1- introduction Flashcards
(21 cards)
how many cells is it estimated that there is in the human body?
3.7 x 10^13 cells
The discovery of cells - 1665: Robert Hooke’s Micrographia published.
Explored the use of microscopes for scientific discovery using a compound microscope.
Hooke coined the term ‘cell’ for the small compartments that are building blocks of biological organisms.
Term suggested by the resemblance of the plant cells observed to honeycomb.
cell theory first proposed in 1839.
all living organisms are composed of one or more cells, cells are the fundamental unit of structure and function.
cells arise only through division of existing cells.
all cells contain inherited information that is used to regulate their activities, information that is transmitted to the next generation of cells.
cells are capable of independent life
cells emerged on earth at least 3.5 billion years ago.
what is the difference between eukaryotes and prokaryotes?
eukaryotes contain membrane bound structures, known as organelles.
what is homeostasis?
a stable internal environment
why do cells need the right conditions to survive?
certain processes (e.g. osmosis) and proteins (e.g. enzymes) will not function properly otherwise.
what helps maintain homeostasis in the cell?
constant protein turnover - proteins are constantly degraded and replaced with newly synthesised copies to ensure a constant supply of new and functional proteins.
feedback within signalling pathways - proteins interact with each other in “signalling pathways”.
what is resolution?
the shortest distance between two points on a specimen where they can still be distinguished as separate.
- limited by the wavelength of the illumination
light microscopy
~ 200 nm resolution
~ 1,000x magnification
various techniques used to enhance the contrast of transparent cells:
- phase contrast
differential interference contrast
fluorescence microscopy
exploits fluorescent dyes that can be excited by light of certain wavelengths to emit light at linger wavelengths.
- dyes that localize to specific structures within the cell
- dyes that are bound to antibodies
- genetically engineered cells with fluorescent proteins
electron microscopy
electron microscopy (EM) uses beams of electrons rather than light:
smaller wavelength = greater resolving power
two forms:
transmission EM (TEM) - transmitted electrons detected (thin slices)
scanning EM (SEM) - reflected electrons detected (any thickness)
scanning probe microscopy
images formed using a probe that scans (interacts with) the surface.
several forms, including atomic force microscopy (AFM)
give cellular level, atomic level, protein complexes, ecosystem and human in order from smallest to largest
atomic level, protein complexes, cellular level, human, ecosystem.
give proteins, eukaryotic cells, small molecules, atoms, protein complexes and organelles in order from smallest to largest.
atoms/ions, small molecules, proteins, protein complexes, organelles and eukaryotic cells.
what are the 5 time scales?
proliferation (days), transcription (mins), contraction (s), action potentials (ms), enzymatic reactions
what are the constant movement in the cellular and subcellular level?
continuous macromolecule activity e.g. synthesis, degradation, transport & trafficking, signalling.
movement of substances into/out of/within cell through active and passive processes.
what is the function of carbohydrates?
energy source; some structural role when attached to lipids or proteins; energy storage.
what is the function of lipids?
energy source; energy storage; insulation; structural components; chemical messengers; protection.
what is the function of proteins?
catalysts for metabolic reactions; structural components; movement; transport; buffers; defense; control and coordination of activities.
what is the function of nucleic acids?
storage and processing of genetic information
what are ions vital for
cell activity, including in maintaining osmotic balance and in signalling (both electrical and chemical)
