27_Lieb_Translation - Lieb Biology 202 Translation Protein...

Info icon This preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Lieb- Biology 202 Translation & Protein Structure Page 1 of 4 I. Polypeptides Amino acids have a central (alpha) carbon atom attached to an amino group (NH 2 ) a carboxyl group (COOH) a side chain (R, for reactive group). In a polypeptide, amino acids are linked by peptide bonds between the carboxyl group of one aa and the amino group of the next. Because this is a dehydration reaction (water is removed), we often refer to amino acid residues in a polypeptide. Just as nucleic acid strands have polarity (a 5' end and 3' end), so do polypeptides. They have an amino terminus and carboxy terminus . II. Levels of protein structure primary structure : sequence of amino acids in a polypeptide. Similarity in amino acid sequence can be used to find evolutionary relationships among proteins and to define families or conserved proteins. motifs or blocks are short regions of conserved sequence (and usually conserved function) that can often be recognized in the primary structure. secondary structure : small structures formed by neighboring amino acid residues. Secondary structures are the basic units that give proteins their shape. alpha helix : a helix stabilized by hydrogen bonds beta pleated sheet : anti-parallel strands stabilized by hydrogen bonds secondary structures can often be predicted from the primary structure tertiary structure : complex folding of entire polypeptide chain into 3D structure. A domain is a region of a polypeptide that folds into a particular structure. quaternary structure : some proteins contain more than one polypeptide (multimers). For example, myosin is a homodimer (two identical monomers make the protein) hemoglobin is a heterotetramer (there are two copies of the alpha subunit and two of the beta subunit in each molecule of hemoglobin).
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern