DNA and protein synthesis terms

DNA replication

Each strand acts as a template for a new strand

Helicase

The enzyme that untwists and unzips the double helix. (Breaks hydrogen bonds)

Topiosomerase

A protein that reduces the super-coiling that occurs as the helices unwinds the double helix.

Primase

Joins the RNA nucleotides together to make the primer.

DNA polymerase

The enzyme that catalyzes elongation of DNA. ( bonds the free nucleotide to the backbone)

DNA ligase

An enzyme that joins fragments of DNA during lagging strand replication

Protein Synthesis

Contains transcription then translation

Transcription

DNA → mRNA

RNA Polymerase separates DNA and the free RNA nucleotides match up to the DNA by base pairing

Translation

mRNA → polypeptide

The tRNA matches with an mRNA codon to attach the amino acid to the polypeptide chain.

DNA

Made of phosphate, deoxyrobse sugar and nitrogenous bases( adenine thymine cytosine guanine)

mRNA

Messenger RNA is single stranded and carries information from DNA to the ribosome. mRNA contains codons which are complementary to the DNA base pair sequence.

tRNA

Transfer RNA - the interpreter… the tRNA finds its specific amino acid, the tRNA anticodon matches with mRNA codon. Amino acid attaches to polypeptide chain.

Ribosome

Made of protein and ribosomal DNA. Contains 2 subunits - large +small

Also has 3 binding sites for tRNA ( p (polypetide) A (amino acid ) E (exit))

Exon

Coding sections in eukaryotic mRNA transcripts that will be translated ( exons are expressed)

Intron

Noncoding RNA sections (cut out before translation)

Promoter

Often has a tata box, this tells RNA polymerase where to begin.

RNA polymerase

An enzyme that transcribes a DNA sequence into RNA molecules

Codon

Made of 3 nucleotides that code for an amino acid.

Point Mutation

A change in just one nucleotide pair of a gene (two strands of DNA)

Substitution

Changes one nucleotide pair

Deletion

Removes a nucleotide pair

Insertion

Adds a nucleotide pair

Silent Mutation

Doesn't affect amino acid sequence (substitution)

Missense mutation

Codes for one wrong amino acid ( substitution)

Frameshift mutation

Shifts the reading frame (groups of three) (insertion or deletion)

Nonsense mutation

Codon changes to a stop codon (substitution, insertion, or deletion)

Label the following: nucleotide, deoxyribose sugars, phosphate, and nitrogenous base

Be able to determine which DNA strand is the template strand and which is the coding strand

What type of bond is along the backbone of DNA between the nucleotides?

covalent bonds

What type of bond is between the complementary base pairs?

Hydrogen bond

What type of bond is between amino acids and a polypeptide chain?

Peptide bonds