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47 terms

Genetics Chapter 1

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Adenine (A)
A purine base that pairs with thymine in the DNA double helix. One of the four DNA bases.
deoxyribonucleic acid (DNA)
information present in a cell that allows it to build a complex multicellular organism. two chains of linked nucleotides in a double helical form are the fundamental substance of which genes are composed.
forward genetics
genetic analysis in which genes are first identified by mutant alleles and mutant phenotypes and later cloned and subjected to molecular analysis
centromere
a constricted region of a chromosome that acts as an attachment point to move the chromosome during cell division.
diploid
organisms whose nuclei contain two complete copies of the genome and so two identical chromosome sets
functional RNA
an RNA type that plays a role without being translated into protein
chromatin
the substance of chromosomes; now known to include DNA and chromosomal proteins
DNA cloning
the process of taking a DNA fragment and replicating it many times over until there are many copies so that essentially it can be treated like a reagent in a test tube.
gene
the fundamental physical and functional unit of heredity, which carries information from one generation to the next
codon
a section of RNA (three nucleotides in length) that encodes a single amino acid.
epigenetic
nongenetic chemical changes in histones or DNA that alter gene function without altering the DNA sequence
gene pair
the two copies of a particular type of gene present in a diploid cell (one in each chromosome set)
cytosine (C)
a pyrimidene base that pairs with guanine. one of the four DNA bases
extranuclear
refers to a small specialized fraction of eukaryotic genomes found in mitochondria or chloroplasts
genetic code
a set of correspondences between nucleotide triplets in RNA and amino acids in protein
genetics
the study of all aspects of genes and inheritance
model organism
An organism selected for intensive scientific study based on features that make it easy to work with (e.g., body size, life span), in the hope that findings will apply to other species.
reverse genetics
an experimental procedure that begins with a cloned segment of DNA or a protein sequence and uses it (through directed mutagenesis) to introduce programmed mutations back into the genome to investigate function
genome
the entire complement of genetic material in a chromosome set
molecular genetics
the study of the molecular processes underlying gene structure and function
ribonucleic acid (RNA)
a single-stranded nucleic acid similar to DNA but having ribose sugar rather than deoxyribose sugar and uracil rather than thymine as one of the bases
genomics
the cloning and molecular characterization of entire genomes
mutation
the process that produces a gene or a chromosome set differing from that of the wild type
ribosomal RNA
a class of RNA molecules, encoded in the nucleolar organizer, that have an integral (but poorly understood) role in ribosome structure and function
guanine (G)
a purine base that pairs with cytosine
natural selection
the differential rate of reproduction of different types in a population as the result of different physiological, anatomical, or behavioral characteristics of the types
Southern blot
the transfer of electrophoretically separated fragments of DNA from a gel to an absorbent sheet such as paper; this sheet is then immersed in solution containing a labeled probe that will bind to a fragment of interest
haploid
a cell having one chromosome set or an organism composed of such cells
Northern blot
the transfer of electrophoretically separated RNA molecules from a gel onto an absorbent sheet, which is then immersed in a labeled probe that will bind to the RNA of interest.
telomere
the tip, or end, of a chromosome
haploid number
the number of chromosomes in the basic genomic set of a species
nucleosome
the basic unit of eukaryotic chromosome structure; a ball of eight histone molecules that is wrapped by two coils of DNA
theory of evolution
all-embracing notion of natural selection acting on variation
histone
a type of basic protein that forms the unit around which DNA is coiled in the nucleosomes of eukaryotic chromosomes
nucleotide
a molecule composed of a nitrogen base, a sugar, and a phosphate group; the basic building block of nucleic acids
thymine (T)
a pyrimidine base that pairs with adenine
homolog
a member of a pair of homologous chromosomes
polymerase chain reaction (PCR)
an in vitro method for amplifying a specific DNA segment that uses two primers that hybridize to opposite ends of the segment in opposite polarity and, over successive cycles, prime exponential replication of that segment only.
transcription
the synthesis of RNA from a DNA template
homologous chromosomes
chromosomes that pair with each other at meiosis or chromosomes in different species that have retained most of the same genes during their evolution from a common ancestor.
transfer RNA (tRNA)
a class of small RNA molecules that bear specific amino acids to the ribosome in the course of translation
homology
similarity due to shared ancestry from a common ancestor
polypeptide
a chain of linked amino acids; a protein
translation
the ribosome- and tRNA -mediated production of a polypeptide whose amino acid sequence is derived from the codon sequence of an mRNA molecule
messenger RNA
an RNA molecule transcribed from the DNA of a gene; a protein is translated from this RNA molecule by the action of ribosomes
probing
method for detecting specific macromolecules in a mixture that makes use of the specificity of intermolecular binding
Western blot
for protein detection, a protein mixture extracted from cells is separated into bands of distinct proteins by electrophoresis and then blotted onto a membrane