US Medicine and Disease Olympiad: Past Papers Solutions

Glycogen

Primary glucose storage form in animals.

Glycosidic Linkage

Bond linking monosaccharides in polysaccharides.

1,6 Alpha Linkage

Type of glycosidic bond creating glycogen branches.

Nucleolus

Nucleus region assembling ribosomal subunits.

Ribosomal RNA (rRNA)

RNA component of ribosomes, essential for protein synthesis.

Ribosomal Subunits

Complex of rRNA and proteins forming ribosomes.

Protein Functions

Roles include catalysis, transport, and movement.

Energy Storage

Primarily done by carbohydrates and lipids.

Gluconeogenesis

Process converting proteins to glucose when needed.

Tight Junction

Intercellular junction preventing protein diffusion in membranes.

Zonula Occludens

Another name for tight junctions in epithelial cells.

Apical Surface

Top surface of epithelial cells facing the lumen.

Basolateral Surface

Bottom surface of epithelial cells facing underlying tissue.

Phosphofructokinase-I (PFK-I)

Key glycolysis enzyme regulated by ATP and AMP.

Fructose-6-Phosphate

Substrate phosphorylated to form fructose-1,6-bisphosphate.

Citrate

Metabolite that inhibits PFK-I in glycolysis.

Hexokinase

Enzyme catalyzing the first step of glycolysis.

Phosphoglucose Isomerase

Enzyme converting glucose-6-phosphate to fructose-6-phosphate.

G3P Dehydrogenase

Enzyme involved in glycolysis, converting G3P to 1,3-BPG.

Desmosome

Cell junction providing mechanical strength between cells.

Hemidesmosome

Anchors epithelial cells to the basement membrane.

Gap Junction

Intercellular junction allowing communication between cells.

ATP

Energy currency of the cell, inhibits PFK-I.

PFK-I

Enzyme activated by AMP, promoting glycolysis.

AMP

Indicator of low energy, activates PFK-I.

Glycolysis

Pathway converting glucose to pyruvate, producing ATP.

Pyruvate

Three-carbon product of glycolysis from glucose.

NADH

Reduced form of NAD+, produced during glycolysis.

CO2

Not produced in glycolysis; generated in citric acid cycle.

Citric Acid Cycle

Metabolic cycle producing CO2 from pyruvate.

Fructose-1,6-bisphosphatase

Enzyme for reverse reaction in gluconeogenesis.

Enolase

Enzyme in glycolysis, not used in gluconeogenesis.

Beta-Oxidation

Process breaking down fatty acids for energy.

Mitochondria

Primary site for beta-oxidation of fatty acids.

Peroxisome

Organelle involved in initial beta-oxidation steps.

Pleiotropy

Single gene affecting multiple phenotypic traits.

Marfan Syndrome

Example of pleiotropy affecting multiple body systems.

Polygenic Inheritance

Trait influenced by multiple genes.

Epistasis

Interaction where one gene affects another's expression.

Norm of Reaction

Phenotypic expression range due to environmental factors.

Pyruvate Kinase

Enzyme catalyzing last step of glycolysis.

Alternative RNA splicing

Combines different exons to produce diverse proteins.

Introns

Non-coding regions removed during mRNA processing.

Exons

Coding regions joined to form mature mRNA.

DSCAM gene

Can produce thousands of protein isoforms via splicing.

siRNA

Short interfering RNA involved in gene silencing.

RISC

Complex that uses siRNA to degrade target mRNA.

RNA interference

Process that inhibits gene expression using RNA.

Lipopolysaccharide

Endotoxin in gram-negative bacteria's outer membrane.

Septic shock

Life-threatening inflammatory response from LPS in bloodstream.

Transduction

Bacterial DNA transfer via bacteriophages.

Bacteriophage

Virus that infects bacteria and transfers DNA.

Genetic recombination

Process of exchanging genetic material between organisms.

Catalase

Enzyme that detoxifies hydrogen peroxide in peroxisomes.

Hydrogen peroxide

Toxic byproduct that catalase converts to water and oxygen.

Transformation

Uptake of naked DNA by a bacterium.

Conjugation

Direct transfer of DNA between bacteria through contact.

Phospholipase

Enzyme that hydrolyzes phospholipids in membranes.

Glycosyltransferase

Enzyme that adds sugar moieties to molecules.

Ribosyltransferase

Enzyme that transfers ribose sugars to substrates.

Caspase

Enzyme that plays a role in apoptosis.

Cyclase

Enzyme that catalyzes the formation of cyclic nucleotides.

Carboxylase

Enzyme that adds carboxyl groups to substrates.

Kinesin

Motor protein moving from minus to plus microtubule end.

ATP hydrolysis

Energy source for kinesin movement along microtubules.

Epigenetic inheritance

Gene function changes without DNA sequence alteration.

Imprinting

Parental influence on gene expression based on origin.

Smooth endoplasmic reticulum

Organelle involved in calcium storage and detoxification.

Non-competitive inhibition

Inhibitor binds away from active site, reducing Vmax.

Vmax

Maximum rate of enzyme-catalyzed reaction.

Km

Substrate concentration at which reaction rate is half Vmax.

Allosteric site

Binding site on enzyme distinct from active site.

Competitive inhibition

Inhibitor competes with substrate for active site.

Calcium storage

Function of smooth ER related to muscle contraction.

Detoxification

Process of neutralizing harmful substances in smooth ER.

Steroid production

Synthesis of steroids occurring in smooth endoplasmic reticulum.

Substrate affinity

Strength of enzyme-substrate interaction, represented by Km.

Conformational change

Structural alteration of enzyme affecting its activity.

Enzyme activity

Rate at which an enzyme catalyzes a reaction.

Molecular Biology of the Cell

Reference book for cellular biology concepts.

Nature Reviews Genetics

Journal discussing genetic inheritance and epigenetics.

Biochemistry

Field studying chemical processes within living organisms.

Oxaloacetate

A four-carbon molecule in the citric acid cycle.

Acetyl-CoA

Key molecule entering the citric acid cycle.

GTP

Energy molecule produced in the citric acid cycle.

FADH2

Electron carrier yielding less ATP than NADH.

IP3

Second messenger opening calcium channels in the ER.

DAG

Second messenger produced alongside IP3 from PIP2.

Calcium Ions (Ca2+)

Released into cytoplasm, increasing intracellular calcium concentration.

G2 Checkpoint

Cell cycle checkpoint for DNA damage repair before mitosis.

Mitosis

Process of cell division producing two identical daughter cells.

Cyclin

Protein that activates cyclin-dependent kinase (CDK) for mitosis.

CDK

Cyclin-dependent kinase, forms MPF with cyclin.

MPF

Maturation-promoting factor stimulating entry into mitosis.

Sister Chromatids

Identical copies of a chromosome separated during mitosis.

Phospholipase C (PLC)

Enzyme cleaving PIP2 to produce DAG and IP3.

PIP2

Phosphatidylinositol bisphosphate, precursor for IP3 and DAG.

Intracellular Calcium Concentration

Increased by IP3-mediated calcium channel opening.

Cell Cycle

Series of phases including G1, S, G2, and M.

M Phase

Phase of cell cycle where mitosis occurs.