Chapter 1 Principles of Life Flashcards
Common characteristics in living organisms is evidence for a common ancestor. What are key common characteristics in living organism?
- common chemical composition
- depend on interactions of complex parts to maintain life
- contain genetic information with nearly universal code for assembly of proteins
- extract energy to carry out life functions
- convert molecules form environment into new biological molecules
- replicate genetic information in same manner for reproduction
- structural similarities in fundamental genes
- evolve through gradual changes in genetic information
*some forms of life don’t show all these characteristics at all times
What is endosymbiosis?
Absorption of smaller cells by larger cells. Leading to the formation of organelles
How did multicellularity evolve
Arose from one cell failing to divide after replicating. Allowed some cells to specialise in certain functions
How does gene replication lead to biodiversity?
Genome replication is imperfect. Each time mutations occur which lead to structural and functional changes in organisms leading evolution of populations over time
How are species named?
Named by genus then species
Binomial
What are the 3 domains of organisms
Archaea, bacteria and eukaryotes
What is the second law of thermodynamics and how does it apply to living organisms?
Organised entities tend to become more random.
Organisation is key for maintaining life (allows organelles andcells to work together), and energy is necessary for maintaining organisation.
Describe internal hierarchy
Atom - small molecule - large molecule - cell - cell specialisation - tissue - organ - system - multicellular organism
Describe external hierarchy
Population - community - landscape - biosphere
Population: groups of one species living together and interacting
Community: populations of the same or different species in one area
Landscape: multiple communities
Biosphere: entire earth
What is a key difference between internal and external hierarchies?
Internal hierarchies are organised by the genome.
External hierarchies are not directed in the same manner and are thus less harmonious
Define a system
Set of interacting parts, where neither parts nor the whole can be understood without taking into account the interactions.
Dynamic and constantly exchanging energy and matter with their surroundings and responding to feedback
What is the difference between positive and negative feedback?
Positive feedback - product of system ‘speeds up’ an earlier process. Usually destabilises a system
Negative feedback - product of system ‘slows down’ an earlier process. Usually stabilises a system
What is the function of system analysis?
Identify components and specify processes by which they interact.
May also specify rates of interactions and how feedback impacts
Define genes
Sequence of DNA that carries the information for building or controlling the building of proteins
What do proteins do?
Govern chemical reactions within cells to form much of an organisms structure. Made of amino acids
How do different cells form different proteins?
By expressing different genes (parts of the genome)
How do mutations in the genome occur?
What is the most common impact?
Mistakes in the DNA replication
Certain chemicals (e.g. Cigarette smoke)
Radiation (including UV radiation)
Most mutations are harmful or have no effect
What were the first genomes sequenced and when?
First genome sequenced in 1976 - virus
First bacterial genome sequenced 1995
First animal genome sequenced 1998 - roundworm
How many different genes are there in the human genome that encode proteins?
21,000
What is evolution?
Chang in genetic makeup of populations over time
What is natural selection and how does it contribute to evolution?
Concept that some individuals contribute more offspring to future generations than others leading to increase of characteristics of that individual that allowed it to survive longer
What are the 2 explanations for adaptations
Proximate explanation - immediate genetic, physical and neurological and behavioural explanation for HOW adaptation works
Ultimate explanation - process that led to adaptation. Involves comparison and variation within species and describes how given traits affect chances of survival and reproduction
Explain genetic drift
Changes due to chance event that do not necessarily improve survival
Describe the scientific method
Observation - questions - hypothesis - predictions - testing
