7.2 Natural and Artificial Selection
in AP Biology
Natural selection is the differential reproductive success of genetic variants and was independently conceived by Charles Darwin and Alfred Russel Wallace.
7.1 Introduction to Evolution and Natural Selection
in AP Biology
“Nothing in biology makes sense except in the light of evolution”—Theodosius Dobzhansky.
6.8 Biotechnology and Virus
in AP Biology
A virus consists only of nucleic acid, proteins, and sometimes a membranous envelope. After infecting a host cell, it uses the host cell’s molecules to make new viruses
6.7 Mutations
in AP Biology
Alterations in a DNA sequence can lead to changes in the type or amount of the protein produced and the consequent phenotype. DNA mutations can be positive, negative, or neutral based on the effect or the lack of effect they have on the resulting nucleic acid or protein and the phenotypes that are conferred by the protein.
6.6 Cell Specialization and Development
in AP Biology
Embryonic cells become committed to a certain fate (determination), and undergo differentiation, becoming specialized in structure and function for their determined fate. Cells differ in structure and function not because they contain different genomes but because they express different genes.
6.5 Regulation of Gene Expression
in AP Biology
All organisms, whether prokaryotes or eukaryotes, must regulate which genes are expressed at any given time. Both unicellular organisms and the cells of multicellular organisms continually turn genes on and off in response to signals from their external and internal environments.
6.4 Translation
in AP Biology
Translation is the synthesis of a polypeptide using the information in the mRNA. During this stage, there is a change in language: The cell must translate the nucleotide sequence of an mRNA molecule into the amino acid sequence of a polypeptide. The sites of translation are ribosomes, molecular complexes that facilitate the orderly linking of amino acids into polypeptide chains.
银花灿烂——我与老年人之间的故事
作者： Molly
您教我写字，我教您用手机——“银花灿烂”公益项目
6.3 Transcription and RNA Processing
in AP Biology
Transcription is the synthesis (production) of RNA using information in the DNA. The two nucleic acids are written in different forms of the same language, and the information is simply transcribed, or “rewritten,” from DNA to RNA.
6.2 DNA Replication
in AP Biology
Watson and Crick’s model predicts that when a double helix replicates, each of the two daughter molecules will have one old strand, from the parental molecule, and one newly made strand.