AP Bio Mendelian Genetics and Probability/ Transcription and Translation

Mendel’s Law of Segregation

Organisms have two variations of every trait, called alleles (one from each parent), and these alleles separate equally into gametes

Mendel’s Law of Independent Assortment

Alleles for different traits separate independently from each other. For example, inheriting flower color and height are not related to each other.

Promoter Region

Region of DNA in eukaryotes that RNA polymerase can bind to. Part of it is called the TATA box.

Transcription Factors

Protein that helps RNA polymerase bind to the promoter sequence and begin transcription

Introns are cut out by

Spliceosomes

Spliceosomes are made of

snRNA and snRNPs

Alternative Splicing is when

Exons from the same gene are arranged in different orders during splicing in order to generate various proteins

Steps of Translation

1. Initiation

2. Elongation

3. Termination

Initiation (in translation)

rRNA reads the start codon AUG. tRNA brings the appropriate anti-codon and translation begins

Elongation (in translation)

The translocation and addition of new amino acids to the polypeptide chain

Termination

When ribosome reaches STOP codon (nonsense codon), proteins called “release factors” make the ribosome disassemble and the polypeptide chain is released

Inducible Operons

Turns off when the protein the gene codes for IS NOT in the environment

Repressible Operons

Turns off when the protein the gene codes for IS in the environment

Corepressor

Protein in repressible operons that help the repressor protein bind to the operator region of the operon

Regulatory Switches

DNA sequences in Eukaryotes where activator/ repressor proteins might bind.

Enhancer

Regulatory switches on which activator proteins or transcription factors bind

Silencers

Regulatory switches which repressor proteins bind to

Repressor proteins

Bind to regulatory switches and turn off/ suppress gene expression

Activator proteins

Bind to regulatory switches and turn off/ up-regulate gene expression

Mediators

Serve as connectors between regulatory proteins and allow them to communicate

Epigenetic changes

Reversible modifications of DNA sequence, such as methylation

Euchromatin

DNA loosely wound around histone proteins; easily accessible

Heterochromatin

DNA wound tightly around histone proteins; less accessible

siRNA (small interfering RNA)

Destroyes mRNA by binding to it to form dsRNA (double stranded RNA). Enzymes in the cell detect and destroy dsRNA.

Differential Gene Expression

Different genes are expressed in different cells, despite all cells containing all genetic information

Aneuploidy

Atypical number of chromosomes

Transformation

The uptake of naked foreign DNA by a cell

Transduction

The transmission of DNA from one organism to another by viruses; as the virus transfers the DNA, the DNA sequence may be recombined or otherwise changed, leading to new mutations and variations

Conjugation

The transmission of DNA through cell-to-cell contact, usually through a connection palled a pilus

Transposition

The movement of DNA between chromosomes or within a chromosomes; these are sometimes referred to as “jumping genes”

Bacterial Transformation

Foreign DNA, such as a plasmid integrates into the host cell’s chromosome or remains separate. Heat shock can create pores through which this is possible

Recombinant DNA

DNA that has been recombined from different source organisms. DNA can be cut using restriction endonucleases and recombined using DNA ligases

Gel electrophoresis

Separates DNA molecules by size and charge

PCR

Amplifies specific DNA fragments