribute uniquely to the overall structure and function of the cytoskeleton?
How do intermediate filaments contribute uniquely to the overall structure and function of the cytoskeleton?
During DNA replication, why is the lagging strand synthesized in short fragments rather than continuously like the leading strand?
During DNA replication, why is the lagging strand synthesized in short fragments rather than continuously like the leading strand?
If a drug were developed to selectively inhibit the enzyme DNA ligase, what specific aspect of DNA replication would be MOST directly affected?
If a drug were developed to selectively inhibit the enzyme DNA ligase, what specific aspect of DNA replication would be MOST directly affected?
Which of the following mechanisms would MOST effectively prevent a cell with damaged DNA from progressing through the cell cycle?
Which of the following mechanisms would MOST effectively prevent a cell with damaged DNA from progressing through the cell cycle?
What is the MOST likely outcome if a cell underwent mitosis without the subsequent cytokinesis?
What is the MOST likely outcome if a cell underwent mitosis without the subsequent cytokinesis?
During anaphase, what is the MOST critical role of the shortening of kinetochore microtubules?
During anaphase, what is the MOST critical role of the shortening of kinetochore microtubules?
What is the MOST immediate effect on cell division following the inactivation of separase?
What is the MOST immediate effect on cell division following the inactivation of separase?
How does the initiation of transcription in eukaryotic cells MOST crucially depend on transcription factors?
How does the initiation of transcription in eukaryotic cells MOST crucially depend on transcription factors?
During the process of translation, what is the MOST critical function of transfer RNA (tRNA)?
During the process of translation, what is the MOST critical function of transfer RNA (tRNA)?
Which process would be MOST directly affected by a mutation in a gene that codes for a ribosomal protein?
Which process would be MOST directly affected by a mutation in a gene that codes for a ribosomal protein?
In primary active transport, if a cell were treated with a drug that inhibits the dephosphorylation of the transport protein, what would be the MOST direct consequence?
In primary active transport, if a cell were treated with a drug that inhibits the dephosphorylation of the transport protein, what would be the MOST direct consequence?
A researcher is investigating a cell that utilizes a unique antiport system, where the influx of a novel neurotransmitter 'X' is coupled with the efflux of $Na^+$. If the extracellular concentration of $Na^+$ is experimentally reduced to near zero, how would this MOST likely affect the transport of neurotransmitter 'X' into the cell?
A researcher is investigating a cell that utilizes a unique antiport system, where the influx of a novel neurotransmitter 'X' is coupled with the efflux of $Na^+$. If the extracellular concentration of $Na^+$ is experimentally reduced to near zero, how would this MOST likely affect the transport of neurotransmitter 'X' into the cell?
A cell actively transports a large polar molecule 'Y' across its plasma membrane using a process that involves a series of protein carriers and requires ATP hydrolysis at multiple steps. If a metabolic inhibitor is introduced, significantly reducing the cell's ATP levels, what aspect of 'Y' transport would be MOST directly compromised?
A cell actively transports a large polar molecule 'Y' across its plasma membrane using a process that involves a series of protein carriers and requires ATP hydrolysis at multiple steps. If a metabolic inhibitor is introduced, significantly reducing the cell's ATP levels, what aspect of 'Y' transport would be MOST directly compromised?
A researcher discovers that a particular cell type is unable to perform transcytosis. The cells can still perform endocytosis and exocytosis separately. What specific defect is MOST likely responsible for this inability?
A researcher discovers that a particular cell type is unable to perform transcytosis. The cells can still perform endocytosis and exocytosis separately. What specific defect is MOST likely responsible for this inability?
Following receptor-mediated endocytosis of a growth factor, a vesicle containing the growth factor and its receptor is internalized. If the cell is unable to acidify the endosome effectively, what is the MOST likely outcome?
Following receptor-mediated endocytosis of a growth factor, a vesicle containing the growth factor and its receptor is internalized. If the cell is unable to acidify the endosome effectively, what is the MOST likely outcome?
A newly synthesized protein is destined for insertion into the plasma membrane. However, a mutation in its gene prevents the proper formation of its signal sequence. What is the MOST likely cellular consequence of this mutation?
A newly synthesized protein is destined for insertion into the plasma membrane. However, a mutation in its gene prevents the proper formation of its signal sequence. What is the MOST likely cellular consequence of this mutation?
A researcher is examining cells with a mutation that impairs the function of COPI-coated vesicles. What cellular process would be MOST directly affected in these mutant cells?
A researcher is examining cells with a mutation that impairs the function of COPI-coated vesicles. What cellular process would be MOST directly affected in these mutant cells?
A cell is exposed to a toxin that disrupts the organization of intermediate filaments but does not affect microtubules or microfilaments. What cellular function would be MOST specifically compromised?
A cell is exposed to a toxin that disrupts the organization of intermediate filaments but does not affect microtubules or microfilaments. What cellular function would be MOST specifically compromised?
During metaphase, a cell is treated with a drug that depolymerizes microtubules specifically at the kinetochore. What would be the MOST likely immediate consequence for the cell?
During metaphase, a cell is treated with a drug that depolymerizes microtubules specifically at the kinetochore. What would be the MOST likely immediate consequence for the cell?
A mutation in a cell line results in a non-functional anaphase-promoting complex/cyclosome (APC/C). What is the MOST likely consequence of this mutation on the cell cycle?
A mutation in a cell line results in a non-functional anaphase-promoting complex/cyclosome (APC/C). What is the MOST likely consequence of this mutation on the cell cycle?
A novel therapeutic strategy aims to disrupt the transmission of signals in cardiac muscle tissue to prevent arrhythmias. Which type of cell junction would MOST likely be targeted to achieve this?
A novel therapeutic strategy aims to disrupt the transmission of signals in cardiac muscle tissue to prevent arrhythmias. Which type of cell junction would MOST likely be targeted to achieve this?
In the context of cellular adhesion and tissue integrity, what would be the MOST immediate consequence of a mutation that disrupts the assembly of keratin intermediate filaments specifically at desmosomes?
In the context of cellular adhesion and tissue integrity, what would be the MOST immediate consequence of a mutation that disrupts the assembly of keratin intermediate filaments specifically at desmosomes?
A researcher is investigating a cell line derived from epithelial tissue and observes that these cells exhibit a significant reduction in paracellular permeability. Which of the following structures is MOST likely upregulated or enhanced in these cells?
A researcher is investigating a cell line derived from epithelial tissue and observes that these cells exhibit a significant reduction in paracellular permeability. Which of the following structures is MOST likely upregulated or enhanced in these cells?
During the inflammatory response, leukocytes migrate from the bloodstream into the surrounding tissue. Which cellular structure is MOST critically involved in facilitating the initial adhesion of leukocytes to the endothelial cells of blood vessels?
During the inflammatory response, leukocytes migrate from the bloodstream into the surrounding tissue. Which cellular structure is MOST critically involved in facilitating the initial adhesion of leukocytes to the endothelial cells of blood vessels?
A cell biologist is studying a novel unicellular organism found in an extreme environment. This organism maintains a high intracellular pH in an acidic environment. Which transport mechanism is MOST likely critical for its survival?
A cell biologist is studying a novel unicellular organism found in an extreme environment. This organism maintains a high intracellular pH in an acidic environment. Which transport mechanism is MOST likely critical for its survival?
In a scenario where cellular ATP production is completely inhibited by a metabolic toxin, which of the following transport processes would be LEAST affected in the short term?
In a scenario where cellular ATP production is completely inhibited by a metabolic toxin, which of the following transport processes would be LEAST affected in the short term?
A researcher discovers a new species of bacteria that thrives in highly saline environments. The cell membranes of these bacteria likely contain modifications to which component to maintain membrane fluidity and stability at high salt concentrations?
A researcher discovers a new species of bacteria that thrives in highly saline environments. The cell membranes of these bacteria likely contain modifications to which component to maintain membrane fluidity and stability at high salt concentrations?
Which of the following is the MOST likely mechanism by which cancer cells alter their glycocalyx to evade immune surveillance and promote metastasis?
Which of the following is the MOST likely mechanism by which cancer cells alter their glycocalyx to evade immune surveillance and promote metastasis?
A researcher is investigating the mechanism by which a novel peptide hormone enters cells. The hormone is found to bind to a cell-surface receptor, triggering internalization via clathrin-mediated endocytosis. However, even when endocytosis is blocked, the hormone still elicits a cellular response. What is the MOST plausible explanation?
A researcher is investigating the mechanism by which a novel peptide hormone enters cells. The hormone is found to bind to a cell-surface receptor, triggering internalization via clathrin-mediated endocytosis. However, even when endocytosis is blocked, the hormone still elicits a cellular response. What is the MOST plausible explanation?
A mutation in a gene encoding a protein component of the COPI complex is identified in a cell line. What cellular process is MOST directly compromised by this mutation?
A mutation in a gene encoding a protein component of the COPI complex is identified in a cell line. What cellular process is MOST directly compromised by this mutation?
A researcher is studying the effects of a drug that inhibits the function of the signal recognition particle (SRP). What is the MOST likely consequence of this drug's action on protein synthesis?
A researcher is studying the effects of a drug that inhibits the function of the signal recognition particle (SRP). What is the MOST likely consequence of this drug's action on protein synthesis?
A researcher introduces a mutation into a cell line that prevents the formation of mature lysosomes. What is the MOST likely outcome of this defect on cellular function?
A researcher introduces a mutation into a cell line that prevents the formation of mature lysosomes. What is the MOST likely outcome of this defect on cellular function?
A targeted therapy aims to disrupt cancer cell division by interfering with mitotic spindle formation. Which of the following cytoskeletal elements would be the MOST appropriate target for this therapy?
A targeted therapy aims to disrupt cancer cell division by interfering with mitotic spindle formation. Which of the following cytoskeletal elements would be the MOST appropriate target for this therapy?
A researcher is studying a cell line that exhibits abnormal chromosome segregation during mitosis. Upon closer examination, they find that the kinetochores are not properly attaching to the mitotic spindle. Which protein is MOST likely dysfunctional?
A researcher is studying a cell line that exhibits abnormal chromosome segregation during mitosis. Upon closer examination, they find that the kinetochores are not properly attaching to the mitotic spindle. Which protein is MOST likely dysfunctional?
During DNA replication, a researcher notices that the lagging strand is not being synthesized correctly, resulting in short DNA fragments accumulating. Which enzyme is MOST likely deficient in its function?
During DNA replication, a researcher notices that the lagging strand is not being synthesized correctly, resulting in short DNA fragments accumulating. Which enzyme is MOST likely deficient in its function?
If a cell were treated with a drug that specifically inhibits the function of RNA polymerase, which cellular process would be MOST directly affected?
If a cell were treated with a drug that specifically inhibits the function of RNA polymerase, which cellular process would be MOST directly affected?
What would be the MOST immediate consequence if a cell were unable to produce functional tRNA molecules?
What would be the MOST immediate consequence if a cell were unable to produce functional tRNA molecules?
Following translation initiation, a mutation prevents translocation from occurring. What is the MOST likely immediate effect?
Following translation initiation, a mutation prevents translocation from occurring. What is the MOST likely immediate effect?
A cell is exposed to a mutagen that causes a frameshift mutation in a gene. How is the resulting protein MOST likely to be affected?
A cell is exposed to a mutagen that causes a frameshift mutation in a gene. How is the resulting protein MOST likely to be affected?
During the formation of a functional protein, which of the following events would be MOST directly affected by disrupting the activity of chaperone proteins in the endoplasmic reticulum?
During the formation of a functional protein, which of the following events would be MOST directly affected by disrupting the activity of chaperone proteins in the endoplasmic reticulum?
Flashcards
What is a cell?
What is a cell?
The basic structural and functional unit of life.
What is the Plasma Membrane?
What is the Plasma Membrane?
The outer boundary of a cell, separating intracellular from extracellular fluids.
What is Glycocalyx?
What is Glycocalyx?
A glycoprotein area abutting the cell that provides biological markers for cell recognition.
What is the Fluid Mosaic Model?
What is the Fluid Mosaic Model?
Signup and view all the flashcards
What are Glycolipids?
What are Glycolipids?
Signup and view all the flashcards
What are Phospholipids?
What are Phospholipids?
Signup and view all the flashcards
What is Transport (Membrane Function)?
What is Transport (Membrane Function)?
Signup and view all the flashcards
What is Enzymatic Activity?
What is Enzymatic Activity?
Signup and view all the flashcards
What are Receptors?
What are Receptors?
Signup and view all the flashcards
What is Intercellular Adhesion?
What is Intercellular Adhesion?
Signup and view all the flashcards
What is Cell-Cell Recognition?
What is Cell-Cell Recognition?
Signup and view all the flashcards
What is Attachment (Membrane Function)?
What is Attachment (Membrane Function)?
Signup and view all the flashcards
What are Tight Junctions?
What are Tight Junctions?
Signup and view all the flashcards
What are Desmosomes?
What are Desmosomes?
Signup and view all the flashcards
What are Gap Junctions?
What are Gap Junctions?
Signup and view all the flashcards
What is Simple Diffusion?
What is Simple Diffusion?
Signup and view all the flashcards
What is Facilitated Diffusion?
What is Facilitated Diffusion?
Signup and view all the flashcards
What is Osmosis?
What is Osmosis?
Signup and view all the flashcards
What is Osmolarity?
What is Osmolarity?
Signup and view all the flashcards
What is Tonicity?
What is Tonicity?
Signup and view all the flashcards
What are Isotonic Solutions?
What are Isotonic Solutions?
Signup and view all the flashcards
What are Hypertonic Solutions?
What are Hypertonic Solutions?
Signup and view all the flashcards
What are Hypotonic Solutions?
What are Hypotonic Solutions?
Signup and view all the flashcards
What is Filtration?
What is Filtration?
Signup and view all the flashcards
Active Transport
Active Transport
Signup and view all the flashcards
Sodium-Potassium Pump
Sodium-Potassium Pump
Signup and view all the flashcards
Symport System
Symport System
Signup and view all the flashcards
Antiport System
Antiport System
Signup and view all the flashcards
Primary Active Transport
Primary Active Transport
Signup and view all the flashcards
Secondary Active Transport
Secondary Active Transport
Signup and view all the flashcards
Vesicular Transport
Vesicular Transport
Signup and view all the flashcards
Exocytosis
Exocytosis
Signup and view all the flashcards
Endocytosis
Endocytosis
Signup and view all the flashcards
Transcytosis
Transcytosis
Signup and view all the flashcards
Vesicular Trafficking
Vesicular Trafficking
Signup and view all the flashcards
Phagocytosis
Phagocytosis
Signup and view all the flashcards
Fluid-Phase Endocytosis
Fluid-Phase Endocytosis
Signup and view all the flashcards
Receptor-Mediated Endocytosis
Receptor-Mediated Endocytosis
Signup and view all the flashcards
Cytoplasm
Cytoplasm
Signup and view all the flashcards
Cytosol
Cytosol
Signup and view all the flashcards
Cytoplasmic Organelles
Cytoplasmic Organelles
Signup and view all the flashcards
Inclusions
Inclusions
Signup and view all the flashcards
Cytoplasmic Organelles
Cytoplasmic Organelles
Signup and view all the flashcards
Membranous Organelles
Membranous Organelles
Signup and view all the flashcards
Nonmembranous Organelles
Nonmembranous Organelles
Signup and view all the flashcards
Mitochondria
Mitochondria
Signup and view all the flashcards
Ribosomes
Ribosomes
Signup and view all the flashcards
Endoplasmic Reticulum (ER)
Endoplasmic Reticulum (ER)
Signup and view all the flashcards
Rough Endoplasmic Reticulum
Rough Endoplasmic Reticulum
Signup and view all the flashcards
Smooth Endoplasmic Reticulum
Smooth Endoplasmic Reticulum
Signup and view all the flashcards
Golgi Apparatus
Golgi Apparatus
Signup and view all the flashcards
Lysosomes
Lysosomes
Signup and view all the flashcards
Endomembrane System
Endomembrane System
Signup and view all the flashcards
Peroxisomes
Peroxisomes
Signup and view all the flashcards
Cytoskeleton
Cytoskeleton
Signup and view all the flashcards
Centrioles
Centrioles
Signup and view all the flashcards
Cilia
Cilia
Signup and view all the flashcards
Nucleus
Nucleus
Signup and view all the flashcards
Chromatin
Chromatin
Signup and view all the flashcards
Cell Cycle
Cell Cycle
Signup and view all the flashcards
Interphase
Interphase
Signup and view all the flashcards
Mitotic Phase
Mitotic Phase
Signup and view all the flashcards
DNA Replication
DNA Replication
Signup and view all the flashcards
Cell Division
Cell Division
Signup and view all the flashcards
Mitosis
Mitosis
Signup and view all the flashcards
Phases of Mitosis
Phases of Mitosis
Signup and view all the flashcards
Cytokinesis
Cytokinesis
Signup and view all the flashcards
Prophase
Prophase
Signup and view all the flashcards
Metaphase
Metaphase
Signup and view all the flashcards
Anaphase
Anaphase
Signup and view all the flashcards
Telophase
Telophase
Signup and view all the flashcards
Transcription
Transcription
Signup and view all the flashcards
Translation
Translation
Signup and view all the flashcards
Cell Theory
Cell Theory
Signup and view all the flashcards
Fluid Mosaic
Fluid Mosaic
Signup and view all the flashcards
Phospholipid Arrangement
Phospholipid Arrangement
Signup and view all the flashcards
Integral Proteins
Integral Proteins
Signup and view all the flashcards
Peripheral Proteins
Peripheral Proteins
Signup and view all the flashcards
Passive Transport
Passive Transport
Signup and view all the flashcards
Active Processes
Active Processes
Signup and view all the flashcards
Vesicles
Vesicles
Signup and view all the flashcards
Contact signaling
Contact signaling
Signup and view all the flashcards
Chemical signaling
Chemical signaling
Signup and view all the flashcards
Microtubules
Microtubules
Signup and view all the flashcards
Chromosomes
Chromosomes
Signup and view all the flashcards
Termination
Termination
Signup and view all the flashcards
Study Notes
- The cell is the basic structural and functional unit of life
- The continuity of life has a cellular basis
- Organismal functions depend on both individual and collective cell functions
- Biochemical activities are dictated by cell shape and specific subcellular structures
- Cells arise from pre-existing cells
- There are over 200 different types of human cells
- Cell types differ in size, shape, subcellular components, and function
Structure of a Generalized Cell
- Generalized cell contains:
- Plasma membrane: flexible outer boundary
- Cytoplasm: intracellular fluid containing organelles
- Nucleus: Control center
Plasma Membrane
- Separates intracellular fluid (ICF) from extracellular fluid (ECF)
- Plays a dynamic role in cellular activity
- Interstitial fluid (IF) is the ECF that surrounds cells
- Glycocalyx a glycoprotein abutting area provides highly specific biological markets which cells recognize
Fluid Mosaic Model
- Lipid bilayer with proteins in a constantly changing fluid mosaic
- Double bilayer of lipids with imbedded, dispersed proteins
- Bilayer consists of phospholipids, cholesterol, and glycolipids
- Glycolipids are lipids with bound carbohydrate
- 75% of membrane lipids are phospholipids
- 20% of the outer membrane surface on lipids
- Phospholipids have hydrophobic and hydrophilic bipoles
- Polar, hydrophilic phosphate heads
- Nonpolar, hydrophobic fatty acid tails
- 5% of the lipid membrane is glycolipids
- Lipids with polar sugar groups are only on the outer membrane surface
- 20% of the lipid membrane is cholesterol, this increases membrane stability
Membrane Proteins
- Allow communication with the environment
- Make up ½ the mass of the plasma membrane
- Have most specialized membrane functions
- Some float freely
- Some tethered to intracellular structures
- Two types of proteins: integral and peripheral
- Integral proteins are firmly inserted into the membrane, and most are transmembrane
- Integral proteins have both hydrophobic and hydrophilic regions and can interact with lipid tails and water
- Integral proteins function as transport proteins, enzymes, or receptors
- Peripheral proteins are loosely attached to integral proteins
- Peripheral proteins include filaments on the intracellular surface for membrane support
- Peripheral proteins function as enzymes and motor proteins for shape change during cell division and muscle contraction, or cell-to-cell connections
Functions of Membrane Proteins
- Transport
- Enzymatic activity
- Receptors for signal transduction
- Intercellular adhesion
- Cell-cell recognition
- Attachment to cytoskeleton and extracellular matrix
Plasma Membrane Surfaces
- Differ in the kind and amount of lipids they contain
- Glycolipids are found only in the outer membrane surface
- Portion of all membrane lipid is cholesterol
Membrane Junctions
- Tight junction is an impermeable junction that encircles the cell via fused adjacent integral proteins
- Tight junctions prevent fluids and most molecules from moving between cells
- Desmosome is anchoring junction that is scattered along the sides of cells and that anchors cells together with "rivets" or "spot-welds"
- Desmosomes occur at plaques, with linker proteins that connect plaques and keratin filaments that extend through the cytosol to opposite plaque for stability
- Gap junction is a nexus that allows chemical substances to pass between cells via transmembrane proteins forming pores (connexons)
- Gap junctions allow the spread of ions, simple sugars, and other small molecules between cardiac or smooth muscle cells
- Some cells are "free" (blood cells, sperm cells)
- Some are bound into communities
Passive Membrane Transport: Diffusion
- Plasma membranes are selectively permeable, meaning some molecules pass easily and some does not
- Simple diffusion involves nonpolar and lipid-soluble substances
- Simple diffusion diffuses directly through the lipid bilayer
- Simple diffusion diffuses through channel proteins
- Facilitated diffusion transports glucose, amino acids, and ions
- Transported substances bind carrier proteins or pass through protein channels
Passive Membrane Transport: Osmosis
- Occurs when the concentration of a solvent is different on opposite sides of a membrane
- Is the diffusion of water across a semipermeable membrane
- Osmolarity means total concentration of solute particles in a solution
- Osmosis causes cells to swell and shrink, and a change in cell volume disrupts cell function
- Tonicity defines how a solution affects cell volume
Passive Membrane Transport: Filtration
- The passage of water and solutes through a membrane by hydrostatic pressure
- Pressure gradient pushes solute-containing fluid from a higher-pressure area to a lower-pressure area
Effects of Solutions of Varying Tonicity
- Isotonic solutions have the same solute concentration as that of the cytosol
- Hypertonic solutions have greater solute concentration than that of the cytosol
- Hypotonic solutions have lesser solute concentration than that of the cytosol
- A cell has ~0.9% NaCl (salt). If placed in more concentrated solution (hypertonic), the cell will shrink. If placed in less concentrated solution (pure water which is hypotonic), the cell will burst.
Types of Membrane Transport
- Passive processes requires no cellular energy, and substances move down their concentration gradient. It includes: Diffusion, osmosis, and filtration
- Active processes requires energy (ATP) and only occurs in living cell membranes
Passive Processes: Diffusion
- Collisions cause molecules to move down or with their concentration gradient
- Speed is influenced by molecule size and temperature
- Molecules will passively diffuse through the membrane if it is lipid soluble, small enough to pass through membrane channels, or assisted by a carrier molecule
Passive Processes: Simple Diffusion
- Nonpolar lipid-soluble substances diffuse directly through the phospholipid bilayer
- E.g., oxygen, carbon dioxide, and fat-soluble vitamins
Passive Processes: Facilitated Diffusion
- Certain lipophobic molecules are transported passively by binding to protein carriers or moving through water-filled channels
Carrier-Mediated Facilitated Diffusion
- Transmembrane integral proteins are carriers and transport specific polar molecules
- Binding of a substrate causes a shape change in a carrier, then passage across the membrane
- The number of carriers present limits the rate of transport, eventually carriers are saturated when all engaged
Channel-Mediated Facilitated Diffusion
- Aqueous channels formed by transmembrane proteins
- Selectively transport ions or water
- Leakage channels are always open
- Gated channels are controlled by chemical or electrical signals
Passive Processes: Osmosis
- Movement of solvent across a selectively permeable membrane
- Water diffuses through plasma membranes, lipid bilayers, or specific water channels called aquaporins (AQPs)
- Occurs when water concentration is different on the two sides of a membrane
- Water concentration varies with the number of solute particles, because solute particles displace water molecules
- Osmolarity is a measure of the total concentration of solute particles
- Water moves by osmosis until hydrostatic pressure and osmotic pressure equalize
- When solutions of different osmolarity are separated by a membrane permeable to all molecules, both solutes and water cross membrane until equilibrium is reached
- When solutions of different osmolarity are separated by a membrane impermeable to solutes, osmosis occurs until equilibrium is reached
Active Transport
- Uses ATP to move solutes across a membrane
- Requires carrier proteins, also known as solute pumps
- Solutes can be moved against the concentration gradient
- Solute is too large for channels
- Solute is not lipid soluble
- Solute is not able to move down concentration gradient
Sodium-Potassium Pump
- Cytoplasmic Na+ binding to the pump protein stimulates phosphorylation by ATP
- Phosphorylation causes the protein to change its shape
- The shape change expels Na+ to the outside, and extracellular K+ binds
- K+ binding triggers release of the phosphate group
- Loss of phosphate restores the original conformation of the pump protein
- K+ is released and Na+ sites are ready to bind Na+ again; the cycle repeats.
- Maintains electrochemical gradients for functions of muscle and nerve tissue
- Allows all cells to maintain fluid volume
- The pump is a carrier (Na+-K+ ATPase) found in all plasma membranes, and is involved in the primary and secondary active transports of nutrients and ions
- Na+ and K+ channels allow slow leakage down concentration gradients, and the Na+-K+ pump works as an antiporter
- The pump works to maintain high intracellular K+ concentration, and high extracellular Na+ concentration
Types of Active Transport
- Symport system moves two substances across a membrane in the same direction. Contransportation always moves more than one substance at a time
- Antiport system moves two substances across a membrane in opposite directions. Contransportation always moves more than one substance at a time
- Primary active transport involves hydrolysis of ATP which phosphorylates the transport protein, causing a conformational change. Required energy directly from ATP hydrolysis
- Secondary active transport uses an exchange pump, such as the Na+-K+ pump, to indirectly drive the transport of other solutes, and requires energy indirectly from ionic gradients created by primary active transport. Depends on ion gradient created by primary active transport.
Vesicular Transport
- Transports large particles and macromolecules across plasma membranes
- Transports large particles, macromolecules, and fluids across membranes in membranous sacs called vesicles
- Requires cellular energy (ATP)
- Exocytosis moves substances from the cell interior to the extracellular space
- Endocytosis enables large particles and macromolecules to enter the cell
- Transcytosis involves moving substances into, across, and then out of a cell
- Vesicular trafficking involves moving substances from one area in the cell to another
- Functions: transports out of and into cell
- Phagocytosis is where pseudopods engulf solids and bring them into the cell's interior, forming a vesicle called phagosome, and use amoeboid motion; cytoplasm flows into temporary extensions
- Used by macrophages and some white blood cells
- Fluid-phase endocytosis (Pinocytosis) involves the plasma membrane infolding, bringing extracellular fluid and solutes into the cell's interior and fuses with the endosome
- Most cells utilize to "sample" environment, nutrient absorption in the small intestine, and where membrane components are recycled back to membrane.
- Receptor-mediated endocytosis, clathrin-coated pits provide the main route for endocytosis and transcytosis
- Allows specific endocytosis and transcytosis which cells can use to concentrate materials in limited supply
Cytoplasm
- The material between the plasma membrane and the nucleus and is located between plasma membrane and nucleus
- Cytosol is largely water with dissolved protein, salts, sugars, and other solutes
- Cytoplasmic organelles make up the metabolic machinery of the cell and each have specialized functions; either membranous or nonmembranous
- Inclusions are chemical substances such as glycosomes, glycogen granules, and pigment, and vary with cell type
Cytoplasmic Organelles
- Specialized cellular compartments
- Membranous organelles include Mitochondria, Peroxisomes, Lysosomes, Endoplasmic reticulum, and Golgi apparatus
- Nonmembranous organelles include Cytoskeleton, Centrioles, and Ribosomes
- Membranes allow crucial compartmentalization
Mitochondria
- Have an outer and inner mitochondrial membrane, cristae, matrix, ribosomes and mitochondrial DNA
- Provide most of cell's ATP via aerobic cellular respiration and require oxygen
- Contain their own DNA, RNA, and ribosomes
- Similar to bacteria; capable of cell division called fission
Ribosomes
- Granules containing protein and rRNA
- The site of protein synthesis
- Free ribosomes synthesize soluble proteins that function in the cytosol
- Membrane-bound ribosomes synthesize proteins to be incorporated into membranes, lysosomes, or exported from cell
Endoplasmic Reticulum (ER)
- Interconnected tubes and parallel membranes
- Continuous with the nuclear membrane
- Two varieties: rough ER and smooth ER
Rough (ER)
- External surface is studded with ribosomes
- Manufactures all secreted proteins
- Responsible for the synthesis of integral membrane proteins and phospholipids for cell membranes
- The protein folds into a three-dimensional conformation
- The protein is enclosed in a transport vesicle and moves toward the Golgi apparatus
Smooth ER
- Tubules arranged in a looping network
- Catalyzes reactions in various organs of the body
- In the liver: lipid and cholesterol metabolism, breakdown of glycogen, detoxification of drugs
- In the testes: synthesis of steroid-based hormones
- In the intestinal cells: absorption, synthesis, transport of fats
- In skeletal and cardiac muscle: storage and release of calcium
Golgi Apparatus
- Stacked and flattened membranous sacs
- Functions in modification, concentration, and packaging of proteins and lipids from the rough ER
- Transport vessels from ER; proteins modified, tagged for delivery, sorted, and packaged in vesicles
- Secretory vesicles leave the Golgi and move to designated parts of the cell
Lysosomes
- Spherical membranous bags containing digestive enzymes (acid hydrolases)
- "Safe" sites for intracellular digestion
- Digest ingested bacteria, viruses, and toxins
- Degrade nonfunctional organelles
- Destroy cells in injured or nonuseful tissue (autolysis)
- Break down bone to release Ca2+
Peroxisomes
- Membranous sacs containing oxidases and catalases
- Detoxify harmful or toxic substances
- Catalysis and synthesis of fatty acids
- Neutralize dangerous free radicals
- Free radicals are highly reactive chemicals with unpaired electrons (i.e., O2)
Cytoskeleton
- The "skeleton" of the cell
- Elaborate series of rods throughout cytosol as proteins link the rods to other cell structures
- Consists of microtubules, microfilaments, and intermediate filaments
Microfilaments
- Thinnest of cytoskeletal elements
- Dynamic strands of protein actin
- Each cell-unique arrangement of strands
- Dense web attached to cytoplasmic side of plasma membrane-terminal web
Intermediate Filaments
- Tough, insoluble, ropelike protein fibers
- Resist pulling forces on cell; attach to desmosomes
- E.g., neurofilaments in nerve cells; keratin filaments in epithelial cells
- Involved in cell motility, change in shape, endocytosis and exocytosis
Microtubules
- Largest of cytoskeletal elements; dynamic hollow tubes
- Composed of protein subunits called tubulins
- Determine overall shape of cell and distribution of organelles
- Mitochondria, lysosomes, secretory vesicles attach to microtubules.
Motor Proteins
- Protein complexes that function in motility (movement of organelles & contraction)
- Powered by ATP
Centrioles
- Small barrel-shaped organelles located in the centrosome near the nucleus
- Pinwheel array of nine triplets of microtubules
- Organize mitotic spindle during mitosis
- Form the bases of cilia and flagella
Cilia
- Outer doublet microtubules, dynein arms, cillium, plasma membrane and Basal body (centriole)
- Movement of mucus across cell surfaces
Nucleus
- Largest organelle, genetic library with blueprints for nearly all cellular proteins. Responds to signals, dictates kinds and amounts of proteins synthesized
- Nuclear envelope, Condensed chromatin, Nucleolus and Pores
Chromatin
- Threadlike strands of DNA and histones
- Arranged in fundamental units called nucleosomes
Cell Cycle
- G1 when cells grow, S when strands are synthesized, and G2
- Interphase
- Growth (G₁), synthesis (S), growth (G2)
- Mitotic phase
- Mitosis and cytokinesis
DNA Replication
- Prior to division a cell makes a copy of DNA
- DNA helices are separated into replication bubbles with replication forks at each end
- Each strand acts as template for complementary strand
- DNA polymerase (enzyme involved) begins adding nucleotides (G pairs with C and A pairs with T)
Cell Division
- Cell division producing gametes are called meiosis
- Essential for body growth and tissue repair
- Mitosis is nuclear division
- Cytokinesis is division of the cytoplasm
- Mitotic cell division produces clones or genetically identical cells
Mitosis
- The phases of mitosis are:
- Prophase
- Metaphase
- Anaphase
- Telophase
Cytokinesis
- Cleavage furrow formed in late anaphase by contractile ring
- Cytoplasm is pinched into two parts after mitosis ends
Early Prophase
- Early mitotic spindle begins to form
- The pair of centrioles start to move to each pole
- The aster extends from the centrosome
- The centromere appears to be joining the two sister chromatids
Late Prophase
- Fragments of the nuclear envelope appear
- Polar Microtubules starting to form
- Kinetochore
- Kinetochore Microtubule attached to the spindle pole
Metaphase
- The spindle is completely formed
- Metaphase plate shows chromosomes aligned perpendicular to spindle poles
Anaphase
- Daughter chromosomes become visible and pulled to their respective centrioles
Telophase and Cytokinesis
- Nucleolus forming again
- Contractile ring forming that will result in cleavage furrow
- Nuclear envelope starting to form
- Nuclear envelope fragments
- Kinetochore microtubules attach to kinetochore of centromeres and draw them toward the equator of the cell
- Polar microtubules assist in forcing poles apart
- Centromeres of chromosomes that were aligned at equator Plane midway between poles is called metaphase plate
- Shortest phase
- Centromeres of chromosomes split simultaneously, each chromatid becomes a chromosome
- Chromosomes are pulled toward poles by motor proteins of kinetochores
- Polar microtubules continue forcing poles apart
- Begins when chromosome movement stops
- Two sets of chromosomes uncoil to form chromatin
- New nuclear membrane forms around each chromatin mass
- Nucleoli reappear
- Spindle disappears
Protein Synthesis
- DNA is the master blueprint for protein synthesis
- A gene is a segment of DNA with a blueprint for one polypeptide
- Triplets (three sequential DNA nitrogen bases) form genetic library
- The bases in DNA are A, G, T, and C
- Each triplet specifies coding for the number, kind, and order of amino acids in a polypeptide
- Three types of RNA all of which are formed by the DNA in the nucleus: Messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA)
- The role of RNA is DNA decoding and messenger
- RNA differs from DNA, uracil is substituted for thymine
- The role of messenger RNA (mRNA) is to carry instructions for building a polypeptide, from gene in DNA to ribosomes in cytoplasm
- The role of ribosomal RNA (rRNA) is as a structural component of ribosomes that along with tRNA, helps translate message from mRNA
- The role of transfer RNAs (tRNAs) is to bind to amino acids and pair with bases of codons of mRNA at ribosome to begin process of protein synthesis
- Occurs in two steps: transcription where DNA information is coded in mRNA and translation where mRNA is decoded to assemble polypeptides Transcription transfers DNA gene base sequence to complementary base sequence of mRNA through three phases of initiation where RNA polymerase separates DNA strands, elongation where RNA polymerase adds complementary nucleotides, and termination where the termination signal indicates "stop"
- Translation converts base sequence of nucleic acids into amino acid sequence of proteins
- Involves mRNAs, tRNAs, and rRNAs Each three-base sequence on DNA (triplet) represented by codon with codon-complementary three-base sequence on mRNA where some amino acids are represented by more than one codon
- Binds specific amino acid at one end (stem)
- Anticodon at other end (head) binds mRNA codon at ribosome by hydrogen bonds
- Three phases that require ATP, protein factors, and enzymes: Initiation, elongation, and termination
- Small ribosomal subunit binds to mRNA to be decoded
- Large and small ribosomal units attach, forming functional ribosome Three steps:
- tRNA binds complementary codon Amino acid of tRNA nearby bonded to amino acid of tRNA
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
