Molecular and Cellular Biology: DNA, Protein Synthesis, and Cell Division

What are the major elements of the human body?

The four major elements that make up roughly 96% of body mass are oxygen, carbon, hydrogen, and nitrogen.

What are the three subatomic particles?

The three subatomic particles are protons (positive charge, located in the nucleus), neutrons (no charge, also in the nucleus), and electrons (negative charge, orbiting the nucleus).

What is atomic number?

Atomic number is the number of protons in the nucleus of an atom, which determines the element's identity.

What is mass number?

Mass number is the total number of protons and neutrons in an atom's nucleus.

What are isotopes?

Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons.

What is an ionic bond?

An ionic bond is a chemical bond formed through the electrostatic attraction between oppositely charged ions.

What is a covalent bond?

A covalent bond is a chemical bond formed when two atoms share one or more pairs of electrons.

What is a hydrogen bond?

A hydrogen bond is a weak bond between a hydrogen atom and an electronegative atom, often involving water molecules.

What are synthesis reactions?

Synthesis reactions are chemical reactions where two or more reactants combine to form a single product.

What are decomposition reactions?

Decomposition reactions are chemical reactions where a single compound breaks down into two or more products.

What are exchange reactions?

Exchange reactions are chemical reactions where parts of two different molecules swap places to form two new compounds.

What is potential energy?

Potential energy is stored energy based on an object's position or arrangement.

What is kinetic energy?

Kinetic energy is the energy of motion.

What is the pH scale?

The pH scale measures the acidity or basicity of a solution, ranging from 0 (acidic) to 14 (basic), with 7 being neutral.

What is a buffer?

A buffer is a solution that resists changes in pH when acids or bases are added, helping to maintain homeostasis.

What are carbohydrates?

Carbohydrates are organic compounds made of carbon, hydrogen, and oxygen, serving as a primary energy source.

What are lipids?

Lipids are a diverse group of hydrophobic organic compounds, including fats, oils, and steroids, primarily used for energy storage and membrane structure.

What are proteins?

Proteins are large biomolecules made of amino acids, essential for structure, function, and regulation of the body's tissues and organs.

What are nucleic acids?

Nucleic acids, such as DNA and RNA, are polymers made of nucleotide monomers that store and transmit genetic information.

What is denaturation?

Denaturation is the process where proteins lose their native structure due to external stress, affecting their function.

What is enzyme specificity?

Enzyme specificity refers to the ability of an enzyme to catalyze only one specific reaction or type of reaction.

What factors influence enzyme activity?

Factors that influence enzyme activity include temperature, pH, and substrate concentration.

What is the role of enzymes?

Enzymes act as biological catalysts that lower the activation energy of reactions, increasing the reaction rate.

What is the primary structure of a protein?

The primary structure of a protein is the unique sequence of amino acids that make up the polypeptide chain.

What is the secondary structure of a protein?

The secondary structure of a protein refers to the local folded structures that form within a polypeptide due to hydrogen bonding, such as alpha helices and beta sheets.

What is the tertiary structure of a protein?

The tertiary structure of a protein is the overall three-dimensional shape formed by the folding of the polypeptide chain.

What is the quaternary structure of a protein?

The quaternary structure of a protein is the arrangement of multiple polypeptide chains into a single functional complex.

What is an enzyme?

A protein that acts as a catalyst to accelerate chemical reactions in biological systems.

How can an enzyme be reused?

Enzymes can be reused because they are not consumed in the reaction; they can catalyze multiple reactions with substrate molecules.

Why can a small amount of enzyme process a large amount of substrate?

Enzymes are highly efficient and can catalyze many reactions per second, allowing a small quantity to process a large amount of substrate.

What happens to enzyme activity above optimal temperature?

Enzyme activity decreases above optimal temperature due to denaturation, which alters the enzyme's structure and function.

Why must the body tightly regulate temperature and pH for enzymes?

Tight regulation of temperature and pH is essential to maintain enzyme structure and function, ensuring metabolic processes occur efficiently.

What is the fluid mosaic model?

The fluid mosaic model describes the plasma membrane as a flexible structure with various proteins embedded in or attached to a bilayer of phospholipids.

What does selectively permeable mean?

Selectively permeable means that the plasma membrane allows certain molecules to pass through while restricting others.

What are the main components of the plasma membrane?

The main components include the phospholipid bilayer, cholesterol, integral proteins, peripheral proteins, glycoproteins, and glycolipids.

What is passive transport?

Passive transport is the movement of substances across a membrane without the use of energy, typically along a concentration gradient.

What is active transport?

Active transport is the movement of substances against their concentration gradient, requiring energy, usually in the form of ATP.

What is osmosis?

Osmosis is the diffusion of water molecules across a semipermeable membrane from a region of lower solute concentration to higher concentration.

What are hypertonic, hypotonic, and isotonic solutions?

Hypertonic solutions have a higher solute concentration than the cell, hypotonic solutions have a lower solute concentration, and isotonic solutions have equal solute concentration.

What happens to a cell in a hypertonic solution?

In a hypertonic solution, a cell will shrink as water moves out to balance solute concentrations.

What happens to a cell in a hypotonic solution?

In a hypotonic solution, a cell will swell and may burst as water moves in to balance solute concentrations.

What are the major cell organelles?

Major organelles include the nucleus, ribosomes, endoplasmic reticulum (rough and smooth), Golgi apparatus, mitochondria, lysosomes, and peroxisomes.

What is the function of the nucleus?

The nucleus stores genetic information and coordinates cell activities such as growth, metabolism, and reproduction.

What are tight junctions?

Tight junctions are cell junctions that prevent leakage of materials between adjacent cells, maintaining a barrier.

What are anchoring junctions?

Anchoring junctions are cell junctions that mechanically bind cells together, providing structural stability.

What are gap junctions?

Gap junctions are cell junctions that allow direct communication between adjacent cells by permitting the passage of small molecules and ions.

What is autocrine signaling?

Autocrine signaling is a mode of cell communication where a cell secretes a signal that binds to receptors on its own surface.

What is paracrine signaling?

Paracrine signaling involves the release of signals by a cell that affect nearby target cells.

What is endocrine signaling?

Endocrine signaling involves hormones released into the bloodstream to target distant cells.

What is anabolism?

Anabolism is the metabolic process that builds larger molecules from smaller ones, requiring energy.

What is catabolism?

Catabolism is the metabolic process that breaks down larger molecules into smaller ones, releasing energy.

What is ATP?

ATP (adenosine triphosphate) is the primary energy carrier in cells, storing and providing energy for various cellular processes.

How is ATP produced from glucose?

ATP is produced from glucose through aerobic cellular respiration, which includes glycolysis, the citric acid cycle, and the electron transport chain.

What is the difference between aerobic and anaerobic respiration?

Aerobic respiration requires oxygen and produces more ATP, while anaerobic respiration occurs without oxygen and yields less ATP.

What role do carbohydrates, lipids, and proteins play in ATP production?

Carbohydrates, lipids, and proteins can all be metabolized to produce ATP, serving as energy sources for cellular processes.

What is aerobic cellular respiration?

The process by which cells convert glucose and oxygen into carbon dioxide, water, and ATP.

What are the overall reactants and products of aerobic cellular respiration?

Reactants: glucose and oxygen; Products: carbon dioxide, water, and ATP.

Where does glycolysis occur?

Glycolysis occurs in the cytosol of the cell.

What happens during glycolysis?

Glucose is split into two pyruvate molecules, resulting in a small net gain of ATP.

Where do the citric acid cycle and electron transport chain occur?

Both occur in the mitochondria of the cell.

What is the role of the citric acid cycle?

The citric acid cycle produces electron carriers (NADH and FADH₂) that are used in the electron transport chain to generate ATP.

What is the role of oxygen in cellular respiration?

Oxygen acts as the final electron acceptor in the electron transport chain.

How do electron carriers link glycolysis and the electron transport chain?

Electron carriers like NADH and FADH₂ transport electrons from glycolysis and the citric acid cycle to the electron transport chain.

What is chemiosmosis?

Chemiosmosis is the process by which a gradient of protons (H⁺ ions) is used to synthesize ATP in the electron transport chain.

What is the approximate ATP yield of glycolysis?

Glycolysis yields a net gain of 2 ATP molecules.

What is the approximate ATP yield of the citric acid cycle?

The citric acid cycle yields about 2 ATP molecules per glucose molecule.

What is the approximate ATP yield of the electron transport chain?

The electron transport chain can yield approximately 28-34 ATP molecules per glucose molecule.

What happens to ATP production if oxygen is unavailable?

If oxygen is unavailable, ATP production shifts to anaerobic pathways, resulting in significantly lower ATP yield.

What distinguishes aerobic from anaerobic ATP production?

Aerobic ATP production requires oxygen, while anaerobic ATP production does not.

What is the fate of pyruvate when oxygen is present?

When oxygen is present, pyruvate enters the mitochondria and is converted into acetyl-CoA for the citric acid cycle.

What is the fate of pyruvate when oxygen is absent?

When oxygen is absent, pyruvate is converted into lactic acid or ethanol, depending on the organism.

Why are anaerobic pathways useful despite low ATP yield?

Anaerobic pathways allow for rapid ATP production and do not require oxygen, which is beneficial during intense exercise.

Why does lactic acid accumulate during intense exercise?

Lactic acid accumulates due to the conversion of pyruvate in the absence of sufficient oxygen during anaerobic respiration.

What happens to lactic acid after intense exercise?

Lactic acid is eventually converted back to pyruvate or glucose in the liver when oxygen becomes available.

What are the main fuels for ATP production?

Carbohydrates (glucose), lipids (fatty acids), and proteins (amino acids) can all be metabolized to produce ATP.

How are fats metabolized for ATP production?

Fats are broken down into fatty acids and glycerol, which enter the energy pathways for high ATP yield.

What must happen to amino acids before they can be used for energy?

Amino acids must undergo deamination, where the amino group is removed, before they can be burned for energy.

What does the body do with excess nutrients?

Excess nutrients are stored as glycogen in the liver and muscles or converted to fat for long-term energy storage.

What is the structure of DNA?

DNA has a double helix structure made of nucleotides, which consist of a sugar, phosphate group, and nitrogenous base.

What are the base-pairing rules of DNA?

The base-pairing rules are adenine (A) pairs with thymine (T), and guanine (G) pairs with cytosine (C).

What is a gene?

A gene is a sequence of DNA that encodes for a specific protein and determines a trait.

How does DNA replication occur?

During DNA replication, the double helix unwinds, and each strand serves as a template for the formation of a new complementary strand.

What is mitosis?

Mitosis is the process of cell division that results in two genetically identical diploid daughter cells.

What is meiosis?

Meiosis is the process that produces gametes (sperm and eggs) and introduces genetic variation through crossing over and independent assortment.

What is the difference between haploid and diploid cells?

Diploid cells contain two sets of chromosomes (one from each parent), while haploid cells contain one set of chromosomes.

What is the purpose of crossing over in meiosis?

Crossing over during meiosis increases genetic variation by exchanging genetic material between homologous chromosomes.

What are the phases of the cell cycle?

The cell cycle consists of interphase (G₁, S, G₂) and the mitotic phase (mitosis and cytokinesis).

What is the outcome of mitosis?

The outcome of mitosis is two genetically identical diploid daughter cells.

What happens if cytokinesis fails after mitosis?

If cytokinesis fails, it can lead to cells with an abnormal number of chromosomes, potentially causing cancer.