Which one of the following lists the four bases
contained in DNA?
adenine, guanine, cytosine, thymine
Which one of the following lists the four bases
contained in RNA?
adenine, guanine, cytosine, Uracil
Which one of the following describes a nucleotide most completely?
nitrogen base, a sugar, and a phosphate group
One strand of a DNA molecule has the base sequence ATAGGT. The complementary base sequence on the other strand of DNA will be _
A particular _____ contains the information for making a specific polypeptide, but _____ can be used to make any polypeptide.
gene and mRNA ... a ribosome and tRNA
Which one of the following statements correctly describes mRNA processing in eukaryotes?
Introns are cut out, and the resulting exons are spliced together.
The two sugar-phosphate strands with their associated nitrogenous bases of a DNA molecule are joined to each other by __
hydrogen bonds between nucleotide bases
A geneticist found that a particular mutation had no effect on the polypeptide encoded by a gene. This mutation probably involved _
substitution of one nucleotide
The number of nucleotide bases on the mRNA that together designate an amino acid is _____; this unit is called a(n) _____.
three ... codon
Which one of the following lists the chemical components of a nucleotide?
a nitrogenous base, a sugar, and a phosphate group
What is the proper order of the following events in the expression of a eukaryotic gene?
2. RNA processing
3, 2, 1
Genetic information is transferred from the nucleus to the cytoplasm of eukaryotic cells in the form of _
A uracil nucleotide is a _____ nitrogenous base attached to the _____, with the 5′ carbon of the sugar attached to a phosphate group.
one-ringed ... carbon of a sugar that has an OH group at the 2′ carbon
Before a DNA virus is assembled and leaves the cell, a number of processes occur. Place these steps into the order in which they occur:
1. Viral DNA is replicated using host cell enzymes.
2. Viral receptors bind to host glycoproteins on the cell membrane.
3. Viral RNA is translated.
2, 1, 3
During translation, amino acid chain elongation occurs until
the ribosome encounters stop codons in the mRNA
The anticodon of an incoming _____ molecule, carrying its amino acid, pairs with the mRNA _____ at the ribosome
tRNA ... codon
When messenger RNA (mRNA) is being made, the RNA base _____ always pairs with the base _____ in DNA.
U ... A
After an RNA molecule is transcribed from a eukaryotic gene, portions called _____ are removed and the remaining _____ are spliced together to produce an mRNA molecule with a continuous coding sequence.
introns ... exons
The genetic information in DNA is contained in _
the sequence of nucleotides along the length of one strand of the DNA molecule
How does RNA polymerase know where to start transcribing a gene into mRNA?
RNA polymerase starts when the enzyme attaches to a certain nucleotide sequence called a promoter at the beginning of a gene
How do retroviruses, such as HIV, differ from other viruses?
They contain the enzyme reverse transcriptase.
The function of tRNA during protein synthesis is to _
deliver amino acids to the growing polypeptide chain
During translation in a eukaryotic cell
polypeptides are synthesized at ribosomes, according to instructions carried by mRNA
Gene expression involves the flow of information from genes to proteins, which is accomplished via _____ and _____
Why, of all cell types, do embryonic stem cells (ES cells) have the greatest potential for use in the treatment of disease?
They are undifferentiated cells that have the potential to differentiate into all of the different specialized cells of the body.
The second-leading cause of death in most developed countries (following heart disease) is _____
It is possible for a cell to make proteins that last for months; hemoglobin in red blood cells is a good example. However, many proteins are not this long-lasting. They may be degraded in days or even hours. What is the advantage of short-lived proteins?
Short-lived proteins enable the cells to adjust (control) gene expression when this is critical to their well-being.
Tumor-suppressor genes are important in the prevention of cancer because they _
produces gene products that prevent uncontrolled cell growth
All your cells contain proto-oncogenes, which can change into cancer-causing genes. Why do cells possess such potential time bombs?
Proto-oncogenes are necessary for normal control of cell division
The lac operon of Escherichia coli, a bacterium, is composed of
three genes and two control sequences, the promoter and the operator
A breakthrough in animal cloning in the late 1990s came with the development of nuclear transplantation. Nuclear transplantation is a process whereby __
a nucleus from an adult donor is placed into a cell without a nucleus, put in culture to produce an early embryo, and implanted into a surrogate mother
Using a cell taken from a multicellular organism to grow a genetically identical new organism is called
Although all of the cells in your body contain a complete set of DNA, different types of cells arise because___
different genes are switched on and off in each type of cell
What kinds of somatic cell gene mutations can frequently lead to the first stages of cancer?
mutations in genes that regulate cell division
DNA synthesis can be described as __________meaning it is a half old and half new replicated strand.
what is the 3 steps of transcription?
1.Initiation-RNA polymerase attaches to the promoter.first few RNA bases are added
2.Elongation-more RNA is added.RNA detaches from DNA,DNA reattaches.
3. Termination-RNA polymerase reaches terminator sequence.RNA &RNA polymerase detaches from DNA. DNA reattaches
what is the 3 steps of translation?
1Initiation-rRNA makes up the ribosome. mRNA carries the genetic code. tRNA brings first amino acid
2.Elongation-additional amino acids are added
codon recognition-(anti-codon) tRNA base pairs with mRNA (codon). Peptide bond formation-joins amino acids translocation-ribosomes moves to the next codon
3. Termination-ribosome reaches a stop codon. no corresponding tRNA. ribosome and polypeptide are released. ribosome and mRNA can be re-used
Prokaryotic is different from Eukaryotic because
no nucleus, RNA is available for translation immediately
Eukaryotic is different from Prokaryotic because
transcription occurs in the nucleus. most be transported to cytoplasm to interact with ribosomes. Allow for additional processing prior to translation
the small circular RNA~300 to 400 nucleotides
infect plant cells . don't code for any protein
mRNA processing and transport
the lactose operon
three genes needed for metabolism of lactose
not needed when there is no lactose,or when glucose is abundant
more tightly packaged DNA is less accessible to transcription machinery
condensed chromosomes are turned off
in x chromosome inactivation: Dosage Compensation-
prevents over expression of genes
*females and males have similar expression of X-linked traits
in x chromosome inactivation:Mosaic-
different tissues exhibit different gene expression(maternal X or parternal X)
must be completed BEFORE leaving nucleus
delaying processing delays translation
alternative splicing leads to alternative proteins
small RNA molecules that decrease gene expression
target mRNA for degradation
inhibit translation destroy or die
initiation of translation
primary means of controlling gene expression
regulatory proteins bind to either enhance or inhibit translation
Cloning adult cells results in offspring that are NEARLY identical to donor. Maternal Twins are natural clones.Mitochondrial DNA is inherited from egg donor
Preserve valuable genetics
Scamper, Second Chance
Produce identical animals for research purposes
Producing transgenic offspring
stem cells: Sources
From spare embryos left over from fertility treatments / informed consent.From cloned human embryos developed in the laboratory
Possible uses of stem cells
To repair / replace damaged human tissue.
Treat / cure diseases and injuries
Result of several mutations in DNA
Step 1: Uncontrolled cell growth
Oncogenes turned on
Step 2: Tumor formation
Tumor supressor genes turned off
Step 3: Metastasis
More tumor supressor genes turned off
Familial Breast Cancer
BRCA1 - codes for a tumor suppressor
Mutation results in 80% risk for developing cancer
Theory that populations of organisms change genetically over time to adapt to their surroundings
Theory of evolution is supported by 5 major types of biological evidence.
Fossil Record. Biogeography. Comparative Anatomy. Comparative Embryology.Molecular Biology
1.Traces of an organism are covered by sediments or volcanic ash
2.Water infiltrates the remains and inorganic molecules in the water replace the minerals in hard tissues
3.Over time increased pressure, due to additional sediments, helps to convert the remains to stony substances
Allow for study of fossils to include historical context
1.Deeper layers occurred first, contain older fossils
2.Thickness and mineral content gives insight to environment conditions that fossils were exposed to
similar structures that evolved from a common ancestor
Bones in human arm, porpoise flipper and bat wing
serve no apparent purpose, but are remnant of ancestral structures
Human coccyx, ankle bones in whale fins
1.Comparison of the early stages of development of various species
2.Similar structures in embryos will develop into different structures
3.Pharyngeal pouches make gills in fish and ears in humans
1.Nucleotide sequences of DNA and RNA
2.Amino acid sequences of proteins
3.Greatest similarities among closest relatives
One of the first to suggest that life evolves
Traits acquired during an animal's life could be passed on to its offspring
Traveled on the 5 year voyage of the Beagle making observations and collecting specimens
the ability of an individual to adapt to its environment as measured by its relative genetic contribution to future generations
differential survival and reproduction of individuals with different variations of traits
Used to show the degree of relatedness between species based on homologous structures
Each branch point represents the common ancestor
random change in allele frequency brought on by chance events
Occurs when individuals move into or out of a population
Currently having a significant impact on human evolution
selection against one extreme, favoring the other extreme
Ex. Light colored mice are selected against, darker colored mice make up a greater proportion of the population over time.
selection against both extremes, favoring the intermediate
Ex. If the light and dark colored mice are selected against, intermediate colored mice make up a greater proportion of the population over time.
selection against intermediates, extremes are favored
ex.If intermediate mice are selected against, mice at either extreme make up a greater proportion of the population over time.
different timing of reproduction
ex.Cicadas species have 17 year and 13 year cycles - occur simultaneously every 221 years
body parts do not physically match
ex.Flowers with various sizes of anthers (pollen bearing parts)
evolutionary changes occur over a brief time span, followed by long periods of little or no change
Use of previously existing structures for a new function.Example: Feathers first appeared in some dinosaurs, but were likely used to provide insulation. Birds used feathers to take flight.
Single lineage results in multiple new species
Example: Hawaiian Honeycreepers evolved from same common ancestor into multiple new species that prefer different food sources
Close interaction between two species cause them to evolve together, may become interdependant
Ex. Hummingbirds are pollinators for certain flowering plants
Geologic Time Scale
Timeline based on fossil record collected over many worldwide sites
Eras are large time periods punctuated by mass extinction events
Theory of Endosymbiosis
partnership in which one organism lives inside another in an interaction that is beneficial to one or both organisms
the three uses of DNA profiling
1.parentage testing-prove paternity
2.forensic analysis-compare crime scene to DNA
what are four applications in DNA technology?
1.human gene that codes for insulin
-many drugs are made this way
2.Bacterial gene that codes for insecticides protein
-reduce pesticide use
3.Bleed plants with high yield
4.Genes that code for quality improvement
what is forensic molecular photo-fitting and how it is used?
DNA found at crime scenes analyzed for many physical traits
what is the human Genome project?
it to 13yrs to determine the complete DNA sequence of the human
3.2billion base pairs
study of FULL set of proteins encoded by a genome.
-advantage of humans are over bacteria
the step of gene therapy
1.normal human gene is located and isolated
2.human gene is inserted into virus
3.Virus is injected into patient
4.Normal human gene is transcribes and translated in the patient
future application of DNA
analysis ~1,000 genes
500 facial genes
500 ancestry markers
accurate facial picture construction
make recombinant DNA
-gene of interest is isolated from one organism
-gene is pasted into a plasmid, circular DNA molecule
-plasmid can then be transferred to another organism easily
Because there are potential risks associated with the use of biotechnology in agriculture,
potential risks associated with biotechnology are evaluated by a variety of U.S. regulatory agencies
The ability to sequence DNA has led to a new field called comparative genetics, which is _
the comparison of whole genomes
Which of the following was the first eukaryote to have its full DNA sequence determined?
Gene therapy involves
adding a functioning version of the defective gene to the cells of an individual
One of the most difficult ethical issues related to DNA technology is the question __
How do we prevent genetic information from being used in a discriminatory manner?
DNA testing (profiling) can be used to determine guilt or innocence of a person suspected of a crime because
every person has a unique DNA sequence
Which of the following choices best defines "recombinant DNA technology"
combining genes from different species
When plasmids, which are small, circular, bacterial, DNA molecules, are used to transfer foreign DNA to other cells, the plasmid is called a __
Human insulin is produced in large quantities by
recombinant E. coli bacteria grown in large fermentation vats
Birds with average-sized wings survived a severe storm more successfully than other birds in the same population with longer or shorter wings. This illustrates
What is the term used to define a secondary sexual characteristic in males, such as manes on lions or colorful plumage on peacocks?
Imagine that a new population of humans is established on a new planet from ten randomly selected people in your biology class. Over thousands of years, the descendants of those ten people reproduce and prosper, but do not reflect well the diversity of humans on Earth. This change in the diversity of people on the new planet is an example of ___
the founder effect
There is a group of small fish living in a lake with a sandy bottom. Most of the fish are light brown, but about 10% are mottled. These fish are normally prey for large birds that live on the shore. A construction company dumps a load of gravel in the bottom of the lake, giving it a mottled appearance. Which of these statements presents the most accurate prediction?
The proportion of mottled fish will increase over time.
Evidence from molecular biology supports the theory of evolution by showing that __
closely related organisms have more similar DNA and proteins
The population of American bison used to number in the millions of animals. Hunting and other problems greatly decreased the number of bison to about 1,000 animals. But today, the numbers are recovering to estimates of more than 200,000 animals. This crash in the population of bison and recent recovery is an example of _
the bottleneck effect
Which of the following is the study of the geographic distribution of species on Earth?
If an earthquake hit a small island so that all but a tiny group of lizards were eliminated and the survivors spread out over the island and the population increased, this would be an instance of
the bottleneck effect
"Natural selection" and "evolution" are two terms that are sometimes confused, even by freshman biology students. What is the relation between natural selection and evolution?
Natural selection is one of several mechanisms of evolution.
The approach to evolution that involves the study of similar structures that appear during the development of different organisms is known as the study of _
Which mechanism for evolution was proposed by Lamarck?
evolution by inheritance of acquired characteristics
Earth probably formed about __________ years ago, and the oldest known living organisms date to __________ years ago.
4.6 billion years ago; 3.5 billion years ago
Which of the following is currently present in large amounts in the atmosphere but was largely absent at the time life is thought to have originated?
The origin of feathers predated the origin of flight; thus, feathers as an adaptation for flight is an example of _____
Bird guides once listed the myrtle warbler and Audubon's warbler as distinct species that lived side by side in parts of their ranges. However, recent books show them as eastern and western forms of a single species, the yellow-rumped warbler. Apparently, the myrtle warbler and Audubon's warbler __
successfully interbreed and produce fertile offspring
Radiometric dating can be used to tell the age of a fossil by measuring _
the decay of radioactive atoms in the fossil
Which of these is an example of temporal isolation?
One species is nocturnal, and the other species is diurnal (active during the day).
Which of the following organelles were likely generated through endosymbiosis?
mitochondria and chloroplasts