Lecture 1 Flashcards
Major characteristics of life
- Biological and ecological hierarchy to life
- Living organisms are made up of cells
- Living organisms are organized
- Life requires energy transfer & transformation
- Cells/organisms reproduce
- Cells/organisms/ecosystems grow & develop
- Cells/organisms interact with their environment: respond to stimuli
- Cells/organisms/ecosystems maintain homeostasis
- Organisms form populations that can evolve & adapt
Structural levels in biological organization.
- Organs: a body part that is made up of multiple tissues and has specific functions in the body
- Tissues: Each tissue is a group of cells that work together, performing a specialized function
- Cell: life’s fundamental unit of structure
- Organelles: various functional components present in cells
Structural levels in ecological levels
- Biosphere: All life on Earth and all the places where life exists
- Ecosystem: All the living things in a particular area, along with all the nonliving components of the environment with which life interacts (soil, water, atmospheric gases, and light)
- Communities: Array of organisms inhabiting a particular ecosystem (plants, animals, mushrooms, fungi, microorganisms like bacteria,…)
- Populations: All individuals of a species living within the bounds of a specified area
Organism: Individual living things
Types of reproduction
- Asexual:
–to make new organism
(mitosis of an amoeba, binary fission in bacteria)
– To make new cells in a multicellular organism (mitosis) - Sexual: occurs through fusion of gametes (via meiosis)
Growth and development
Grow: Size and/or #cells. Mostly through the reproduction of cells (mitosis).
Development: All the changes that take place during an organism’s life
Stimulus
physical or chemical change in the internal or external environment
Homeostasis
the maintenance of relatively stable internal environment despite continuous changes in the external environment.
- A dynamic state of equilibrium, always readjusting as needed
Maintaining homeostasis
At level of the cell and organism
- At level of the cell:
pH, water content, levels of ATP … - At level of the organism:
Huge temperature changes outside→ minimal changes in body temperature.
Amount of sugar & other nutrients: huge changes throughout the day → small changes in blood levels.
Other variables that change, but only slightly: blood volume, pH of blood, O2 and CO2 levels
Negative feedback - Homeostasis
Negative Feedback is a regulatory mechanism that returns a variable to its target value
Reverses the direction of change to re-establish target conditions & so maintain homeostasis
Ex. Blood sugar falls below normal: negative feedback mechanism bring it back up to target (normal) value
Positive feedback
Positive feedback is a process that occurs in a feedback loop in which the response enhances the original stimulus: move further away from starting point, not back to it
For example blood clotting, and child labour
Characteristics of life point to 5 common themes
Organization theme: life is organized in such a way that at each level it becomes more complex, and new properties emerge (ex Cell is > a collection of organelles: it is alive, organelles are not)
Information theme: life’s processes involve the expression & transmission of genetic information: genes are expressed, DNA is passed from 1 generation to the next.
Energy & matter theme: life requires the transfer & transformation of energy & matter: at the cellular level & at the ecosystem level (ie producers, consumers, decomposers)
Interaction theme: Cellular level + & - feedback systems of molecules. Organismal level: cells interact with each other. Ecosystem level: organisms interact with each other & their physical environment.
Evolution theme: populations of living organisms can evolve, resulting in both unity of features (if have a common ancestor) and diversity.
3 domains and its kingdoms
Bacteria Domain
Archaea Domain
Eukarya Domain:
- Kingdoms: Fungus, Plant, Animal, Protistan kingdoms
Taxonomic classification hierarchy
Domains* Kingdoms* Phyla Classes Families Genera* Species*
Taxonomic classification Binomial System
2 part-name: Genus & species Genus: Closely related species Species: group of organisms with similar structure, function & behaviour eg: Homo (Genus) sapiens (species)
Characteristics shared by all cells ie what do all cells have
(1) a plasma membrane, an outer covering that separates the cell’s interior from its surrounding environment;
(2) cytoplasm, consisting of a jelly-like region within the cell in which other cellular components are found;
(3) DNA, the genetic material of the cell; and
(4) ribosomes, particles that synthesize proteins
