Download From DNA to Proteins

From DNA to Proteins
The genetic code is used as a blueprint to make ______________.
To manufacture proteins, cells follow a very systematic 2 step procedure that first
______________DNA in the nucleus into __________
and then ______________the mRNA
into chains of __________ __________ in the cells ribosomes.
RNA is very similar to DNA except that it:
•
contains a different sugar (______________ instead of deoxyribose)
•
has only a ______________ strand of nucleotides instead of two strands
•
contains the nitrogen base ______________ (U) instead of ______________ (T)
3 types of RNA
•
______________ RNA (rRNA), along with protein, makes up the ribosomes
•
Messenger RNA (__________) copies DNA’s code & carries the genetic information to the
ribosomes
•
______________ RNA (tRNA) transfers amino acids to the ribosomes where proteins are
synthesized
The “m” in “mRNA” stands for “______________,”
because mRNA copies genetic information from DNA
(which is found in the ______________) and carries it to
another part of the cell (the ribosomes).
Think of the genetic code the mRNA is
carrying as a series of three-letter
“words.” Each of these three-letter
words is called a ______________.
Different ______________code for different amino acids. For example, the
codon for the amino acid methionine is AUG (adenine, uracil, guanine). The
codon for the amino acid serine is UCA (uracil, cytosine, adenine).
Another type of RNA, called tRNA (“t” stands for
“______________”) matches the codons in mRNA to
the correct amino acids.
As the mRNA strand moves along the ______________,
the amino acids are joined in the correct sequence to
form a protein. This process is called ______________.
This chart shows the amino acids coded
for by each of the 64 possible mRNA
codons. To find which amino acid the
codon CAA codes for, follow these steps.
(1) Look on the left side of the chart to
find the large row of codons that begin
with C. (2) Move across this row until you
get to the column of codons whose second
base is A. (3) Move down this column until
you get to the row of codons whose third
base is A. The codon CAA codes for the
amino acid glutamine.
Suppose a DNA mutation led to a change in a single mRNA codon. Now suppose this codon
changed from GCC to GCG.
By looking at the codon chart, you can see that both of these codons code for the amino acid
alanine. So even though the DNA and mRNA have changed, there is no change in the protein!