btech final 14

What does "reprogramming" refer to in cell biology?

Ability of fully differentiated cells to become pluripotent

What is the initial potency of a fertilized egg in terms of its ability to form different cell types?

Totipotent

As development progresses, what happens to the potency of cells?

Potency decreases

What guides the funneling of cells into distinct developmental paths?

Signaling and interactions between cells

In developmental biology, what does potency refer to?

Range of cell types a cell can become

At the blastocyst stage, which part forms the embryo itself?

Inner cell mass

From which part of the blastocyst are pluripotent embryonic stem cells derived?

Inner cell mass

How does early differentiation primarily occur at the molecular level?

Altering gene expression

What happens to gene content in fully differentiated cells?

Gene content remains the same

Which term defines transformation of somatic cells into embryonic stem cells?

Reprogramming

What is the primary function of the somatic cell in nuclear transfer experiments?

Contributes nucleus for reprogramming

Why is donor nucleus reprogramming essential in nuclear transfer experiments?

Enables generation of genetically identical organism

What role does the recipient oocyte play in nuclear transfer experiments?

Supplies essential cytoplasm for reprogramming

What is the significance of creating a genetically identical organism?

Tests concept of reproductive cloning

What does reproductive cloning refer to?

Generating fully identical organisms with donor genes

How is the nucleus from a differentiated somatic cell introduced into an enucleated egg?

Using specialized pipettes

Who was the first mammal to be cloned?

Dolly the sheep

What technique was used to create Dolly?

Nucleus transplantation

Approximately how many oocytes were required in Dolly's cloning?

Over 400 oocytes

What happens to nucleus reprogramming capability as cells become more specialized?

It decreases

Why is differentiation a challenge in cloning?

Reprogramming becomes less effective

Which scientists won the Nobel Prize in 2012 for reprogramming research?

Gurdon and Yamanaka

Which scientist developed induced pluripotent stem cells?

Shinya Yamanaka

What was the major achievement of Yamanaka's iPS cell research?

Reprogramming differentiated cells into pluripotent stem cells

How are iPS cells typically created?

Using specific transcription factors

What is the medical significance of iPS cells?

Potential treatment for many diseases and injuries

What is the defining characteristic of iPS cells?

Potential to differentiate into many cell types

Which human cells were reprogrammed into iPS cells in Yamanaka's experiment?

Human fibroblast cells

Which specific factors were used by Yamanaka for reprogramming?

Oct4 and c-Myc

What is one characteristic of cancer?

Systematic breakdown of control mechanisms

What is the principal role of proto-oncogenes in normal cells?

Regulating growth and survival until mutation

What is the typical outcome when proto-oncogenes undergo mutation?

They become oncogenes promoting uncontrolled cell growth

What is the central role of tumor suppressor genes in regulating cell growth?

Halting cell division or inducing cell death

What initiates the transition from G1 phase to S phase in the cell cycle?

G1 cyclin expression

What do cells consider when determining whether to enter the cell cycle?

Balance of growth-promoting and inhibiting signals

Which transcription factor controls transcription activation during the cell cycle?

E2F transcription factor

During early G1 phase, what is the role of Rb protein in relation to E2F?

Prevents E2F from binding DNA

How does G1 cyclin CDK contribute to cell-cycle regulation?

Phosphorylates Rb preventing Rb from binding E2F

What does Rb stand for?

Retinoblastoma

Which disease results from a defect in the Rb gene?

Retinoblastoma

Which tissue is primarily impacted by retinoblastoma?

Retinal tissue

What inheritance pattern is typical of familial retinoblastoma?

Autosomal dominant

What is notable about unaffected individuals carrying a defective Rb gene?

They can have affected offspring

When does cancer predisposition become relevant in individuals with one functional Rb gene?

When a second mutation occurs in the other Rb gene

Which mechanisms are linked to Rb gene inactivation leading to cancer?

Point mutation, chromosome loss/translocation, and epigenetic changes

What specialized compartment in colon crypts is crucial for cell renewal and regeneration?

Stem cell niche

After renewal from the stem cell niche, where do colon crypt cells migrate?

Toward the intestinal lumen

What does the cancer barrier refer to in colon tumor formation?

Obstacles preventing tumor formation and cancer-cell accumulation

What risk is associated with hindrance of cancer-cell shedding in the colon?

Accumulation of cancer cells within the colon

Which gene is associated with Familial Adenomatous Polyposis (FAP)?

APC gene

What does FAP stand for?

Familial Adenomatous Polyposis

What is a consequence of APC gene mutations?

Familial Adenomatous Polyposis

What is the primary consequence of APC gene loss in colon cancer?

Continuous activation of Wnt signaling

Which molecule accumulates when APC is lost?

β-catenin

What is a common feature of early colon cancer after APC loss?

Uncontrolled cell growth and tumor formation

Which condition involves ABL activation due to chromosomal translocation?

Chronic Myelogenous Leukemia (CML)

What event activates the ABL gene in CML?

Chromosomal translocation

What are genes like ABL called when they can cause uncontrolled growth after mutation?

Proto-oncogenes

What is the primary mechanism of action of Gleevec (imatinib)?

Inhibits ABL kinase and renders it inactive

Which type of immunity provides a broad defense mechanism and is less specific to pathogens?

Innate immunity

What is a characteristic feature of adaptive immunity?

Highly specific to pathogens

Which type of immunity involves production of antibodies by B cells?

Humoral immunity

Cell-mediated immunity primarily relies on which immune cells?

T cells

What common feature is present in both humoral and cellular immunity?

Antigen receptors

What is the main role of antigen receptors?

Identifying specific antigens for immune response

What is another term for an antibody/B-cell receptor?

Immunoglobulin (IG)

What is the basic structural composition of an antibody?

Two identical heavy chains and two light chains

What are the two forms of antibodies?

Secreted and membrane-bound

Which antibody form is predominantly used during infections?

Secreted form

What are the primary components of the T-cell receptor (TCR)?

Alpha and beta chains

What is a key characteristic of antibodies regarding specificity?

Each antibody targets a unique structure

What role do hypervariable regions play in antigen recognition?

Crucial for precise antigen recognition

What is the relationship between each B cell and the antibodies it produces?

Each B cell produces a unique antibody

Why is it impractical to have a unique gene for every antibody?

Large number of potential antibody specificities

Which mechanism contributes to generation of diverse antibody specificities?

Somatic recombination

How many V, D, and J segments are available for the heavy-chain gene?

45 V, 23 D, and 6 J segments

What is the minimum requirement for a functional antibody heavy chain?

One V, one D, and one J segment

Why is having many V, D, and J segments significant?

Generates a wide range of antibody specificities

Which recombinases mediate V(D)J recombination?

RAG1 and RAG2

What may occur during junctional imprecision?

Nucleotide insertion or deletion

How does junctional imprecision contribute to antibody diversity?

Introduces variations in nucleotide sequences

How does somatic mutation enhance antibody affinity?

Introduces random mutations in the variable region

What is the primary outcome of affinity maturation?

Enhanced antibody affinity for antigens

What is the consequence of allelic exclusion?

Each B cell expresses only one antibody

What is allelic expansion used for in monoclonal antibody production?

Cloning and propagating B cells with identical specificity

What is the purpose of monoclonal antibody production?

Producing antibodies from a single B-cell clone

How does antibody affinity during secondary infection compare with primary infection?

Stronger in secondary infection

What are monoclonal antibodies primarily used for in targeted therapies?

Targeting specific molecules or cells involved in disease processes

Which growth factor receptor is overexpressed in approximately 30% of breast cancers?

HER2

What role does HER2 overexpression play in cancer development?

Enhances cell growth, survival, and proliferation

What type of treatment is Herceptin?

Antibody-based therapy

What specific target does Herceptin recognize?

HER2

How does Herceptin affect HER2 function?

Blocks HER2 function

What additional mechanism of action does Herceptin possess?

Recruits immune cells to kill cancer cells

What is the primary source of peptides presented by MHC Class I molecules?

Intracellular proteins in the cytoplasm

Which T cells primarily interact with MHC Class I?

CD8 cytotoxic T cells

On which cells is MHC Class II primarily expressed?

B cells and dendritic cells

What is the main source of peptides presented by MHC Class II molecules?

Extracellular substances taken up via phagocytosis

Which T cells primarily interact with MHC Class II?

CD4 helper T cells

What is the primary function of CD8 T cells?

Kill infected cells