Make Proteins! • Proteins are important organic molecules • See. p. 186 • Why are proteins soimportant?
Proteins… • are complex molecules • are made of lots of smaller units called amino acids
are made in the cell by cell organelles called ribosomes • every protein is made of a specific sequence of amino acids
Amino Acids • amino acids are the small units that proteins are made of • there are 20 amino acids • amino acids are found n the cytoplasm and nucleus of cells
Amino acids and DNA • DNA is a complex molecule consisting of nucelotides • the nucleotides contain bases, sugars and phosphates
bases are the “rungs” • the sugars and phosphates are the sides
a codon is a set of three bases that will produce a particular amino acid
Where do genes fit in? • A gene is a section of DNA that gives the instructions to make a specific protein (such as enzymes, hormones, haemoglobin, etc.)
A gene is therefore the set of codons designed to make a sequence of amino acids (which is a protein)
So…. • DNA is therefore responsible for the making of proteins! • How does this happen???
Transcription • in the nucleus of a cell, a section of the DNA (a gene!) unwinds a bit at a time • extra DNA components are “fed into” the unwound bit, creating a single, complementary strand called mRNA • in mRNA T’s are replaced with U’s • this mRNA is the template or instructions for the cell to make a specific protein
Translation • the mRNA works its way out of the nucleus into the cell • cool little protein making “devices” called ribosomes attach to the mRNA and use it to link up amino acids in the particular order as specified by the bases • this creates a protein molecule