genome
all the genetic material in an organism's cells
DNA
nucleic acid molecule shaped as a double helix; capable of replicating and determining the inherited structure of a cell's proteins
nucleotide
the subunit of DNA; composed of phosphate, deoxyribose sugar, and a nitrogenous base (A, G, C, or T)
RNA
a type of nucleic acid consisting of ribonucleotides; usually single-stranded; functions in protein synthesis and as the genome of some viruses
ribonucleotide
the subunit of RNA; composed of phosphate, ribose sugar and a nitrogenous base (A, G, C, or U)
chromosome
a single piece of supercoiled DNA with associated organizational proteins; found in the nucleus of eukaryotic cells; contains genes that encode traits
chromatin
a loose, more dispersed form of DNA, existing as a mass of very long, thin fibers; state of the DNA when the cell is not dividing
gene
a section of DNA that codes for how to make a certain protein
protein
biomolecule that consists of CHONS; subunits are amino acids; constructed using the information found in genes
trait
an observable, genetically determined characteristic of an organism
transcription
the process in which the genetic code sequence in DNA is copied to mRNA; occurs in the nucleus of eukaryotic cells
translation
the process in which the genetic information coded in mRNA is read by a ribosome and directs the formation of a specific protein; occurs in the cytoplasm
mRNA
messenger RNA; synthesized from DNA, attaches to ribosomes in the cytoplasm and specifies the primary structure of a protein
rRNA
ribosomal RNA; a globular form of RNA that is combined with proteins to form a ribosome
tRNA
transfer RNA; molecule that functions as an interpreter between nucleic acid and protein language by picking up specific amino acids and recognizing the appropriate codons in the mRNA
RNA polymerase
enzyme that matches a complementary ribonucleotide to the DNA template strand then seals it onto the growing mRNA strand using dehydration synthesis
transcription initiation
transcription factors align RNA polymerase
transcription elongation
RNA polymerase uses code on the template strand of the DNA to build a strand of mRNA
transcription termination
RNA polymerase stops building mRNA when it reaches the terminator sequence on the DNA
promoter
DNA sequence found just before the start of a gene where transcription factors bind to help guide RNA polymerase into place
terminator
DNA sequence found at the end of the gene that triggers RNA polymerase to stop transcription
complementary base pairing
the alignment of hydrogen bonding between particular pyrimidines and purines (Adenine & Thymine; Guanine & Cytosine)
template strand
the side of the DNA used to create mRNA during transcription; read 3' - 5'; also known as the sense strand
sense strand
the side of the DNA used to create mRNA during transcription; read 3' - 5'; also known as the template strand
nontemplate strand
the side of the DNA temporarily held aside during transcription (not used); runs 5' - 3'; also known as the antisense strand
antisense strand
the side of the DNA temporarily held aside during transcription (not used); runs 5' - 3'; also known as the nontemplate strand
splicing
eukaryotic mRNA editing in which introns are removed from the pre-mRNA and exons are ligated together; splicing of pre-mRNA can be different in different tissues
introns
noncoding sections within a eukaryotic gene that are cut out of the mRNA
exons
the coding regions of a eukaryotic gene that are kept and spliced together during mRNA editing
ligase
the enzyme that connects two fragments of nucleic acid to make a single fragment; connects mRNA exons during editing
mRNA cap
a short sequence of modified nucleotides added to the 5' end of the mRNA molecule
poly A tail
the modified end of mRNA in which 50-250 adenine nucleotides are added to the 3' end
triplet
sequence of three nucleotide bases on DNA
codon
sequence of three ribonucleotide bases on mRNA
anticodon
sequence of three ribonucleotide bases on tRNA
ribosome
cell organelle constructed by the nucleolus and functioning as the site of protein synthesis in the cytoplasm; consists of two subunits composed of rRNA and protein molecules
small ribosomal subunit
binds on first during translation
large ribosomal subunit
binds onto the small ribosomal subunit once the first tRNA molecule has bound to the start codon
A site
accepts the new incoming tRNA
P site
the amino acid chain from the tRNA at this site is peptide bonded to the incoming amino acid at the A site
E site
where empty tRNAs from the P site are shifted to exit the ribosome
amino acids
the monomers of proteins
polypeptide chain
a linear chain of amino acids
peptide bonds
the bonds that join amino acids
AUG
start codon; codes for methionine
methionine
the first amino acid in most proteins; called for by the start codon AUG
stop codon
codes for a releasing factor which triggers the ribosome to stop translation, detach from the mRNA and release the polypeptide chain
operon
a group of genes whose transcription is controlled by a promoter and operator
operator
the DNA sequence prior to a group of genes where the repressor can bind to prevent transcription
repressor
a protein that can bind to the operator and prevent the trancription of the genes
inducer
a specific small molecule that inactivates the repressor in an operon
transcription factors
a regulatory protein that binds to DNA and affects transcription of specific genes
TATA box
a DNA sequence in eukaryotic promoters crucial in forming the transcription initiation complex
TATA binding protein
finds and binds to the TATA box, the DNA sequence that signals the start of transcription, and then distorts the DNA helix so other transcription factors can join in
enhancers
a DNA sequence that recognizes certain transcription factors that can stimulate transcription of nearby genes
histones
proteins that assist in DNA coiling in eukaryotes; DNA helix is wrapped around a group of 8 histones to form a nucleosome
proteome
the set of proteins expressed by an organism's cells
mutation
a change in a cell's DNA sequence
point mutation
mutation in which one nucleotide base is exchanged for another; also known as a substitution mutation
silent mutation
a base substitution which results in the same amino acid being encoded
missense mutation
a base substitution which results in a different amino acid being coded for
nonsense mutation
a base substitution in which the new codon codes for stop; often results in the polypeptide chain ending too early
frameshift mutations
mutation that shifts the "reading" frame of the genetic message by inserting or deleting a nucleotide; may change every amino acid that follows the point of the mutation
addition
mutation that inserts an additional nucleotide into the gene; results in a frameshift
deletion
mutation that deletes a nucleotide from the gene; results in a frameshift
mutagen
any external, environmental agent that induces mutations
allele
different coding versions of a gene; create the variants for a trait
sickling hemoglobin
variant form of hemoglobin produced from a single point mutation in the hemoglobin gene
somatic cell
any body cell other than a reproductive cell
germ cell
a cell that develops into a reproductive cell
homeotic gene
genes that determine which parts of the body form what body parts
syndactyly
a genetic mutation that results in the fusion of digits
polydactyly
a genetic mutation that results in the formation of additional digits