Dna & the Gentic code; DNA replciation

Origin of replication

Specific DNA sequence where replication begins

DNA helicase

Enzyme that unwinds the DNA double helix

Replication fork

Y-shaped region where DNA strands separate during replication

Single stranded DNA binding proteins

Proteins that stabilize separated DNA strands.

Topoisomerase

Enzyme that prevents DNA from getting tangled up ahead of the replication fork

Primer

Short RNA sequence that provides a starting point for DNA synthesis

Template strand

DNA strand used to make a complementary strand

Complementary strand

Newly synthesized strand matching the template by base-pair rules

Primase

Enzyme that synthesizes RNA primers.

Leading strand

DNA strand synthesized

Lagging strand

DNA strand synthesized discontinuously away from the replication fork.

Okazaki fragments

Short DNA fragments formed on the lagging strand

DNA polymerase I

Replaced primers with DNA

DNA polymerase III

The enzyme that synthesizes DNA beginning at the 3’ end of the primer

DNA Ligase

Covalent my links Okazaki fragments

Deoxynucleoside triphosphates

DNA building blocks

Mismatch repair

System that fixes incorrectly paired DNA bases

Transcription

Process of making RNA from a DNA template

RNA polymerase

Enzyme that synthesizes RNA during transcription

Translation

Process of making proteins from mRNA.

Ribosome

Cellular structure where protein synthesis occurs (Contains both RNAs and proteins)

Codon

Three-nucleotide sequence in mRNA that specifies an amino acid

Start (initiation) codon

Codon (usually AUG) that signals the beginning of translation.

Stop (termination) codon

Codon that signals the end of translation

Open reading frame (ORF)

Continuous stretch of codons beginning with a start codon and ending with a stop codon

Coding sequence

Portion of a gene that encodes a protein

Untranslated Region (UTR)

mRNA regions not translated into protein but important for regulation.

What did Fredrick Griffiths determine?

harmless bacteria permanently inherit traits from dead, virulent bacteria “Transformation”

Transformation

Uptake of foreign DNA by a cell, causing a genetic change

Alfred Hershey & Marsha Chase

Scientists who proved DNA, not protein, is genetic material using bacteriophages

Bacteriophages

A virus that infects bacteria

James Watson and Francis Crick

Scientists who proposed the double-helix structure of DNA

Semi-conservative

Method of DNA replication where each new DNA molecule contains one original strand and one new strand.