Search for notes by fellow students, in your own course and all over the country.
Browse our notes for titles which look like what you need, you can preview any of the notes via a sample of the contents. After you're happy these are the notes you're after simply pop them into your shopping cart.
Title: Prokaryotic and eukaryotic cells
Description: A* QUALITY A-LEVEL BIOLOGY NOTES HIGH GRADES GUARANTEED! DETAILED SUMMARY OF THE COMPLETE CHAPTER AMAZING VALUE
Description: A* QUALITY A-LEVEL BIOLOGY NOTES HIGH GRADES GUARANTEED! DETAILED SUMMARY OF THE COMPLETE CHAPTER AMAZING VALUE
Document Preview
Extracts from the notes are below, to see the PDF you'll receive please use the links above
CHAPTER 2 : Basic components of living systems
Prokaryotic and eukaryotic cells
Prokaryotic cells
-Prokaryotic organisms are always unicellular, relatively simple structure
-DNA is not contained within a nucleus
-Have some organelles, they’re not membrane-bound
DNA
-Structure of DNA is contained within prokaryotes is fundamentally the same as in
eukaryotes but it’s packaged differently
-Prokaryotes generally have one molecule of DNA, a chromosome, which is
supercoiled to make it more compact
-Genes on the chromosome are often grouped into operons, number of genes are
switched off or on at the same time
Ribosomes
-Prokaryotic cells have smaller ribosomes compared to eukaryotic cells
-Relative size is determined by the rate at which they settle, or form a sediment in a
solution
-Larger eukaryotic organisms are designated 80S and smaller prokaryotic
ribosomes, 70S
-They’re both important for protein synthesis, although larger 80S ribosomes are
involved in formation of more complex proteins
Cell wall
-Prokaryotic cells have a cell wall made from peptidoglycan, also known as murenin,
it’s a complex polymer formed from amino acids and sugars
Flagella
-Flagella of prokaryotes is thinner than the equivalent structure of eukaryotes and
don’t have the 9+2 arrangement
-Energy to rotate the filament that forms the flagellum is supplied from the process of
chemiosmosis, not from ATP as in eukaryotic cells
-Basal body attaches the filament comprising the flagellum to the cell-surface
membrane of a bacterium
-Molecular motor causes hook to rotate giving the filament a whip like movement,
propelling the cells
A comparison with eukaryotic cells
-Eukaryotic cells are more complex than prokaryotic cells
-Their DNA is in a nucleus and exists as multiple chromosomes, which are
supercoiled, each wraps around a number of proteins (histones), forming a complex
for efficient packing, called chromatin
-Chromatin coils and condenses to form chromosomes
-Eukaryotic genes are generally switched on and off individually
The similarities and differences between prokaryotic and eukaryotic cells
Feature
Prokaryotic
Eukaryotic
Nucleus
Not present
Present
DNA
Circular
Linear
Extra chromosomal DNA
Circular DNA called
plasmids
Only present in certain
organelles such as
chloroplast and
mitochondria
Organelles
Non membrane-bound
Both membrane-bound
and non membranebound
Cell wall
Peptidoglycan
Chitin in fungi, cellulose in
plants, not present in
animals
Ribosomes
Smaller, 70S
Larger, 80S
Cytoskeleton
Present
Present, more complex
Reproduction
Binary fission
Asexual or sexual
Cell type
Unicellular
Unicellular and
multicellular
Cell-surface membrane
Present
Present
DNA organisation
Protein folds and
condense DNA
Associated with proteins
called histones
Title: Prokaryotic and eukaryotic cells
Description: A* QUALITY A-LEVEL BIOLOGY NOTES HIGH GRADES GUARANTEED! DETAILED SUMMARY OF THE COMPLETE CHAPTER AMAZING VALUE
Description: A* QUALITY A-LEVEL BIOLOGY NOTES HIGH GRADES GUARANTEED! DETAILED SUMMARY OF THE COMPLETE CHAPTER AMAZING VALUE