Test 3 Study Guide Flashcards
Ch. 16, 17, 21, 23, 25, 26
Alteration of chromatin structure
alterations in the way DNA is packaged within the nucleus of a cell; modifications through histone proteins and DNA methylation
Site of binding of the DNA binding proteins
the major groove (recognize and interact with specific nucleotide sequences to perform functions like gene regulation); initiates important cellular processes like transcription, DNA replication, or DNA repair
Negative repressible control of operons
gene expression is normally “on” but can be turned “off” by a repressor protein that binds to the operator region when a specific molecule, corepressor, is present
Positive induction of operons
a regulatory protein/ an activator binds to DNA and enhances transcription of the operon genes only when an inducer is present
Basal transcriptional apparatus for transcription
a set of proteins, including general transcription factors and RNA polymerase, essential for the basic initiation of transcription at a gene’s promoter region
Stimulation of flowering in Arabidopsis
by exposure to long days (photoperiod), triggering the production of a protein, flowering locus (FT)
DNase I sensitivity
regions of chromatin that are sensitive to cleavage by the DNase I enzyme
Gene regulation by histones
regulates gene expression by compacting DNA and interacting with it through chemical modifications
Different aspects of epigenetics
DNA methylation, histone modifications, noncoding RNA regulation, chromatin remodeling, epigenetic inheritance, role of environmental factors
Sex determination in honey bees
fed “royal jelly”/ siRNAs (small inhibitor RNA) that suppress Dnmt3, less DNA methylation occurs, and expression of genes encoding queen characteristics; DNA methylation = worker bee, no/ less DNA methylation = queen bee
Major event of retinoblastoma cancer
a change/ mutation in the RB1 gene; this gene helps prevent cells from growing out of control
Colon cancer
ras mutations; 5-10% of colon cancer is hereditary
Mutations in proto-oncogenes and tumor suppressor genes
mutations in proto-oncogenes transform them into oncogenes that promote uncontrolled cell division; mutations in tumor suppressor genes stop/ limit cell growth and can lead to them to lose inhibitory function
Hardy-Weinberg equilibrium
large randomly breeding population, allelic frequencies will remain the same from generation to generation assuming there is no mutation, random mating, no gene flow, infinite population size and no selection
How to figure out allele and genotype frequencies using Hardy-Weinberg equation
p^2 + 2pq + q^2 = 1; p is frequency of dominant allele, q is frequency of recessive allele, 2pq is frequency of heterozygous genotype
Markers/ techniques used to investigate genetic variation
SNPs, SSR, RFLPs, AFLP, VNTRs;
single nucleotide polymorphisms (SNPs), micro-satellites (SSR), restriction fragment length polymorphisms (RFLPs), amplified fragment length polymorphism (AFLP), variable tandem repeats (VNTRs)
Biological species concept
definition of a species as a group of organisms whose members are capable of interbreeding with one another but are reproductively isolated from the members of other species. Because different species do not exchange genes, each species evolves independently. Not all biologists adhere to this concept
Genes and human disorders resulting from gene imprinting
Pader-Willi syndrome (low muscle tone in infancy, deletion of chromosome 15), Angelman syndrome (developmental delay, intellectual disability, etc; deletion of chromosome 15), Beckwith-Wiedemann syndrome (accelerated growth,, chromosome 11)
CpG islands
in promotor regions; they are unmethylated near promoters of actively transcribed genes
Structural gene
DNA sequence that encodes a protein that function in metabolisms or biosynthesis or that has a structural role in the cell
Gene regulation
mechanisms and systems that control the expression of genes
Repressible operons
operon in which transcription is normally on (taking place); something must happen to repress transcription/ turn it off
Inducible operons
operon in which transcription is normally off (not taking place); something must happen to induce transcription/ turn it on
Repressor
regulatory protein that binds to a DNA sequence and inhibits transcription
Antisense RNA
small RNA molecule that base pairs with a complementary DNA or RNA sequence and affects its functioning
Enhancer
sequence that stimulates maximal transcription of distant genes; affects only genes on the same DNA molecule (cis acting), contains short consensus sequences, is not fixed in relation to the transcription start site, can stimulate promoters in its vicinity, and may be upstream or downstream of the gene; the function is independent of sequence orientation
Chromatin remodeling complexes (CRCs)
large, multi-protein assemblies that help cells access DNA by using ATP hydrolysis to alter, mobilize, and restructure the structure of nucleotides
DNA methylation
modification of DNA by the addition of methyl groups by specific enzymes to certain positions on the bases
Paramutation
when one allele creates a heritable alteration in another allele without change in DNA sequence
Histone acetylase
histone tails are modified by the addition of an acetyl group; gene regulation; removes + charge on histones
Polycomb group protein
a family of protein complexes that regulate chromatin and repress gene transcription in animals and plants; stem cell identity, differentiation and disease
Gene imprinting
process that determines whether a gene is expressed based on whether it was inherited from the mother or father
Clonal evolution
process by which mutations that enhance the ability of cells to proliferate predominate in a clone of cells, allowing the clone to become increasingly rapid in growth and increasingly aggressive in proliferation properties
Metastasis
the movement of cells that separate from malignant tumors to other sites, where they establish secondary tumors
Philadelphia chromosome
chromosome 9 and 22 break and exchange parts; genetic abnormality in leukemia cancer cells that occurs when part pf the ABL gene on chromosome 9 breaks off and attaches to the BCR gene on chromosome 22
Gene pool
set of all genes in a population
Inbreeding coefficient
a measure of inbreeding; the probability (ranging from 0 to 1) that two alleles are identical by descent
Fixed allele frequency
a single allele at a specific gene locus is present in 100% of a population
Ana and Cladogenesis
evolution taking place within a single lineage; evolution in which one lineage split into two
Sympatric speciation
speciation that arises in the absence of any geographic barrier to gene flow, in which reproductive isolating mechanisms evolve within a single population
Allopatric speciation
speciation that occurs when a geographic barrier splits a population into two groups and blocks the exchange of genes between them
Phylogenetic tree
graphical representation of the evolutionary relationships among different organisms
Cis regulatory elements
DNA sequences that control gene expression by binding to transcription factors and other DNA-binding proteins; regulate noncoding DNA sequences and regulate transcription of neighboring gene
Trans regulatory elements
DNA sequences that regulate the expression of genes on different DNA molecules; encoding upstream regulators
Horizontal gene transfer
transfer of genes from one organism to another by a mechanism other than reproduction
Hardy-Weinberg Law
principle of population genetics stating that if a population is large; randomly mating; and not affected by mutation, migration, or natural selection, then allelic frequencies of a population do not change and the genotypic frequencies stabilize after one generation in the proportions p^2 (the frequency of AA, 2pq (frequency of Aa), and q^2 (frequency of aa), where p equals the frequency of allele A and q equals the frequency of allele a
Constitutive gene
a gene that is not regulated and is expressed continually
