Chapter 8 The developing cell Flashcards
What is the cell cycle?
Cycle of cell growth, maturity, and division producing 2 genetically identical daughter cells
Highly ordered sequence of events used by somatic cells in multicellular organisms.
How long does the cell cycle take for embryo cells?
8-60 minutes
What is the duration of the cell cycle for liver cells?
Approximately 1 year
What are the main stages of the cell cycle?
Interphase, Mitosis, Cytokinesis
What occurs during the G1 phase of interphase?
Cell increases in size & mass; metabolic processes remain active
Includes protein synthesis, hormone production, and respiration.
What is the G1 checkpoint responsible for?
Cells check for chemicals needed for replication, DNA damage, cell size, and nutrient sufficiency.
During which phase is DNA replicated?
Synthesis (S) phase
What happens during the G2 phase of interphase?
Chloroplasts and mitochondria increase in size and number; centrioles replicate
Cell continues to grow and prepares for mitosis.
What is mitosis primarily responsible for?
Nuclear division producing 2 genetically identical nuclei.
What are the stages of mitosis?
Prophase, Metaphase, Anaphase, Telophase
What is cytokinesis?
Equal division of cytosol and organelles, forming 2 genetically identical daughter cells.
What is the role of cyclins in the cell cycle?
Control sequence and timing of the cell cycle by activating CDKs.
What can mutations in cyclin or CDK genes lead to?
Failure to repair DNA, potentially resulting in cancer.
What is the lifespan of erythrocytes?
Approximately 120 days
What are chromosomes made of?
One molecule of DNA, found in pairs, carrying hundreds to thousands of genes.
What are chromatids?
Parts of a chromosome after semi-conservative replication, genetically identical to each other.
What defines homologous chromosomes?
Pairs of chromosomes with same structure and gene sequence, but different origins and alleles.
What is the function of telomeres?
Protect chromosomes from damage and prevent fusion with neighboring chromosomes.
What happens to telomeres with each cell division?
They shorten, usually by 25-200 base pairs.
What is apoptosis?
Programmed cell death in multicellular organisms.
What is necrosis?
Unregulated cell death due to trauma, leading to cell membrane rupture.
What is the significance of apoptosis during development?
Essential for processes like fetal development and immune system formation.
What are stem cells characterized by?
Undifferentiated state, ability to divide by mitosis, and large nuclear:cytoplasmic ratio.
What are totipotent stem cells?
Stem cells that can form all cell types in a body, including placental cells.
What are pluripotent stem cells?
Stem cells that can give rise to all body cell types but not placental cells.
What are multipotent stem cells?
Stem cells that can develop into a limited number of cell types.
What occurs during the G0 phase of the cell cycle?
Cells enter a resting state and no longer divide.
What happens during cell differentiation?
Cells become specialized and switch off certain genes.
What are stem cells that can develop into more than one cell type but are more limited than pluripotent cells called?
Multipotent stem cells
Examples include adult stem cells in bone marrow and cord blood stem cells.
What is multipotency?
The ability of a stem cell to differentiate into discrete cell types
For example, a multipotent blood stem cell can differentiate into various types of blood cells.
Define totipotent stem cells.
Stem cells that can differentiate into all types of cells within an organism
Found in very early embryos before the 50 cell stage in animals and in meristematic tissue in plants.
What are pluripotent stem cells?
Stem cells that can give rise to any cells of the organism except extra-embryonic cells
Examples include the inner cell mass of the blastocyst.
List three uses of pluripotent stem cells.
- Cell replacement therapies
- Drug testing in vitro
- Studying development of diseases in vitro
What characterizes multipotent stem cells in terms of their appearance?
Typically round cells with very little cytoplasm relative to the size of their nuclei
Example includes haemocytoblasts in bone marrow.
What are some potential future uses for multipotent stem cells?
Possible future use for nervous system diseases such as Parkinson’s and Alzheimer’s disease
Also used to treat leukemia and other blood cancers.
What is one ethical problem with potential stem cell therapies?
The technology could be used for reproductive cloning
Cloning humans raises ethical concerns.
What is a significant concern regarding the creation of stem cell lines?
It requires the destruction of human embryos
Some believe this constitutes the taking of a human life.
What argument is made regarding the rights of human embryos?
Some argue that human embryos have the same rights as individuals
They have the potential to develop into an individual.
What is a concern associated with stem cell transplants?
They have the potential to produce tumors
Tumors can arise from the transplanted cells.
What are induced pluripotent stem cells (iPSCs)?
Differentiated adult cells reprogrammed back into pluripotent stem cells
These may cause tumors called teratomas.
True or False: Embryonic stem cell (ESC) research has produced viable long-term treatments.
False
ESC research has not yet yielded viable long-term treatments, unlike some adult stem cell treatments.
