1.5.5 Ribosomes Flashcards
Ribosomes are small organelles that are either
free in the cytoplasm (of all cells) or are attached to the rough endoplasmic reticulum (only in eukaryotic cells)
Ribosomes are the site of
protein synthesis (where proteins are made)
Ribosomes read
RNA
Ribosomes read to make
polypeptides (proteins)
Ribosomes read RNA to make polypeptides (proteins) in a process known a
translation
Ribosomes are themselves formed from
RNA and proteins
The RNA that forms part of the structure of ribosomes is a specific type of RNA known as
ribosomal RNA (rRNA)
The rRNA in ribosomes has enzymatic properties that
catalyse the formation of peptide bonds between amino acids
Each ribosome is a mixture of
ribosomal RNA and proteins
Ribosomes in eukaryotic cells are larger than those in
prokaryotic cells
In both cell types, ribosomes are composed of
a small subunit and a large subunit
80S ribosomes (composed of 60S and 40S subunits) are found in
eukaryotic cells
70S ribosomes (composed of 50S and 30S subunits) are found in
prokaryotic cells
70S ribosomes (composed of 50S and 30S subunits) are found in prokaryotic cells, as well as in
the mitochondria and chloroplasts of eukaryotic cells
The large subunit is the site of
translation
A diagram of a ribosome, showing the small and large subunits
