Amino Acids/ Proteins
What AA enantiomer orientation (L or D) is naturally occurring in the human body?
L (levo-)
Stereoisomers at one chiral carbon are called epimers. The human body uses ___ enzymes to interconvert between two epimer pairs.
epimerases
The bilayer organization of the cell membrane is primarily a result of the physical properties of what macromolecules?
A. zonula adherens
B. zonula occludens
C. gap junctions
D. macula adherens
E. hemidesmosomes
B. zonula occludens
How large is the small subunit, large subunit and total Eukaryotic ribosome?
Small: 40
Large: 60
Total: 80
What disease results from a toxic build-up of branched chain amino acids, is treated with a special diet, and features a distinct sweet odor of urine among the patient?
What are the two broad categories of lipids?
Glycerol-based and non-glycerol-based
A laboratory solution contains 100 mmol/L CaCl₂. Assuming complete dissociation, what is its approximate osmolarity?
A. 100 mOsm/L
B. 150 mOsm/L
C. 200 mOsm/L
D. 300 mOsm/L
E. 400 mOsm/L
D
The chemical properties of which specific constituent of the extracellular matrix (ECM) is most responsible for attracting the water molecules that hydrate the tissue?
Glycosaminoglycans (or GAGs) are chains of disaccharides with hydrophilic properties, due to their charged polarity. While the other listed constituents may also have some hydrophilic properties, the high abundance of GAGs within the ground substance of the ECM are the major constituent that attracts the water molecules into the ECM. GAGs can be found as a ‘free’ macromolecule, but more often numerous GAGS are bound to a core protein to form proteoglycans (see rationale of the proteoglycan core proteins).
1. poly
2. Multiple products
What happens to the α-amino group in an AA after its carbon skeleton has been catabolised?
Converted to free NH4+ --> urea and excretion downstream
What are the essential fatty acids (EFA) and what are symptoms of EFA deficiency?
EFAs: Linoleic acid (ω-6) and α-Linolenic acid (ω-3)
Symptoms: dry, scaly dermatitis as a result of an
inability to synthesize molecules that
provide the water barrier in skin
Following their final production within the neuronal cell body, the secretory vesicles of ACh travel within the axon of the neuron to reach the axon terminal. Which specific cellular organelles is most likely involved in directing the movement of these secretory vesicles?
Microtubules are the components of the cytoskeleton typically responsible for intracellular movement (or transport) of vesicles and other cellular components.
Epiglottal cartilage provides flexible structural support to the epiglottis, i.e. it undergoes deformation in response to external forces and returns to its original shape when the forces are removed. What ECM constituents are primarily responsible for this functional characteristic of epiglottal cartilage?
Elastic fibers are the protein fibers of the ECM that are capable of stretching in response to tensile forces and returning back to their original length when the forces ceases. The high density of elastic fibers (elastin being the most common form) in certain cartilages, tendons, and ligaments (and even some muscles tissues) are the component of the ECM that provides these tissues the ability to undergo deformation without damage and return to their initial shape.
Repetitive DNA that is generally not transcribed highly clustered together is known as ___, while SINEs and and LINEs are examples of repetitive DNA that is ___
1. Satellite
2. Dispersed
What is considered the "21st Amino Acid"?
Selenocysteine
Se substitution for terminal thiol group
Maltose is a disaccharide of what two sugars connected by what type of bond? Is it a reducing or non-reducing sugar?
Glucose + Glucose
α(1,4) glycosidic bond
Reducing sugar
SGLT 1 in the small intestine is a __(type)__ transporter which allows __ to travel down its concentration gradient and ___ to flow against its concentration gradient.
1. Symporter, secondary active
2. NA+
3. Glucose
A. cadherins
B. netrins
C. connexins
D. performins
E. aquaporin
C. Connexins:
The lateral membrane borders of epithelial cells contain a variety of integral and peripheral membrane proteins that mediate cell adhesion and cell communication. Gap (i.e. communicating) junctions are formed by the assembly of subunits of the connexin family of integral membrane proteins. Together, 12 connexin proteins join to form a pore (connexon) that provide ionic coupling between adjacent cells. Gap junctions permit the rapid exchange of ions, metabolites, and small signaling molecules between cells and throughout the epithelium. Gap junctions are present among many cells found in the tissues of the body (e.g. neurons, cardiac myocytes, and others) to share resources and coordinate functions.
What is the Philadelphia Chromosome and what does it cause in a patient?
Translocation of part of ch22 onto ch9 leads to Chronic Myelogenous Leukemia
1. How does misfolding of the prion protein (PrP) leads to prion disease and 2.It is a disruption in what type of structure? (ex: primary, secondary, tertiary or quaternary)
PrP changes from an α-helical structure to a β-sheet-rich structure
Secondary structure
Eicosanoids result from glycerophospholipids stores in cellular membranes. There are 4 major types of eicosanoids (ex: thromboxanes responsible for vasoconstriction and leukotriens which mediate immune responses). Please describe the other two eicosanoids and their primary functions.
Prostaglandins: Produced in most tissues, Control vasoconstriction/dilation, Smooth muscle contraction/relaxation, Induce labor, Required for fever response
Prostacyclins: Produced in vessel endothelium, Control of vasodilation
Describe the downstream effects of insulin binding to an insulin receptor on GLUT4 and extracellular glucose.
GLUT4 is the main insulin-regulated glucose transporter
protein found in adipose and skeletal muscle tissues.
• When blood sugar is low, most GLUT4 stays trapped
inside vesicles inside the cell.
• After a meal, blood sugar levels rise, causing the
pancreas to release insulin into the bloodstream..
• Insulin binds to its receptor on the cell membrane,
initiating the movement of GLUT4 vesicles to the
plasma membrane.
• Once at the surface, GLUT4 transports glucose into the
cell, down its concentration gradient.
Fill in the blanks with the appropriate cytoskeletal protein
1. Cilia are made of ____ and responsible for ___ on the apical surface of the lumen
2. Microvilli are made of ____ and responsible for ___ on the apical surface of the lumen
3. Stereocilia are made of ___ and responsible for ___ on the apical surface of the lumen
1. Microtubules, movement
2. Microfilaments, absorption
3. Microfilaments, absorption
What are the two DNA double strand break repair strategies. Describe them
1. Non-homologous end joining (NHEJ)
◦ Jagged breaks are ligated and filled in without reference to the homologous
chromosome as a guide.
◦ Often creates mutations at ligation sites of repaired chromosome.
2. Homologous recombination (HR)
◦ The other chromosome copy (maternal/paternal) is used as a guide for homology-
directed repair.
◦ Original sequence (of the guide chromosome) is established on the repaired
chromosome.