Chapter 7: Nucleic Acids and Protein Synthesis



Chapter 7: Nucleic Acids and Protein Synthesis

Section 3: Protein Synthesis

Protein Synthesis

The nitrogenous bases in DNA contain information that directs protein synthesis

Because most enzymes are proteins, proteins control biochemical pathways within the cell

Not only do proteins direct the synthesis of lipids, carbohydrates, and nucleotides, but they are also responsible for _____________________________________ and _____________________________________

The Nature of the Genetic Code

Proteins are made by stringing amino acids together to form long chains called ___________________________________

Each polypeptide contains a combination of any or all of the _________________

___________________________________________________

DNA and RNA each contain different nitrogenous bases

In order to code for the 20 different amino acids, more than one nucleotide must make up the code word for each amino acid

The code words of the DNA nucleotides are copied onto a strand of ______________________________________

Each combination of three nucleotides on the messenger RNA is called a _____________________

Each codon specifies a particular amino acid that is to be placed in the polypeptide chain

There is one codon, __________________, that can either specify the amino acid ________________________________ or serve as a started for the synthesis of a protein

1 __________________________

There are also three _______________________________

These codons act like the period at the end of a sentence

1 Signify the __________________________________________________

Translation

The decoding of mRNA into a protein is known as _________________________

The mRNA does not produce a polypeptide by itself

Instead, there is a mechanism that involves the two other main types of RNA and the ribosome

1 ________________________________________

1 Carries amino acids to the ribosomes

2 ________________________________________

1 Makes up the major part of the ribosomes

The Role of Transfer RNA

In order to translate the information from a single codon of mRNA, such as AUG, we would have to find out which amino acid is coded for by AUG

The codon AUG codes for the amino acid methionine

Methionine is then brought to the polypeptide chain by _________________

There are three exposed bases on each tRNA molecule

These nucleotides will base pair with a codon on mRNA

Because these three nucleotides on tRNA are complementary to the three nucleotides on mRNA, the three tRNA nucleotides are called the ______________________________

Attached to each tRNA molecule is the amino acid specified by the codon to which it base pairs

By matching the tRNA anticodon to the mRNA codon, the correct amino acid is put into place

Each tRNA acts like a tiny beacon for its specific amino acid

The Role of the Ribosome

The process of protein synthesis takes place in the _________________________

Ribosomes are made up of two subunits

1 _________________________

2 _________________

The first part of protein synthesis occurs when the two subunits of the ribosome bind to a molecule of mRNA

The AUG binds to the first anticodon of tRNA, signaling the beginning of a polypeptide

Soon the anticodon of another tRNA binds to the next mRNA codon

This second tRNA carries the second amino acid that will be placed into the chain of the polypeptide

As each anticodon and codon bind together, a ____________________________ forms between the two amino acids

The polypeptide chain continues to grow until the ribosome reaches a __________________________________ on the mRNA

When the stop codon reaches the ribosome, the ribsome releases the newly formed polypeptide, completing the process of translation

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