Genetics
The scientific study of heredity
Fertilization
The process in sexual reproduction in which male and female sex cells join to form a new cell
True-breeding
Organisms that produce offspring identical to themselves if allowed to self-pollinate
Trait
A specific characteristic that varies from one individual to another
Hybrid
Offspring of crosses between parents with different traits
Gene
A sequence of DNA that codes for a protein and thus determines a trait
Allele
A different form of a gene
Segregation
The separation of alleles during gamete formation
Gamete
A sex cell
Punnet Square
A diagram showing the possible gene combinations from a genetic cross
Homozygous
An organism that has two identical alleles for a particular trait
Heterozygous
An organism that has two different alleles for the same trait
Phenotype
The physical characteristics of an organism
Genotype
The genetic makeup of an organism
Independent Assortment
Independent segregation of genes during the formation of gametes
Incomplete Dominance
A situation in which one allele is not completely dominant over another
Codominance
A situation in which both alleles of a gene contribute to the phenotype of the organism
Multiple Alleles
Three or more alleles of the same gene
Polygenic Traits
A trait controlled by two or more genes
Transformation
A process in which one strain of bacteria is changed by the genes from another strain of bacteria
Bacteriophage
A virus that infects bacteria
Nucleotide
A monomer of nucleic acids made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base
Base Pairing
The principle that states bonds in DNA can form only between adenine and thymine and between cytosine and guanine
Messenger RNA (mRNA)
A type of RNA molecule that carries copies of instructions for the assembly of amino acids into proteins from DNA to the rest of the cell
Ribosomal RNA (rRNA)
A type of RNA molecule that makes up the major part of ribosomes
Transfer RNA (tRNA)
A type of RNA molecule that transfers amino acids to ribosomes during protein synthesis
Transcription
A process in which part of the nucleotide sequence of DNA is copied into a complementary sequence of RNA
RNA Polymerase
An enzyme that binds to DNA and separates the DNA strands during transcription
Promoter
A region of DNA that indicates to an enzyme where to bind to make RNA
Intron
A sequence of DNA that is not involved in coding for a protein
Exon
Expressed sequence of DNA; codes for a protein
Codon
A three-nucleotide sequence on mRNA that codes for a single amino acid
Translation
Decoding of a mRNA message into a polypeptide chain
Anticodon
A group of three bases on a tRNA molecule that are complementary to an mRNA codon
Mutation
Change in a DNA sequence that affects genetic information
Point Mutation
A gene mutation involving changes in one or a few nucleotides
Frameshift Mutation
A mutation that shifts the reading frame of the genetic message by inserting or deleting a nucleotide
Polyploidy
A condition in which an organism has an extra set of chromosomes
Operon
A group of genes operating together
Operator
A Region of a chromosome in an operon to which the repressor binds when the operon is turned off
Differentiation
The process in which cells become specialized in structure and function
Hox Gene
A series of genes that controls the differentiation of cells and tissues in an embryo
Diploid
A cell that contains both sets of homologous chromosomes
Haploid
A cell that contains only a single set of chromosomes
How is DNA replicated?
The DNA molecule is unzipped by enzymes and new complementary bases are attached following the rules of base pairing
What did Griffith conclude?
That a factor in heat-killed disease causing bacteria can transform harmless bacteria into disease causing bacteria
What did Avery conclude?
That genes are composed of DNA
How are proteins made?
DNA is transcribed into mRNA by RNA polymerase. The mRNA moves to ribosomes and tRNA brings the correct amino acids to build a polypeptide chain.
DNA polymerase
An enzyme involved in DNA replication that joins individual nucleotides to produce a DNA molecule