Lecture 18 Review

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary function of axons in neurons?

To send electrical impulses away from the neuronal cell body (correct)

To communicate signals through chemical synapses

To receive signals from muscle fibers

To form protective barriers around neurons

Which type of signaling occurs at short ranges within the same cell?

Endocrine signaling

Intercellular signaling

Neuronal signaling

Autocrine signaling (correct)

What role does the Delta/Notch signaling pathway play in cellular communication?

It facilitates the release of hormones into the bloodstream

It allows for the passive diffusion of molecules between cells

It mediates either inductive signaling or lateral inhibition (correct)

It enhances synaptic transmission between neurons

What is the purpose of synapses in neural signaling?

To terminate axons and facilitate communication with other neurons Signup and view all the answers

What type of signaling occurs over long distances in the body?

Endocrine signaling Signup and view all the answers

What is the primary role of ligands in cell signaling?

To transmit external signals to cells Signup and view all the answers

Which of the following is NOT a possible effect of cell signaling?

Direct alteration of ligands Signup and view all the answers

Which statement best describes the process of cell signaling?

Signal transduction involves relaying and amplifying signals. Signup and view all the answers

What is the estimated number of protein-coding genes involved in cell signaling in humans?

More than 7,000 Signup and view all the answers

In the context of signaling, what does 'migration' refer to?

The movement of cells in response to a signal Signup and view all the answers

Which function is least likely to be influenced by cell signaling?

Detoxification of substances Signup and view all the answers

What is a primary effect of an extracellular signaling molecule?

Altering effector gene expression Signup and view all the answers

Which of the following pathways is unlikely to be directly regulated by cell signaling?

Endogenous toxin degradation pathway Signup and view all the answers

What is the primary function of signal transduction in cells?

To transmit and amplify extracellular signals Signup and view all the answers

Which of the following is NOT one of the four major signaling systems?

Mitotic Signup and view all the answers

What is the primary function of positive feedback loops in cellular memory?

They enhance the expression of protein A and its controlling genes. Signup and view all the answers

What mechanism is involved in lateral inhibition during cell signaling?

Delta-Notch signaling Signup and view all the answers

Which type of receptors act as intracellular receptors?

Nuclear hormone receptors Signup and view all the answers

How are histone modifications inherited by daughter cells?

By the action of histone modifying enzymes. Signup and view all the answers

How do cell surface receptors elicit cellular responses?

By activating intracellular molecules Signup and view all the answers

What role does maintenance methyltransferase play in cell memory?

It maintains DNA methylation patterns during cell division. Signup and view all the answers

What role do molecular switches play in cell signaling?

To transduce signals between proteins Signup and view all the answers

What concept describes the transmission of gene expression patterns without altering DNA sequences?

Epigenetic inheritance Signup and view all the answers

What is a key question regarding the maintenance of cell identity?

How do cells remember developmental decisions? Signup and view all the answers

In female mammals, what mechanism is responsible for dosage compensation of X-linked genes?

Inactivation of one X chromosome. Signup and view all the answers

What does the term 'mosaics' refer to in the context of X inactivation in females?

The varying gene expression across different tissues. Signup and view all the answers

Neutrophils respond to which type of signaling factors?

Chemotactic factors Signup and view all the answers

What happens to melanocytes when the X chromosome carrying the O allele is inactivated?

They become orange due to B allele expression. Signup and view all the answers

Which of the following statements about epigenetic changes is true?

They modify chromatin structure without changing nucleotide sequences. Signup and view all the answers

What action is primarily associated with cortisol?

Affects metabolism of proteins, carbohydrates, and lipids Signup and view all the answers

Which hormone is a derivative of the amino acid tyrosine and stimulates metabolism in many cell types?

Epinephrine Signup and view all the answers

Which of the following hormones is produced by the testis?

Testosterone Signup and view all the answers

What is the chemical nature of nitric oxide (NO)?

Dissolved gas Signup and view all the answers

Which of the following is a function of epidermal growth factor (EGF)?

Stimulates epidermal and other cell types to proliferate Signup and view all the answers

Which hormone induces and maintains secondary female sexual characteristics?

Estradiol Signup and view all the answers

What neurotransmitter is known to be an excitatory agent at many nerve–muscle synapses?

Acetylcholine Signup and view all the answers

What action is associated with histamine?

Causes blood vessels to dilate and become leaky Signup and view all the answers

Which of the following is true regarding the local mediators mentioned?

They include proteins such as EGF and PDGF Signup and view all the answers

The inhibitory neurotransmitter in the central nervous system is:

GABA Signup and view all the answers

What determines the response of a target cell to a signaling molecule?

The type of receptor the target cell has Signup and view all the answers

Which of the following is a characteristic of signaling molecules?

They can vary in size and type Signup and view all the answers

What role do kinases play in intracellular signaling pathways?

They function as molecular switches Signup and view all the answers

How can the same signal lead to different responses in different target cells?

Different receptors or interpretation mechanisms are present Signup and view all the answers

What type of signals act over long distances and are typically transported through the blood?

Endocrine signals Signup and view all the answers

Which type of receptor binds steroid hormones to regulate transcription?

Nuclear hormone receptors Signup and view all the answers

What is the role of feedback regulation in intracellular signaling pathways?

To modulate the cell's response to a signal Signup and view all the answers

In terms of signal integration, what do animal cells do with multiple signals?

They integrate and distribute them to create diverse responses Signup and view all the answers

Which type of signaling involves direct interaction between cells?

Contact-dependent signaling Signup and view all the answers

What is a function of second messengers in signaling pathways?

They provide rapid amplification of the signal Signup and view all the answers

Which of the following describes a characteristic of paracrine signaling?

It involves signaling that is limited to neighboring cells Signup and view all the answers

Which statement is true regarding intracellular signaling pathways?

They may involve multiple adaptors and messengers Signup and view all the answers

What is a common characteristic shared by steroid hormones?

They regulate gene transcription via intracellular receptors Signup and view all the answers

Study Notes

Cell Signaling I

Learning Objectives:
- Understand signal transduction.
- Understand the four major signaling systems: endocrine, paracrine, neuronal, and contact-dependent.
- Understand lateral inhibition mediated by contact-dependent Delta-Notch signaling.
- Understand nuclear hormone receptors acting as intracellular receptors.
- Understand that cell surface receptors use intracellular molecules to elicit cellular responses.
- Understand the concept and major types of molecular switches in signal transduction.

Prelim 3 Information

Exams are taken on Canvas.
Check your new seat assignment by Friday, Nov 8th (either Cal Auditorium or Klarman G70).
Material covers lectures 14-18 and sections 8-9. Grading is based on material taught in class.
Practice Prelim 3 is available on Canvas.
TA review sessions are Saturday/Sunday from 1-4 PM in Biotech Racker Room (instructions on Canvas).
Instructor office hours: Wednesday 1:30-2:30 PM in Biotech 258 and Thursday 7-8 PM on Zoom.
Full instructions are on Canvas. Following instructions is crucial; not following them can result in a 0 on the prelim.
Using AI or Grammarly during the Canvas exam violates Cornell Academic Integrity and will result in a 0.

Gene Expression II Wrap-up

The wrap-up focuses on mechanisms of transcription regulation, generating specialized cell types, and maintaining cell identity.

Cell Memory Mechanisms

Positive Feedback Loops: Protein A activates transcription of itself and other genes controlling cell fate. This creates a self-amplifying process.
Histone Modifications: Parental patterns of histone modifications are inherited and reestablished by enzymes recognizing the same modifications; this passes on patterns to daughter cells.
DNA Methylation: DNA methylation patterns can be passed on to daughter cells through maintenance methyltransferase.

Dosage Compensation

A mechanism to equalize the amount of X chromosome gene expression in males and females.
In mammals, this involves the random inactivation of one X chromosome in females, making them mosaics.
X inactivation is irreversible and uses an epigenetic mechanism.

Cell Signaling I: Migration

Neutrophils respond to chemotactic factors. (Image provided shows a neutrophil responding to chemotactic factors).

Protein-Coding Genes and Cell Signaling

Approximately 7,000 of the ~21,000 protein-coding genes are involved in cell signaling in humans.

General Principles of Cell Signaling

Extracellular signaling molecules (ligands) include proteins, peptides, amino acids, nucleotides, steroids, fatty acids, gases, light, and mechanosensory signals.
Ligands bind to cell-surface or intracellular receptors.
Intracellular signaling pathways relay, amplify, integrate, and distribute signals.
Signaling pathways may alter cell behavior (e.g., cell division, growth, survival, migration, secretion, contraction, differentiation and metabolism).

Types of Receptors

Intracellular Receptors: Small, hydrophobic molecules can pass through the cell membrane and bind to intracellular receptors.
Cell-Surface Receptors: These receptors bind to extracellular signal molecules, activating intracellular signaling pathways.

Steroid Hormones

Steroid hormones bind to intracellular receptors and regulate transcription.
Different hormones bind to different receptors, and each receptor usually regulates different sets of target genes.

Intracellular Signaling Pathways

Intracellular signaling pathways involve relay proteins, second messengers, and feedback mechanisms, which integrate signals and regulate cell function. This leads to altered metabolism, shape/movement, or gene expression in target cells.
Signal transduction occurs rapidly or slowly and this impacts intracellular adaptations in the cell.

Integration of Signals

Cells integrate multiple signals from different sources. This allows the cell to respond more complexly to intracellular signaling.

Animal Cell Responses

Animal cells integrate and distribute multiple signals to produce diverse responses such as apoptosis (programmed cell death), growth + division, and differentiation.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on the fundamental aspects of cell signaling and communication in this quiz. Explore various signaling pathways, mechanisms involved in neuronal signaling, and the effects of ligands. This quiz is designed for students studying biological sciences or cellular biology.