Cell communication and Cell cycle Flashcards
What happens in the G1 stage of interphase?
Cell grows and functions normally.
G1 is the first stage of interphase, where the cell prepares for DNA replication.
What occurs during the S (Synthesis) stage of interphase?
DNA replication occurs.
This is the phase where the cell duplicates its genetic material.
What is the purpose of the G2 stage of interphase?
Prepares for mitosis by duplicating organelles and checking for errors.
G2 is crucial for ensuring the cell is ready for division.
List the four phases of mitosis.
- Prophase
- Metaphase
- Anaphase
- Telophase
These phases describe the process of nuclear division.
What happens during prophase?
Chromosomes condense, spindle fibers form.
Prophase is the first phase of mitosis where chromosomes become visible.
What occurs in metaphase?
Chromosomes align at the equator.
This alignment is critical for proper separation of chromatids.
What happens during anaphase?
Sister chromatids separate and move to poles.
Anaphase ensures that each daughter cell receives an identical set of chromosomes.
What occurs in telophase?
Two nuclei form, chromosomes de-condense.
Telophase is the final stage of mitosis, leading to the end of nuclear division.
What is cytokinesis?
The cytoplasm divides, forming two identical daughter cells.
Cytokinesis typically follows mitosis and completes the cell division process.
What does the G1 checkpoint check for?
Checks for DNA damage before replication.
The G1 checkpoint is crucial for preventing the replication of damaged DNA.
What is the purpose of the G2 checkpoint?
Ensures DNA replication is error-free.
This checkpoint helps to maintain genomic integrity.
What does the M checkpoint verify?
Verifies proper chromosome attachment to spindle fibers.
This checkpoint is essential for accurate chromosome segregation.
How does cancer occur at the cellular level?
Uncontrolled cell division due to mutations in genes that regulate the cell cycle.
These mutations can arise from various factors, leading to tumor formation.
What are oncogenes?
Mutated proto-oncogenes that cause excessive cell growth (e.g., RAS gene).
Oncogenes promote cancerous growth when activated.
What are tumor suppressor genes?
Normally prevent division; mutations turn them off (e.g., p53 gene).
Tumor suppressor genes play a protective role against cancer development.
What is apoptosis?
Programmed cell death.
Apoptosis is a critical process for eliminating damaged or unnecessary cells.
How does the failure of apoptosis contribute to cancer?
Cancer cells bypass apoptosis, leading to uncontrolled proliferation.
This evasion of cell death allows cancer cells to survive and grow unchecked.
What is metastasis in cancer?
Cancer cells break off, travel through the bloodstream, and invade other tissues.
Metastasis is a key factor in cancer progression and severity.
What factors cause mutations leading to cancer?
- UV radiation
- Carcinogens (chemicals)
- Viruses (HPV)
- Genetic predisposition
These factors can damage DNA and lead to cancerous changes.
What are the three steps of a signal transduction pathway?
- Reception
- Transduction
- Response
These steps describe how cells convert external signals into internal actions.
What happens during the reception step of a signal transduction pathway?
Ligand binds to a receptor (on membrane or inside cell).
This step is crucial for initiating the signaling process.
What occurs in the transduction step of a signal transduction pathway?
Signal relayed via secondary messengers or a phosphorylation cascade.
This step amplifies the signal and transmits it inside the cell.
What is the response step in a signal transduction pathway?
Cellular activity changes (e.g., enzyme activation, gene expression).
The response results in a physiological change in the cell.
How does the epinephrine transduction pathway work?
- Epinephrine binds to a GPCR
- G-protein activates adenylyl cyclase
- Adenylyl cyclase converts ATP to cAMP
- cAMP activates protein kinase
- Protein kinase triggers glycogen breakdown, releasing glucose
This pathway illustrates how a hormone can trigger a rapid response in the body.
