DNA & Chromosome Structure
Each nucleotide consists of these three parts.
nitrogenous base, deoxyribose sugar, phosphate(s)
this enzyme synthesizes a new DNA strand in the 5'-3' direction
DNA polymerase
What is the "central dogma"?
DNA-->RNA-->Protein
Name the 3 types of RNA and their functions.
mRNA-carries the info
tRNA- carries the amino acids
rRNA-synthesizes the protein
what is transcription
transcribing the gene (DNA) into messenger RNA
1. Initiation- proteins called transcription factors bind to TATA box on
promoter region of the gene
2. Elongation-RNA polymerase makes a complimentary RNA copy of the DNA
3. Termination-the new RNA copy and RNA polymerase are released from the
gene
Product= precursor mRNA
This bond covalently links adjacent nucleotides in a single DNA strand.
phosphodiester
this enzyme seals the nicks between okazaki fragments
DNA ligase
Transcription factors bind to the _____ region which is _______ of the gene.
promoter, upstream
The start codon is ____ and codes for ____.
AUG, methionine
RNA processing
turns precursor mRNA into mRNA that is ready to be
translated
1. 5’ G cap added-functions as site of ribosome attachment in translation
2. 3’ poly-A tail added-functions as protection from RNA-degrading enzymes
3. Intron sequences removed-allows for “mixing up” of exons so that 1 gene
can code for multiple proteins saving space in the DNA
Product= mRNA
This bond holds together two strands of DNA.
hydrogen bonds
What steps are common for ALL DNA repair mechanisms?
excision, resynthesis, ligation
This is added to pre-mRNA to provide protection against degradation by enzymes.
3' poly A tail
How does termination occur in translation?
release factor binds to the A site of the ribosome
What is translation
translating the mRNA into protein using the genetic code-
culminating event of gene expression
Involves 3 types of RNA: transfer RNA (tRNA) carries amino acids, ribosomal RNA
(rRNA) synthesizes the protein by forming peptide bonds, mRNA provides the
information (amino acid sequence)
1. Initiation-everything starts at the “start codon” which is usually AUG
(methionine)
2. Elongation- formation of peptide bonds to link together adjacent amino
acids
3. Termination-when ribosome reaches a stop codon, release factor binds at A
position and the translation machinery/newly synthesized protein is
released
What is chromatin?
DNA and all associated proteins
lagging
What is RNA splicing used for?
removal on intron sequences from pre-mRNA
The _____ code is universal for all living things and viruses.
genetic code
Gene
hereditary unit of DNA, each gene encodes for a protein
What is the order of chromosome packing during condensation?
nucleosomes (beads on a string), 30nm fibers, looping of those fibers
Why is homologous repair only possible during mitosis?
only then are the chromosomes replicated allowing the "extra copy" to serve as a template for resynthesis
WHY and HOW does mature mRNA leave the nucleus after processing?
because translation occurs in the cytoplasm, thru a nuclear pore
What happens during elongation of translation?
formation of peptide bonds by ribosomal RNA
Gene expression
refers to the process of accessing information in the DNA to build proteins.