11.3-11.11 Flashcards
What are transcription factors?
Proteins that promote the binding of RNA polymerase to a gene
What interacts with dna to turn eukaryotic gene transcription on/off
Variety of regulatory proteins
What must occur before RNA polymerase can bind to a promoter and transcribe a specific eukaryotic gene?
Transcription factors must bind to enhancers to facilitate the attachment of RNA polymerase to the promoter.
What does alternative rna splicing do after transcription?
may generate two or more types of mRNA from the same transcript.
How many protein coding genes appear to undergo alternate splicing?
90%
How is it possible that just under 21,000 human genes can produce more than 100,000 polypeptides
Through alternate splicing: Each kind of polypeptide is encoded by an mRNA molecule containing a different combination of exons.
What determines how much protein is made
The lifetime of an mRNA molecule and factors involved in translation
What will the protein need in later stages of gene expression?
May need to be activated and then the cell will break it down
If the enzyme responsible for cleaving inactive insulin is deactivated, what effect will this have on the form and function of insulin?
The final molecule will have a shape different from that of active insulin and therefore will not be able to function as a hormone
What percent of human genomes codes for proteins?
1.5%
What can prevent gene expression when bound to proteins?
Variety of small rna molecules
by forming complexes with mRNA molecules
What are microRNA’s
Small single stranded rna molecules can bind to complementary sequences on mRNA molecules
If a gene has the sequence AATT CGCG, what would be the sequence of an miRNA that turns off the gene?
It would be transcribed as the mRNA sequence UUAAGCGC; an miRNA or sequence AAUUCGCG would bind to and disable this mRNA
Where can gene expression be regulated?
Nucleus and cytoplasm
Of the nine regulatory “valves” shown here, which five can also operate in a prokaryotic cell?
Control of (1) transcription; (2) mRNA breakdown; (3) translation; (4) protein activation; and (5) protein breakdown
What controls the development of an animal From a fertilized egg
Series of RNAs and proteins produced in the embryo
What is a homeotic gene
master control gene that regulates groups of other genes that determine the anatomy of parts of the body, such as which body parts will develop where in a fly.
What techniques do scientist use to study how genes work together?
Nucleic acid hybridization
DNA microarray
What is nucleic acid hybridization?
allows researchers to identify cells in which a target gene is expressed.
What is a DNA microarray
can gather data about which genes are turned on or off in a particular cell.
What can be learned from a DNA microarray?
Which genes are active (transcribed) in a particular sample of cells
What does cell to cell signaling do?
coordinates cellular activities via proteins or other kinds of molecules, carrying messages from signaling cells to receiving cells.
How does a signaling molecule act?
by binding to a receptor protein in the plasma membrane.
What is a signal transduction pathway?
series of molecular changes that converts a signal on a target cell’s surface to a specific response inside the cell.
To turn on a gene, must a signal molecule actually enter a target cell?
No; a signal molecule can bind to a receptor protein in the outer membrane of the target cell and trigger a signal transduction pathway that activates transcription factors.
What do similarities among organisms suggest?
That signal transduction pathways evolved early in the history of life on earth
In what sense is the joining of yeast mating types “sex”?
The process results in the creation of a diploid cell that is a genetic blend of two parental haploid cells.
What does totipotent mean?
Capable of producing every kind of specialized cell in the organism
What is an organism produced through asexual reproduction?
Clone
What type of cloning is used extensively in agriculture?
Plant cloning
What is the process of regeneration?
The regrowth of of lost body parts
What does it mean when cells differentiate?
Cells change there form to where they are needed
What is nuclear transplantation?
A way animal cloning has been achieved
How does nuclear transplantation occur?
- Replaces nucleus of a cell with a nucleus from an injected somatic cells
- then the recipient cell will divide
- The recipient cell forms a blastocyst
- Blastocyst is implanted into surrogate
What is reproductive cloning?
When cloned animal is identically genetic to the donor of the nucleus
What was nucleus transplantation first performed on?
Frog embryos
What was the first successful cloning?
Sheep, Dolly
What are embryonic stem cells?
Cells in an embryo that can become any type of cell
What is therapeutic cloning?
Use embryonic stem cells to treat the disease
What are adult stem cells?
Serve to replace non producing cells in adults
What is the ultimate goal of therapeutic cloning?
To supply cells for the repair or damaged or diseased organs
What types of issues arise with cloning?
Ethical
What does cancer result from?
Mutations in genes that control cell division
What is a proto-oncogen?
A normal cell
What is an oncogene
Cell that has been altered causing cancer
Where does onco come from?
Greek for tumor
What is a tumor suppressor?
It controls cells division
What happens when tumor suppressors are turned off?
Masses and malignant tumors can form
How many mutations does it take for a cell to become cancerous?
Multiple (3)
What is the most commonly known cancer?
Colon
Why cancer a gradual process?
Because of the multiple mutations
Can colon cancer happen in young healthy people?
Yes
What happens if colon cancer is caught early?
It can be treated
What interferes with normal signal transduction pathways?
Faulty proteins
What can activate a signal transduction pathways that would lead to cancer?
Oncogenes
What can reduce the risk of cancer?
Lifestyle factors
What is the second leading cause of death in the United States?
Cancer
What are agents that alter dna and make a cell cancerous?
Carcinogens
Example of a carcinogen that causes a mutation?
UV radiation
What is one substance known to cause more types and cases than any other single agent?
tobacco
Tobacco is the leading cause of what cancer
Lung
What can also help reduce the risk of cancer?
Food choices
Not smoking Exercising Avoid overexposure to sun Eat high fiber, low fat diet Are all what?
Ways to help prevent cancer
Regular visits to the doctor can help identify what? When?
Tumors
Early
