Biology Chapter 11

Growth factors

Proteins that stimulate cell division, or for other proteins that affect the cell cycle. Many proto-oncogenes code for growth factors.

Regeneration

The regrowth of lost body parts. Ex: salamander tail

Promoter

The site where the RNA polymerase attaches and initiates transcription.

Metastasis

The spread of cancer cells beyond their original site

Reproductive cloning

results in the birth of a new living individual

Repressor

Binds to the operator and blocks the attachment of RNA polymerase to the promoter. Suppresses the transcription of a gene.

Operator gene

A DNA segment that acts as a switch that is turned "on" or off", depending on whether lactose is present or absent. The operator and protein together determine whether RNA polymerase can attach to the promoter and start transcribing the genes.

Enhancers

A DNA sequence that recognizes certain transcription factors that can stimulate transcription of nearby genes.

Oncogene

A gene that causes cancer is called an oncogene.

Proto-oncogene

A normal gene with the potential to become an oncogene.

Signal transduction pathway

A sgnal molecule can act by binding to a receptor protein and initiating a signal transduction pathway. (cell-to-cell signaling in which the target cell's response is the transcription (turning on) of a gene)

Stem cell

A single cell that can replicate itself, or differentiate into many cell types.

Familial Adenomatous Polyposis

An inherited disorder characterized by cancer of the large intestine (colon) and rectum.

Carcinogens

Cancer-causing agents found in the environment, including ultraviolet (UV) radiation and tobacco products.

Lactose (lac) operon

Control system that manages the regulation of lactose metabolism. It is composed of three gene codes, lacZ, lacY, and lacA. They are adjacent in the DNA and turned on and off as a single unit called the lactose (lac) operon.

p53 Gene

Controls normal cell growth. Mutations in p53 cause the cell to lose control of cell division.

lacZ gene

Encodes for beta-galactosidase. Enzymatically cleaves lactose and converts to glucose and galactose (used by bacteria for metabolism). Beta-galactosidase—-> Glucose + Galactose

lacY gene

Encodes for galactoside permease. Protein required for transport of lactose into the cell.

lacA

Encodes galactoside transacetylase.

Zygote

Every cell in your body was produced through successive rounds of mitosis starting from the zygote, the original cell that formed after fusion of aperm and egg during fertilization.

Nuclear transfer

Involves replacing the nucleus of an egg cell or a zygote with a nucleus removed from an adult body cell such as a skin cell

Transcription factors

Many proteins, collectively called transcription factors, acting together to bind to DNA sequences called enhancers and the promoter.

Homeotic genes

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

Gene regulation

Mechanisms that turn on certain genes while other genes remain turned off. A gene that is turned on is being transcribed into specific proteins.

Introns

Noncoding segments of nucleic acid that lie between coding sequences.

Apoptosis

Programmed cell death which all cells undergo. Varies between cell types.

RNA processing

RNA processing includes -The addition of a cap and a tail -The removal of introns (the noncoding DNA segments that interrupt the genetic message), and -RNA splicing (the splicing together of exons)

Gene expression

The overall process by which genetic information flows from genes (DNA) to RNA to Proteins

Hematopoietic stem cells

Umbilical cord blood, mobilized peripheral blood, and bone marrow

Alternative Gene (RNA) Splicing

Within a cell, exon splicing can occur in more than one way, generating different mRNA molecules from the same starting RNA molecule. With this sort of alternative gene (RNA) splicing, an organism can produce more than one polypeptide from a single gene.

Operon

a group of related genes that operate together.

Cancer

any malignant growth or tumor caused by abnormal and uncontrolled cell division. Cancer cells do not undergo apoptosis, but continue to grow and divide.

Extrons

expressed sequence of DNA; codes for a protein

Barr Bodies

inactivated X chromosomes found only in females

Condition: Lactose Absent

lac operon in "off" mode occurs when the active repressor binds to the operator and blocks the attachment of RNA polymerase to the promoter. No lactose present, no transcription.

Condition: Lactose Present

lac operon in the "on" mode occurs when the inactive repressor binds to allolactose (a lactose metabolite). The operator is free to bind the RNA Polymerase that can now transcribe all the enzymes needed to metabolize lactose. With lactose present, transcription occurs.

Tumor-suppressor genes

make proteins that stop cell division and kill cells.

Breast cancer

malignant tumor of breast. Mutations in BRCA can cause breast cancer that can be genetically transferred to the offspring.

Malignant cell

potentially life-threatening cancer cells

X chromosome inactivation

process that occurs in female mammals in which one of the two X (XX) chromosomes in each cell is inactivated at random. After one X chromosome is inactivated in the embryonic cell, all of that cell's descendants will have the same X chromosome inactivated.

cellular differentiation

the process by which a cell specializes to carry out a specific role