Mol bio lecture 2 pt2

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Questions and Answers

What is a key consequence of terminal differentiation in cells?

Change in gene expression patterns (correct)

Increased motility and proliferation

Loss of cellular identity

Enhanced ability to respond to all growth signals

During which stage of early embryonic development does the shift from maternal control to zygotic control occur?

Zygote development into morula

Fertilization

Mid-blastula transition (correct)

Formation of germ layers

What defines pluripotent cells?

Ability to develop into almost all cell types except extraembryonic tissues (correct)

Ability to differentiate into any cell type, including extraembryonic tissues

Cells that have fully differentiated into specific cell types

Cells that can only contribute to one type of tissue

What role do transcription factors play in cellular differentiation?

Control gene expression patterns associated with differentiation Signup and view all the answers

Which process occurs immediately after the formation of germ layers in embryonic development?

Organogenesis Signup and view all the answers

What characterizes differentiated cells compared to stem cells?

Altered responsiveness to growth signaling Signup and view all the answers

What is the definition of 'determination' in the context of cellular differentiation?

The commitment of a cell to a specific fate Signup and view all the answers

Which transcription factor is primarily responsible for maintaining pluripotency?

Oct4 Signup and view all the answers

What describes the concept of morphogenesis?

The development of tissues and organs during embryogenesis Signup and view all the answers

What contributes to the shift in gene expression during the transition from zygotic control?

The embryo using its own genome for transcription Signup and view all the answers

What is a primary characteristic of the G1 phase in pluripotent cells compared to differentiated cells?

Shorter G1 phase Signup and view all the answers

In embryonic development, what characterizes the cells immediately after the fertilized ovum stage?

They are totipotent and capable of forming any cell type Signup and view all the answers

During reprogramming, cells exhibit what kind of cell cycle profile?

Intermediate cell cycle profile Signup and view all the answers

How does the S phase duration in pluripotent cells compare to that in differentiated cells?

S phase is longer in pluripotent cells Signup and view all the answers

What role do cyclins play in the cell cycle?

Control progression of the cell cycle Signup and view all the answers

Which statement best describes the primary function of transcription factors in programming?

They promote changes in gene expression leading to differentiation Signup and view all the answers

How does the length of the overall cell cycle in pluripotent cells compare to that in differentiated cells?

Overall cycle is shorter in pluripotent cells Signup and view all the answers

Which process describes the conversion of a differentiated cell back to a pluripotent state?

Reprogramming Signup and view all the answers

How does chromatin's state during mitosis affect gene transcription?

Chromatin is condensed, leading to suppressed transcription. Signup and view all the answers

What alteration typically occurs in the phosphorylation of Rb in pluripotent cells?

Altered timing of phosphorylation occurs Signup and view all the answers

What is the primary characteristic of gene transcription during the G1 phase after mitosis?

Transcription is reactivated to prepare for the next cell cycle. Signup and view all the answers

How is the cell cycle of differentiated cells generally characterized?

Slower rate and more controlled Signup and view all the answers

What unexpected finding was revealed about the gene transcription after mitosis?

Specific transcription factors are actively involved in reactivation immediately after mitosis. Signup and view all the answers

Which of the following statements about chromatin conditions during mitosis is true?

It suppresses transcriptional activity due to tight packaging. Signup and view all the answers

What role do chromatin remodeling complexes play immediately after mitosis?

They facilitate the reestablishment of transcriptional programs. Signup and view all the answers

What was a common belief about gene transcription after mitosis prior to new research findings?

A longer period of chromatin relaxation was required before transcription could resume. Signup and view all the answers

Why is the transcriptional reactivation immediately after mitosis significant?

It demonstrates cells' preparedness for the next cell cycle phase. Signup and view all the answers

What happens to gene transcription activity during the mitotic phase?

Transcription is largely suppressed due to condensed chromatin. Signup and view all the answers

What is the primary consequence of constitutive binding of APC and CDC20 during cell cycle progression?

Continuous activation of the APC/C Signup and view all the answers

Which aspect distinguishes differentiated cells from their stem cell counterparts?

Altered gene expression patterns Signup and view all the answers

During which stages does a true change in chromosome content occur?

After S-phase and anaphase Signup and view all the answers

What would likely happen if securin is irreversibly bound to separase during mitosis?

Cohesion remains intact Signup and view all the answers

What type of error would cause a cell to stall in prophase?

Disruption of microtubule dynamics Signup and view all the answers

What is the role of Cyclin D in the cell cycle?

It is crucial for progressing through the G1 phase at the restriction point. Signup and view all the answers

Which statement accurately describes the function of the Retinoblastoma Protein (Rb)?

It regulates the restriction point by inhibiting E2F transcription factors. Signup and view all the answers

What is the distinction between totipotent and pluripotent cells?

Pluripotent cells can differentiate into any cell type but not into extraembryonic tissues. Signup and view all the answers

What does the process of differentiation entail?

Acquisition of a more specialized structural and functional role. Signup and view all the answers

Which factor is crucial for activating genes necessary for DNA replication?

Rb after phosphorylation Signup and view all the answers

What role do transcription factors play in stem cells?

They can induce a pluripotent state through reprogramming. Signup and view all the answers

What characterizes 'morphogenesis' during development?

It includes the development of the shape and form of tissues and organs. Signup and view all the answers

What is the consequence of dysregulated activation of separase during mitosis?

It causes premature separation of sister chromatids. Signup and view all the answers

Which of the following describes terminal differentiation?

It contributes to behaviors like motility and proliferation. Signup and view all the answers

What is the main function of tumor suppressors like p53 and p21 in the cell cycle?

To induce cell cycle arrest in the presence of DNA damage. Signup and view all the answers

Study Notes

Gene Transcription in Mitosis

During mitosis, chromatin is highly condensed, resulting in suppressed transcriptional activity.
Transcription is globally reduced due to limited accessibility of the transcriptional machinery to DNA.
After mitosis, transcription reactivation begins, crucial for cell growth and preparation for the next cycle.
Recent findings indicate specific genes are reactivated immediately post-mitosis, contradicting earlier beliefs about transcription remaining silent during this period.

Role of Transcription Factors in Differentiation

Terminal differentiation affects cell behaviors, including motility and proliferation.
Differentiation results in distinct patterns of gene expression, leading to functional diversity among cells.
Differentiated cells often exhibit reduced proliferative potential compared to naïve or stem cells.
Key gene expression patterns linked to cell division and different responsiveness to growth signals are altered in differentiated cells.

Pluripotency vs. Differentiation

Pluripotent cells can become most cell types, while differentiated cells are more specialized.
Pluripotent cells exhibit shorter G1 and G2 phases, and a longer S phase, allowing rapid division.
Differentiated cells have longer G1 phases and a controlled, slower cycle, maintaining tissue homeostasis.

Programming and Reprogramming

Programming refers to differentiation from a pluripotent state, while reprogramming involves reverting differentiated cells back to pluripotency, as seen in iPSCs.
Programming is controlled by transcription factors that drive differentiation.
Reprogramming requires specific transcription factors to restore pluripotency.

Terms and Definitions

Totipotent: Cells that can differentiate into all cell types, including embryonic and extraembryonic tissues (e.g., zygote).
Pluripotent: Cells that can become nearly all cell types, excluding extraembryonic tissues (e.g., embryonic stem cells).
Embryonic Stem Cell (ESC): A type of pluripotent stem cell derived from the inner cell mass of a blastocyst, capable of self-renewal.
Differentiation: Process by which a less specialized cell evolves into a more specialized state.
Morphogenesis: Development of cells and tissues into their distinct shapes and forms during embryogenesis.

Developmental Stages

Shifts from maternal control to zygotic control occur at the mid-blastula transition (MBT), where transcription begins using the embryo's genome.
Early embryonic stages consist of totipotent cells leading to pluripotent states, eventually transitioning to committed cells during organogenesis.
Germ layer formation and differentiation occur as structures mature and cells acquire specific functions.

Effects of Dysregulated Cell Cycle Proteins

Dysregulated separase activation can cause premature sister chromatid separation; not halting mitosis but causes errors.
Continuous activation of APC/C could lead to premature cyclin degradation, affecting cell cycle progression.
Inactivation of securin prevents correct separase activation, potentially delaying mitosis.

Key Regulatory Proteins

Cyclins and cyclin-dependent kinases (CDKs) regulate cell cycle progression.
Rb protein and E2F transcription factors play crucial roles at the restriction point, ensuring controlled progression through the cell cycle.
Tumor suppressors p53 and p21 induce cell cycle arrest in response to DNA damage, preventing flawed propagation.

Observations of Chromosome Changes

Changes in chromosome content happen post-S phase and after anaphase, marking significant transitions in the cell cycle.
Conflicts during prophase might occur due to disruptions in microtubule dynamics or other mitotic processes.

Developmental Influence Factors

Determination and differentiation during embryogenesis are influenced by positional factors, hormones, paracrine factors, and external teratogens.
The overall progression during embryonic development transitions from totipotent to pluripotent to differentiated states.

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Description

This quiz explores the dynamics of gene transcription during mitosis and the role of transcription factors in cell differentiation. It discusses how chromatin's condensed state during mitosis impacts transcriptional activity and the subsequent reactivation vital for cell growth. The quiz also covers the significance of gene expression patterns in differentiating cells and their varied responses to growth signals.