Comprehensive Biology and Genetics: Cell Structure, DNA, Evolution, and Metabolism

What are the unifying themes of life?

Life evolves over time, structure and function are interrelated, life's processes involve information flow, matter and energy are transformed, and biology consists of complex systems.

What accounts for life's unity and diversity?

Evolution accounts for life's unity and diversity.

How do species arise according to evolutionary theory?

Species arise through 'descent with modification' from common ancestors.

What drives the process of natural selection?

It is driven by the conditions necessary for it to occur, leading to traits becoming more predominant in a population.

What is the ultimate source of genetic variation?

Mutations are the ultimate source of genetic variation.

How does natural selection differ from artificial selection?

Natural selection occurs naturally, while artificial selection is driven by human intervention.

What is sexual selection?

Sexual selection involves reproductive mate selection providing the selective pressure.

What does the fossil record indicate about life on Earth?

The fossil record indicates that life has changed over the course of Earth's history.

What are the basic units of matter?

The basic units of matter are elements and compounds.

What defines an atom?

An atom is the smallest unit of matter retaining the properties of an element, comprised of protons, neutrons, and electrons.

What is the atomic number?

The atomic number is the number of protons in an atom.

What is the mass number?

The mass number is the number of protons plus neutrons in an atom.

What are isotopes?

Isotopes are atoms of the same element with different numbers of neutrons.

What is a covalent bond?

A covalent bond is formed when atoms are held together by shared valence electrons.

What is an ionic bond?

An ionic bond results from the attraction between opposite charges when an electron is transferred from one atom to another.

What are hydrogen bonds?

Hydrogen bonds result from the attraction between the partial positive charge on hydrogen and a partial negative charge on an electronegative atom.

What are Van der Waals interactions?

Van der Waals interactions are attractions between nonpolar molecules based on transient regions of positive and negative charges.

What unique properties does water have?

Water has high cohesion, adhesion, surface tension, and resists temperature changes.

What is the pH scale?

The pH scale measures hydrogen ion concentrations.

What are acids and bases?

Acids donate H+ ions, while bases deplete H+ ions.

What are macromolecules?

Macromolecules are polymers synthesized via dehydration reactions and broken down via hydrolysis reactions.

What are the four major classes of biological molecules?

Carbohydrates, lipids, proteins, and nucleic acids.

What is the primary structure of a protein?

The primary structure is the sequence of amino acids joined by covalent (peptide) bonds.

What defines the secondary structure of a protein?

The secondary structure consists of regular coils (α helices) and folds (β pleated sheets) stabilized by hydrogen bonds.

What is the tertiary structure of a protein?

The tertiary structure is the overall shape determined by interactions among various side chains (R groups).

What is the quaternary structure of a protein?

The quaternary structure results from interactions between multiple polypeptide chains.

What are nucleic acids composed of?

Nucleic acids are composed of nucleotides linked into a polynucleotide chain.

What is the difference between DNA and RNA?

DNA is double-stranded with Thymine, while RNA is single-stranded with Uracil.

What are the common features of all cells?

All cells have a plasma membrane, cytosol, chromosomes, and ribosomes.

What are prokaryotic cells?

Bacteria and Archaea that are smaller (1−10 μm), lack a membrane-bound nucleus, and lack membrane-bound organelles.

What are eukaryotic cells?

Protists, Fungi, Plants, and Animals that are larger (10−100 μm), have a membrane-bound nucleus, and contain membrane-bound organelles.

What is the endosymbiont theory?

It suggests that mitochondria and chloroplasts originated from prokaryotic endosymbionts.

How does the surface-area-to-volume ratio (SAV) affect cell function?

As a cell gets larger, the SAV ratio decreases, limiting material transfer but allowing greater storage capacity.

What is the role of biologists using microscopes?

To study cells, where magnification, resolution, and contrast affect the ability to display cellular details.

What are the differences between Light Microscopes (LM) and Electron Microscopes (EM)?

LM uses visible light and can image live specimens, while EM uses electrons for high-resolution images but cannot image live specimens.

What is the endomembrane system?

It includes the nuclear envelope, endoplasmic reticulum, Golgi apparatus, transport vesicles, lysosomes, vacuoles, and plasma membrane.

What is the fluid-mosaic model?

A model describing cellular membranes as comprised of proteins embedded in a fluid phospholipid bilayer.

What factors affect membrane fluidity?

Temperature and fatty acid composition, with cholesterol helping to maintain fluidity.

What is passive transport?

Movement of substances down their concentration gradient without energy.

What is active transport?

Movement of substances against their concentration gradients, requiring energy.

What is the sodium-potassium pump?

An example of active transport that moves 3 Na+ out and 2 K+ into the cell using ATP.

What is metabolism?

The totality of an organism's chemical reactions.

What are catabolic pathways?

Metabolic pathways that break down complex molecules, releasing energy.

What are anabolic pathways?

Metabolic pathways that build complex molecules, consuming energy.

What is free energy (G)?

The portion of a system's energy that can do work.

What are exergonic reactions?

Reactions characterized by a net loss of free energy and are spontaneous.

What are endergonic reactions?

Reactions that have a net gain of free energy and are non-spontaneous.

What is ATP?

Adenosine triphosphate, the main source of energy for driving endergonic reactions.

What do enzymes do?

They speed up metabolic reactions by lowering the activation energy.

What is dynamic equilibrium in chemical reactions?

A state where the forward and reverse reaction rates are equal, and concentrations remain stable.

How do cells control metabolic reactions?

Using activation energy, enzymes, and enzyme regulators.

What is the role of activation energy in metabolic reactions?

It is the energy required to reach the high-energy transition state.

What is energy coupling?

Using energy from favorable reactions to perform energetically unfavorable reactions.

What is the significance of the laws of thermodynamics in energy transformations?

They govern how energy can be transferred and transformed, affecting metabolic processes.

What is the difference between kinetic and potential energy?

Kinetic energy is associated with motion, while potential energy is based on location or structure.

What is the role of transport proteins in cellular membranes?

They facilitate the movement of hydrophilic substances across the membrane.

What is cotransport?

The process where the active transport of one solute indirectly drives the transport of other solutes.

What is bulk transport?

Used for large molecules or quantities, involving endocytosis and exocytosis.

What is cellular respiration?

A catabolic pathway that oxidizes organic fuels to generate ATP.

What is the overall chemical equation for cellular respiration?

Glucose + Oxygen → Carbon Dioxide + Water + Energy.

What are redox reactions?

Reactions involving oxidation (loss of electrons) and reduction (gain of electrons).

What is oxidation?

A substance loses electrons and becomes oxidized.

What is reduction?

A substance gains electrons and becomes reduced.

What is an oxidizing agent?

A substance that causes oxidation by gaining an electron.

What is a reducing agent?

A substance that causes reduction by losing an electron.

What role does NAD+ play in cellular respiration?

It functions as a high-energy electron shuttle, becoming reduced to NADH.

What are the two ways ATP is generated in cellular respiration?

Substrate-Level Phosphorylation and Oxidative Phosphorylation.

Where does glycolysis occur?

In the cytosol.

What are the major products of glycolysis?

Net ATP (2 used, 4 payoff) and NADH.

Where does the citric acid cycle occur?

In the mitochondrial matrix.

What are the major products of the citric acid cycle?

CO2, NADH, FADH2, and ATP.

Where does oxidative phosphorylation occur?

In the inner mitochondrial membrane.

What is the function of the Electron Transport Chain (ETC)?

It transfers high-energy electrons and couples energy release to the movement of H+ ions.

What is chemiosmosis?

The process where protons diffuse across the membrane, powering ATP formation.

What happens if oxygen is limited in cellular respiration?

ATP production is affected, and the cell can generate ATP via fermentation.

What is photosynthesis?

The process by which autotrophs synthesize complex organic compounds using solar energy.

What is the overall chemical equation for photosynthesis?

CO2 + H2O + Energy → Glucose + O2.

Where does photosynthesis occur?

In chloroplasts.

What are the two stages of photosynthesis?

Light Reactions and the Calvin Cycle.

What occurs during the light reactions of photosynthesis?

Water is split, producing O2, NADPH, and ATP.

What is the Calvin Cycle?

The process that forms sugar from CO2 using ATP and NADPH.

What is the role of rubisco in the Calvin Cycle?

It incorporates CO2 into RuBP during carbon fixation.

What adaptations do C4 plants have for photosynthesis?

They use an enzyme with high affinity for low CO2 to fix carbon into a four-carbon molecule.

What adaptations do CAM plants have for photosynthesis?

They open stomata at night to fix CO2 into organic acids.

What is the significance of stomata in plants?

They regulate the supply of CO2 and O2 during photosynthesis.

What is the cell cycle?

The series of phases that a cell goes through to divide.

What are the phases of mitosis?

Prophase, Prometaphase, Metaphase, Anaphase, Telophase, and Cytokinesis.

What is a duplicated chromosome?

A chromosome that consists of two identical sister chromatids joined by a centromere.

What is the role of microtubules in mitosis?

They control chromosome movement during cell division.

How do prokaryotes reproduce?

Through binary fission, where the single chromosome replicates and daughter chromosomes move apart.

What is the role of the eukaryotic cell cycle control system?

To control growth and prevent issues like cancer.

What are checkpoints in the cell cycle?

Checkpoints are points where internal and external signals determine if the cell proceeds.

What is the result of unchecked cell division?

It can lead to cancer.

What is the human life cycle's ploidy for somatic cells?

Somatic cells are diploid (2n=46).

What type of cells do meiosis produce?

Meiosis produces haploid gametes (1n=23).

What happens during fertilization?

Gametes fuse to form a zygote (2n).

What is the critical difference between meiosis and mitosis?

Meiosis involves the pairing of homologous chromosomes.

What is independent assortment?

Homologous pairs of chromosomes orient randomly at Metaphase I.

What is crossing over?

It is the exchange of homologous portions of two nonsister chromatids.

What does random fertilization increase?

It increases the total number of unique diploid combinations.