bio exam

Proteins

Polymers made up of smaller units called amino acids, essential for building body structure, facilitating chemical reactions, and enabling communication between cells. Specific examples include Hemoglobin, which carries oxygen in red blood cells, and enzymes like Lactase that aid in digestion.

Lipids

Diverse group of hydrophobic molecules including fats and oils, crucial for forming cell membranes and storing energy. Specific examples are Phospholipids, which make up cell membranes, and triglycerides found in animal fats and oils.

Carbohydrates

Organic compounds consisting of sugars and starches that provide energy and structural support to cells. Detailed examples include Monosaccharides like Glucose, Disaccharides such as Sucrose, and Polysaccharides like Starch, which is a major energy source in plants.

Nucleic Acids

Biopolymers essential for all known forms of life, which store and transmit genetic information, including DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). An example is how DNA determines phenotypic traits in organisms.

Peptide Bond

The covalent bond that links amino acids together in proteins, forming a polypeptide chain. An example is the peptide bonds that link amino acids in Insulin, a hormone involved in glucose metabolism.

Glycosidic Linkage

Covalent bonds between sugar molecules, critical in the formation of carbohydrates. Specific examples include the glycosidic bond in Sucrose, which links glucose and fructose.

Ester Bond

Type of bond formed between glycerol and fatty acids, significant in the formation of lipids. An example is the ester bonds in Triglycerides, where three fatty acids bond to a glycerol backbone.

Phosphodiester Bond

Type of bond that links nucleotides in nucleic acids, crucial for the structure of DNA and RNA. For example, phosphodiester bonds form the backbone of a DNA strand by linking the sugar of one nucleotide to the phosphate group of another.

Denaturation

The structural alteration of proteins resulting from extreme conditions, rendering them nonfunctional. An example includes the coagulation of proteins in egg whites when cooked.

Amino Acid

Building blocks of proteins characterized by a central carbon attached to an amino group, carboxyl group, and a unique side chain. A specific example is Glycine, the simplest amino acid, which serves as a foundation for protein structures.

Fatty Acid

Long hydrocarbon chains with a carboxyl group, essential in lipids. An example includes Stearic acid, a saturated fatty acid found in animal fats, which impacts the solid state of fats at room temperature.

Mono/Di/Polysaccharide

Types of carbohydrates categorized by the number of sugar units. For instance, Glucose is a monosaccharide, Sucrose is a disaccharide made of glucose and fructose, and Starch is a polysaccharide providing energy storage in plants.

Nucleotide

The basic unit of nucleic acids, composed of a sugar, phosphate group, and nitrogenous base. An example is Adenine, a key nitrogenous base in DNA and RNA.

Saturated Fat

A type of fatty acid containing no double bonds, typically solid at room temperature. An example is Butter, high in saturated fats, affecting heart health.

Unsaturated Fat

A type of fatty acid with one or more double bonds, usually liquid at room temperature. An example is Olive oil, commonly used for cooking and salad dressings due to its health benefits.

Condensation Reaction

A chemical reaction where two molecules combine, releasing water as a byproduct. An example is the formation of a disaccharide from two monosaccharides like Glucose molecules.

Hydrolysis Reaction

A reaction that breaks down a compound by adding water, crucial in digestion. An example is breaking down Lactose into its constituent sugars, Glucose and Galactose.

Hydrophilic

Molecules that interact readily with water. Sugar dissolving in water is a quintessential example demonstrating hydrophilic properties.

Hydrophobic

Molecules that repel water, tending to aggregate in aqueous environments. An example is Oil, which does not mix with water.

Fluid-Mosaic Model

A descriptive model of cell membrane structure illustrating its flexibility and various molecular components. An example is the arrangement of proteins and phospholipids in a plasma membrane.

Diffusion

The passive movement of molecules from an area of higher concentration to an area of lower concentration. Perfume molecules spreading through the air in a room is a common example.

Osmosis

A specific type of diffusion involving the movement of water across a semipermeable membrane. An example is water entering a plant cell from the soil.

Hypertonic

A solution with a higher concentration of solutes compared to the inside of a cell, leading to cell shrinkage as water exits. An example is a Salt solution causing animal cells to lose water.

Hypotonic

A solution with a lower concentration of solutes compared to a cell, which causes the cell to swell as water enters. Freshwater putting pressure on plant cells is a classical example.

Isotonic

A solution with equal concentrations of solutes compared to a cell, resulting in no net movement of water. Normal saline used in medical settings is a prime example.

Facilitated Diffusion

The passive transport process where molecules cross a membrane with the assistance of protein channels. An example is Glucose entering cells via specific transporter proteins.

Endocytosis

The cellular process in which substances are engulfed from outside the cell. An example is White blood cells engulfing bacteria through this method.

Exocytosis

The process by which cells expel materials, facilitating communication and waste removal. An example is Neurons releasing neurotransmitters into the synapse.

Phagocytosis

The process by which a cell engulfs large particles or microorganisms. An example is Macrophages consuming pathogens as part of the immune response.

Pinocytosis

The process by which a cell takes in liquid from its surroundings. An example is Intestinal cells absorbing fluid containing nutrients from digested food.

Coenzyme

Non-protein molecules that assist enzymes in catalysis. An example is NAD+, which plays a crucial role in the metabolic pathways of energy production.

Co-factor

Inorganic substances that help enzymes catalyze reactions. An example includes Zinc ions, which assist in the activity of various enzymes.

Endergonic Reaction

Chemical reactions that require energy input from the surroundings to proceed. Photosynthesis is a key example, where plants convert sunlight into chemical energy.

Exergonic Reaction

Reactions that release energy to the surroundings. Cellular respiration serves as a classic example, converting glucose into usable energy.

Oxidation

The process of losing electrons during a reaction. Rusting of iron in the presence of moisture exemplifies this chemical process.

Reduction

The process in which a molecule gains electrons. The formation of water from hydrogen and oxygen during combustion is a fundamental example.

Active Site

The specific region on an enzyme where the substrate binds, facilitating the enzyme's catalytic activity. An example includes the active site of Lactase where lactose binds.

Activation Energy

The minimum amount of energy that must be supplied for a chemical reaction to occur. Striking a match provides the activation energy needed to ignite it.

Substrate

The reactant molecule that an enzyme acts upon. Lactose is the substrate for Lactase, demonstrating its specificity.

Product

The end result of a chemical reaction; the molecules generated during the reaction. For example, Glucose is produced from the digestion of carbohydrates.

Induced-fit Model

The model proposing that an enzyme changes shape when the substrate attaches, enhancing the binding efficiency. An example is how enzymes adapt to fit their substrates better during the catalysis process.

Enzyme-Substrate Complex

The transient structure formed when an enzyme binds its substrate. An example is the complex formed during Lactase's action on Lactose.

Enzymes

Biological catalysts that accelerate chemical reactions by lowering activation energy barriers. Examples include Amylase, which breaks down starches into sugars.

Glycolysis

The metabolic pathway that converts glucose into pyruvate, yielding energy. Key steps include phosphorylation of glucose, splitting into two three-carbon molecules, and producing ATP and NADH.

Pyruvate Oxidation

A crucial step before entering the Krebs cycle, converting pyruvate to Acetyl-CoA. Steps include decarboxylation of pyruvate, reduction of NAD+, and formation of Acetyl-CoA.

Electron Transport Chain

The final stage of cellular respiration, where high-energy electrons are passed along a series of proteins to generate ATP. It involves proton pumping across the membrane, resulting in ATP synthesis as protons diffuse back.

Krebs Cycle

A series of biochemical reactions that generate energy through the oxidation of Acetyl-CoA. Steps include the formation of citrate, electron donation to NADH and FADH2, and ATP production.

Catabolic

Metabolic pathways that break down molecules for energy. Cellular respiration exemplifies catabolic processes.

Anabolic

Metabolic pathways that use energy to build complex molecules. An example is Protein synthesis, where amino acids are linked to form proteins.

Anaerobic

Metabolic processes that occur in the absence of oxygen. An example is Lactic acid fermentation that occurs in muscles during intense exercise.

Aerobic

Metabolic processes that require the presence of oxygen. Cellular respiration is a primary example, as it requires oxygen to produce energy.

NADH/FADH₂

Electron carriers that store and transport energy within the cell. They are produced during Glycolysis and the Krebs cycle and contribute to ATP synthesis in oxidative phosphorylation.

ATP

The primary energy carrier in biological systems, providing energy for cellular processes. An example includes ATP's role in muscle contraction.

Chemiosmosis

The process of generating ATP using a proton gradient across a membrane. An example is ATP synthesis during the electron transport chain in both respiration and photosynthesis.

P680/P700

Specific light wavelengths absorbed by reaction centers in Photosystems I and II during photosynthesis, with P680 being optimal at 680 nm and P700 at 700 nm.

Photosystem

A protein-pigment complex in chloroplasts essential for capturing light energy to drive photosynthesis. Photosystem II initiates light reactions in the thylakoid membranes.

Chlorophyll

The green pigment found in plants that absorbs light for photosynthesis, primarily found in chloroplasts. It is responsible for converting solar energy into chemical energy.

Carbon Fixation

The process of converting carbon dioxide into organic molecules, primarily occurring during the Calvin cycle in photosynthesis. Rubisco catalyzes this essential step.

Rubisco

The enzyme that catalyzes the conversion of carbon dioxide into organic compounds during the Calvin cycle. It is the most abundant enzyme on Earth, highlighting its ecological importance.

NADPH

A crucial electron donor utilized in the light-independent reactions of photosynthesis. NADPH is generated during the light-dependent reactions and helps in the synthesis of glucose.

Photon

A quantum of light energy absorbed by chlorophyll and other pigments during photosynthesis. Photons are essential for initiating the light reactions.

Stomata

Microscopic openings on the leaf surface that facilitate gas exchange. Stomata allow carbon dioxide to enter and oxygen to exit, playing a vital role in photosynthesis.

RuBP

Ribulose bisphosphate, a five-carbon sugar essential for the Calvin cycle, binding with CO₂ to initiate carbon fixation.

Photorespiration

An inefficient pathway where Rubisco fixes oxygen instead of CO₂, leading to energy loss and reduced photosynthetic efficiency. Often occurs in hot conditions.

CAM/C4/C3 Plants

Various strategies plants use to fix carbon during photosynthesis, with CAM plants (like cacti) conserving water, C4 plants (like corn) efficiently performing photosynthesis in high light, and C3 plants (like wheat) being the most common.

Homeostasis

The ability of an organism to maintain stable internal conditions despite external changes. An example is the regulation of body temperature in mammals to maintain optimal function.

Nephron

The fundamental structural and functional unit of the kidney responsible for filtering blood and producing urine. Each human kidney contains approximately one million nephrons.

Glomerulus

A network of capillaries located at the beginning of a nephron, responsible for filtering blood to form a filtrate. It marks the first step in urine formation.

Bowman’s Capsule

A cup-like sac that encases the glomerulus and collects the initial filtrate during the process of filtration in the nephron.

Loop of Henle

A U-shaped portion of the nephron that plays a vital role in concentrating urine and recovering water and salts from filtrate.

Proximal/Distal Tubule

Segments of the nephron where selective reabsorption and secretion occur. The Proximal tubule reabsorbs nutrients like glucose, while the Distal tubule regulates ionic balance.

Renal Medulla/Cortex/Pelvis

The three main anatomical regions of the kidney, with the cortex being the outer layer for filtration, the medulla involved in the concentration of urine, and the pelvis where urine drains into the ureter.

Ureter/Urethra/Bladder

Components of the urinary system that play key roles in the transport, storage, and expulsion of urine; the ureters carry urine from the kidneys to the bladder for storage.

Reflex Arc

The neural pathway involved in a reflex action, consisting of sensory neurons, interneurons, and motor neurons. The knee-jerk reaction serves as a common example.

Neurotransmitter

Chemicals that transmit signals across synapses between neurons. Examples include Dopamine, which plays a significant role in mood regulation and pleasure.

Motor/Sensory Neurons

Neurons that transmit signals; Motor neurons carry commands from the central nervous system to muscles, while Sensory neurons relay sensory information from receptors to the brain.

Myelin Sheath

The insulating layer around axons that increases the speed of electrical signal transmission. Examples include the myelin sheaths surrounding peripheral nerve fibers.

Nodes of Ranvier

The periodic gaps in the myelin sheath that facilitate rapid conduction of nerve impulses via saltatory conduction, crucial for efficient signal transmission.

Resting/Action Potential

The charge difference across a neuron's membrane when it is inactive (resting potential typically at -70 mV) versus during a nerve impulse (action potential when it spikes above 0 mV).

Depolarization/Repolarization

Phases in the action potential; depolarization occurs when sodium channels open, causing the inside of the neuron to become positively charged, whereas repolarization restores the negative charge.

Peripheral/Central NS

Divisions of the nervous system; the Central nervous system includes the brain and spinal cord, while the Peripheral nervous system encompasses all nerves branching from the CNS.

Sympathetic/Parasympathetic NS

Subdivisions of the autonomic nervous system; sympathetic activates the fight-or-flight response, while parasympathetic promotes rest and digestion.

Hormone

Biochemical messengers produced by glands that regulate physiological activities. Examples include Insulin, which helps control blood sugar levels.

Protein/Steroid Hormones

Categories of hormones; Protein hormones bind to specific receptors on cell surfaces, while Steroid hormones diffuse across membranes to bind to interior receptors. Testosterone is an example of a steroid hormone.

Pituitary/Hypothalamus

Interlinked components of the endocrine system; the hypothalamus regulates the pituitary gland, which releases hormones that control various body functions.

DNA/RNA Polymerase

Enzymes that synthesize DNA or RNA by adding nucleotides to a growing chain, essential for DNA replication and transcription, respectively.

Leading/Lagging Strand

Strands of DNA during replication; the leading strand is synthesized continuously toward the fork, while the lagging strand is synthesized in fragments known as Okazaki fragments.

Replication Fork

The area where the DNA double helix unwinds and replication occurs; it appears as a Y-shaped structure during DNA replication.

Codon/Anticodon

Three-nucleotide sequences found in mRNA (codon) and tRNA (anticodon) that match to specify amino acids during protein synthesis. AUG is an example of a start codon.

Exons/Introns

Exons are coding segments of a gene, while introns are non-coding regions. During mRNA processing, introns are removed to form mature mRNA.

Promoter/Operator

Regulatory regions of DNA; the promoter is where RNA polymerase binds to initiate transcription, and the operator controls access to the promoter.

Helicase

An enzyme that unwinds the DNA double helix ahead of the replication fork, making the strands accessible for copying.

Ligase

An enzyme that connects DNA fragments, essential for sealing nicks and gluing Okazaki fragments on the lagging strand during DNA replication.

tRNA/mRNA

Types of RNA involved in protein synthesis; mRNA conveys genetic information from DNA to the ribosome, while tRNA transports specific amino acids to the ribosome during translation.

Transcription/Translation

Processes for synthesizing RNA from DNA (transcription) and synthesizing proteins from RNA (translation). During transcription, DNA is copied into mRNA in the nucleus.

Lac/Trp Operons

Models for gene regulation in prokaryotic cells; the lac operon is activated by the presence of lactose, while the trp operon is involved in tryptophan synthesis and is repressed when tryptophan levels are high.

Lac Operon (No Lactose)

When lactose is absent, the Lac Operon is turned off. The repressor protein binds to the operator region of the operon, blocking RNA polymerase from transcribing the genes required for lactose metabolism (e.g., LacZ, LacY). Consequently, the enzymes for lactose breakdown are not produced.

Lac Operon (With Lactose)

When lactose is present, some of it is converted to allolactose, which serves as an inducer. Allolactose binds to the repressor protein, causing it to change shape and release from the operator. This allows RNA polymerase to bind to the promoter and transcribe the genes needed for lactose metabolism, enabling the utilization of lactose as an energy source.

Trp Operon (No Tryptophan)

When tryptophan is absent, the Trp Operon is activated. The repressor protein is inactive, allowing RNA polymerase to bind to the promoter and transcribe the genes required for tryptophan biosynthesis, leading to the production of tryptophan.

Trp Operon (With Tryptophan)

When tryptophan is present, it binds to the repressor protein, activating it. The activated repressor then binds to the operator region of the operon, blocking RNA polymerase from transcribing the genes required for tryptophan synthesis, thereby inhibiting the production of tryptophan.