BIO161 Lecture Series Review Flashcards

Flashcards covering the major biological concepts from biochemistry and genetics to photosynthesis and metabolism as presented in the BIO161 lecture series.

Chlorophyll a

The main pigment in plants and cyanobacteria and the only pigment that can directly convert light to chemical energy.

Absorption Spectrum

The range and efficiency of photons a molecule is capable of absorbing, which for photosynthetic pigments is the visible range.

Reaction Center

One or more chlorophyll a molecules in a protein matrix that passes excited electrons out of the photosystem to an electron acceptor.

Calvin Cycle

Also called C3 photosynthesis, this set of light-independent reactions uses ATP and NADPH to fix carbon into G3P in the stroma.

Photorespiration

An process where respiration releases CO2, essentially undoing carbon fixation; it occurs when high temperatures lead to low CO2 and high O2 inside the leaf.

Chromatin

The structure of DNA during interphase consisting of 40% DNA and 60% protein, typically appearing as a 'bowl of spaghetti' spatially organized into TADs.

Karyotype

A visual profile of an individual's complete set of chromosomes arranged by size, number, and shape, typically isolated during metaphase.

Sister Chromatids

Identical DNA molecules held together by a centromere that represent the two sides of a duplicated chromosome.

Mitosis

The process of cell division for somatic cells divided into five phases: prophase, prometaphase, metaphase, anaphase, and telophase.

Proto-oncogenes

Normal genes that become oncogenes (cancer-causing) when mutated; they drive cell growth and only one copy must be affected to impact the cell.

p53 gene

A tumor-suppressor gene known as the 'guardian of the genome' that plays a key role in the G1 checkpoint by pausing the cell cycle for DNA repair or initiating cell death.

Allele

Alternative forms for a specific trait or gene, categorized as dominant or recessive.

Phenotype

The physical appearance that results from expressing the alleles of an individual.

Pleiotropy

A single gene that can affect more than one trait, often seen in human diseases like cystic fibrosis.

Epistasis

An interaction where the action of one gene obscures the effects of another gene, such as in the coat color of labrador retrievers.

Barr Body

A highly condensed, randomly inactivated X chromosome found in mammalian female cells as a form of dosage compensation.

Maternal Inheritance

Traits controlled by genes in mitochondria or chloroplasts that are passed from mother to offspring.

Nondisjunction

The failure of homologs or sister chromatids to separate properly during meiosis, resulting in aneuploidy.

Transformation

The transfer of genetic material physically between cells, first observed when dead S strain bacterial cells transferred virulence to live R strain cells.

Chargaff's Rules

The observation that there is an equal proportion of purines and pyrimidines, specifically that $A = T$ and $C = G$.

Okazaki Fragments

DNA fragments on the lagging strand that are synthesized discontinuously and joined by DNA ligase.

Telomerase

An enzyme that synthesizes telomere repeat sequences at the ends of strands using an internal RNA template to prevent chromosome shortening.

Operon

Multiple genes in prokaryotes that are organized in the same metabolic pathway and transcribed together.

Enhancers

The binding sites for specific transcription factors in eukaryotes that act over large distances by bending DNA into loops.

Alternative Splicing

A posttranscriptional regulation process that produces multiple mature mRNA transcripts from a single gene.

Ubiquitin

A molecule added to proteins to mark them for degradation by a proteasome.

Atomic Number

The number of protons in an atom, which defines the element.

Isotopes

Atoms with the same number of protons and electrons but different numbers of neutrons.

Ionic Bond

A chemical bond formed by the attraction of oppositely charged ions, typically forming crystal matrices.

Hydrogen Bonds

Weak attractions (~5-10% as strong as covalent bonds) between hydrogen and partially negative atoms responsible for water's unique physical properties.

Buffers

Pairs of molecules that help resist changes in pH by releasing or absorbing $H^+$ ions to keep the concentration constant.

Deductive Reasoning

Applying general principles that are already known to predict a specific result.

Inductive Reasoning

Constructing general scientific principles based on specific observations.

Cell Theory

The proposal that all organisms are composed of cells, cells are the smallest living things, and cells arise only from the division of existing cells.

Nucleolus

The region within the nucleus where ribosomal RNA ($rRNA$) synthesis takes place.

Endosymbiosis

The theory that eukaryotic cells evolved from a symbiosis where one prokaryote was engulfed by another, forming mitochondria and chloroplasts.

Cytoskeleton

A network of protein fibers (actin filaments, microtubules, and intermediate filaments) that supports cell shape and facilitates movement.

First Law of Thermodynamics

The principle that energy cannot be created or destroyed, only changed from one form to another.

Entropy

A measure of the randomness or disorder of a system ($S$) which is continuously increasing according to the Second Law of Thermodynamics.

Free Energy

The energy available to do work at a constant temperature in a system, calculated as $riangle G = riangle H - T riangle S$.

Enzymes

Biological catalysts that decrease the activation energy of reactions without being changed or consumed.

Glycolysis

A 10-step biochemical pathway in the cytoplasm that converts 1 glucose into 2 pyruvate while netting 2 ATP and 2 NADH.

Chemiosmosis

The process where ATP synthase uses the energy from a proton gradient formed by the electron transport chain to catalyze the addition of a phosphate to ADP.

Fermentation

A process where an organic molecule is the final electron acceptor, allowing NAD+ to be regenerated for glycolysis when oxygen is absent.