Prokaryotic and eukaryotic cells - 2.6 (1) Flashcards
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What are animals, plants and fungi?
complex multicellular organisms
The cells making up these organisms are…
eukaryotic
What did eukaryotic cells evolve from?
less complex prokaryotic cells
Where do these prokaryotic cells, present in great numbers, live?
in an incredibly diverse range of habitats
What can these unicellular organisms be divided into?
two types of evolutionary domains - Archaea and Bacteria
Did Archaea and Bacteria evolve from an ancient common ancestor?
yes
What may have prokaryotic cells been the earliest forms of?
life on Earth
When did prokaryotic cells first appear?
around 3.5 billion years ago when the surface of the Earth was a very hostile enviroment
What do scientists believe in regards to these early cells?
that they were adapted to living in extremes of salinity, pH and temperature
What are these organisms known as?
extremophiles and they still exist today
Where can extremophiles be found?
in hydrothermal vents and salt lakes - similar enviroments to those believed to have made up the early Earth
What are these extremophiles usually of the domain of?
Archaea
Where have these extremophiles recently been found in?
more hospitable enviroments such as soil and the human digestive system
What are prokaryotic organisms always considered as?
unicellular with a simple structure
Are prokaryotic cell’s DNA contained within a nucleus or not?
they are not contained within a nucleus
Do prokaryotic cells have a few organelles and if so, are they membran-bound or not?
they do although they are not membrane-bound
Is the structure of the DNA contained within prokaryotes the same as eukaryotes?
yes but it is packaged differently
What do prokaryotes only have one molecule of?
DNA, a chromosome
What is the chromosome in prokaryotes supercoiled to become?
to make it more compact
What are the genes on the chromosome often grouped into?
operons, meaning a number of genes are switched on or off at the same time
The ribosomes in prokaryotic cells are smaller than those in…
eukaryotic cells
What is the relative size of the ribosomes determined by?
the rate at which they settle, or form a sediment, in solution
What are the larger eukaryotic ribsomes designated as?
80S
What are the smaller prokaryotic ribosome designated as?
70S
