Classification of Life and Abiogenesis vs Biogenesis
Today's Outline
Topic: Classification of Life / Abiogenesis vs Biogenesis
Class Outline:
HeLa Discussion
Notes
Assigned Questions
Today's Assigned work:
Abiogenesis/Biogenesis Questions
Quote: "Kites rise highest against the wind - not with it."
HeLa Discussion: Overview of HeLa Cells
What was the symptom that caused Henrietta to go to the doctor and what did they find?
Henrietta Lacks experienced a tumor on her cervix, which led her to seek medical attention.
Doctors diagnosed her with cervical cancer, progressing rapidly.
What were Margaret and George Gey looking for, and what did they do with them?
George Gey was searching for human cells that could continuously grow in culture without dying.
He took a biopsy of Henrietta’s cancerous cells without her knowledge or consent.
What was remarkable about HeLa cells?
HeLa cells were the first human cells that could be grown indefinitely outside the human body.
They were characterized as immortal due to their ability to divide endlessly.
List at least 3 uses that researchers had for the HeLa cells.
Development of the polio vaccine
Research in cancer genetics
Testing the effects of radiation on human cells
Development of drugs for various diseases such as leukemia and Parkinson's disease
How did the doctors talk David Lacks into allowing them to take cell samples from Henrietta?
They presented it as a routine procedure to gather samples for research, assuring him it was essential for her treatment.
How did the Lacks family find out about the HeLa cells, 24 years later?
They were informed during a conversation with a researcher who was seeking to understand the genetic history of the HeLa cells.
They learned that Henrietta’s cells were used widely in research and developed a significant commercial value.
What had happened with the growth of HeLa cells around the world?
HeLa cells became widely distributed and studied globally, with millions of cultures existing.
Identify two ethical questions that the Lacks case brings up.
The issue of informed consent when using human tissue for research purposes.
The ownership of biological materials after a patient's death
What are some of the changes in scientific research that have been made as a result of this case?
Stricter regulations regarding informed consent
Ethical guidelines for the use of human cells in research
Recognition of patient rights and the need for transparency in research practices
About HeLa - Henrietta Lacks
Definition: HeLa is an immortal cell line used in scientific research.
Origin: Derived from the cervical cancer cells of Henrietta Lacks, who died on October 4, 1951.
Awareness: Neither Henrietta nor her family were aware that her cells were harvested for research purposes.
Characteristics:
First cells that could divide indefinitely outside the human body, thus deemed immortal.
Over 800 billion cells have been produced from her original sample.
Significance of HeLa Cells
Robustness: HeLa cells are noted for their unique properties, dividing continuously and remaining difficult to destroy.
Impact: HeLa cells have significantly influenced various scientific discoveries, including:
Development of the polio vaccine
Advancements in virology
Identification of cancer-causing genes
Research leading to drugs for conditions including leukemia and Parkinson's disease
Establishing methods for cell freezing and in vitro fertilization
Studies on the effects of radiation and environmental changes on human cells
Use as alternatives to lab animals for testing medical and cosmetic products
Research on aging and immune responses
Controversies Surrounding HeLa Cells
Cells were taken from Henrietta Lacks without her or her family’s consent.
Highlights the need for laws protecting patient rights and the informed consent process.
Ethical debates about selling cells/tissue for profit.
The robustness of HeLa cells led to contamination issues with other cell cultures.
Issues of gene patents related to HeLa cells.
Classification of Life
10 Characteristics of Life
Organization
Living things are organized on both molecular and cellular levels.
Composition of life at various levels:
Cell: Basic unit of life.
Tissue: Group of cells performing a common function.
Organ: Group of tissues performing a common function.
Organ System: Group of organs performing a common function.
Organism: A complete living entity.
Reproduction
Essential for the survival of a species, not for an individual.
Types of reproduction:
Asexual Reproduction: No gametes involved.
Sexual Reproduction: Involves gametes (sex cells).
Growth and Development
Involves cellular division leading to growth.
Some cells specialize, undergoing differentiation to perform distinct functions.
Nutrition (Feeding)
Organisms must obtain energy to live through various metabolic processes.
Types based on energy acquisition:
Autotrophs: Generate energy from sunlight.
Heterotrophs: Obtain energy from consuming nutrients.
Respiration
The process of breaking down food to produce energy, fueling cellular activities.
Excretion
The process of discharging waste substances from the body.
Responsiveness
Living organisms respond to environmental stimuli using their senses.
Example: Physically reacting to unpleasant smells or touch.
Movement
Refers to both internal (organelles and fluids) and external (locomotion) movement of organisms.
Homeostasis
The ability to maintain stable internal conditions despite external changes, including temperature and pressure.
Evolution
Changes in the characteristics of organisms across generations due to environmental pressures.
Major Question in Biology
Can living things come from nonliving things?
Origins of Life Theories
Abiogenesis: The theory that non-living things can give rise to living organisms, synonymous with spontaneous generation.
Biogenesis: The principle that life arises only from pre-existing life forms, opposing the notion of spontaneous generation.
Historical Perspectives
Aristotle (384-322 BC) introduced the theory of spontaneous generation, suggesting that living things can arise from nonliving matter, a concept that persisted for nearly 2000 years.
Examples of Spontaneous Generation Beliefs
Example #1: Flooding of the Nile led to nutrient-rich mud coinciding with large appearances of frogs, leading to a conclusion that mud created frogs.
Example #2: Decaying grain in leaky barns led to a belief that mice were generated from spoiled grain.
Example #3: Conditions in ancient cities allowed for the conclusion that sewage transformed into rats.
Transition to Scientific Methodology
Prior to experimentation, beliefs were largely based on observation without scientific testing.
The need for empirical data and experiments became evident to counter spontaneous generation claims.
Key Experiments Concerning Spontaneous Generation
Van Helmont's 17th-century Experiment
In an unscientific attempt, he placed sweaty underwear and grains in a jar and claimed that mice were generated from this combination.
This experiment lacked proper scientific methodology.
Francesco Redi’s Experiment (1668)
Aimed to test spontaneous generation using open and closed jars with meat.
Findings:
No maggots appeared in closed jars, while open jars had maggots, leading to the conclusion that flies generated maggots, not meat.
John Needham’s Experiment (1745)
He boiled broth which later showed microbial growth, supporting spontaneous generation claims but lacked proper boiling duration to kill microbes.
Lazzaro Spallanzani’s Experiment (1765)
He boiled broth for an extended period and sealed the containers, preventing microbial growth and disproving Needham’s findings.
Louis Pasteur's Experiment (1864)
Used swan-necked flasks to show that microbial growth came only from contamination, ultimately disproving the theory of spontaneous generation for microscopic organisms.
Conclusion: Life arises from life, not nonliving matter, marking a significant turning point in biological sciences.
Conclusion
The debate on abiogenesis versus biogenesis was settled, favoring biogenesis as established through key experiments and scientific inquiry.
To Do
Work on the Biogenesis vs Abiogenesis worksheet.