MCAT® Exam flashcards

Fungi are a diverse kingdom of eukaryotic organisms that are heterotrophic, typically grow as filamentous structures (hyphae), and have cell walls made of chitin.

• Eukaryotic, with nucleus, mitochondria, and endomembrane system.
• Lack chloroplasts and are heterotrophic (absorptive feeders).
• Cell walls are composed of chitin.
• Reproduce via spores.

Memory trick: Eukaryotic 'FEATURES' classify the 'KINGDOMS'.

Regulation of an enzyme or other protein by binding an effector molecule at a site other than the protein's active site (or DNA-binding site), causing a conformational change that affects its activity.

• Effector binds to an allosteric site, not the active site.
• Induces a conformational change in the protein.
• Can either activate or inhibit protein function.
• Common in enzyme regulation and transcription factors.

Memory trick: Allosteric Alligator: bites a different spot, changes the whole protein's mood.

Archaea are a domain of single-celled microorganisms that are prokaryotes, meaning they lack a cell nucleus and other membrane-bound organelles. They are often found in extreme environments and possess unique biochemical features.

• Prokaryotic (no nucleus or membrane-bound organelles)
• Often extremophiles (thrive in harsh conditions)
• Unique cell wall composition (not peptidoglycan like bacteria)
• Distinct rRNA sequences

Memory trick: Every Big Apple has a Core.

Enzymes are biological catalysts, typically proteins, that accelerate biochemical reactions. Their activity is highly specific and sensitive to environmental factors like temperature and pH, which affect their three-dimensional structure.

• Are typically proteins
• Act as biological catalysts
• Have specific active sites
• Sensitive to temperature and pH

Memory trick: Primary's Peers Promote Proper Protein.

Covalent modification is a type of enzyme regulation where a chemical group is added to or removed from an enzyme via a covalent bond, leading to a change in its activity.

• Common examples include phosphorylation/dephosphorylation.
• Often involves kinases (adding phosphate) and phosphatases (removing phosphate).
• Can activate or inactivate an enzyme.

Memory trick: Enzymes can be regulated by many 'MODS' to their activity.

The enzymatic activity, residing in the ribosomal large subunit, responsible for catalyzing the formation of peptide bonds between incoming amino acids during protein synthesis (translation).

• Catalyzes peptide bond formation.
• Part of the large ribosomal subunit.
• Is a ribozyme (RNA molecule with catalytic activity).
• Essential for polypeptide chain elongation.

Memory trick: Peptidyl Transferase: Makes the Peptides, Transfers the chain!

Thyroid hormones (T3 and T4) are crucial regulators of basal metabolic rate, growth, and development, primarily by influencing mitochondrial activity and gene expression.

• Increase metabolic rate and oxygen consumption in most tissues.
• Stimulate ATP production and heat generation.
• Essential for normal brain development and function.

Memory trick: Low thyroid means low 'ENERGY' production.

A type of enzyme inhibition where the inhibitor binds to an allosteric site on the enzyme, not the active site. This binding induces a conformational change that reduces the enzyme's catalytic efficiency (Vmax) without affecting the substrate's ability to bind (Km).

• Inhibitor binds to an allosteric site.
• Does not compete with substrate for the active site.
• Decreases Vmax (maximum reaction rate).
• Km (substrate affinity) remains unchanged.

Memory trick: Don't Compete, Just Non-Competitively Change the Game.

The process by which a cell converts an extracellular signal into an intracellular response, typically involving a series of molecular events (pathway).

• Begins with ligand binding to a receptor.
• Amplifies and diversifies signals.
• Crucial for cell growth, differentiation, and metabolism.

Memory trick: Signals Transduce: Receive, Relay, Respond.

Non-enzymatic attachment of sugars (like glucose) to proteins, forming advanced glycation end-products (AGEs).

• Occurs in hyperglycemia.
• Alters protein structure and function.
• Contributes to diabetic complications.
• HbA1c is an example.

Memory trick: Sugar Sticking is Glycosylation's Gig

A network of membranes involved in various metabolic processes, including lipid synthesis, detoxification, and calcium storage, but lacking ribosomes.

• Lacks ribosomes, hence 'smooth'.
• Synthesizes lipids, phospholipids, and steroids.
• Metabolizes carbohydrates.
• Detoxifies drugs and poisons.

Memory trick: Smooth SER: Steroids, Storage, Synthesis, and S-Detox (Smooth Detox)

A rigid outer layer in bacteria, primarily composed of peptidoglycan, that provides structural support, maintains cell shape, and protects the cell from osmotic lysis.

• Composed mainly of peptidoglycan (murein).
• Provides structural integrity and protects against osmotic pressure.
• Gram-positive bacteria have a thick peptidoglycan layer.
• Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane.

Memory trick: Cell Wall's main ingredient is PEPTIDOGLYCAN, like bricks in a wall!

A series of protein complexes and electron carriers located in the inner mitochondrial membrane that transfer electrons from NADH and FADH2 to oxygen, creating a proton gradient for ATP synthesis.

• Comprises four main complexes (I, II, III, IV) and mobile carriers.
• Pumps protons into the intermembrane space.
• Oxygen is the final electron acceptor.

Memory trick: Glycolysis (glucose split), Krebs (cycles for carriers), ETC (electrons pump protons, make ATP).

The overall three-dimensional shape of a single polypeptide chain, resulting from interactions between the side chains of amino acids.

• Determines the protein's specific function.
• Involves various bonds: hydrogen, ionic, disulfide, hydrophobic interactions.
• Incorrect folding leads to loss of function.

Memory trick: Primary's sequence, Secondary's folds, Tertiary's 3D, Quaternary's groups.

Peptidyl transferase is the enzymatic activity of the ribosome (a ribozyme) responsible for catalyzing the formation of peptide bonds between amino acids during protein synthesis.

• Located in the large ribosomal subunit (50S in prokaryotes, 60S in eukaryotes).
• Forms the peptide bond between the growing polypeptide chain and the incoming amino acid.
• It is a ribozyme, meaning the RNA component of the ribosome has the catalytic activity.

Memory trick: Ribosomes are the 'PEPTIDE' factories.

Small, circular, double-stranded DNA molecule that is distinct from a bacterial cell's chromosomal DNA and can replicate independently.

• Often carry genes beneficial for survival (e.g., antibiotic resistance).
• Used extensively in genetic engineering as vectors.
• Can be transferred between bacteria via conjugation.

Memory trick: Plasmids 'P'ass genes 'P'erfectly.

Enzyme activity is highly sensitive to environmental conditions such as temperature, pH, and substrate concentration, which affect the enzyme's structure and catalytic efficiency.

• Optimal temperature maximizes kinetic energy for reactions without denaturation.
• Optimal pH maintains proper ionization states for active site residues.
• Deviations from optimal conditions can reduce activity or cause denaturation.

Memory trick: Enzymes are 'P'icky about 'T'emperature and 'P'H.

The specialized synapse between a motor neuron and a skeletal muscle fiber, where neurotransmitter release initiates muscle contraction.

• Motor neuron releases acetylcholine (ACh).
• ACh binds to receptors on the muscle fiber (motor end plate).
• Binding causes depolarization and muscle action potential.
• Leads to excitation-contraction coupling.

Memory trick: ACh Antagonist: Muscle Action Arrested

The physiological response of the respiratory system to restore blood pH balance by altering the rate and depth of breathing, primarily to adjust CO2 levels.

• Hyperventilation reduces CO2, increasing pH.
• Hypoventilation increases CO2, decreasing pH.
• Acts rapidly but may not fully correct severe imbalances.

Memory trick: Respiratory blows off CO2, Renal pees out H+ or keeps HCO3-.

A form of intermediate inheritance in which one allele for a specific trait is not completely expressed over the other allele, resulting in a third, intermediate phenotype in the heterozygote.

• Heterozygous phenotype is a blend of homozygous phenotypes.
• Neither allele is fully dominant.
• Example: Red + White = Pink flowers.

Memory trick: Dominance is a spectrum: Complete, Incomplete, Co-express.

Essential amino acids are amino acids that cannot be synthesized by the human body and must be obtained from the diet. They are crucial for protein synthesis and various metabolic functions.

• There are 9 essential amino acids for humans.
• They are required for the construction of all proteins.
• Deficiencies can lead to impaired growth and various health issues.

Memory trick: Missing 'building blocks' means no new 'structures'.

A hormone system that regulates blood pressure and fluid balance. When blood pressure or volume drops, the kidneys release renin, which initiates a cascade leading to the production of Angiotensin II and Aldosterone.

• Renin is released by kidney juxtaglomerular cells.
• Renin converts angiotensinogen to Angiotensin I.
• ACE converts Angiotensin I to Angiotensin II.
• Angiotensin II causes vasoconstriction and Aldosterone release.

Memory trick: Renin Rushes: When blood pressure drops, Renin Rushes out of the kidney!

T-lymphocytes (T cells) are a type of white blood cell central to cell-mediated immunity, responsible for recognizing and eliminating infected cells, cancer cells, and coordinating immune responses.

• Helper T cells (CD4+) activate B cells, macrophages, and cytotoxic T cells.
• Cytotoxic T cells (CD8+) directly kill target cells presenting specific antigens.
• Regulatory T cells suppress immune responses to prevent autoimmunity.
• Key for defense against intracellular pathogens (viruses, some bacteria/fungi).

Memory trick: T-cells are 'CELL'ular 'COMMANDERS'.

Iron is an essential mineral that is a central component of the heme group in hemoglobin, the protein responsible for binding and transporting oxygen in the blood.

• Transferrin transports iron in the bloodstream.
• Iron deficiency leads to anemia (reduced oxygen-carrying capacity).
• Crucial for cellular respiration enzymes as well.

Memory trick: Iron's role: Oxygen, Energy, Immunity.

The bacterial growth curve describes the four distinct phases of growth that a bacterial population experiences in a closed system: lag, log, stationary, and death phases.

• Lag phase: adaptation, little to no division.
• Log phase: exponential growth, maximum division rate.
• Stationary phase: growth rate equals death rate.
• Death phase: more cells die than divide.

Memory trick: Bacteria 'LAUGH' (Lag), 'LIVE' (Log), 'STOP' (Stationary), 'DIE' (Death).

A pattern of inheritance where an affected individual has one copy of a mutated gene and one normal gene on a non-sex chromosome (autosome). The mutated gene is dominant, meaning only one copy is needed to express the trait.

• Affected individuals in every generation (vertical transmission).
• Affected offspring have at least one affected parent.
• Males and females are affected equally.
• Affected individuals have a 50% chance of passing the allele to each child.

Memory trick: Dominant: Dad or Mom, always showing up.

Small endocrine glands located in the neck, usually behind the thyroid gland, that produce parathyroid hormone (PTH), which plays a crucial role in regulating calcium and phosphate levels in the blood.

• Produces parathyroid hormone (PTH).
• PTH increases blood calcium levels.
• Achieves this by stimulating osteoclasts, kidney reabsorption, and vitamin D activation.
• PTH also decreases blood phosphate levels.

Memory trick: Parathyroid: PTH puts the calcium up high!

Autosomal recessive inheritance describes a pattern of inheritance where two copies of an abnormal gene (one from each parent) must be present for the disease or trait to develop.

• Affected individuals typically have unaffected parents (carriers).
• Trait often skips generations.
• Males and females are affected equally.
• Probability of affected offspring from two carrier parents is 25%.

Memory trick: Calculate 'PARENT' probabilities first, then the 'CHILD'.

Confirmation bias is the tendency to search for, interpret, favor, and recall information in a way that confirms or supports one's prior beliefs or values.

• Leads to selective attention and interpretation.
• Can make individuals resistant to contradictory evidence.
• Impacts decision-making and critical evaluation.

Memory trick: Confirm What You Believe, And Others Deceive.

Psychological discomfort from conflicting beliefs/actions; motivates individuals to reduce this conflict.

• Arises from conflicting cognitions (beliefs, values, actions).
• Creates psychological discomfort.
• Motivates individuals to reduce the conflict, often by changing beliefs or rationalizing actions.

Memory trick: Dissonance makes your thoughts feel 'off-key'.

Individuals are less likely to help a victim in an emergency when other bystanders are present.

• Increased number of bystanders decreases likelihood of help.
• Caused by diffusion of responsibility, social influence, audience inhibition.
• Highlights impact of group size on individual action.

Memory trick: Bystander: Many eyes, no one acts.

Philosophical skepticism questions the possibility of certain knowledge in a particular domain or about reality in general, often advocating for the suspension of judgment.

• Ancient Greek skepticism (e.g., Pyrrhonism) aimed for tranquility through suspending belief.
• Modern skepticism often focuses on epistemic justification.
• Distinguished from everyday doubt or cynicism.

Memory trick: Skeptics ask 'Show me the proof!' and if there isn't any, they suspend judgment.

The Spiral of Silence is a political science and mass communication theory stating that individuals are less likely to voice their opinions on controversial issues if they believe they are in the minority, due to a fear of social isolation.

• Driven by fear of isolation.
• Perceived public opinion influences individual expression.
• Leads to a perceived majority growing stronger, silencing dissent.

Memory trick: Silence Spirals When Opinions Falter.

Validity refers to an argument's structure: if premises are true, conclusion must be true. Soundness means an argument is valid AND all its premises are actually true.

• Validity is about logical structure.
• Soundness requires both validity and true premises.
• An argument can be valid but not sound if premises are false.

Memory trick: Validate the structure, then sound out the truth.

Autonomy in bioethics is the principle that individuals have a right to self-determination and independent decision-making regarding their own medical care, provided they have decisional capacity.

• Requires informed consent before treatment.
• Respects patient's values and preferences.
• Can conflict with other principles like beneficence.

Memory trick: A Big Naughty Jester. Autonomy, Beneficence, Non-maleficence, Justice.

Overgeneralization is a cognitive distortion or learning error where a rule, principle, or pattern is applied too broadly, extending it to situations or instances where it is not appropriate or valid.

• Common in language acquisition and learning.
• Involves applying a known rule to exceptions.
• Can lead to errors but is a natural part of learning.

Memory trick: Rules Run Wild, When Not Kept Mild.

Mental shortcut where judgments of probability are based on how easily examples come to mind, leading to overestimation of vivid events.

• Relies on ease of recall from memory.
• Vivid or recent events are more 'available'.
• Can lead to biased risk assessment.

Memory trick: Availability: What's 'available' in your mind seems more likely.

The representativeness heuristic is a mental shortcut where people judge the probability of an event by how well it matches a prototype or stereotype, often overlooking base rate frequencies.

• Leads to judgments based on similarity rather than objective probability.
• Can result in base rate neglect when ignored.
• Used in scenarios like diagnosing conditions or judging personality traits.

Memory trick: REPRESENT the typical, AVAIL the easy, ANCHOR the first, FRAME the view.

Moral relativism is the philosophical position that moral judgments are not universally true or false, but are true or false only relative to some particular standpoint, such as a culture or historical period.

• Opposes moral absolutism and universalism.
• Can apply to individuals (subjectivism) or cultures (cultural relativism).
• Implications for cross-cultural ethical evaluation and moral progress.

Memory trick: RELATIVES have their own rules, not universal ones.

The recency effect is a cognitive bias in which individuals tend to remember or give more weight to the most recently presented information or events when forming judgments or making decisions.

• Often paired with the primacy effect as part of the serial position effect.
• Impacts memory recall, performance evaluations, and decision-making.
• More pronounced when there is a short delay between information and recall.

Memory trick: RECENT events are RECALLED most RECENTLY.

A double-blind study is an experimental procedure in which neither the participants nor the researchers (or those administering the treatment) know who is receiving the particular treatment and who is receiving a placebo.

• Prevents participant expectations from influencing results (participant bias).
• Prevents researcher expectations from influencing results (observer/experimenter bias).
• Enhances the objectivity and internal validity of research findings.

Memory trick: Blinded Eyes Keep Minds From Sway.

Group discussion leads to decisions more extreme than the average initial inclinations of its members.

• Shift towards extremity (riskier or more cautious).
• Explained by social comparison and persuasive arguments.
• Differs from groupthink, which focuses on conformity and poor decision-making.

Memory trick: Polarization: The group pulls everyone to the 'poles' of opinion.

Observer bias (or experimenter bias) is a type of cognitive bias where the expectations of an observer or researcher influence the outcome of an experiment or study.

• Can lead to unintentional manipulation of results.
• Often mitigated by blinding (single-blind or double-blind designs).
• Applies to how data is collected, interpreted, or how subjects are treated.

Memory trick: The OBSERVER'S beliefs can OBSCUR the truth.

Paradoxical unity is a philosophical concept where seemingly contradictory or opposing elements are understood not as mutually exclusive but as coexisting, integrated, and essential components of a unified whole.

• Integrates contradictions rather than separating them.
• Often found in spiritual, mystical, or philosophical traditions.
• Emphasizes the holistic nature of complex concepts.

Memory trick: Contradictions Unite in a Single, Grand Design.

Increased preference for a stimulus due to repeated, often unconscious, exposure to it.

• Familiarity breeds liking.
• Operates even with subliminal or unconscious exposure.
• Commonly used in advertising and marketing.

Memory trick: More exposure = more 'Aww, I like that!'

Prior moral actions provide a psychological 'license' to engage in subsequent immoral or less moral behavior without guilt.

• Good deeds can justify future bad deeds.
• Reduces guilt associated with ethical transgressions.
• Operates unconsciously or through rationalization.

Memory trick: Moral License: Good deeds are like a 'get out of jail free' card for your conscience.

Mistaken belief that success with random events increases the probability of further success; each event is independent.

• Common in sports (e.g., basketball shots).
• Assumes streaks impact future independent probabilities.
• Contrasts with the gambler's fallacy.

Memory trick: Hot Hand: 'H' for 'Hot', 'H' for 'Happening now, so it will continue'.

Cognitive bias where low-ability individuals overestimate their competence and high-ability individuals underestimate theirs.

• Incompetent people lack metacognitive ability to recognize their incompetence.
• Competent people assume tasks easy for them are easy for others.
• Leads to inflated self-assessments at low skill levels, deflated at high skill levels.

Memory trick: Dunning-Kruger: The ignorant are on top, the experts are humble.

Social contagion is the spontaneous spread of behaviors, emotions, or ideas among people within a group or crowd, often without explicit communication or direct instruction.

• Involves the rapid spread of phenomena.
• Can affect emotions, behaviors, or ideas.
• Often occurs unconsciously or implicitly.

Memory trick: Ideas Catch Like Wildfire, Spreading Far and Wide.

Algorithmic thinking is a problem-solving approach that involves defining a problem, breaking it down into smaller, manageable steps, and then following a predefined sequence of instructions or rules to arrive at a solution.

• Systematic, step-by-step process.
• Guarantees a solution if one exists.
• Often used in computing and logical reasoning.

Memory trick: Algorithms Lead to Solutions, Step by Step.

Latent demand is a state where consumers have a strong desire for a good or service, but it cannot be satisfied because the product or service does not exist or is not readily available.

• Represents an unexpressed or unmet need.
• Often becomes apparent when new options are introduced.
• Important in market research and urban planning.

Memory trick: Hidden Needs Emerge When Options Appear Indeed.

Social proof is a psychological and social phenomenon wherein people assume the actions of others in an attempt to reflect correct behavior for a given situation.

• People look to others for cues on how to behave.
• Especially potent in ambiguous or uncertain situations.
• Used in marketing, persuasion, and behavioral interventions.

Memory trick: Proof From Others Makes You Move.

Selection bias occurs when the method of selecting participants for a study results in a sample that is not representative of the population being studied, or when the comparison groups in a study are not truly equivalent.

• Occurs during participant selection or assignment.
• Leads to non-equivalent groups.
• Threatens the internal validity of a study.

Memory trick: Careful Who You Pick, Or Your Study's Flawed Quick.

The base rate fallacy is a cognitive bias in which people tend to ignore base rate information (i.e., the general prevalence of an event or characteristic) in favor of specific, but less reliable, individuating information.

• Involves neglecting statistical probabilities.
• Often prioritizes anecdotal or specific details over general data.
• Leads to flawed judgments or decisions.

Memory trick: Don't Neglect Basic Statistics, Or You'll Fall.

Proposes that language structure influences or determines its speakers' worldview and cognition.

• Strong version: language determines thought (rarely supported).
• Weak version: language influences thought (more widely accepted).
• Examples often involve how different languages categorize color, time, or space.

Memory trick: Sapir-Whorf: Words shape Worlds.

Specificity is a measure of a diagnostic test's ability to correctly identify individuals who do NOT have the condition (true negatives).

• Calculated as True Negatives / (True Negatives + False Positives)
• High specificity means a low rate of false positives
• Crucial for confirming the absence of a disease

Memory trick: SENsitive people get POSITIVE results, SPECific people get NEGATIVE results.

Placebo effect: positive outcomes from inert treatment due to positive expectations. Nocebo effect: negative outcomes from inert treatment due to negative expectations.

• Both involve patient expectations influencing outcomes.
• Placebo: positive expectations, positive outcomes.
• Nocebo: negative expectations, negative outcomes.

Memory trick: Placebo is 'P'ositive, Nocebo is 'N'egative.

Universalism is a philosophical and ethical position that certain ideas, values, or human experiences are fundamental, applicable to all individuals, and transcend cultural, historical, or geographical boundaries.

• Emphasizes commonalities across humanity.
• Contrasts with relativism or particularism.
• Often applied to human rights, ethics, and psychology.

Memory trick: One World, One Heart, All Share a Start.

Words in different languages that appear similar but have distinct etymological origins and often different meanings.

• Look or sound similar across languages.
• Do NOT share a common linguistic ancestor.
• Often have different meanings, leading to confusion.

Memory trick: Don't be fooled by linguistic look-alikes; check their family tree.

External validity is the extent to which the findings of a research study can be generalized to other populations, settings, and conditions beyond the specific study context.

• Crucial for applying research findings to real-world scenarios.
• Threats include selection bias, situational effects, and participant characteristics.
• Often enhanced by diverse sampling and realistic experimental designs.

Memory trick: I Can See Everything. Internal, Construct, Statistical, External.