Scientists are studying the structure and function of receptor x, a single-polypeptide protein that is found in the membrane around certain types of cells. receptor x contains no alpha-helices or beta sheets. a specific molecule outside the cells is recognized and bound by receptor x. the binding of the molecule to receptor x causes the cells to have a particular response. identify the process used to form the covalent peptide bonds that join amino acids into a polypeptide

This protein doesn't have a secondary structure (i.e., alpha helices or beta sheets), thereby it interacts with the specific molecule trough its loops

Explanation:

Protein loops may interact with diverse molecules including nucleic acids (RNA and DNA), proteins, signal molecules, etc. These protein sequences (loops) interact with both polar and non-polar head groups

The process used to form the covalent peptide bonds joining amino acids into polypeptide is :  Condensation reaction

Although your question is incomplete attached below is the missing data related to your question.

Covalent Peptide bonds are bonds formed between the carboxyl group of a molecule reacting with the amino group of a different molecule producing water molecule as part of its product. and this process is known as dehydration synthesis mechanism  ( aka Condensation reaction )

Hence the process used to form the covalent peptide bonds joining amino acids into a polypeptide is Condensation reaction

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c. earths continental crust is thicker than its lithosphere.

because, the lithosphere is the outermost layer of the earth/ 100 km thick and is defined by its machanical properties.the lithosphere contains oceanic and continental crust that varies in age and thickness across locations and geologic time. the lithosphere is the coolest layer of the earth in terms of temperature. the term lithosphere should not be confused with the use of "geosphere" which is used to indicate all of earth systems, including the atmosphere, hydrosphere   and biosphere. the surface of the earth can be divided into the continental crust and the oceanic crust.   the continental crust is made mostly of granite while the oceanic crust is made of basalt. the average thickness of the continental crust is 25 miles and the average thickness of the oceanic crust is 5 miles.   three types of rock, igneous, sedimentary, and metamorphic, make up the surface of the earth. that's why 3 option is preferable.

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