Notes for Science

Activation Energy

The minimum energy required to start a chemical reaction.

Enzyme Function

Enzymes bind substrates and facilitate their conversion to products.

Catalase

An enzyme that breaks down hydrogen peroxide into water and oxygen.

Oxidation

Loss of electrons.

Reduction

Gain of electrons.

High Specific Heat

Water resists temperature changes.

Covalent Bonds

Atoms share electrons.

Ionic Bonds

Atoms transfer electrons.

Hydrogen Bonds

Weak attractions between polar molecules.

Nucleotide

Consists of a sugar, phosphate, and nitrogenous base.

Double Helix

Two strands of DNA held together by hydrogen bonds between bases.

ATP

Adenosine triphosphate, provides energy for cellular processes.

NADH/FADH2

Electron carriers that transport electrons to the electron transport chain.

O2

Final electron acceptor in aerobic respiration.

Hypertonic Solution

Higher solute concentration outside the cell; leads to cell shrinking.

Hypotonic Solution

Lower solute concentration outside the cell; leads to cell swelling.

Isotonic Solution

Equal solute concentration; results in no net water movement.

Electron Transport Chain

A series of protein complexes in mitochondria that transfer electrons.

ATP Synthase

Enzyme that synthesizes ATP using the proton gradient.

Light Reactions

Photosynthesis stage that produces ATP and NADPH.

Calvin Cycle

Uses ATP and NADPH to fix carbon dioxide into glucose.

Fluid Mosaic Model

Describes the structure of cell membranes.

Transport Proteins

Facilitate the movement of substances across the membrane.

Mitosis

Process that produces two identical daughter cells.

Meiosis

Process that produces four genetically unique gametes.

Independent Assortment

Random distribution of chromosomes during gamete formation.

Crossing Over

Exchange of genetic material between homologous chromosomes.

Law of Segregation

Each gamete receives one allele of each gene.

Law of Independent Assortment

Genes on different chromosomes are inherited independently.

Helicase

Enzyme that unwinds DNA during replication.

Primase

Enzyme that synthesizes RNA primers during DNA replication.

DNA Polymerase

Synthesizes new DNA strands by adding nucleotides.

Ligase

Enzyme that joins Okazaki fragments during DNA replication.

Leading Strand

DNA strand synthesized continuously during replication.

Lagging Strand

DNA strand synthesized in fragments during replication.

Transcription

Process where DNA is transcribed to mRNA.

Translation

Process where mRNA is translated to protein.

Gene Regulation

Control of gene expression by promoters, enhancers, and repressors.

Types of Mutations

Substitution, insertion, deletion, inversion, duplication.

Natural Selection

Differential survival and reproduction of individuals.

Genetic Drift

Random changes in allele frequencies in a population.

Gene Flow

Movement of alleles between populations.

Allopatric Speciation

Speciation that occurs due to geographic isolation.

Sympatric Speciation

Speciation that occurs without physical separation.

Phylogenetic Trees

Diagrams showing evolutionary relationships among species.

Divergent Evolution

Evolution leading to differences from a common ancestor.

Convergent Evolution

Evolution leading to similarities in unrelated groups.

Example of Divergent Evolution

Darwin's finches.

Example of Convergent Evolution

Wings in bats and birds.