Bio Chapter 13

DNA microarray

A _________________ is a slide with thousands of different kinds of single-stranded DNA fragments attached in a tightly spaced array (grid) Each DNA fragment is obtained from a particular gene; a single microarray thus carries DNA from thousands of genes, perhaps even all the genes of an organism

True

A cell can acquire an oncogene from a virus or from the mutation of one of its own proto-oncogenes True or False

oncogene

A gene that causes cancer is called an __________

proto-oncogene

A normal gene with the potential to become an oncogene is called a ________________

nuclear transplantation

Animal cloning is achieved through a procedure called ________________________-: - involves replacing the nucleus of an egg cell or a zygote with a nucleus removed from an adult body cell If properly stimulated, the recipient cell may then begin to divide • If the animal to be cloned is a mammal, further development requires implanting the early embryo into the uterus of a surrogate mother

signal transduction pathway

A signal molecule can act by binding to a receptor protein and initiating a _________________________, a series of molecular changes that converts a signal received outside a cell to a specific response inside the target cell

ON

Activators are proteins that turn genes _______by binding to DNA

rise to only a few related types of specialized cells

Adult stem cells are further along the road to differentiation than ES cells and can therefore give _________________________

block translation

After binding, some miRNAs trigger breakdown of their target mRNA, whereas others _____________

the remaining cDNA glows in the microarray

After unbound cDNA is rinsed away, ____________________

carcinogens

Although some cancers occur spontaneously, most cancers arise from mutations that are caused by _____________, cancer-causing agents found in the environment

Cancer

Any mutation that keeps a growth-inhibiting protein from being made or from functioning may contribute to the development of __________

prokaryotes

Armed with a variety of operons, E. coli and other ___________ can thrive in frequently changing environments

operator

Between the promoter and the enzyme genes, a DNA segment called an _____________acts as a switch that is turned on or off, depending on whether a specific protein is bound there The operator and protein together determine whether RNA polymerase can attach to the promoter and start transcribing the genes • In the lac operon, when the operator switch is turned on, all the enzymes needed to metabolize lactose are made at once

second

Cancer is the ___________-leading cause of death (after heart disease) in most industrialized countries

DNA packing

Cells may use _____________for the long-term inactivation of genes

gene regulation

Cells with the same genetic information can develop into different types of cells through _______________________, mechanisms that turn on certain genes while other genes remain turned off

Cancer

Changes in genes whose products inhibit cell division are also involved in ___________

melanoma

Excessive exposure to UV radiation from the sun can cause skin cancer, including a deadly type called ____________ you can decrease your risk by using sun protection (clothing, lotion, hats, etc.)

signal molecule

First, the signaling cell secretes the ____________- This molecule binds to a specific receptor protein embedded in the target cell's plasma membrane

DNA

For a proto-oncogene to become an oncogene, a mutation must occur in the cell's __________

hormones

For example, a cell can produce and secrete chemicals, such as ____________, that affect gene regulation in another cell

cDNA

If a molecule in the __________ mixture is complementary to a DNA fragment at a particular location on the grid, the ________ molecule binds to it, becoming fixed there

malignant tumor

If detected during a colonoscopy, suspicious polyps can usually be removed before they become a serious risk • Further mutations eventually lead to formation of a ________________ — a tumor that has the potential to spread • It typically takes at least six DNA mutations (usually creating at least one active oncogene and disabling at least one tumor-suppressor gene) before a cell becomes fully cancerous

lactose

If you drink a milk shake, for example, there will be a sudden rush of the sugar ___________ In response, E. coli will express three genes for enzymes that enable the bacterium to absorb and digest this sugar • After the lactose is gone, these genes are turned off; the bacterium does not waste its energy continuing to produce these enzymes when they are not needed • Thus, a bacterium can adjust its gene expression to changes in the environment

Cell Signaling

In a multicellular organism, the regulation process can cross cell boundaries, allowing information to be communicated between and among cells

embryonic stem cells (ES cells)

In mammals,_______________________are obtained by removing cells from an early embryo and growing them in laboratory culture

polyp

Later, additional DNA mutations (such as the inactivation of a tumor-suppressor gene) cause the growth of a small benign tumor (called a __________ in the colon wall • The cells of the polyp look normal, although they divide unusually frequently

bacteria

Many operons have been identified in _________________ Some are quite similar to the lac operon, whereas others have somewhat different mechanisms of control - for example, operons that control amino acid synthesis cause bacteria to stop making these molecules when they are already present in the environment, saving materials and energy for the cells - in these cases, the amino acid activates the repressorArmed with a variety of operons, E. coli and other prokaryotes can thrive in frequently changing environments

carcinogens

Mutations often result from decades of exposure to ________________

promoter

One control sequence, called a __________, is the site where the enzyme RNA polymerase attaches and initiates transcription of the genes for lactose-digesting enzymes

ultraviolet (UV) radiation

One of the most potent carcinogens is ______________________

chemical modification

Other proteins require __________________before they become active • Selective breakdown of proteins: some proteins that trigger metabolic changes in cells are broken down within a few minutes or hours

microRNAs (miRNAs)

Recent research has established an important role for a variety of small single-stranded RNA molecules, called __________________, that can bind to complementary sequences on mRNA molecules in the cytoplasm

operon

Such a cluster of related genes and sequences that control them is called an _______

off

The "default" state for most genes in multicellular eukaryotes seems to be _____________, ...with the exception of "housekeeping" genes for routine activities such as the digestion of glucose

RNA polymerase

The DNA-protein assembly promotes the binding of _______________ to the promoter

signal transduction pathway

The binding activates a ___________________consisting of a series of relay proteins within the target cell. Each relay molecule activates the next

translation

The final opportunities for regulating gene expression occur after ____________ - for example, the hormone insulin is synthesized as one long, inactive polypeptide that must be chopped into pieces before it becomes active

off

The lac operon is in ________ mode when there is no lactose available

changing the repressor's shape

The lactose interferes with attachment of the lac repressor to the operator by binding to the repressor and ________________________________ • In its new shape, the repressor cannot bind to the operator, and the operator switch remains on • RNA polymerase is no longer blocked, so it can now bind to the promoter and from there transcribe the genes for the lactose enzymes into mRNA • Translation produces all three lactose enzymes

transcription factor

The last relay molecule in the series activates a _________________ that triggers the transcription of a specific gene

lac (short for lactose)

The operon considered here, the _____________________operon, illustrates principles of gene regulation that apply to a wide variety of prokaryotic genes

on

The operon is in _____ mode when lactose is present

gene expression

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

clone

The resulting animal will be a ___________ (genetic copy) of the donor

tumor-suppressor genes

These genes are called _____________________ because the proteins they encode normally help prevent uncontrolled cell growth

(cDNA)

This complementary DNA _____________ is synthesized using nucleotides that have been modified to fluoresce (glow). The fluorescent cDNA collection thus represents all of the genes being actively transcribed in the cell • A small amount of the fluorescently labeled cDNA mixture is added to the DNA fragments of the microarray

reproductive cloning

This type of cloning is called _______________because it results in the birth of a new animal

repressor

Transcription is turned off because a protein called a______________binds to the operator and physically blocks the attachment of RNA polymerase to the promoter

Colon

_________ cancer begins when an oncogene arises through mutation, causing unusually frequent division of normal-looking cells in the colon lining

Pluripotent

___________ descended from totipotent stem cells with limited functions - capable of giving rise to several different cell types (ex: bone marrow stem cells)

DNA packing

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

Adult stem cells

_____________ can also replace some of the body's cells after birth due to damage & growth

Totipotent

_____________ capable of giving rise to any cell type (ex: embryo cells) thereby possibly developing into a complete organism

Multipotent

_________________can differentiate into a few cell types, but only those of a closely related family of cells

one half

miRNAs may regulate the expression of _____________ of all human genes • miRNAs are now used via a technique called RNA interference:- the injection of small RNA molecules into a cell to turn off specific genes

enhancers

typically involves many proteins (collectively called transcription factors) acting in concert to bind to DNA sequences called _________ and to the promoter