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Monohybrid Cross
The cross between plants that differ only in one trait
Locus
Physical location of a trait or gene on a chromosome
Dominant Allele
Allele that exerts its phenotype on a heterozygote; masks the expression of the recessive allele
Recessive Allele
Allele that exerts its phenotype on a homozygote; masked by the dominant allele.
Homozygous
Organism with two identical alleles
Heterozygous
Organism with two different alleles at a gene locus
Genotype
An individual's alleles received at fertilization
Phenotype
They physical appearance of an individual; determine d by proteins produced by corresponding alleles
Dihybrid Cross
Cross between plants that differ in two traits
Law of Independent Assortment
Each pair of factors segregates independently of the other pairs, All possible combinations of factors can occur in the gametes
Punnentt Square
Visual representation developed by Reginald Punnett that is used to calculate the expressed results of simple genetic crosses
Testcross
Cross between an individual with a recessive phenotype and an individual with a dominant phenotype to see if it is homozygous or heterozygous dominant
Autosome
Any chromosome other than a sex chromosome
Carriers
Individuals that do not express the genetic disorder in their phenotype but are able to pass it onto their children because they still have it in their genotype
Multiple Alleles
Inheritance pattern in which there are more than two alleles for a particular trait; blood type
Codomiance
Inheritance pattern in which both alleles of a gene are equally expressed in a heterozygote
Single Stranded Binding Proteins (SSB)
Attach to newly separated DNA to prevent it from re-forming the helix so replication can occur
DNA Primase
Places short primers on the strands to be replicated
DNA Ligase
"Glue" that mends okazaki fragments together and recombinant DNA together
Replication Fork
V shape that forms wherever DNA is being replicated
Uracil (U)
Pyrimidine in RNA with a single ring structure; complementary base pairs to Adenine
Messenger RNA (mRNA)
Takes message from DNA in the nucleus to the ribosomes in the cytoplasm
Transfer RNA (tRNA)
Transfers amino acids to the ribosomes
Ribosomal RNA (rRNA)
Makes up the ribosomes where polypeptides are synthesized
Transcription
Process of an RNA molecule being produced based on a DNA template
Translation
mRNA transcript is read by a ribosome and converted into a sequence of amino acids in a polypeptide
Central Dogma of Molecular Biology
Processes that dictate the flow of information from DNA to RNA to protein in a cell; DNA - RNA - Protein; DNA - mRNA - polypeptide
Genetic Code
Universal code that has existed for eons and allows for conversions of DNA and RNA's chemical code to a sequence of amino acids in a proten
Triplet Code
three nucleotides in a genetic code
RNA Polymerase
Joins nucleotides in RNA together in the 5' to 3' direction
Promoter
Sequence of DNA in an operon that RNA polymerase binds to, to begin transcription; they signal the start of the operon and the location of transcription
Incomplete Dominance
Inheritance patter in which offspring have an intermediate phenotype
Incomplete Penetrance
Dominant alleles that are not present or fully expressed
Pleiotropy
When a single mutant gene affects two or more distinct and seemingly unrelated traits
Polygenetic Inheritance
When a single trait is governed by two or more sets of alleles
Multifactorial Traits
Polygenic traits subject to environmental influences
X-Linked
Genes that are carried on the x chromosome
Hemizygous
An individual possessing only one allele for a gene on the x chromosome
Adenine (A)
Purine double ring nucleotide base; complementary base pairs to Thymine
Guanine (G)
Purine double ring nucleotide base; complementary base pairs to Cytosine
Thymine (T)
Pyrimidine single ring nucleotide base; complementary base pairs to Adenine
Cytosine (C)
Pyrimidine single ring nucleotide base; complementary base pairs to Guanine
Double Helix
Double spiral, three dimensional shape of DNA
Complementary Base Pairing
Hydrogen bonding between particular purines and pyrimidines
DNA Replication
Process of copying a DNA molecule
Template
A mold used to produce a shape complementary of itself
Semiconservative replication
Process of DNA replication that results in two double helix molecules each having one parental strand and one new strand
Codon
Also known as a triplet Codon; three nucleotides in a genetic code
mRNA Transcript
mRNA molecule formed during transcription that has a sequence of bases complementary to a gene
Introns
Intervening sequence found between exons in mRNA; removed by RNA processing before translation
Exons
Segment of mRNA containing the protein coding portion of a gene that remains within the mRNA after splicing has occured
Ribozyme
An enzyme made of RNA rather than just protein
Anticodon
A group of three bases that is complementary and anitparallel to a specific mRNA codon
Polyribosome
The entire complex of mRNA and multiple ribosomes
Initiation
The step that brings all the translation components together
Elognation
The stage during protein synthesis when a polypeptide increases in length one amino acid at a time
Termination
The final step in protein synthesis that occurs at a stop codon
Proteomics
The study of the structure, function, and interaction of cellular proteins
Structural genes
The genes that code for the enzymes and proteins that are involved in the metabolic pathway of the operon
Operon
Model to explain gene regulation in prokaryotes
Regulator Gene
Gene that codes for the protein that acts as a repressor to control whether the operon is active or not
Operator
a short portion of DNA located before the structural genes. If the repressor is attached to the it, the operon is not functional
Inducer
Molecule that brings about activity of an operon by joining with a repressor and preventing it from binding to the operator
Chromatin
A stringy material made up of DNA associated with a variety of proteins
Barr Body
Highly condensed chromatin adhering to the inner edge of the nuclear membrane
Epigenetic inheritance
Variations in the pattern of inheritance that are not due to changes in the sequence of the DNA nucleotides
Transcriptional Control
Most critical level of control of gene expression with the use of transcription factors, and other proteins that regulate either the initiation of transcription or the rate at which it occurs
Transcription Factors
Protein required for the initiation of transcription by RNA polymerase
Transcription Activator
Protein that participates in the initiation of transcription by binding to the enhancer regulatory regions
Enhancers
DNA sequence that acts as a regulatory element to increase the level of transcription when regulatory proteins, such as transcription activators, bind to it
Posttranscriptional Control
Gene expression following transcription that regulates the way mRNA transcripts are processed
Micro RNA (miRNA)
Small snippets of RNA that can bind to and disable the translation of mRNA in the cytoplasm
Small-interfering RNA (siRNA)
Type of small RNA that joins with an enzyme to form an active silencing complex, which targets specific mRNAs in the cell for breakdown
RNA Interference
Process of interfering with the normal gene expression pathway
Translational control
Gene expression regulated by influencing the interaction of the mRNA transcripts with the ribosome
Posttranslational Control
Alternation of gene expression by changing a protein's activity after it is translated
Proteases
Enzymes that break down proteins
Proteasomes
Special structures that proteases are typically found in
Gene Mutation
Permanent change in the sequence of bases in DNA
Spontaneous Mutations
Mutations that arise from abnormalities in normal biological processes
Induced Mutations
Mutations that are caused from mutagens
Mutagens
Environmental factors that can alter the base composition of DNA
Carcinogens
Cancer-causing mutagens
DNA Repair Enzymes
One of several enzymes that restore the original base sequence in an altered DNA strand