A2.1 Flashcards
origin of cells
What is a greenhouse gas?
a gas that absorbs and reacts with infrared radiation emitted from the surface of the planet hence causing the earth to heat up
What is the pre-biotic soup hypothesis?
The idea that high energy or UV radiation led to the formation of the first biological molecule
Why are viruses regarded as non-living?
They lack the organelles to carry out metabolism independently
What are the 3 principles that define life?
Living organisms must be able to evolve through natural selection (reproduce and have a hereditary system with genetic variation),
life forms are contained and separate from but in communication with their outside surroundings,
life forms are chemical and physical machines that receive and respond to information
What is NASA’s working definition of life?
Life is a self-sustaining chemical system capable of Darwinian evolution
How can cells be produced?
the division of pre-existing cells
what is the protocell first theory?
A cell like compartment with basic metabolism which eventually evolved to have a genetic system
What are the 3 common features of all cells?
a stable partially permeable membrane
genetic material that controls the functions and behaviour and can be passed on
metabolic processes that allow energy generation, enabling growth, self maintenance and reproduction
what steps would be required to form living cells from non living materials?
- the synthesis of simple organic molecules such as sugars and amino acids
2.the assembly of these molecules into polymers
3.the development of self replicating molecules - the retention of these molecules within membranous sacs
What is the gene first theory?
A genetic molecule that could divide which eventually formed genetic variants that could assemble a cell and start metabolising
What is the metabolism first theory?
a self-sustaining system of simple reactions which eventually evolved cells and genetic systems
What are the main molecules that make up most living things?
carbon, hydrogen, oxygen
some nitrogen, phosphorus and sulfur
What was the miller Urey experiment?
They investigated how simple organic molecules might have risen on earth before life.
How did miller and Urey conduct this experiment?
By simulating pre-biotic earth in an enclosed environment with things such as sparks for lightning.
What were the results of the Miller and Urey experiment?
they discovered that amino acids as well as other compounds were formed naturally and it confirmed that organic molecules can be synthesised outside of cells in the absence of oxygen
