Ch. 11 - How Genes are Controlled

based on study guide

Gene expression

The overall process by which genetic information flows from genes to proteins

Gene regulation

mechanisms that turn on or turn off genes - carried out through short stretches of DNA that turn all three genes on and off at once, coordinating their expression.

Operon

a cluster of related genes and sequences that control them

Operator

control sequence between the promoter and the enzyme genes

repressor protein

binds to the operator and physically blocks the attachment of RNA polymerase to the promoter

promoter

the (control sequence) site where the enzyme RNA polymerase attaches and initiates transcription.

RNA polymerase

An enzyme that links together the growing chain of RNA nucleotides during transcription, using a DNA strand as a template.

Lac operon

three lactose-digesting genes are adjacent in the DNA and turned on and off as a single unit.

Eukaryotic gene structure

segments of coding sequences (exons) interrupted by noncoding sequences (introns).

DNA enhancer

noncoding DNA control sequences

DNA silencers

A eukaryotic DNA sequence that inhibits the start of gene transcription; may act analogously to an enhancer, binding a repressor.

Transcription factors

In the eukaryotic cell, a protein that functions in initiating or regulating transcription. Transcription factors bind to DNA or to other proteins that bind to DNA

Activators

proteins that turn genes on by binding to DNA. Activators act by making it easier for RNA polymerase to bind to the promoter.

DNA packing

prevent gene expression by preventing RNA polymerase and other transcription proteins from binding to the DNA

Barr bodies

inactivated X chromosome; compacted X chromosome

X chromosome inactivation

In female mammals, one X chromosome in each somatic cell is highly compacted and almost entirely inactive.

Homeotic genes

Master control genes- regulate groups of other genes that determine what body parts will develop in which locations

Small RNAs

• miRNAs- small single stranded RNA molecules that can bind to complementary sequences on mRNA molecules

• siRNAs- carries out RNA interference which blocks gene expression

Signal transduction

1. The signaling cell secretes the signal molecule

2. This molecule binds to a specific receptor protein embedded in the target cell’s plasma membrane.

3. The binding activates a signal transduction pathway consisting of a series of relay proteins within the target cell. Each relay molecule activates the next.

4. The last relay molecule in the series activates a transcription factor © 2019 Pearson Education, Inc. A cell-signaling pathway that turns on a gene (part 2: activated transcription factor to new protein) Nucleus Transcription mRNA New protein 6 Translation 5

5. Activation of transcription factor triggers transcription of specific gene

6. Translation of the mRNA produces a protein that can then perform the function originally called for by the signal.

Cloning

The production of multiple copies of a gene.

Reproductive cloning

Using a body cell from a multicellular organism to make one or more genetically identical individuals.

Therapeutic cloning

The cloning of human cells by nuclear transplantation for therapeutic purposes, such as the replacement of body cells that have been irreversibly damaged by disease or injury.

Oncogene

a gene that causes cancer

Proto Oncogene

a normal gene with the potential to become an oncogene - code for growth factors (proteins that stimulate cell division)

Tumor suppressor gene

Genes whose products inhibit cell division - proteins they encode normally help prevent uncontrolled cell growth

Inherited cancer

An individual inheriting an oncogene, or a mutant version of a tumor-suppressor gene is a step closer to accumulating the necessary mutations for cancer