A2 Unity ad Diversity : Cells Flashcards
Origin of cells, cells structure and viruses
organic molecules
Molecules that contain carbon and hydrogen. Most biological molecules, including proteins, carbohydrates, lipids and nucleic acids are organic molecules.
Metabolism
Chemical reactions that take place within the cell(s) of an organism.
Homeostasis
The maintenance of constant internal conditions, despite changes in their external environments
Miller–Urey hypothesis
spontaneous generation of simple organic molecules such as amino acids, carbohydrates and lipids occurred in the conditions on pre-biotic Earth.
The ‘metabolism first’ hypothesis
life began with simple metabolic reactions that led to the formation of simple metabolic pathways, which then formed more complex molecules which formed the basis of cells.
The ‘lipid world’ hypothesis
lipid bilayers evolved before RNA, providing a protective layer to encapsulate the RNA.
endosymbiosis
A theory that eukaryotic cells evolved by engulfing and incorporating prokaryotic cells, which then became organelles within the eukaryotic cell.
horizontal gene transfer
The exchange of genetic material between individuals that does not involve reproduction.
stromatolites
Fossils formed by microorganisms.
hydrothermal vents
Openings in the ocean bed where hot water, rich in minerals, is released into the oceans.
anaerobic
Describes conditions in which air or oxygen is absent.
autotroph
Convert abiotic sources of energy into energy stored in organic compounds,
light microscope
A microscope that uses light to view specimens, usually with a magnification of 400–1500 times.
micrometers (μm)
one thousandth of millimetre
or
one millionth of a meter
usually used to measure cells
nanometer (nm)
one millionth of a millimetre
or
one billionth of a metre
usually used to measure proteins and viruses
magnification equation
mag = image size / actual size
electron microscope
Instrument using a beam of electrons to obtain a magnified image of a very small object such as a sub-cellular structure.
resolution
The shortest distance between two separate points in a microscope’s field of view that can still be distinguished as separate objects.
Freeze fracture microscopy
Microscopy technique where sample frozen then broken into small pieces which are observed using an electron microscope to see the internal structure.
Cryogenic electron microscopy
Microscopy technique where samples are frozen to cryogenic temperatures to fix the molecules which are viewed using electron microscope.
Immunofluorescence
A microscopy technique that attaches a fluorescent tag to antibodies which bind to antigens on specimen using light microscopes
florescent dyes
Dyes that attach to certain structures and appear as brightly coloured spots using light microscopes
plasmid
Small circular DNA molecule, physically separate from chromosomal DNA, found in bacteria and some other microscopic organisms and can be transfered between them
polysaccarides
A major class of biomolecules, composed of long chains of carbohydrate molecules.