Section 5 Flashcards
A modified form of guanine nucleotide added onto the 5’ end of a pre-mRNA molecule
5’ cap
One of a ribosome’s three binding sites for tRNA during translation, holds the tRNA carrying the next amino acid to be added to the polypeptide chain. (A stands for aminoacyl tRNA.)
A site
Any of the alternative versions of agene that may produce distinguishable phenotypic effects
allele
A type of eukaryotic gene regulation at the RNA-processing level in which different mRNA molecules are produced from the primary transcript, depending on which RNA segments are treated as exons and which as introns.
alternative RNA splicing
An organic molecule possessing both a carboxyl and an amino group, serve as the monomers of polypeptides
amino acid
An enzyme that joins each amino acid to the appropriate tRNA
aminoacyl-tRNA synthetase
A nucleotide triplet at one end of a tRNA molecule that base-pairs with a particular complementary codon on an mRNA molecule
anticodon
Referring to the arrangement of the sugar-phosphate backbones in a DNA double helix (they run in opposite 5′ S 3′ directions).
antiparallel
The generation of offspring from a single parent that occurs without the fusion of gametes. In most cases, the offspring are genetically identical to the parent.
asexual reproduction
A maternal effect gene that codes for a protein responsible for specifying the anterior end in Drosophila melanogaster.
bicoid
Definition of a species as a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring but do not produce viable, fertile offspring with members of other such groups.
biological species concept
originally, the idea that information flows from DNA to RNA to protein, but not in the opposite direction
central dogma
In a duplicated chromosome, the region on each sister chromatid where it is most closely attached to its sister chromatid
centromere
The X-shaped, microscopically visible region where crossing over has occurred earlier in prophase I between homologous nonsister chromatids.
chiasma
A cellular structure consisting of one DNA molecule and associated protein molecules.
chromosome
A three-nucleotide sequence of DNA or mRNA that specifies a particular amino acid or termination signal; the basic unit of the genetic code.
codon
The reciprocal exchange of genetic material between nonsister chromatids during prophase I of meiosis.
crossing over
A nucleic acid molecule, usually a double-stranded helix, in which each polynucleotide strand consists of nucleotide
monomers with a deoxyribose sugar and the nitrogenous bases adenine (A), cytosine (C), guanine (G), and thymine (T); capable of being replicated and determining the inherited structure of a cell’s proteins.
deoxyribonucleic acid
The sugar component of DNA nucleotides, having one fewer hydroxyl group than ribose, the sugar component of RNA nucleotides.
deoxyribose
The events involved in an organism’s changing gradually from a simple to a more complex or specialized form.
development
A cell containing two sets of chromosomes (2n), one set inherited from each parent.
diploid cell
A linking enzyme essential for DNA replication; catalyzes the covalent bonding of the 3′ end of one DNA fragment (such as an Okazaki fragment) to the 5′ end of another DNA fragment (such as a growing DNA chain).
DNA ligase
The presence of methyl groups on the DNA bases (usually cytosine) of plants, animals, and fungi. (The term also refers to the process of adding methyl groups to DNA bases.)
DNA methylation
An enzyme that catalyzes the elongation of new DNA (for example, at a replication fork) by the addition of nucleotides to the 3′ end of an existing chain.
DNA polymerase
The process by which a DNA molecule is copied
DNA replication
An allele that is fully expressed in the phenotype of a heterozygote.
dominant allele
The form of native DNA, referring to its two adjacent antiparallel polynucleotide strands wound around an imaginary axis into a spiral shape.
double helix
One of a ribosome’s three binding sites for tRNA during translation. The E site is the place where discharged tRNAs leave the ribosome. (E stands for exit.)
E site
Describes effects on gene expression due to differences in DNA packaging, such as modifications in histones or chromatin structure.
epigenetic
A sequence within a primary transcript that remains in the RNA after RNA processing; also refers to the region of DNA from which this sequence was transcribed.
exon
A haploid reproductive cell, such as an egg or sperm, that is formed by meiosis or is the descendant of cells formed by meiosis
gamete
A discrete unit of hereditary information consisting of a specific nucleotide sequence in DNA (or RNA, in some viruses).
gene
The process by which information encoded in DNA directs the synthesis of proteins or, in some cases, RNAs that are not translated into proteins and instead function as RNAs.
gene expression
A process in which chance events cause unpredictable fluctuations in allele frequencies from one generation to the next, most pronounced in small populations
genetic drift
The genetic makeup, or set of alleles, of an organism.76
genotype
A cell containing only one set of chromosomes (n).
haploid cell
An enzyme that untwists the double helix of DNA at replication forks, separating the two strands and making them available as template strands.
helicase
In a population, the proportion of the total variation in a trait that is due to genetic differences among individuals.
heritability