Bio 183 Test 4
Define the term "DNA library" and indicate (in general terms) how one is made.
"Genomic library" sequenced and identified DNA fragments from each selected colony containing bacteria with recombinant vectors 1- isolate and collect DNA-add to restriction enzyme (reverse trans) insert pieces into vectors 2-transform bacteria with recombinant vectors(RNA-to-DNA)-vectors also contain gene that confers resistance to ampicillin 3- place on petri plates containing ampicillin,allow cells to grow÷-form bac colonies(bacs didnt incorp a plasmid=dont grow)
explain the role of cytosolic factors in embryonic development
"Germ plasm" In cleavage- separation mainly of stored mRNA cause initial differences among cells and cause differentiation among gametes. Theyre hereditary info passed from generation to generation. Cells containing them are the first to form & located at posterior end of embryo
Describe one experiment of Spemann and indicate what it demonstrated about morphogens.
"organizer experiment" he removed above the blastopore of amphibian at beginning of gastrulation and put it on opp. side of another gastrula--implanted tissue formed a notochord & induced a second embryo to form on ventral side. showed important effect of morphogen in vertebrate embryos is establishment of body axes during gastrulation
Indicate what types of information are stored in databases relative to molecular genetics.
-DNA sequences -Methods -Enzyme and metabolism databases. -Protein sequences. -Specialized organism.
Explain the difference between the use of human embryos for reproductive cloning vs. therapeutic cloning; what are the potential benefits of the latter procedure?
-Has the goal of reproducing stem cells for medical purposes. -heart muscle, spinal cord, brain damage
Regarding applications of biotechnology: Define the term "gene therapy" and indicate how it might be used in the future.
-Introduce clone genes into living organism to cure diseases. -blood disorders cancer cardiovascular disease and even aids.
Explain what is meant by the term "gene cloning" and indicate the main goals of this procedure.
-Make multiple copies of a gene. -goals: Produce large amounts of DNA of a specific gene, Expressing the cloned gene to produce the encoded protein.
Define the term "reproductive cloning" and indicate how a cloned animal differs from a transgenic animal.
-Reproductive cloning is when an entire organism is duplicated. -differs from transgenic animals in which all the genetic material is use from the donor. Not modified.
Regarding the Human Genome Project: Indicate two political questions/problems that have arisen as a result of this project.
-Should human's know their own gene composition? -Should insurance/employer have access to this info? -patent genes?
Regarding applications of biotechnology: Indicate how recombinant bacteria have been used as "chemical factories' and why this is important in the medical field
-To make insulin, growth hormone, blood clotting factors and vaccines. -Important bc; the products are from humans, which avoid allergic reactions.
Define the term "bioinformatics" and explain why this branch of biology requires the use of computers.
-Use of computers to handle biological information. -Is required because of the high amount of information.
Describe the steps that were used in cloning Dolly the sheep; what is "nuclear transfer?"
-egg from another species of sheep was acquired the nucleus was removed. -a sheep's somatic cell nucleus was acquired and then placed in the other species egg. -electrical spark was apply to the egg, and then place in back in the different species sheep. -that's nuclear transfer.
Distinguish between the terms genome and proteome.
-genome--> info in genes "blueprint" -proteome-->the types of proteins within a cell.
Regarding the use of vectors in gene cloning: Explain how a specific gene can be identified within a colony using cDNA.
-obtain cDNA for gene of interest. Thin filter is place above colonies. Filter is lifted off of the plate; contains spots of bacteria. Treat it w/ chemicals to break down the bacterias. cDNA is added, which binds the gene of interest to filter. filter is washed away to get rid of other genes. X-ray shows the location of cDNA probe in the filter. location traced back to colonies.
Regarding the use of transgenic animals and plants in agriculture: List some pros and cons of using transgenic plants and animals in agriculture (see reading assignments).
-pros: Reduce the costs of needed products. -cons: genes can end up anywhere, birth defects
Describe a viroid and indicate what type of cells it infects.
A single, circular strand of RNA. Viroid is a piece of RNA that infects plant cells They are replicated within the nucleus or chloroplasts of plant cells by using RNA polymerase and are transmitted to other plants through seeds or pollen. Some cause no symtoms while other cases plants are stunted
Regarding the use of vectors in gene cloning: Indicate the purpose of the vector and name the two types of vectors used.
Allows a gene of interest to be taken up and replicated by bacteria Bacterial plasmids and Viruses
Give two examples of ways in which mitochondrial DNA has been used to study human ancestry.
Analysis of human mitochondrial DNA can be used to determine weather a person is related to a dead person, another living person, or in what region of the would a persons ancestors lived
Distinguish between the terms antigen, antibody, and antibiotic; indicate the role each each plays in combatting bacterial infections.
Antigen- often foreign microorganisms (bacteria or viruses) or can also be foreign proteins (pollen) STIMULATES an immune response Antibody- Y-shaped protein, secreted by activated B-lymphocytes into blood stream, binds to bacterial antigen to INITIATE the destruction of bacteria Antibiotic- drug that kills/prevents growth of bacteria-no effect against viruses/fungal infect. Antibio. (penicillin)WORKS by killing bacteria only & is produced naturally by certain fungi & bacteria
Describe how the human immune system combats a viral infection, indicating the role of antigens, cytotoxic T lymphocytes, and helper T lymphocytes.
Antigens- activate lymphocytes to divide & increase their numbers then enter bloodstream or lymph vessels where they're carried to the site of infection Cytotoxic T- attack cells infected by a virus (binds to infected cell & secretes proteins "perforins" which insert into PM of infected cells--cell bursts/killed cant replicate more viruses) & destroy cancerous cells HelpT- secrete cytokines to stimulate proliferation of other lymphocytes (causes cytoT divide repeatedly) and respond to any future attacks by the same virus
Define the term "horizontal gene transfer" and indicate its significance in terms of evolution and in development of bacterial resistance to antibiotics
Any process where an organism transfers genetic material to another cell that is not its offspring DNA transferred between bacteria of two different species (by transformation, transduction, and bacterial conjugation) A non-resistant strain can receive a plasmid from the resistant bacterium of another species and acquire resistance to antibiotics
describe the role of lymphocytes in combatting bacterial infection
B cells fight against bacteria by detecting presence of antigens through pieces of dead bacteria/or their toxins. Then divide to inc. their number then SECRETE PROTEIN ANTIBODY--travels to infected tissue and binds to bacterial antigen and kills bacteria (w/ help from other chemicals). Once infection overcome the antibody-secreting cells die. Antibodies can also neutralize circulating toxins.
Compare the general function of B lymphocytes vs. T lymphocytes in combating infections within the body; which lymphocytes are most important in bacterial vs. viral infections?
B lym important in BOTH bacterial&viral infections KILL&NEUTRALIZE bac-- secrete specific antibodies when detected foreign pro(antigens)thru exposure of dead bac/their toxins-binds protein tothe bac antigen B lym attack viruses once OUTSIDE the bodys cell--T lymph bind to the cell&secrete protein"perforins" which insert into the PM of infected cells T lym primarily attack VIRAL antigens T- also attach to infected cells and cancer cells
Name and describe a disease caused by a virus that infects: bacteria
Bacteriophages infect by injecting DNA. The multiplication of viruses in bac cell cause burst and releases new virus to infect more bacteria. Ex. measles can only infect humans
name the places in the body where lymphoid tissues are found
Bone marrow(B lymph mature) and thymus(T lymph mature) are the major lymphoid organs Both types of lymphocytes are also fund in lymph nodes, tonsils, spleen and lining of intestinal tract
Regarding membrane fluidity: How is it affected by cholesterol?
Cholesterol decreases fluidity and stabilizes membrane at higher temps; at low temps it prevents membranes from freezing, maintaining fluidity.
Indicate why people infected with HIV may have no symptoms for several years, but then develop full blown AIDS.
Complete viruses release via exocytosis w/ little harm to macrophage. When the protein associated with the HIV virus becomes mutated, it begins to bind to the surface of T cells. When new viruses leave cell they rupt PM-killing the cell. Then invade & destroy other T-cells--weakens immune response; leads directly to full blown AIDS
List 3 ways in which DNA can be transferred between bacteria and describe (in general terms) how each transfer occurs
Conjugation- DNA is transferred directly from one bacterium to another through a tube Transformation- DNA is released from a dead bacterium and is taken up by a live bacterium Transduction- DNA is transferred from one bacterium to another by a virus that infects both bacteria
Describe the basic structure of a virus
Contain nucleic acids(DNA or RNA), a capsid (protein) coat surrounding nucleic acids, a few enzymes and attachment structures such as spikes--bared by the capsid by which the virus attaches to cells.
describe the relationship between cytosolic factors and primordial germ cells
Cytosolic factors stage at certain regions during cleavage; primordial germ cells are specialized by the presence of cytosolic factors.
Compare the replication of a DNA virus (within a bacterial cell) to that of an RNA virus (within a eukaryotic cell); what is the role of reverse transcriptase?
DNA VIRUS: host cell transcribes the viral DNA & produces new viral components.(Host cell replicates viral DNA- transcribes it -then translates viral RNA) RNA VIRUS: host cell uses viral enzyme "reverse transcriptase" to make a copy of viral DNA (1stStep-synth of viral DNA using reverse transcript.) Reverse transcriptase is a enzyme that RNA viruses use to make the host cell copy DNA from viral RNA (causes cell to synth DNA complement to viral RNA)
Regarding the Human Genome Project: Describe, in general terms, how it was performed (reading assignment).
DNA was obtained anonymously from 100 people, but only a few samples were used. DNA sequences remain annon; not even donors know if their samples were actually used or not Main goal was to determine nucleotide sequence of all DNA in human cells. Determined human DNA consists of 3 billion nucleotides
Regarding prions: Describe "mad cow disease" and the steps being taken to prevent its spread to humans.
Disease of the nervous system caused by a prion that infects (accumulates) the brain, spinal cord, and intestine tissue. It causes changes in the temperament of the cow followed by loss of coordination and difficulty standing. Prions can be transmitted to humans who consume these items. Brain, spinal cord, and intestine have been BANNED for sale as food and in most countries cows are inspected for this disease.
Regarding the proteome of a multicellular organism: Explain how the number of different proteins produced by an organism can exceed the number of genes in its genome.
Due to alternative splicing, several proteins can be produced from a single gene.
Indicate the function of each of the following viral structures: capsid
Entire capside enters the cell&breaks open to release RNA (injects the infectious nucleic acid into the cells cytoplasm) along w/ reverse transcriptase causing cell make new viral DNA thats transcribed
Indicate several ways that cells can communicate within an embryo
Exocytosis- releasing stored chemical messengers that interact w/ receptors of nearby cells Membrane proteins- extend from cell surface & bind with adjacent cell mem. proteins to generate a signal. Gap junctions- movement of cytoplasmic molecules through them; directly from one cell to another
Regarding the use of transgenic animals and plants in agriculture: Describe several ways in which transgenic plants are being used in agriculture; what are "genetically modified foods"?
Genetically modified foods come from transgenic plants that have improved quality from being genetically modified in some way. This is an important step in reducing health problems Provide foods of higher nutritional quality; resistant to insect damage; resistant to herbicides and they cleanup toxic substances in the environment ex. soybean plant treated w/ herbicide to kill weeds- planting transgenic soybeans allows farmer to eliminate weeds without harming his crop
Explain why AIDS is such a deadly disease
HIV infects&kills many HELPER T lymphocyt makes AIDS patients likely to die of common bac/vir infect b/c of damaged immune sys
Name and describe a disease caused by a virus that infects: humans
Influenza virus is responsible for the flu. It frequently mutates(easily passed) and strains A & B cause serious illness in humans. Vac protect
Define the term "knockout mouse" and explain how knockouts are used in medical research.
Introduced gene has been mutated to prevent its expression and the function of the gene is said to be "knocked out" Used to serve as models for human disease Can be studied to learn more about the disorder and to explore effectiveness of different treatments. Powerful technique for understanding gene function
Regarding extranuclear DNA: Explain its probable origin
It was present in prokaryotes that became endosymbionts of eukaryotic cells- prokaryotes became more&more dependent of their eukaryotic hosts and eventually degenerated into the organelles seen today, but retained at least some of their DNA
Regarding extranuclear DNA: Indicate where it is located within eukaryotic cells.
Located within mitochondria and chloroplasts
List several diseases caused by bacteria and indicate the role played by toxins.
Lyme disease, gonorrhea, cholera, leprosy, syphilis, tuberculosis, meningitis, Botulism(botox- toxin injected under skin & paralyzes muscles that normally contract & cause wrinkling) Lyme Disease-deer tick bite that transmit spirochete into blood stream-early symp.=rash Syphilis-STD spread by contact w/ bacteria in open sore on genital, vagina, anus, lips, ect Bact cause disease by secreting toxins(causes damage)
Describe, in general terms, how a cDNA probe is made.
Made using reverse transcriptase to copy mRNAs from the cytoplasm of cells. Add mRNA to solution containing enzyme reverse transcriptase along with 4 nucleotides required for DNA synthesis and a primer. The enzyme acts by adding nucleotides to a pre-existing DNA strand making a newly synthesized DNA complimentary to the original RNA Can not be used to ID regions of DNA within nucleus correspond to the gene that produced original mRNA
Describe several ways in which bacteria are useful (or even essential) to human life
Many beneficial bacteria that live within the human body Antibiotics (such as penicillin) are produced naturally by certian fungi and bacteria Play a essential role in natures chemical recycling b/c secretion of streptomycin (antibiotic produced by bacteria) kills other bacteria that would compete or harm Streptomyces Engineered to produce human hormones&chemicals used to make plastics, drugs & food additives
Regarding the use of transgenic animals and plants in agriculture: Describe several ways in which transgenic animals are being used in agriculture; what is "molecular pharming"?
Molecular farming is the use of domestic animals to produce milk containing human proteins *Domestic animals as a source of genes for human gene therapy. Uses farm animals to produce medically important proteins (pharmeceuticals) Used to develop transgenic animals resistant to costly disseases
Regarding membrane fluidity: How is it affected by saturated vs. unsatuated fatty acids within the phospholipids?
More saturated=decrease fluidity; More unsaturated=increase fluidity; Membranes w/ more unsaturated phospholipids remain fluid at lower temps than those with fewer unsaturated phos
Regarding the ways in which proteins are embedded in the plasma membrane: Can they move within the membrane?
Most can move freely but some are anchored and cant move.
Indicate several types of human injury or disease that might be cured through use of stem cells.
NERVE- implantation of cell into brain to treat Parkinson disease. Also treat injuries to spinal cord SKIN- treatment of burns and skin disorders CARDIAC- repair heart damage from heart attacks CARTILAGE- repair joints damaged from injury or arthritis BONE- repairs damaged bone or replace w/new bone LIVER- repair or replacement of liver tissue damage by injury or disease SKELETAL MUSCLE-repair/replace of damaged muscle
Regarding restriction enzymes: indicate where are they obtained.
Obtained from bacteria(various species)
Regarding applications of biotechnology: Explain why PCR has become the method of choice in forensic DNA fingerprinting.
PCR is used to clone genes. Requires a lot less DNA- as small as a few dandruff flakes or single hair follicle. DNA at crime site may be present in small amounts and its now possible by amplifying the DNA regions of interest to obtain enough DNA from these small amounts. PCR is used for DNA fingerprinting b/c fingerprint is based on presence of short tandem repeat sequences in human DNA& its polymorphic (10,000+diff seq) so STR pattern is just as distinct
Give several examples of animals that have been cloned, and discuss the potential benefits of reproductive cloning.
Pigs have been cloned in hope to donate organs for human organ replacement b/c its thought that cloned pig transgenic with some human genes allow human receiving it to tolerate pigs organs Domestic animals and endangered species can produce clones by nuclear transfer Preservation of endangered species is important May be possible to resurrect extinct species by using a nucleus form preserved tissues and eggs from related living species
Regarding the production of transgenic multicellular organisms: Explain how the process of producing a transgenic plant differs from producing a transgenic animal; why is it easier?
Plants- can be produced by infection by bacteria that contain the gene of interest (when cells are exposed to bacteria they get infected and the plasmid is incorporated into plant cells DNA) Animals- created by inserting specific gene into egg OR injected into very young embryo(innercellmass) Plants are easier b/c individual somatic cells can form an entire plant. Animals harder b/c must insert into an egg or very young emb before develops into specific cell types
Describe the types of stem cells found during embryonic development and within the adult; how does the potency of these stem cell differ?
Potency becomes restricted as development proceeds Totipotent- fertilized egg (zygote): ultimate stem cell b/c it can produce an entire organism Pluripotent- inner cell mass(emb stem cells) of blastocyst stage- still differentiate into all cell types Multipotent- (ADULTS)(after gast/organogen)potential much more restricted.--most adult stem cells can produce several types of cells within specific tissue Unipotent- (ADULTS)can only differentiate into 1 cell type-ex. spermatagonia only produce sperm
Regarding applications of biotechnology: Explain the role the recombinant bacteria may play in bioremediation.
Potential use of recombinant bacteria is in environmental cleanup.
Regarding prions: Indicate their general structure.
Prions consists of a single, specific type of protein (PrP)
Discuss the prospects for reproductive cloning of humans; do biologists approve of this procedure?
Probably possible to clone humans using same technique that produces cloned animals, but hasn't been done due to moral consideration. Biologists do not approve(almost all) they consider it a breach of ethics But a few claim to have cloned humans (ex one produced cloned child)
Be able to describe the 3-dimensional structure of a protein and the basic structure of a phospholipid; which regions are hydrophilic vs. hydrophobic?
Proteins are composed of amino acid chains that are folded to form secondary and tertiary structures. Helical regions of protein are hydrophobic and the rest of the protein is hydrophilic Phospholipid is composed of 2 fatty acids and a phosphate group. Polar head is hydrophilic and fatty acid tails are hydrophobic.
Explain the purpose of 2-dimensional electrophoresis; how do the two types of gels that are used in this procedure differ?
Separates individual proteins to identify them by using mass spectrometry to determine the amino acid sequence. Iso-electric focusing gel- has pH gradient from 4 to 10. Applied current separates the proteins into bands based on their ELECTRICAL CHARGE, proteins move to the point where their net charge is 0 Tube gel- placed at one end of slab and current is applied. Proteins separate according to their MASS at a rate that corresponds to their MASS
Compare bacterial cells to eukaryotic cells regarding: chromosome structure, process of cell division, and rate of cell division
Simpler- single chromosome compacted by proteins and forms loops and supercoiling to enable it to fit in nucleoid region of cell. EU have SETS OF CHROM Reproduce by binary fission-first its replicated and produces two copies of chrom -then chrom move to opp. ends of cell-then PM pinches inward and new cell walls are deposited to separate daughter cells Simple struc&ONLY 1 CHROM involved causes much faster rate. EU-- TAKE ALOT OF TIME to ensure daughter cell receives correct number&types chrom
Describe a plasmid and indicate several reasons why plasmids are beneficial to bacteria
Small, circular pieces of DNA that are NOT part of the chromosome. They improve bacterias chance of survival. They are beneficial to bacteria b/c they enable some bacteria to utilize rare nutrients, resists antibiotics, and become pathogens or code for proteins that are secreted to kill other bacteria.
Regarding membrane fluidity: How is it affected by temperature?
Temperature decreases=fluidity decreases; temperature increases=fluidity increases. Temp lowered to zero prevents potential movement of membrane proteins. Temperature at 37 deg C (body temp) allows movement.
Name 4 animals that are widely used for research in the field of developmental genetics.
The fruit fly, roundworm, mouse, and zebra fish.
Explain why viruses are not thought to be cells; how does the size of viruses compare to that of prokaryotic and eukaryotic cells?
They cant reproduce inside of a host cell and dont perform any metabolic processes They are extremely small, less than 1 micrometer in size
Explain why the genetic diversity of bacteria would be limited without transfer of DNA from one bacterium to another
They cant reproduce sexually so they have to transfer DNA to increase genetic diversity. The only source of diversity would be mutations without transfer of DNA from one bacterium to another.
Regarding the use of vectors in gene cloning: Define the term "restriction enzymes" and explain how they are used to insert genes into a vector.
They cut DNA in specific places, producing DNA fragments Used in gene cloning to insert genes of interest into a vector. Biologists use them to cut DNA in specific nucleotide sequences to provide DNA fragments. Produces short single strands on each side of the cut and sticky ends allow the fragments to attach to sticky ends of the opened vector
Regarding prions: Explain how they replicate and name the type of cells they infect.
They infect normal cells. Replication: Abnormal PrP protein enters a cell and converts normal protein into abnormal form, abnormal PrP proteins bind & convert 2 more proteins-Over-time all the normal PrP is converted to abnormal form
Regarding the production of transgenic multicellular organisms: Explain why the gene of interest must be inserted into an egg or very young embryo in order to produce a transgenic animal.
They still have potential for expressing all their genes b/c they havent yet began to develop into specific cell types
Name and describe a disease caused by a virus that infects: plants
Tobacco Mosaic virus: transmitted from plant-to-plant by insects eating leaves or humans touching infected then non-infec--causes damage to flowers, fruit & leaves but rarely kills the plant
Regarding the ways in which proteins are embedded in the plasma membrane: How are some proteins anchored?
Transmembrane proteins: extend through membrane&protrude each side. Central region is helical structures(hydrophobic)& lie in phobic center of mem. Polar parts exposed to polar lipid groupsORaqueous enviro on either side of mem Lipid-anchored proteins-covalently attached to membrane lipid. both are integral mem proteins Peripheral proteins- loosely attached to mem lipids or integral mem protein by ionic or hydrogen bonds. Removed by exposing mem to high salt conc.
Describe the recent breakthrough in stem cell production, and discuss the pros and cons for use of these cells in medical applications.
Two teams of scientists turned human skin cells into embryonic stem cells w/out embryo source. They added 4 genes which reprogrammed the chrom. of the skin cells into blank slates that turn into any of 220 cell types of human body, heart, brain, blood or bone
Define the term "maternal inheritance" and explain how it applies to extranuclear DNA.
Type of uniparental inheritance in which all the progeny have the genotype and phenotype of female parent. Applies to extranuclear DNA b/c in eukaryotic organisms mitochondrial DNA is inherited from the female parent. (mitochondrion preparing to divide will replicate its DNA and during division it will distribute it to both daughter cells) Approach used for current studies of human ancestry and mitochondrial DNA is analyzed
Indicate the purpose of DNA fingerprinting and describe the RFLP method.
Used in forensic investigations to match DNA of suspected criminal to DNA found at crime scene RFLP method uses restriction enzymes to "cut" the DNA strand into diff lengths that are unique to a person.(useful in DNA analysis at crimes) Restriction enzymes specifically separate strands at certain patterns of DNA code. It splits the DNA strand then gel electrophoresis is used after RFLP to determine length&compare DNA. (each band is a group DNA fragments of a different size
Explain how the computer program BLAST is used.
Used to determine which animal species have proteins similar to a given human protein based on amino acid sequence Used to locate genes of other species that are homologous to a known gene
Indicate the purpose of microarrays.
Used to determine which genes have been expressed by a given cell type & cDNA probe is used to determine which genes have been expressed by a cell. The solution of cDNAs is added to many wells of a microarray plate, each well contains short sequence of DNA found in a specific gene of the cells genome. All wells containing expressed genes will hybridize w/ cDNA and become fluorescent & can be seen using a fluorescent microscope.
Regarding the proteome of a multicellular organism: Indicate whether or not different cell types differ in number and/or type of proteins present.
Yes-- the number of different proteins that the organism can produce far exceeds the number of genes within the genome
Describe the role of hormones in the metamorphosis of a) amphibians and b) insects
a)thyroxine added to tadpoles water=it will undergo metamorphosis prematurely b)juvenile hormone&ecdysone have opp. actions. juvenile secreted from ventral brain structure during larval period and opposes differentiation, larva can grow but not undergo metamorphosis; declines are larva grows and when reaches 0 Ecdysone elicits pupa formation and metamorph. begins within pupa and adult insect forms. So ecdysone is resp. for growth and differentiation
Regarding the production of transgenic multicellular organisms: Define the term "transgenic animal".
animal whose genome contains a gene introduced from another organism of the same or different species
Explain why embryonic stem cells are especially useful in medical research.
b/c they are pluripotent--have potential to divide in culture and differentiate into ANY cell type. If cultures of specif. cell types could be obtained then new tissues would be transplanted into human body whenever needed
Explain pattern formation and indicate its significance during embryonic development
body plan forms- most have 3 body axes:dorsal-ventral, right-left, and anterior-posterior cell division(promotes growth), migration(reach correct location), differentiation(specialized cells), and death(eliminates cells in-between ex. fingers) all they play a role in pattern formation ex. development of mammal limbs process that happens during organogenesis causing body plan of organism to take shape
Define the term "stem cell"
cells from the inner cell mass of a blastocyst that divide and eventually differentiate into specialized cell types which form organs and tissues of animals. Undifferentiated cells are also found in bone marrow, growing tissue and embryonic tissue(inner cell mass) They dont have specialized structure or function yet but differentiate into specific types during organogenesis and later stages in development
explain positional information and indicate its significance during embryonic development
combination of the number & type of contacts with its neighbors gives a cell info on its position within embryo. these are cells from inner mass of a blastocyst that can produce all cell types in the human body
Regarding restriction enzymes: explain how they are used in genetic technology
cut DNA at very specific nucleotide sequences to produce DNA fragments- DNA sequencing techniques and DNA probes to analyze structure&function of genes. One use is to begin the process of DNA fingerprinting.
Indicate the role played by genes and hormones in mammalian sex differentiation; Are hormones needed for development of both male and female reproductive systems?
default embryo is female No hormones intervene=gonad becomes ovary/female ducts develop into oviducts &uterus/potential sperm degenerates Y chrom needed for embryo differentiate as male. A gene on Y chromosome produces a protein that stimulates embryonic gonad to develop testis. Hormone signals req'd for development of male characteristics of an embryo
Distinguish between a cell that has been "determined" vs. a cell that has undergone differentiation.
determined-cell has 1 possible fate but is not yet differentiated (does not yet function as muscle) differentiation- cell functions as a muscle. caused by muscle specific genes that produced proteins that prevent cell from division making it become a muscle cell which fuses w/ other cells to form muscle fiber
Describe how the polymerase chain reaction (PCR) is used to copy DNA; define the terms thermocycling, primers, and hybridization.
doesn't require vectors or bacterial cells must know nuclear sequence at each end-creates copies of a specific gene/region of DNA (doubles # of gene/DNA) products of one cycle become reactants of the next "chain reaction" and is controlled by changing temperatures of the reaction Raised 92-94= DNA strand of the dbl helix unwind. Lower 50=Primers bind to specific regions of the DNA Raised to 72=A DNA polymerase that works at high temps synthesizes a complimentary strand of DNA
describe the role of gradients in development of the vertebrate neural tube and somites; what is meant by the term "induction"?
dorsal lip moves interior causing the embryo to form a notochord. The notochord secretes morphogens during the end of gastrulation-- at least 2 morphogens are secreted & stimulate overlying ectoderm to form a neural plate & fold upward to form neural tube. Morphogens diffuse laterally & initiate segmentation of adjacent mesoderm to form somites. Induction- diffusing substances that cause development of adjacent regions (ex.morphogens diffuse laterally initiating segmentat of adj. mesoderm forming somites)
Explain how a gradient can be produced
fertilized ovum divides and cytoplasmic factors stay in cells at one end of embryo causing cells to secrete morphogen that diffuses/transported to other end. this forms a concentration gradient with the highest concentration of morphogen at the end where it was initially secreted
Define the term "homologous genes" and indicate why they are important in biological research.
genes form different species that are derived from a common ancestor and have similar functions; Used in bio to determine evolutionary relationships btwn species or organisms & Used by comparing genes of homologous species to determine the function of a protein produced by a gene Researchers can locate species which are homologous to a given human gene by using a computer program- BLAST
Explain how stem cells are able to maintain their population while producing differentiated cells
growth pattern allows then to maintain their population so differentiated cells can be produced continuously throughout life---one daughter cell specializes and other daughter cell remains stem cell when they divide one daughter cell remains a stem cell and the other daughter cell leaves cell cycle and differentiaties into specific cell type, such as red blood cell
Indicate how and where cytosolic factors originate
mRNA/nutrients/other chemicals are stored within the cytoplasm of the ovum. mRNA are cytoplasmic factors of germ plasm. When the zygote divides (cleavage) they're deposited asymmetrically to daughter cells, so some are localized to a specific cytoplasmic region.
Indicate the function of a "master gene" during development
produces regulatory protein MyoD that has 2 functions: binds to master gene DNA to inc. transcript. which produces more MyoD. Also binds to a muscle-specific gene, turning it on--gene produces activator that turns on other muscle-specif genes and cell produces contactile proteins found in muscle. Muscle-specific genes also cause cell differentiation b/c produce proteins that prevent cell from dividing-cell becomes muscle cell and fuses w/ other cells forming muscle fiber
Indicate the function of each of the following viral structures: external structures, such as spikes
project from the sheath and attach the virus to specific receptors on cell surface
explain morphogens and indicate their significance during embryonic development
provides positional info using conc. gradient along embryonic axis "organizer" substance that diffuses(laterally) /transported to other end of embryo&form gradient cells respond to high/low conc. of morphogen in gradient- initiates segmentation establish body axes during gastrulation/nerulation
describe the role of macrophages in combatting bacterial infection
pursue and capture bacteria then engulf them by phagocytosis xtra: Macrophages came from white blood cells called monocytes that enter tissues throughout body and change into macrophages
Indicate how embryonic stem cells are obtained
removing inner cell mass from embryo at blastocyst stage. Human blastocysts are available from in vitro fert. procedures b/c many more embryos are produced than implanted in would-be mothers---there are thousands in freezers across the country ---but now banned so only stem cell lines made prior to ban are available
indicate the role of the biocoid protein in fruit fly development
role is to elicit development of anterior-posterior axis. mRNA is at one end and makes the proteins during blastula stage, so protein is present in the gradient w/ highest concentration at what will become the anterior end of the embryo (normal embryo-seg. occurs and head/tail develop mutated emb-seg. occurs and both ends develop tails)
Indicate the function of each of the following viral structures: nucleic acids
store and transmit genetic info and use that info to direct synthesis of a new protein to replicate(synth new proteins&assemble new capsids)
Explain the function of homeotic genes and the significance of their arrangement on the chromosome; how widespread are these genes in the animal kingdom?
they control development of individual body segments arranged in order that they are expressed along anterior-posterior gradient of embryo(ex. gene at front causes mouth parts to develop) suggests a "universal body plan" these genes are present in ALL animals and appeared early in history
Regarding restriction enzymes: describe their purpose in nature.
used by bacteria to prevent infection by viruses b/c when a viral DNA enters the bacterium a restriction enzyme can cut the viral DNA into fragments making it harmless