AP Biology Unit 4 Notch Signaling

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Questions and Answers

What is the approximate ratio of flies with gray bodies and long wings to flies with ebony bodies and curly wings in the second parental cross?

9:3:3:1

4:1

3:1 (correct)

1:1

Which body color and wing shape are determined to be dominant in Drosophila?

Gray body and long wings

The probability of producing flies that have gray bodies and vestigial wings is _____ if crossed with a homozygous gray body and vestigial wings fly.

0.5

What explains the progression of cells past sequential cell cycle checkpoints in mitosis?

Interactions between cyclins and cyclin-dependent kinases Signup and view all the answers

Match the observations to their significance in the study of separase and cancer.

Increased separase expression = Increased sensitivity to Sepin-1 Low concentration of Sepin-1 = No effect on cell viability High concentration of Sepin-1 = Higher cell death rate Signup and view all the answers

Separase is most active at the metaphase-anaphase transition.

True Signup and view all the answers

What is the ratio of Sepin-1 required to kill 50% of the cells in the most sensitive cell line compared to the least sensitive?

1:3 Signup and view all the answers

Which of the following statements best explains Delta's role in regulating cell communication through the Notch signaling pathway?

Delta restricts cell communication to short distances within a developing embryo. Signup and view all the answers

Which of the following statements best explains how cell surface proteins, such as MHC proteins and T cell receptors, mediate cell communication over short distances?

They interact directly with proteins on the surfaces of other cells. Signup and view all the answers

An explanation of how plant cells communicate across cell walls will most likely refer to the diffusion through plasmodesmata of which of the following?

Small, water-soluble molecules Signup and view all the answers

The cell cycle of yeast cells grown in the nutrient-poor environment is approximately what percent of the cell cycle of yeast cells grown in the nutrient-rich environment?

168 Signup and view all the answers

Which of the following statements best predicts the effect of the cell cycle arrest on proliferating yeast cells?

The yeast cells will replicate their chromosomes but will fail to complete cytokinesis. Signup and view all the answers

Which of the following effects on the coagulation cascade is most likely to result from inhibiting thrombin activity with argatroban?

The rate of fibrin formation will decrease. Signup and view all the answers

Which of the following provides correct information about cell signaling that supports the claim regarding the SRY gene?

The SRY gene produces a protein that binds to specific regions of DNA in certain tissues. Signup and view all the answers

Which of the following statements best describes the role of cyclic AMP in the signal transduction pathway?

It acts as a second messenger that helps relay and amplify the signal within the cell. Signup and view all the answers

Which of the following conditions will most likely cause a normal body cell to become a cancer cell?

The environment contains mutagens that induce mutations that affect cell-cycle regulator proteins. Signup and view all the answers

A DNA mutation changes the shape of the extracellular domain of transmembrane receptor protein A. What is the most likely consequence of the mutation?

The molecule that normally binds to protein A will no longer attach, deactivating the cellular response. Signup and view all the answers

How can GSK3β mutations lead to the development of cancer?

Cells with inactive GSK3β fail to trigger apoptosis. Signup and view all the answers

Which of the following statements best predicts the effect of a mutation that results in a loss of the glucocorticoid receptor's ligand binding function?

The glucocorticoid receptor will remain associated with the accessory proteins. Signup and view all the answers

Which of the following best supports the claim that ethylene initiates the signal transduction pathway that leads to the ripening of fruit?

Loss-of-function mutations in ethylene receptors result in changes to the ripening process. Signup and view all the answers

If a person travels from sea level to a high elevation location, which of the following correctly predicts the response to the decreased blood oxygen level?

More erythropoietin will be secreted from the kidneys, increasing production of erythrocytes. Signup and view all the answers

Which of the following best predicts the effect of inhibiting cyclic AMP phosphodiesterase in a muscle cell stimulated by epinephrine?

Phosphorylase kinase will remain active because protein kinase A will no longer be deactivated. Signup and view all the answers

Which of the following statements best helps justify the researcher's claim that the epinephrine signaling pathway controls a catabolic process in muscle cells?

It catalyzes the conversion of glycogen to glucose-1-phosphate. Signup and view all the answers

What will most likely result from the irreversible binding of GDP to the G protein?

The G protein will remain inactive, preventing signaling. Signup and view all the answers

Which of the following statements best describes the role of adenylyl cyclase in the epinephrine signaling pathway?

It accelerates the production of a second messenger. Signup and view all the answers

How does the signaling pathway involving epinephrine regulate glucose homeostasis in muscle cells?

It involves enzymes activating other enzymes. Signup and view all the answers

Which of the following presents a correct interpretation of the changes in chromosome number depicted during cell division?

Chromosomes enter metaphase containing two chromatids attached by a centromere. Signup and view all the answers

What is the expected percent change in the DNA content of a typical eukaryotic cell as it progresses through the cell cycle from the start of the G1 phase to the end of the G2 phase?

+100% Signup and view all the answers

Which of the following patterns is shown by the data regarding the percentage of cells in each phase of mitosis?

In mutant 3 cells, more time is spent in prophase/prometaphase than in the later stages of mitosis. Signup and view all the answers

Which of the following best describes how the amount of DNA in the cell changes during M phase?

The amount of DNA is halved as the cell divides into two daughter cells. Signup and view all the answers

Describe the first interaction that must occur between the R7 precursor cell and the R8 cell for the R7 precursor to differentiate to an R7 photoreceptor cell.

The response indicates that the Sev RTK on the R7 precursor binds with Boss on the R8 cell. Signup and view all the answers

Describe how the defect in the Single-Mutant (Sev−) R7 precursor cell causes the cell to become a cone cell instead of a photoreceptor cell.

The response indicates that the Ras protein cannot bind to the mutated intracellular portion of Sev and become phosphorylated, or activated, so Ras does not induce the intracellular signaling pathways necessary for differentiation of the R7 precursor cell to a photoreceptor cell. Signup and view all the answers

Evaluate the likely accuracy of the prediction regarding the presence of activated Ras in the Double-Mutant (Sev−RasD) R7 precursor cell enabling it to differentiate into an R7 photoreceptor cell.

The prediction is most likely supported by the data. Because the Ras protein is already activated, it does not need to become phosphorylated, or activated, by binding to the intracellular portion of Sev, so Ras can signal and the R7 precursor cell should become an R7 photoreceptor cell. Signup and view all the answers

Explain how one receptor can induce different phenotypes in different cell types.

The response indicates that the proteins that interact with/are activated by/are phosphorylated by the Sev RTK in different cell types may differ OR that the proteins that are activated later in the intracellular signaling pathway may differ. Signup and view all the answers

Describe how fertilization contributes to genetic variability during inheritance studies.

The response indicates that fertilization joins gametes with different allele combinations of the genes for body color and wing shape. Signup and view all the answers

Study Notes

Notch Signaling Pathway

Notch is a receptor protein in developing fruit fly embryos, interacting with the ligand Delta on adjacent cells.
Activation of Notch leads to the release of its intracellular tail, which influences gene expression.
Delta's role is to restrict cell communication to short distances within the embryo.

Immune Response Communication

Vertebrate immune responses utilize both short and long-distance communication.
Cell surface proteins like MHC and T cell receptors facilitate direct protein interactions between neighboring cells.

Plant Cell Communication

Plasmodesmata are channels that connect adjacent plant cell cytoplasms.
These channels allow the diffusion of small, water-soluble molecules for communication.

Yeast Cell Cycle

Yeast cell cycle durations differ significantly between nutrient-rich and nutrient-poor environments.
In nutrient-poor conditions, the overall cell cycle time is approximately 168 minutes longer.

CDC15 Gene Mutation Effects

A mutation in the CDC15 gene in budding yeast causes cell cycle arrest during telophase at elevated temperatures.
Affected yeast cells can replicate chromosomes but cannot complete cytokinesis.

Coagulation Cascade Regulation

Thrombin is crucial in the blood coagulation cascade, where its inhibition by argatroban leads to decreased fibrin formation.

SRY Gene Function

The Y chromosome contains the SRY gene which dictates male sex differentiation by producing a protein that binds to specific DNA regions.

Cyclic AMP in Signal Transduction

Cyclic AMP acts as a second messenger in signal transduction pathways, amplifying and relaying signals within the cell.

Cancer Cell Characteristics

Cancer cells disregard normal signals to cease division.
Exposure to mutagens can induce mutations affecting cell-cycle regulators, leading to cancer development.

Mutations in Signal Transduction

A mutation in transmembrane receptor proteins can prevent ligand binding, disrupting normal cellular responses.

GSK3β and Cancer

GSK3β can function as either an oncogene or tumor suppressor, with inactive forms failing to trigger apoptosis in cells, promoting cancer.

Glucocorticoid Receptor Mutations

Mutations that impair glucocorticoid receptor function prevent it from dissociating from accessory proteins, affecting cellular responses.

Ethylene and Fruit Ripening

Ethylene initiates ripening by activating transcription factors; loss-of-function mutations in ethylene receptors can alter ripening processes.

Erythropoietin Response to Oxygen Levels

At high elevations, decreased oxygen triggers the kidneys to secrete more erythropoietin to enhance erythrocyte production.

Epinephrine Signaling Pathway

Epinephrine activates a signaling pathway involving enzymes, influencing glucose metabolism in muscle cells.

G Protein Binding Effects

Irreversible GDP binding to G proteins may lead to increased intracellular glycogen levels.

Adenylyl Cyclase Function

In the epinephrine signaling pathway, adenylyl cyclase accelerates the production of cyclic AMP, a second messenger.

M Phase DNA Content

During M phase of the cell cycle, DNA content is halved as the cell divides into daughter cells.

Genetic Variability in Drosophila

Fertilization merges diverse allele combinations, contributing to variability in offspring phenotypes.

R7 Precursor Cell Differentiation

The binding of Sev RTK in R7 precursor cells to Boss on R8 cells is critical for differentiation into R7 photoreceptors.

Single-Mutant R7 Phenotype Outcome

In the Sev− mutant, Ras cannot bind to the dysfunctional Sev, preventing necessary signaling for photoreceptor differentiation.

Double-Mutant R7 Cell Prediction

The prediction that activated Ras in Sev−RasD mutants can induce differentiation into R7 photoreceptors is supported, as it bypasses the need for Sev activation.

Variable Phenotypes from RTK Signaling

Different phenotypes induced by the same receptor in various cell types result from distinct interacting proteins or downstream signaling pathways.### Inheritance Patterns in Drosophila
Students study inheritance patterns by using Drosophila flies, focusing on genes for body color and wing shape.
Each gene has two alleles, with one completely dominant over the other.
Initial cross involved true-breeding flies for ebony body and vestigial wings with those for gray body and long wings.

Phenotype Ratios in F2 Generation

After crossing F1 flies, 500 F2 flies were analyzed for phenotypes, yielding an average data set.
A dihybrid cross with a 9:3:3:1 ratio indicates the genes are likely on separate chromosomes.
A subsequent cross showed a 3:1 ratio of dominant to recessive phenotypes, suggesting possible gene linkage.

Role of Separase in Mitosis

At the metaphase-anaphase transition, separase cleaves protein complexes, enabling sister chromatid separation.
Separase is often overexpressed in cancer cells, prompting research into its inhibition as a cancer treatment.

Sepin-1 and Cancer Cell Growth

Sepin-1 is a compound identified to inactivate separase, tested on various cancer cell lines.
Increasing concentrations of Sepin-1 were added to cell cultures to evaluate its effect on cancer cell viability.

Experimental Design and Controls

Independent variables include the type of cancer cell lines and concentrations of Sepin-1.
Control for the experiment showed that low concentrations (approx. 0.2 µM) of Sepin-1 allowed for 100% cell viability, ensuring that Sepin-1 is the growth inhibitor.

Sensitivity Analysis of Cancer Cells

Greater sensitivity to Sepin-1 correlates with higher levels of separase in cancer cells.
A 1:3 ratio between Sepin-1 concentrations required to kill sensitive versus least sensitive cell lines (approx. 10 µM vs. 30 µM).

Future Clinical Relevance

The effectiveness of Sepin-1 treatment will be assessed by sampling cancer cells from patients periodically.
A decrease in the number of cells in metaphase would indicate a reduction in the cell cycle rate, suggesting that Sepin-1 is effective in decreasing separase activity.

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Description

Explore the Notch signaling pathway in this quiz focused on AP Biology Unit 4. Understand how Notch receptors and their ligands like Delta interact during fruit fly development and influence gene expression. Test your knowledge with detailed flashcards!