Bio Ch 12 Flashcards
Pyrimidine
thymine & cytosine (single ring)
Purine-based nucleotides
adenine & guanine (double ring)
Double helix
double spiral; describes the 3D shape of DNA
Complementary base pairing
a purine (large, 2-ring base) is always bonded to a pyrimidine (smaller, one-ring base)
DNA Replication
process of copying a DNA molecule
Template
most often a mold used to produce a shape complementary to itself
Semiconservative replication
each daughter DNA double helix contains an old strand from the parental DNA double helix and a new strand
DNA Polymerase
during replication, an enzyme that joins the nucleotides complementary to a DNA template
telomeres
special nucleotide sequence that does not code for proteins; use a repeat sequence such as TTAGGG
Replication fork
in eukaryotic DNA replication, the location where the 2 parental DNA strands separate
Uracil
in RNA, this base replaces the thymine found in DNA
Messenger RNA (mRNA)
takes a message from DNA in the nucleus to the ribosomes in the cytoplasm
Transfer RNA (tRNA)
transfers amino acids to the ribosomes
Ribosomal RNA (rRNA)
along with ribosomal proteins, makes up the ribosomes, where polypeptides are synthesized
Transcription
process by which an RNA molecule is produced based on a DNA template; DNA is copied, base by base, into mRNA, tRNA, & rRNA
Translation
mRNA transcript is read by a ribosome and converted into the sequence of amino acids in a polypeptide
Central Dogma of Molecular Biology
Flow of info from DNA to RNA to protein to trait
Genetic Code
universal code that has existed for eons and allows for conversion of DNA and RNA’s chemical code to a sequence of amino acids in a protein; each codon consists of three bases that stand for one of the 20 amino acids found in proteins or directs the termination of translation
Triplet code
each coding unit (codon) would need to be made up of 3 nucleotides
Codon
3-base sequence in messenger RNA that during translation directs the addition of a particular amino acid into a protein or directs termination of the process
RNA Polymerase
joins nucleotide strands together in the 5’ to 3’ direction
Promoter
defines the start of transcription, the direction of transcription, & the strand to be transcribed
mRNA transcript
mRNA molecule formed during transcription that has a sequence of bases complementary to a gene
Exons
protein-coding regions
introns
non-protein coding regions
Ribozyme
enzyme made of RNA rather than just protein used to cut and remove introns
Anticodon
group of 3 bases that is complementary and antiparallel to a specific mRNA codon
Wobble Hypothesis
1966, Francis Crick: 1st 2 positions in a tRNA anticodon pair obey he A-U/G-C configuration rule; 3rd position can be variable; helps ensure that despite changes in DNA base sequences, the resulting sequence of amino acids will produce a correct protein (1 of reasons genetic code is said to be degenerate)
Polyribosome
entire complex of mRNA and multiple ribosomes is called this; greatly increases the efficiency of translation
Initiation
step that brings all the translation components together
Elongation
stage during protein synthesis when a polypeptide increases in length one amino acid at a time
Translocation
ribosome moves forward, peptide-bearing tRNA is now in the P site of the ribosome
Termination
final step in protein synthesis
Proteomics
field of biology dedicated to understanding the structure of proteins and how they function in metabolic pathways
Histones
group of proteins involve in forming the nucleosome strucure of eukaryotic chromatin
Nucleosome
in the nucleus of a eukaryotic cell, a unit composed of DNA wound around a core of 8 histone proteins, giving the appearance of a string of beads
Euchromatin
active chromatin containing genes that are being transcribed
Heterochromatin
highly compacted chromatin that is not accessible for transcription
