AP®︎ Biology: Unit 6 Flashcards
Master key terms and definitions for Unit 6 of AP Biology – Gene Expression and Regulation to help you prep for quizzes and the AP exam.
DNA and RNA as Hereditary Material
DNA stores hereditary information; some organisms and viruses use RNA instead.
DNA stores hereditary information; some organisms and viruses use RNA instead.
Prokaryotes usually have one circular chromosome; eukaryotes usually have multiple linear chromosomes.
Proteins that package and condense eukaryotic DNA into organized chromosomes.
Small extra-chromosomal circular DNA molecules found in prokaryotes and some eukaryotes.
Purines, A and G, have two rings; pyrimidines, C, T, and U, have one.
Alternating sugar and phosphate groups form the structural sides of a nucleic acid strand.
The order of nucleotides along a strand that encodes genetic information.
DNA is double-stranded with A, T, G, C; RNA is single-stranded with A, U, G, C.
A nucleic acid monomer made of a sugar, phosphate group, and nitrogenous base.
Nitrogenous bases pair specifically: A with T in DNA or U in RNA, and G with C, enabling accurate copying and expression of genetic information.
The process of copying DNA before cell division to produce two identical DNA molecules.
Each new DNA molecule contains one original strand and one newly synthesized complementary strand.
A 1958 experiment using nitrogen isotopes that demonstrated DNA replication is semiconservative.
New DNA is synthesized by adding nucleotides only to the 3 prime end.
The Y-shaped region where parental DNA strands separate and new strands are synthesized.
An enzyme that unwinds the double helix by breaking hydrogen bonds between base pairs.
An enzyme that relieves twisting strain ahead of the replication fork by relaxing supercoils.
An enzyme that adds complementary nucleotides to build a new DNA strand.
Leading is synthesized continuously toward the fork; lagging is synthesized discontinuously away from it.
Short DNA segments formed discontinuously on the lagging strand during replication.
An enzyme that seals breaks in the sugar-phosphate backbone, joining DNA fragments together.
Error-correction by DNA polymerase that removes mismatched nucleotides during replication.
Short RNA starters made by primase allow DNA polymerase to begin synthesis.
Synthesis of an RNA molecule from a DNA template by RNA polymerase.
Enzyme that reads template DNA and builds complementary RNA in the 5' to 3' direction.
An RNA molecule's base sequence and shape determine what role it performs.
Forms the structural and functional core of ribosomes.
Modified guanine added to the 5' end of eukaryotic mRNA for ribosome recognition and stability.
String of adenines added to the 3' end of eukaryotic mRNA that increases stability.
Different exon combinations from one transcript produce multiple mature mRNAs from one gene.
Initial eukaryotic RNA is enzymatically modified into mature mRNA before translation.
Introns are removed and exons are joined to form mature eukaryotic mRNA.
The DNA template strand is the original strand read to build a complementary nucleic acid strand; in transcription it is the noncoding, antisense strand read 3' to 5' to synthesize RNA.
A promoter is a specific DNA sequence where RNA polymerase binds, along with transcription factors in many cases, to begin transcription.
Synthesis of a polypeptide from an mRNA template at a ribosome.
Occurs on cytoplasmic ribosomes in both cell types and on rough ER ribosomes in eukaryotes.
Free ribosomes make cytosolic proteins; rough ER ribosomes make secreted or membrane proteins.
In prokaryotes, ribosomes begin translating mRNA while it is still being transcribed.
Initiation starts synthesis, elongation adds amino acids, and termination releases the finished polypeptide.
rRNA binds mRNA at AUG, and the first tRNA carrying methionine starts polypeptide synthesis.
The rules matching mRNA codons to amino acids during protein synthesis.
Most amino acids are specified by more than one codon.
Almost all organisms use the same codon-to-amino acid assignments.
Repeated codon recognition and peptide bond formation extend the growing polypeptide chain.
A covalent bond joins adjacent amino acids as the polypeptide grows.
A stop codon ends translation and the completed polypeptide is released.
UAA, UAG, and UGA signal the end of translation rather than an amino acid.
Gene sequences determine amino acid sequences, which shape proteins and influence observable traits.
Changes in mRNA codons can alter amino acid sequence, protein structure, and phenotype.
Reverse transcriptase copies viral RNA into DNA, reversing the usual information flow.
Viral DNA inserts into the host genome, then is transcribed and translated to make new viruses.
Translation begins at AUG, then each mRNA codon is matched to an amino acid.
The shared genetic code across organisms supports that all life evolved from common ancestors.
tRNA is an RNA molecule that carries a specific amino acid to the ribosome and uses its anticodon to pair with an mRNA codon during translation.
A codon is a three-nucleotide mRNA sequence that specifies an amino acid or stop signal, and an anticodon is the complementary three-nucleotide sequence on tRNA.
Control of which genes are expressed, when they are expressed, and at what levels.
DNA stretches that bind regulatory proteins and control transcription of nearby or distant genes.
Prokaryotic DNA sequence where a repressor binds to block transcription of an operon.
Constitutive genes are always expressed; inducible genes are activated only under certain conditions.
Heritable changes in gene expression caused by chromatin or DNA modifications, not DNA sequence changes.
Addition of methyl groups to DNA, usually reducing transcription and silencing genes.
Chemical changes to histone proteins that loosen or tighten chromatin and alter transcription.
Traits result from which genes are expressed and the amount of each gene product made.
Ordered activation of genes during development, often triggered by earlier transcription factors.
Cluster of prokaryotic genes transcribed together from one promoter and regulated as a unit.
Inducible systems are usually off and turned on; repressible systems are usually on and turned off.
An inducible operon for lactose metabolism that is activated when lactose inactivates the repressor.
A repressible operon for tryptophan synthesis that is shut off when tryptophan activates the repressor.
Control of multiple related genes so they are expressed together in response to shared signals.
Common regulatory proteins that bind similar control sequences in multiple genes to coordinate expression.
Cells become specialized by expressing tissue-specific proteins needed for their particular functions.
Transcription factors are regulatory proteins that bind specific DNA sequences to activate or repress transcription.
The enzyme binds promoter DNA with transcription factors to begin RNA synthesis from a gene.
Repressors and corepressors that inhibit transcription by binding DNA or blocking transcriptional machinery.
Different cells express different sets of genes from the same genome.
Regulated gene expression creates different cell products, causing specialized functions and phenotypic differences.
Small RNAs such as miRNAs, siRNAs, and piRNAs reduce gene expression after transcription.
Enhancers and silencers are regulatory DNA sequences that increase or decrease transcription when bound by activator or inhibitory regulatory proteins, often acting at a distance from the gene.
A change in one nucleotide pair, usually by substitution of one base for another.
Insertion adds bases, deletion removes bases, and frameshift shifts codon reading when bases are not in threes.
A base substitution that creates a premature stop codon, producing a shortened polypeptide.
A DNA change that does not alter the amino acid sequence of the protein.
Altered DNA can change RNA or protein type or amount, producing different observable traits.
Coding changes can alter protein sequence, while regulatory changes can alter when or how much is made.
Mistakes during copying or correction of DNA can introduce random sequence changes.
External agents such as radiation and reactive chemicals that increase the rate of DNA mutations.
Failure of homologous chromosomes or sister chromatids to separate properly during cell division.
Aneuploidy is an abnormal chromosome number; triploidy is three complete chromosome sets.
Having more than two complete sets of chromosomes, often affecting vigor or fertility.
Deletions remove segments, duplications repeat them, inversions reverse them, and translocations move them elsewhere.
DNA uptake, viral DNA transfer, direct cell-to-cell DNA transfer, and movement of DNA segments.
Mixing of genetic material between related viruses that infect the same host cell.
Conserved mechanisms like mutation, meiosis, crossing over, and gene transfer that generate heritable diversity.
A disorder caused by CFTR mutations that disrupt ion transport across cell membranes.
A dark-fur phenotype caused by mutation that improves camouflage in dark environments.
A beta-globin mutation causing sickled red blood cells, harmful overall but advantageous against malaria when heterozygous.
A DNA change may be beneficial, harmful, or neutral depending on environmental conditions.
Heritable DNA changes create variation that natural selection can increase or decrease.
A base substitution that changes one amino acid in a polypeptide sequence.
A mutation is a heritable change in DNA sequence that can result from replication errors, mutagens, or other processes and may alter gene product or phenotype.
The use of living systems or cells to develop useful products and technologies.
DNA formed by joining genetic material from different sources into one molecule.
Isolating a DNA fragment and making many identical copies, often using a vector.
Amplifies specific DNA sequences through repeated denaturation, primer annealing, and extension cycles.
Separates DNA fragments by size and charge as they move through a gel.
The introduction of foreign DNA into bacterial cells for replication or expression.
Determining the exact order of nucleotides in a DNA molecule.
A unique banding pattern used to compare DNA samples from different individuals or organisms.
Organisms whose genetic material has been altered using biotechnology rather than natural reproduction.
Animals engineered to contain and express genes from another species.
Comparing DNA samples to identify individuals from biological evidence.
Comparing DNA sequences to infer evolutionary relationships among organisms.
