Comprehensive Biology and Genetics: Cell, DNA, and Virus Fundamentals

What is the goal of basic science?

To expand knowledge without any expectation of short-term practical application.

What types of bonds can electrons create between atoms?

Ionic, covalent, hydrogen bonds, and van der Waals interactions.

What is hydrolysis?

A reaction that breaks down polymers into monomers using a water molecule.

What are common examples of monosaccharides?

Glucose, galactose, and fructose.

What is the function of starch and glycogen?

They are storage forms of glucose in plants and animals, respectively.

What are lipids characterized by?

Being nonpolar and hydrophobic.

What are the main components of phospholipids?

A glycerol or sphingosine backbone, two fatty acid chains, and a phosphate-containing group.

What is the basic structure of steroids?

Four fused carbon rings.

What role does cholesterol play in the plasma membrane?

It helps maintain the membrane's fluid nature.

What is a peptide bond?

A bond that links each amino acid to its neighbors.

What is the primary structure of a protein?

The unique sequence of amino acids.

What is the unified cell theory?

All organisms are made of one or more cells, the cell is the basic unit of life, and new cells arise from existing cells.

What is the size range of prokaryotic cells?

0.1 to 5.0 μm in diameter.

What is the function of lysosomes?

They digest macromolecules and recycle worn-out organelles.

What is the endomembrane system?

A system that includes the nuclear envelope, lysosomes, vesicles, ER, Golgi apparatus, and plasma membrane.

What do tight junctions do in animal cells?

They create watertight seals between adjacent cells.

What is the function of chloroplasts?

They are involved in photosynthesis.

What is the role of the Golgi apparatus?

It sorts, tags, packages, and distributes lipids and proteins.

What do microtubules do?

They help the cell resist compression and serve as tracks for motor proteins.

What is the function of plasmodesmata in plant cells?

They are channels that connect adjacent plant cells for communication.

What is the fluid nature of the membrane attributed to?

Temperature, fatty acid tail configuration, cholesterol presence, and the mosaic nature of proteins.

What drives diffusion in a system?

Substances move from high to lower concentration areas until evenly distributed.

What is free energy?

The energy available to do work in a system, represented as ∆G.

What is activation energy?

The initial energy input required to reach the transition state of a reaction.

What does the second law of thermodynamics state?

Every energy transfer involves some loss of energy in an unusable form, leading to increased disorder.

What is ATP?

Adenosine triphosphate, the primary energy-supplying molecule for living cells.

What are the components of ATP?

A nucleotide, a five-carbon sugar, and three phosphate groups.

How does ATP provide energy for cellular work?

Through hydrolysis into ADP + Pi, releasing energy that can be coupled with endergonic reactions.

What is the induced fit model in enzyme activity?

The induced fit model suggests that enzymes undergo conformational changes upon substrate binding to achieve optimal interaction.

What is feedback inhibition?

Feedback inhibition is a regulatory mechanism where the end products of a metabolic pathway inhibit an enzyme involved in that pathway.

What happens to ATP when it is used for energy?

When ATP is used, it loses one or two phosphate groups, resulting in ADP or AMP.

What are the two processes of ATP regeneration?

The two processes are substrate-level phosphorylation and oxidative phosphorylation.

What is glycolysis?

Glycolysis is the metabolic pathway that breaks down glucose into two three-carbon sugars, producing ATP and NADH.

What is the net gain of ATP from glycolysis?

The net gain from glycolysis is two ATP and two NADH molecules.

What happens to pyruvate in the presence of oxygen?

In the presence of oxygen, pyruvate is converted into acetyl CoA, which enters the citric acid cycle.

What is the citric acid cycle?

The citric acid cycle is a series of reactions that remove high-energy electrons and carbon dioxide from acetyl CoA.

What are the end products of the electron transport chain?

The end products are water and ATP.

What is the role of NADH and FADH2 in cellular respiration?

NADH and FADH2 carry high-energy electrons to the electron transport chain for ATP production.

What occurs during fermentation?

Fermentation regenerates NAD+ without producing ATP, allowing glycolysis to continue in the absence of oxygen.

What is phosphorylation in the context of ATP?

Phosphorylation is the process where a phosphate group from ATP is temporarily attached to a substrate to facilitate a reaction.

What is the function of coenzyme A in metabolism?

Coenzyme A carries acetyl groups into the citric acid cycle for further catabolism.

What is allosteric regulation?

Allosteric regulation involves the binding of molecules to an enzyme at a site other than the active site, altering its activity.

How does temperature affect enzyme activity?

Temperature can influence enzyme activity; extreme temperatures may denature enzymes, reducing their effectiveness.

What is the significance of the citric acid cycle in metabolism?

The citric acid cycle is crucial for extracting high-energy electrons from acetyl CoA, which are used in ATP production.

What is the difference between substrate-level phosphorylation and oxidative phosphorylation?

Substrate-level phosphorylation directly generates ATP from a substrate, while oxidative phosphorylation generates ATP using the electron transport chain and chemiosmosis.

What are photoautotrophs?

Organisms that can perform photosynthesis and require chlorophyll.

Where does photosynthesis occur in eukaryotic autotrophs?

In chloroplasts

How do prokaryotes perform photosynthesis?

Through folded membranes and in the cytoplasm.

What initiates the light-dependent reactions of photosynthesis?

A photon striking the antenna pigments of photosystem II.

What is the Calvin cycle?

The light-independent reactions of photosynthesis that use CO2 to form carbohydrates.

What is the role of signaling molecules in cells?

To communicate between cells and initiate cellular responses.

What are the four categories of signaling in multicellular organisms?

Paracrine, endocrine, autocrine, and direct signaling.

What is paracrine signaling?

Signaling that occurs over short distances.

How do endocrine signals travel?

Through the bloodstream by hormones.

What are gap junctions?

Connections that allow small molecules to flow between neighboring cells.

What happens when a ligand binds to an ion channel-linked receptor?

It forms a pore through the plasma membrane for ions to pass.

What are second messengers?

Small, non-protein molecules that transmit signals within a cell.

What is the significance of terminating a cellular signaling cascade?

To ensure the response is appropriate in timing and intensity.

How do yeasts communicate during mating?

By using cell-surface receptors and signaling cascades.

What is quorum sensing in bacteria?

A process where bacteria secrete signaling molecules called autoinducers.

What surrounds eukaryotic chromosomes?

A nuclear membrane.

What is the main function of ATP produced in photosynthesis?

To provide energy for the formation of sugar molecules.

What happens to G3P molecules in the Calvin cycle?

Some leave to form carbohydrates, while others regenerate RuBP.

What type of chromosome do prokaryotes have?

A single circular chromosome composed of double-stranded DNA.

What is the role of sister chromatids?

They are duplicated chromosomes composed of two identical halves.

What is interphase?

The long preparatory period of the cell cycle during which chromosomes are replicated.

What is karyokinesis?

The process of mitosis, which consists of five stages: prophase, prometaphase, metaphase, anaphase, and telophase.

What is cytokinesis?

The final stage of cell division where cytoplasmic components are separated.

What is the role of FtsZ in bacterial cell division?

It directs bacterial cytokinesis by forming a ring that helps in the division of the cell.

What is meiosis?

A process that produces haploid gametes from diploid parent cells through two rounds of nuclear division.

What are the outcomes of meiosis compared to mitosis?

Meiosis produces four genetically different daughter nuclei, while mitosis produces two genetically identical daughter nuclei.

What is the role of gametes in sexual reproduction?

Gametes are haploid cells that fuse during fertilization to produce a diploid zygote.

What is the product rule in probability?

It is used to find the probability of two or more independent events occurring together by multiplying their individual probabilities.

What are the two main stages of the cell cycle?

Interphase and the mitotic phase.

What is the difference between homologous chromosomes and sister chromatids?

Homologous chromosomes are pairs of chromosomes from each parent, while sister chromatids are identical copies of a single chromosome.

What is the result of the first division in meiosis?

It separates homologous chromosomes, reducing the ploidy level.

What is the significance of the 3:1 ratio in Mendel's F2 offspring?

It confirms that recessive traits are transmitted faithfully from the parent generation.

What is the outcome of the second division in meiosis?

It separates sister chromatids into individual chromosomes, resulting in four unique daughter cells.

What is the result of crossing true-breeding homozygous individuals for a trait?

All offspring will be heterozygotes for that trait.

What phenotype do F1 offspring exhibit when crossed from homozygous parents with dominant and recessive traits?

The same phenotype as the parent homozygous for the dominant trait.

What is the expected genotype ratio in F2 offspring from a self-cross of heterozygous individuals?

One quarter homozygous dominant, half heterozygous, and one quarter homozygous recessive.

What is incomplete dominance?

A situation where the heterozygote exhibits a phenotype that is intermediate between the homozygous phenotypes.

What is the inheritance pattern of recessive lethal alleles?

They are only lethal in homozygotes.

What is Mendel's law of independent assortment?

Genes assort into gametes independently of one another.

What does a dihybrid cross demonstrate?

Independent assortment when genes are on different chromosomes or distant on the same chromosome.

What is epistasis?

When the expression of an allele for one gene masks or modifies the expression of an allele for a different gene.

What does Sutton and Boveri's Chromosomal Theory of Inheritance state?

Chromosomes are the vehicles of genetic heredity.

What method did Sturtevant devise?

A method to assess recombination frequency and infer linked genes' relative positions.

What are aneuploidies?

Disorders in chromosome number that are typically lethal to the embryo.

What is X inactivation?

A process that typically results in milder phenotypic effects for aberrations in sex chromosomes.

Who first isolated DNA and what did he call it?

Friedrich Miescher called it nuclein.

What are the key features of the double-helix structure of DNA?

Complementary base sequences, anti-parallel orientations, and a uniform diameter of 2 nm.

What is the process of DNA replication?

Each strand of the double helix serves as a template for copying the new complementary strand.

What is the difference between prokaryotic and eukaryotic chromosomes?

Prokaryotes have a single, circular chromosome, while eukaryotes have linear DNA packaged into nucleosomes.

How many base pairs are in one turn of the DNA helix?

10 base pairs.

What is the origin of replication in prokaryotes?

A specific sequence on the chromosome where DNA replication begins.

What role do single-strand binding proteins play in DNA replication?

They bind to single-stranded DNA near the replication fork to keep it open.

What is the function of primase in DNA replication?

It synthesizes an RNA primer to initiate DNA synthesis.

How does DNA polymerase add nucleotides during replication?

It adds nucleotides only to the 3' end of a previously synthesized primer strand.

What enzyme seals the DNA after replication?

DNA ligase.