A2 Cells Flashcards
Mr Buckley
Cell theory
All cells are formed from preexisting cells.
All living things are composed of cells.
The cell is the basic unit of life
In which of Pasteer’s experiments is bacteria present?
When heat is applied and the neck of the flask is broken off.
When heat is applied and the flask is tilted as the bacteria attaches to the bacteria and cannot move.
What are the four processes needed for spontaneous origin cells on earth?
- Synthesis of simple organic molecules from inorganic compounds. Also known as catalysis.
Example: Photosynthesis, a global process, involves the reaction of inorganic compounds CO₂ and H₂O with sunlight to produce organic sugars within green plant parts.
- The self-assembly of these organic molecules (monomers) into polymers. This is polymerisation.
- The formation of a polymer that can self replicate (enabling inheritance). Usually RNA.
- Packaging of molecules into membranes with an internal chemistry different from surroundings
Monomers (examples)
Amino acids, nitrogenous bases, fatty acids and simple sugars.
What was the miller-Urey experiment
The Miller–Urey experiment (or Miller experiment) was an experiment in chemical synthesis carried out in 1952 that simulated the conditions thought at the time to be present in the atmosphere of the early, prebiotic Earth.
Mrs Engh
Metabolism
Reproduction
Sensitivity (responsiveness)
Excretion
Nutrition
Growth
Homeostasis
Why aren’t viruses considered living?
Lack of metabolism and reliance on a host cell metabolic events for replication.
LUCA
last universal common ancestor
What does LUCA represent?
The immediate antecessor of the three current domains of life which are: bacteria, archaea and eukaryotes
What is the evidence for LUCA?
- Genetic code is universal and all life shows a common mechanism of transcription and translation.
- Certain genes are broadly distributed across all cellular organisms e.g) instructions for DNA replication
Are fatty acids hydrophilic or hydrophobic
They have hydrophilic heads and hydrophobic tails.
What will happen with non-polar fatty acids in water?
They will arrange to form micelles as the hydrophobic tails coalesce to avoid contact with the polar solution.
How can RNA be the first genetic material?
- Can self-replicate - RNA can form complementary template sequences that can be used to produce new identical molecules.
- Can act as a catalyst - RNA catalysts (ribozymes) are involved in peptide bond formation and intron splicing in modern cells
What are used of staining when using a microscope
Iodine - starch will be shown as brown or blue-black and glycogen will be shown as red
Methylene blue - useful for identifying DNA or the nucleus
Gram stain - divides bacteria into two types. Gram positive or negative depending on size and composition of cell wall.
How do you calculate actual size, magnifications and image size?
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