Kaplan — Biochemistry Flashcards
Motif
Repetitive organization of secondary structural elements together
Collagen
Characteristic tri-helical fiber (three left-handed helices woven together to form a secondary right-handed helix) and makes up most of the ECM of connective tissue
Elastin
Component of ECM of connective tissue that can stretch and recoil like a spring
Keratins
Intermediate filament proteins found in epithelial cells
Contribute to the mechanical integrity of the cell and function as regulatory proteins
Actin
Protein that makes up microfilaments and thin filaments of the myofibrils
Have a positive and negative ends
Tubulin
Protein that makes up microtubules
Microtubules
Important for providing structure, chromosome separation in mitosis and meiosis, intracellular transport with lines in and dine in
Has a polarity
Microtubule polarity
Positive end usually in the periphery of the cell
Motor proteins
Display enzymatic activity (acting as ATPases) that power the conformational change necessary for motor function
Myosin
Primary motor protein that interacts with actin
Has a single head and neck
Kinesins
Motor proteins with two heads associated with microtubules
Key role in aligning of chromosomes during metaphase and depolymerizing microtubules during anaphase of mitosis
Moves toward positive end
Dyneins
Motor proteins with two heads that are associated with microtubules
Deal with sliding movement of cilia and flagella
Moves toward negative end
Binding proteins
Proteins that transport or sequester molecules by binding to them
Cell adhesion molecules (CAMs)
Proteins that are found on the surface of most cells and aid in the binding of the cell to the ECM and other cells
Cadherins
Group of glycoproteins that mediate calcium-dependent cell adhesion
Integrins
Group of proteins that all have two membrane-spanning chains called alpha and beta
Facilitate binding and communicating with the ECM
Selectins
Bind to carbohydrate molecules that project from other cell surfaces
Important role in host defense
Antibodies
Proteins produced by B-cells that function to neutralize targets in the body
Immunoglobulin (Ig)
Antibody
Antibody structure
Y-shaped proteins made of two identical heavy chains and two identical light chains that are held together by disulfide linkages and non-covalent interactions
Antigen
Target of antibodies
Opsonization
Marking the pathogen for destruction by white blood cells
Agglutinating
Clumping together the antigen and antibody into large insoluble protein complexes that can be phagocytized and digested by macrophages
Biosignaling
Process in which cells receive and act on signals
Ion channels
Proteins that create specific pathways for charged molecules, allowing for their facilitated diffusion
Undated channels
No gates preventing ion movement and are therefore unregulated
Voltage-gated channels
Regulated by membrane potential change near the channel
Ligand-gated channels
Binding of a specific molecule to the channel causes it to open or close
Enzyme-linked receptors
Three domains: membrane-spanning domain, ligand-binding domain, catalytic domain
Membrane-spanning domain
Anchors the enzyme-linked receptor in the cell membrane
Ligand-binding domain
Stimulated by the appropriate ligand and induces a conformation change in the enzyme-linked receptor
Catalytic domain
Activated by a conformational change in enzyme-linked receptors
Example of enzyme-linked receptors
Receptor tyrosine kinases (RTK)
G protein-coupled receptor
Large family of integral membrane proteins involved in signal transduction and have 7 membrane-spanning alpha-helices
Heterotrimeric G protein
Method of functionality that are connected to guanine nulceotides
G_s
Stimulates adenylate cyclase which increases levels of cAMP in the cell
G_i
Inhibits adenylate cyclase which decreases levels of cAMP
G_q
Activates phospholipase C which cleaves a phospholipid from membrane to form PIP2 which is cleaved to form DAG and IP3
IP3
Open calcium channels in the endoplasmic reticulum
Trimeric G protein cycle
Ligand binds the receptor and becomes activated (GDP → GTP)
Alpha subunit dissociates from beta and gamma subunits
Alpha subunit alters the activity of the adenylate cyclase and is dephosphorylated
It will then rebind the beta and gamma subunits
Homogenization
Crushing, grinding, or blending of tissue of interest into evenly mixed solution
Centrifugation
Isolate proteins from much smaller molecules before other isolation techniques must be employed
Electrophoresis
Subjecting compounds to an electric field which moves them according to their net charge and size
Negatively charged compounds will migrate to the positively charged anode