Biology ch 11

Transcription factors bind to noncoding DNA sequences called....and help RNA polymerase bind to the promoter

enhancers

The use of activators is efficient because a typical animal or plant cell needs to turn on (transcribe) only a small percentage of its genes, those required for the cell's specialized structure and ___________.

function

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

gene expression

all body cells contain a complete set of _________, even if they are not expressing all of them

genes

The process of translation—in which an mRNA is used to make a protein—offers additional opportunities for control by regulatory molecules. Red blood cells, for instance, have a protein that prevents the translation of hemoglobin mRNA unless the cell has a supply of ________, an iron-containing chemical group essential for hemoglobin function.

heme

The control of gene expression makes it possible for cells to produce specific kinds of proteins when and where they are __________, allowing cells to respond quickly and efficiently to information from the environment.

needed

Animal cloning is achieved through a procedure called....

nuclear transplantation

The default state for most genes in multicellular eukaryotes seems to be _______; research indicates that a typical human cell expresses only about 20% of its protein-coding genes at any given time.

off

Note that the genes for "housekeeping" enzymes, such as those that provide energy through glycolysis, are "______" in all the cells. In contrast, the genes for some proteins, such as insulin(pancreas) and hemoglobin(red blood cells), are expressed only by particular kinds of cells.

on

In the lac operon, when the operator switch is turned on, all the enzymes needed to metabolize lactose are made at ________

once

A gene that causes cancer is called an

oncogene

Unlike prokaryotic genes, however, most eukaryotic genes are not grouped into __________. Instead, each eukaryotic gene usually has its own promoter and other control sequences.

operons

Enzyme complexes that break down protein are called ____

proteasomes

A gene that is turned on is being transcribed into mRNA, and that message is being translated into specific ____________

proteins

Another control mechanism operating after translation is the selective breakdown of proteins. Some proteins that trigger metabolic changes in cells are broken down within a few minutes or hours. This regulation allows a cell to adjust the kinds and amounts of its ___________ in response to changes in its environment.

proteins

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

proto-oncogene

After an mRNA is produced in its final form, its "lifetime" can be highly variable, from hours to weeks to months. Controlling the timing of mRNA breakdown provides another opportunity for regulation. But all mRNAs are eventually broken down and their parts ___________.

recycled

A good indication that some animal cells can also tap into their full genetic potential is _____________, the regrowth of lost body parts

regeneration

If the animal to be cloned is a mammal, further development requires implanting the early embryo into the uterus of a surrogate mother. The resulting animal will be a clone (genetic copy) of the donor. This type of cloning is called ____________ _________ because it results in the birth of a new animal

reproductive cloning

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.

signal transduction pathway

In fact, repressor proteins that turn genes off are less common in eukaryotes than __________, proteins that turn genes on by binding to DNA and make it easier for RNA polymerase to bind to the promoter

activators

Discrete mass usually surrounded by connective tissue -cells retain structural features of surrounding cells -Only become dangerous when they crowd normal cells -Generally easily removed with surgery

Benign tumor

a series of mitotic cell divisions, begins the process of development

Cleavage

an organism can produce more than one type of polypeptide from a single gene. A typical human gene contains about ten exons; nearly all genes are spliced in at least two different ways, and some are spliced hundreds of different ways.

Alternative RNA splicing

___________ starts as a cell(s) that has completely lost its organization, structure, and regulatory control. -Normal cells have regulatory mechanisms that keep rates of division in check, cancers don't -Normal cells exhibit cell adhesion and stay in one place, while cancer cells often begin to migrate elsewhere (metastasize) -100 different tyes

Cancer

Cancer causing agents (can be chemical or physical) found in environment -Viruses and bacteria -chemicals -radiation -tobacco -diet -Genetic predisposition

Carcinogens

(also called a DNA chip or gene chip) is a glass slide with many tiny wells, each containing a different fragment of single-stranded DNA that derives from a particular gene. The wells are arranged in a tightly spaced array, or grid.

DNA microarray

If your blood cells and skin cells have the same genes, how can they be so different?

Each cell type expresses different genes than the other cell type.

process that begins forming cell layers (endoderm, mesoderm, ectoderm) and embryonic membranes -cells no longer true "stem cells" but can still become multiple tissue types

Gastrulation

mechanisms that turn on certain genes while other genes remain turned off

Gene regulation

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

Homeotic genes

-A cell must grow and divide uncontrollably without responding to inhibitory signals from surrounding cells -The cell must undergo physical changes to lost adhesion These changes happen when normal structural and regulatory genes mutate or otherwise cease to function

How cancer develops

A mass of cells, that have lost most organization structure, and regulatory control, but remain in one place (still retain cell adhesion

In situ cancer tumor

Similar to in situ, but lost adhesion and undergo metastasis

Malignant cancer tumor

small, single-stranded RNA molecules, called.....can bind to complementary sequences on mRNA molecules. Each miRNA 1 forms a complex with one or more proteins that can 2 bind to any mRNA molecule with at least seven or eight nucleotides of complementary sequence. If the mRNA molecule contains a sequence complementary to the full length of the miRNA, the complex 3 degrades the target mRNA. If the mRNA molecule matches the sequence along just part of the miRNA, the complex 4 blocks its translation.

MicroRNAs

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

Operator

A cluster of genes with related functions, and a promoter and operator

Operon

Groups of organs that work together to perform a broad and "life critical function"

Organ systems

structures composed of two or more tissue types joined together to perform a specific function

Organs

Binding site for RNA polymerase and the place where transcription begins

Promoter

normal regulatory genes that promote cell growth -When mutated or damaged, become oncogenes (cancer causing)

Proto-oncogenes

In addition to microRNAs, there is another class of small RNA molecules called small interfering RNAs (siRNAs). The blocking of gene expression by siRNAs is called.... allows researchers to disable specific genes in order to investigate their functions.

RNA interference (RNAi)

A protein that blocks the transcription of a gene or operon

Repressor

repressor proteins, which may bind to DNA sequences, inhibiting the start of transcription

Silencers

Gastrulation associated with differential gene expression resulting in _______________ of cell types

Specialization

Cleavage continues cell divisions until a fluid filled spherical structure is formed (Blastula or blastocyst) -Cells in the blastocyst are _______ cells, can become any type of cell

Stem

A mutation in E. coli makes the lac operator unable to bind the active repressor. How would this mutation affect the cell? Why would this effect be a disadvantage?

The cell would wastefully produce the enzymes for lactose metabolism continuously, even in the absence of lactose.

In eukaryotic cells, a protein that initiates or regulates transcription. These bind to DNA or to other proteins that bind to DNA

Transcription factor

1 a protein called a repressor binds to the operator and 2 physically blocks the attachment of RNA polymerase to the promoter.

Transcription is turned off

The lactose interferes with attachment of the lac repressor to the operator by 1 binding to the repressor and 2 changing the repressor's shape, the repressor cannot bind to the operator, and the operator switch remains. 3 RNA polymerase is no longer blocked, so it can now bind to the promoter and from there 4 transcribe the genes for the lactose enzymes into mRNA. 5 Translation produces all three lactose enzymes

Transcription is turned on

a cell mass resulting from hyperplasia (increased cell division); not all are immediately dangerous, but can become so -First step from hyperplasia to cancer is usually dysplasia (abnormal structural change)

Tumor

Normal regulatory genes that stop unchecked cell growth, division, differentiation, or adhesion -lack regulatory ability when mutated or damaged

Tumor suppressor genes

How can a signal molecule from one cell alter gene expression in a target cell without entering the target cell?

by binding to a receptor protein in the membrane of the target cell and triggering a signal transduction pathway that activates transcription factors

The final opportunities for regulating gene expression occur after translation. For example, the hormone insulin is synthesized as one long, inactive polypeptide that must be chopped into pieces before it comes active. Other proteins require _________ modification before they become active.

chemical

During a DNA microarray study, a researcher collects all of the mRNA transcribed in a particular type of cell at a given moment. This collection of mRNA is mixed with reverse transcriptase, a viral enzyme that produces DNA that is complementary to each mRNA sequence. These fragments are called ___________ ______ because each one is complementary to one of the mRNAs.

complementary DNAs (cDNAs

1 First, 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 (green) within the target cell. Each relay molecule activates the next. 4 The last relay molecule in the series activates a transcription factor that 5 triggers the transcription of a specific gene. 6 Translation of the mRNA produces a protein that can then perform the function originally called for by the signal.

the target cell's response is the transcription (turning on) of a gene

The purpose of this procedure is not to create a living organism but rather to produce embryonic stem cells.

therapeutic cloning

a group of specialized cells that are similar in structure and perform a common function

tissue

Changes in genes whose products inhibit cell division are also involved in cancer. These genes are called.... because the proteins they encode normally help prevent uncontrolled cell growth

tumor-suppressor genes

These similarities suggest that these homeotic genes arose very early in the history of life and that the genes have remained remarkably____________ over eons of animal evolution

unchanged