Lecture 1 Flashcards
9 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: 8. respond to stimuli
- Cells/organisms/ecosystems maintain homeostasis
- Organisms form populations that can evolve & adapt
Biological organization:
atom→molecule→macromolecule→organelle→cell→tissue→organ→organ system→organism
Chemical level: atoms, molecules, organelles
Biological organization of humans at different levels
Cellular level: single cell
Tissue level: groups of similar cells
Organ level: contains two or more types of tissues
Organ system level: organs that work closely together
Organismal level: all organ systems combined to make the whole organism
Ecological organization:
Population→community→ecosystem→biosphere
Population:
group of individuals of the same species, living in the same area
Community:
all populations of organisms living in a particular area at the same time
Ecosystem:
a community + its nonliving, physical environment
Biosphere:
all of the ecosystems on Earth
characteristics of cells
The cell is the smallest unit considered to be alive (organelles are not alive)
All new cells come from preexisting cells
Humans are made up of about 50 trillion cells
Unicellular or multicellular
Cells do:
Metabolism: all reactions to build up or breakdown molecules, cells, tissues
Maintain homeostasis
Living organisms get their energy from?
the sun or by consuming other organisms.
Self sufficient ecosystem:
producers, consumers, decomposers
types of reproduction
Asexual reproduction: mitosis
Sexual reproduction: occurs through fusion of gametes, meiosis
growth vs development
Grow: size &/or number of cells. Mostly through the reproduction of cells (mitosis)
Development: all the changes that take place during an organism’s life
definition of stimuli
physical or chemical change in the internal or external environment
physical and biological stimulus?
Physical environment: abiotic component
Biological environment: other living organisms
Homeostasis:
maintenance of a relatively stable internal environment despite continuous changes in the external environment. It’s a dynamic state of equilibrium, always readjusting as needed
what is homeostasis defined at cell level and organism level
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:
Regulatory mechanism that returns a variable to its target value
Reverses the direction of change to re-establish target conditions and so maintain homeostasis.
Positive feedback:
Loop in which the response enhances the original stimulus: move further away from starting point, not back to it
Usually controls infrequent events that do not require continuous adjustment
Evolution: unity and diversity of life
Change in environment
Those best suited to change survive
Offspring (descendants) have these traits
The characteristics of life point to 5 common themes
- Organization theme: life is organized in such way that at each level it becomes more complex, and new properties emerge
- Information theme: expression and transmission of genetic information: genes are expressed, DNA is passed from one generation to next
- Energy and matter theme: transfer and transformation of energy and matter: at the cellular level and at the ecosystem level (producers, consumers, decomposers)
- Interaction theme: cellular level: + and - feedback. Organismal level: cells interact with each other. Ecosystem level: organisms interact with each other and their physical environment
- Evolution theme: populations of living organisms can evolve, resulting in both unity of features and diversity
how many species currently living
2 million species currently living
Taxonomy:
naming and classifying organisms
3 domains:
prokaryotic cells (bacteria and Archaea), eukaryotic cells (Eukarya)
4 kingdoms:
fungus, plant, animal, protistan kingdoms
Taxonomic classification is hierarchical:
Domains→Kingdoms→Phyla→Classes→Orders→Families→Genera→Species
do prokaryotic cells have mitochondria
no.
