Bio chapter 16 and 17 Flashcards
start point
in transcription, the nucleotide position on the promoter where RNA polymerase begins synthesis of RNA
E site
one of a ribosome’s three binding sites for tRNA during translation. The E site is the place where discharged tRNAs leave the ribosomes ( E stands for exit)
Terminator
in bacteria, a sequence of nucleotides in DNA that marks the end of a gene and signals RNA polymerase to release the newly RNA molecule and detach from DNA
DNA polymerase
An enzyme that catalyzes the elongation of new DNA (for example, at a replication fork) by the addition of nucleotides to the 3’ end of existing chain. There are several different DNA polymerases; DNA polymerase III and DNA polymerase I play major roles in DNA replication in E. coli
Mismatch repair
The cellular process that uses specific enzymes to remove and replace incorrectly paired nucleotides.
nucleotide pair substitution
a type of point mutation in which one nucleotide in a DNA strand and its partner in the complementary strand are replaced by another pair of nucleotides
lagging strand
a discontinuously synthesized DNA strand that elongates by means of Okazaki fragments, each synthesized in 5’ 3’ direction away from the replication fork.
TATA box
A DNA sequence in eukaryotic promoters crucial in forming the transcription initiation complex.
transcription factor
a regulatory protein that binds to DNA and affects transcription of specific genes
DNS ligase
A linking enzyme essential for DNA replication; catalyzes the covalent bonding of 3’ end of one DNA fragment( such as an Okazaki fragment) to the 5’ end of another DNA ( such as a growing DNA chain).
Coding strand
contemplate strand of DNA, which has the same sequence as the mRNA except it has thymine instead of uracil
P site
one of a ribosome’s three binding sites for tRNA during translation. the P site holds the tRNA carrying the growing polypeptide chain.
Silent mutation
a nucleotide- pair substitution that has no observable effect on the phenotype; for example within a gene, mutation that result in a codon that codes for the same amino acid
Chromatin
The complex of DNS and proteins that makes up eukaryotic chromosomes. when the cell is not dividing, chromatin exists in its dispersed form, as a mass of very long, thin fibers that are not visible with a light microscope.
heterochromatin
Eukaryotic chromatin that remains highly compacted during interphase and is generally not transcribed
mutagen
A chemical or physical agent that interacts with DNA and can cause a mutation.
DNA replication
The process by which a DNA molecule is copied; also called DNA synthesis
messenger RNA (mRNA)
A type of RNA, synthesized during a DNA template, that attached to ribosomes in the cytoplasm and specifies the primary structure of a protein.
