Questions and Answers
What are the major functions of proteins? (Select all that apply)
Explain the primary structure of proteins.
Linear sequence of amino acids that determines the secondary structure.
What connects amino acids together?
A peptide bond.
Why is sickle cell anemia an example of a primary structure mutation?
Signup and view all the answers
Explain the secondary structure of proteins.
Signup and view all the answers
What is an alpha helix?
Signup and view all the answers
What is a beta sheet?
Signup and view all the answers
What does proline do in protein structure?
Signup and view all the answers
What are motifs?
Signup and view all the answers
Where do super secondary structures work?
Signup and view all the answers
What is a zinc finger?
Signup and view all the answers
Where are zinc fingers found?
Signup and view all the answers
What is a leucine zipper?
Signup and view all the answers
Where are leucine zippers found?
Signup and view all the answers
What are prions?
Signup and view all the answers
What diseases are prions responsible for?
Signup and view all the answers
Explain the tertiary structure of proteins.
Signup and view all the answers
How are secreted proteins stabilized?
Signup and view all the answers
Explain quaternary structure.
Signup and view all the answers
What is denaturation?
Signup and view all the answers
What levels of structure are disrupted by denaturing agents?
Signup and view all the answers
Describe the denaturing agents.
Signup and view all the answers
What does G6PD deficiency have to do with denaturation?
Signup and view all the answers
Study Notes
Major Functions of Proteins
- Provide structural support for cells and tissues
- Facilitate movement within organisms
- Involved in signal transduction processes
- Bind to various molecules and ions
- Transport substances across cellular membranes
- Act as catalysts in biochemical reactions
Primary Structure of Proteins
- Defined by the linear sequence of amino acids (AA)
- Determines higher order structures including secondary structure
- Mutations in the primary structure can lead to functional deficiencies
Peptide Bonds
- Form connections between amino acids
- Result from a condensation reaction between the amino group of one AA and the carboxyl group of another
Sickle Cell Disease Mutation
- Caused by a mutation where glutamate is replaced with valine
- Alters the charge of the hemoglobin molecule, impacting its functionality
Secondary Structure of Proteins
- Comprises arrangements of the polypeptide chain stabilized primarily by hydrogen bonds
- Two main types: alpha helix and beta sheet
Alpha Helix
- Features a coiled, helical structure
- Side chains of amino acids extend outward from the helix
Beta Sheet
- Formed by the packing of beta strands
- Characterizes the orientation of adjacent strands, which can be parallel or antiparallel
Role of Proline
- Disrupts the formation of alpha helices
- Lacks a free hydrogen atom for hydrogen bonding due to its unique structure
Motifs in Protein Structure
- Comprise specific arrangements of secondary structures that adopt characteristic 3D shapes
- Also referred to as super secondary structures
Function of Super Secondary Structures
- Engage in binding small ligands, ions, and interact with DNA
Zinc Finger Structure
- A type of super secondary structure containing zinc ions coordinated with cysteine and histidine residues
- Important in DNA-binding proteins
Locations of Zinc Fingers
- Present in receptors for lipid-soluble hormones that exhibit DNA-binding activity
Leucine Zipper Structure
- Another super secondary structure where leucine residues from two alpha helices intertwine
- Facilitates protein dimerization
Locations of Leucine Zippers
- Found in DNA-binding proteins such as transcription factors
Prions
- Infectious proteins that induce structural changes in normal neural proteins
- Promote the conversion from alpha helices to beta sheets
- Form aggregates that resist degradation through digestion or heat
Diseases Linked to Prions
- Associated with conditions like kuru, mad cow disease, and Creutzfeldt-Jakob disease
Tertiary Structure of Proteins
- Refers to the complete 3D folded shape of a polypeptide
- Comprised of distinct structural and functional domains
- Stabilized by interactions between side chains and associations of supersecondary motifs
Stabilization of Secreted Proteins
- Achieved through the formation of covalent disulfide bonds
Quaternary Structure of Proteins
- Involves the assembly of two or more tertiary structures
- Common forms include dimers and tetramers
- Stabilized by noncovalent interactions and interchain disulfide bonds
Denaturation of Proteins
- Refers to the loss of native conformation leading to a loss of biological activity
- Denatured proteins can aggregate due to exposed hydrophobic side chains becoming insoluble
Levels of Structure Affected by Denaturation
- Denaturation disrupts secondary, tertiary, and quaternary structures but leaves primary structure intact
Denaturing Agents
- Extreme pH or ionic strength changes, detergents, elevated temperatures, and heavy metals contribute to protein denaturation
G6PD Deficiency and Denaturation
- Increased peroxide levels in red blood cells can denature hemoglobin, leading to the formation of Heinz bodies due to oxidative stress
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Test your knowledge on the major functions and structures of proteins with these flashcards. Learn about protein functions like structural support, movement, and binding, as well as the primary structure and peptide bonds. Perfect for studying biochemistry concepts related to proteins.