Inheritance and Gene Expression

Bacterial DNA Replication #

Basic Principles of Transcription and Translation

messenger RNA(mRNA)

Transcription

"The synthesis of RNA using information in the DNA."

"carries a genetic from the DNA to the protein-synthesizing machinery of the cell."

Translation

"The synthesis of a polypeptide using the information in the mRNA."

Ribosomes

"Molecular complexes that facilitate the orderly linking of amino acids into polypeptide chains."

Primary Transcript

"The initial RNA transcript from any gene, including those specifying RNA that is not translated into protein."

Genes program protein synthesis via genetic messages in the form of messenger RNA.

Codons

Triplet Code

*"The genetic instructions for a polypeptide chain are written in the DNA as a series of non-overlapping, three nucleotide words in mRNA, which is then translated in to a chain of amino acids.

Template Strand

"Provides the pattern, or template, for the sequence of nucleotides in an RNA transcript."

Coding Strand

*"The non-template DNA strand

Reading Frame

*"Correct way of reading (transcribing), DNA to RNA.

Molecular Components of Transcription

RNA Polymerase

"Enzyme that pries the two strands of DNA apart and joins together RNA nucleotides complementary to the DNA template strand."

Promoter

"DNA sequence where RNA polymerase attaches and initiates transcription."

Terminator

"The sequence that signals the end of transcription."

Transcription Unit

"The stretch of DNA downstream from the promoter that is transcribed into an RNA Molecule."

Starting Point

"The nucleotide where RNA polymerase actually begins synthesis of the mRNA."

Transcription Factors

"A collection of proteins mediate the binding of RNA polymerase and the initiation of transcription."

Transcription Initiation Complex

"The whole complex of transcription factors and RNA polymerase II bind to it."

TATA Box

"Role of transcription factors and a crucial promoter DNA sequence in forming the initiation complex at a eukaryotic promoter."

RNA Processing

RNA Splicing

"Where large portions of the RNA molecules are removed and the remaining portions are reconnected."

Introns

"The noncoding segments of nucleic acid that lie between coding regions."

Exons

"They are eventually expressed, usually by amino acid sequences."

Making a primary Transcript

RNA Polymerase II transcribes introns and exons from the DNA

mRNA molecule that enters the cytoplasm is an abridged version.

Spliceosome

"The removal of introns is accomplished by a large complex made of proteins and small RNA's."

Ribozymes

"RNA Molecules that function as enzymes."

Domains

"A modular architecture consisting of discrete structural and functional regions."

AntiCodon

"The particular nucleotide triplet that base-pairs to a specific mRNA codon."

Transfer RNA

aminoacyl-tRNA Synthetases

"Enzyme that is able to bind to all 20 different amino acids."

Structure of Ribosome

Wobble

"The Flexible base pairing at this codon position."

3 sites

A Site

E Site

P Site

"Holds the tRNA carrying the growing polypeptide chain."

"Holds the tRNA carrying the next amino acid to be added to the chain."

"Discharged tRNA's leave from this site(Exit)."

Polyribosomes

"They enable a cell to rapidly make many copies of a polypeptide."

Mutations

Point Mutations

"Are responsible for the huge diversity of genes found among organisms because its the ultimate source of new genes."

"Changes in a single nucleotide pair of a gene."

Silent Mutation

"Which has no observable effect on the phenotype."

Missense Mutations

"Substitutions that change one amino acid to another one."

Nonsense Mutations

"Causes translation to be terminated prematurely."

Insertions

"Are additions or losses of nucleotide pairs in a gene."

Deletions

Frameshift Mutations

"Occurs whenever the number of nucleotides inserted or deleted is not a multiple of three."

Mutagens

"Interact with DNA in ways that cause mutations."

Gene Expression

"The process by which DNA directs the synthesis of proteins."

DNA

Double Helix Shaped

Antiparallel

Origins of Replication

Short stretches of DNA that have a specific sequence of nucleotides.

Helicases

Enzyme that unravel and untwist the double helix at the replication forks.

Topoisomerase

An enzyme that helps relieve this strain by breaking, swiveling, and rejoining DNA strands.

Chromatin

"Eukaryotic DNA is precisely combined with a large amount of protein. Fits into the nucleus through an elaborate, multilevel system of packing."

Heterochromatin

"Visible as irregular clumps with a light microscope."

Euchromatin

"True Chromatin"

Chromosomes

Histones

"Proteins that are responsible for the first level of DNA packing in chromatin."

Nucleosome

"The basic unit of DNA packing; the "string" between beads is called linker DNA."

Helicase

Single-Strand binding protein

Topoisomerase

Primase

DNA Pol III

DNA Pol I

DNA Ligase