Exam 3 Flashcards
An _____ is an inherited feature that varies from individual to individual
Character
an _____ is one particular variation of a character
trait
Most human genes come in alternate versions called _____
alleles
If an organism has two non-identical versions of a gene, the one that is expressed in the organism is called the _____ allele
dominant
If an organism has two non-identical versions of a gene, the one that is not expressed in the organism is called the _____ allele
recessive
What is different between two alleles of the same gene?
The information they carry. For example, one allele might carry the information for blue eye pigment, while the other carries the information for brown eye pigment
Two alleles of the same gene ____
can be the same or can be different
When I say a flower is “purple”, what have I described?
Its phenotype
Imagine that eye color in cats is controlled by a single gene and that there are two alleles: black eyes and orange eyes. All of the offspring of a cross between a black-eyed cat and an orange-eyed cat have black eyes. This means that the allele for black eyes is _____ the allele for orange eyes
dominant to
a homozygous milk chocolate Easter bunny is crossed with a homozygous dark chocolate Easter bunny. Assuming dark chocolate is dominant over milk chocolate and the traits segregate according to Mendelian genetics, which traits will be observable in the offspring?
All dark
Assuming complete dominance, what is the expected ratio of genotypes of the offspring following the cross of two heterozygotes?
1:2:1
Assuming complete dominance, whats the expected ratio of phenotypes of the offspring following the cross of two heterozygotes?
3:1
Define Mendel’s law of independent assortment.
The inheritance of one character has no effect on the inheritance of another character
In a cross involving two autosomal traits on different chromosomes in which the parents are purebred for the opposite forms of both traits, how many of the offspring would be expected to be homozygous recessive for both traits?
1 out of 16
The following F1 cross is made: BBGg x Bbgg. Which is NOT a possible outcome in the F2 generation?
BbGG
What is Mendel’s law of independent assortment?
Independent assortment means that each pair of alleles segregates independently of the other pairs of alleles.
Mendel formulated his principles of inheritance based on ______
observations on the outcomes of breeding experiments. The underlying processes were unknown at the times
Mendel observed that pairs of alleles were separated or segregated in gametes and that they were rejoined in fertilization. We know that pairs of ____ are segregated in ____ and then are rejoined through fertilization
homologous chromosomes….meiosis
As we now understand it, the Law of Independent Assortment applies _____
to pairs of genes that are on different chromosomes, but NOT to pairs of genes that are close together on the SAME chromosome
If you are a male, the Law of Assortment indicates that your gametes contain ____
a random mix of the chromosomes you inherited from each parent
How have Mendel’s laws fared as we have learned more about cell biology and processes such as meiosis?
Our new knowledge has helped to explain some of the exceptions to Mendel’s law of inheritance
Sickle-cell disease is caused by a recessive form of hemoglobin. Two parents that do NOT have the disease give birth to a chid that does. What are the genotypes of the mother and father for the hemoglobin gene?
Both parents are heterozygous
Assuming incomplete dominance, if a homozygous red-flowered plant is crossed with a homozygous white-flowered plant, what will be the color of the offspring?
Pink
Which of the following processes generates a continuum (spectrum) of varying phenotypes?
Polygenic inheritance
Fur color in rabbits is controlled by multiple alleles. What does this mean?
Rabbits fur color is controlled by a single gene, but there are multiple versions of that gene
Which of the following statements apply to the variation in human skin color?
-Human skin color variation evolved recently in hominid evolution, once some populations of our human ancestors migrated out Africa.
- Human skin color variation likely evolved in response to differences in the intensity of sunlight around the world.
- human skin color variation is primarily determined by the type and amount of melanin pigment in the skin
Which of the following statements accurately describes melanin’s functions?
Lighter skin has less of the dark-brown eumelanin that protects cells from UV damage
Darker skin is more prevalent in high-UV areas. Dr. Nina Jablonski proposed a hypothesis to explain the selective pressure for darker skin in these environments. On what evidence did she base this hypothesis?
the melanin in darkly pigmented skin protects circulating folate from being destroyed by the UV radiation, and folate is important in human reproduction
Based on the risk factors discussed in the video, which of the following groups would be most likely to develop the bone disease rickets?
children born to parents with dark skin living far from the equator
In what way does natural selection depend on the specific environment in which an organism lives?
when the environment changes, traits that were beneficial to an organism may become harmful and vice versa.
Genes located near one another on the same chromosome are often inherited together. These are called ______
linked genes
Imagine that five hypothetical genes are arranged on a chromosome in the following order: G–H–I–J–K. Which two genes are most likely to have a crossover occur between them?
G and K
If genes are described as “sex-linked’, then they are ______
typically on the X chromosome
Recessive disorders related to genes found on the X chromosome but not on the Y chromosome are more commonly expressed in ______
Males
The inheritance pattern for red-green color blindness is different for males compared to females. Red-green color blindness is much more common in males than in females. What does this suggest about the gene for red-green color blindness?
The gene for this trait is located on the X sex chromosome
How could an embryonic stem cell be used to repair a severed spine?
Embryonic stem cells can grow into any other cell type, including a nerve cell
Guar are increasingly rare wild oxen found in Asia. How would you clone this animal?
Fusing a guar cell nucleus with an egg cell from a domestic cow that has had its nucleus removed
Mitosis occurs in _____; meiosis occurs in _____
Somatic or body cells…germ cell in the testes or ovaries
Looking through a light microscope at a cell undergoing division, you see that the condensed have lined along the midline of the cell. The homologous pairs are NOT joined in tetrads. Each chromosome takes its own place in line, independent of its homolog. You are witnessing _____
Metaphase of mitosis
Fertilization joins ___ to produce a ____
haploid gametes…diploid zygote
Duplication of the chromosomes to produce sister chromatids ______
occurs in both mitosis and meiosis
If it weren’t for ____, chromosome number would double with every generation of sexual reproduction
meiosis
Which of the following is the largest unit of DNA organization?
genome
A sugar, a phosphate, and a base are the components of a _____
nucleotide
a page is to a book as a ____ is to the genome
gene
How many polynucleotides are found in one molecule of DNA
two
Which of the following make up the backbone of a polynucleotide strand?
sugar and phosphate
What do the letters DNA stand for?
Deoxyribonucleic acid
What is different from one DNA nucleotide to the next?
The base
Which part of a nucleotide molecule in DNA encodes genetic information?
The base
What is the monomer of the DNA molecule?
Nucleotide
After DNA replication, _________
Each of the two daughter DNA molecules contains one strand from the original DNA molecule and one newly synthesized strand
How are DNA and RNA differ?
DNA contains the bases A, G, C, and T; RNA contains the bases A, G, C, and U
If DNA directs the production of RNA, what does RNA make?
RNA makes proteins
Which of the following statements is incorrect regarding DNA and RNA?
All of the above are correct
What does transcription occur in the nucleus and not in the cytoplasm in eukaryotes?
DNA cannot leave the nucleus
Which process results in the creation of mRNA?
Transcription
During transcription of a specific gene, which of the following serves as a template for the formation of RNA?
One strand of DNA
What is a gene?
All of these and more are part of the expanding definition of a gene.
What process enables several different proteins to be produced from one gene?
RNA splicing
What does “transfer RNA” actually transfer?
Amino acids
If the codon is AAA, what is the complementary anticodon?
UUU
Where does translation occur in eukaryotes?
In the cytoplasm only
The gene for the beta chain of normal human hemoglobin has the sequence CTC at the position for the seventh amino acid acid in the protein. A point mutation changing the sequence to CAC results in sickle cell hemoglobin. Use the genetic code to determine the change in the amino acid at position seven of the hemoglobin beta chain.
Glutamic acid to valine
How many nucleotides are required to code for 10 amino acids?
30
The central dogma describes how the genes in the nucleus work to produce an organism’s phenotype. Another way of putting it is that the central dogma follows the flow of information from _____
DNA to protein
DNA carries out two basic functions in cells: (1) information storage and transfer (genes can be copied and passed to offspring) and (2) the “blueprint” function (genes provides instructions for building proteins). The key process for information storage and transfer to offspring cells is _____
DNA replication
A gene is a sequence of NDA nucleotide bases that codes for a single protein. Approximately how many nucleotide bases would be required to code for a protein chain is 100 amino acids long?
300
tRNA molecules work to______
translate mRNA to produce a specific amino acid sequence
Which of the following events occurs during transcription?
A molecule of RNA is formed based on the sequence of nucleotides in DNA
Which of the following is a correct statement about mRNA?
mRNA moves from the nucleus to the cytoplasm following RNA processing
The site of translation is
ribosomes in the cell cytoplasm
which of the following does not play a role in translation?
DNA
Which of the following does not occur during RNA processing?
mRNA attaches to the small subunit of a ribosome
How did stickleback populations come to live exclusively in fresh water?
Some stickleback populations became trapped in lakes that formed at the end of the last ice age
Why do some stickleback populations lack pelvic spines?
- In lakes where there are no large predatory fish, there is no advantage to having pelvic spines.
- in lakes with dragonfly larvae, pelvic spines can be disadvantageous, allowing the predatory larvae to grab the fish.
Why did Kingsley and and his team cross marine and freshwater sicklebacks?
To find the location of the gene(s) causing the difference between stickleback populations with and without spines
What did researchers discover about the genetic mutation causing the loss of pelvic spines?
-It is found in a regulatory region (a “switch”) upstream of the coding region of the PITX1 gene
- It occurred in a similar DNA region in freshwater stickleback populations all over the world.
How do multiple lines of evidence (from the field, the fossil, record, and molecular genetics) work together to illustrate stickleback evolution?
-Data obtained by analyzing living fish in lakes show the selective pressures in different environments.
- the fossil data show a pattern of evolution over long stretches of time
- genetic evidence reveals the precise molecular mechanism responsible for the change in pelvic structures in stickleback populations
- if the same morphological changes occur in the fossil record as in living populations, we might deduce that the genetic mechanism discovered in the living populations might be responsible for the changes observed in fossils
Barr bodies are associated with _____
X chromosome inactivation
Do all cells of the body express the same genes?
No, since they don’t all need to make the same proteins
Can one gene make different proteins?
Yes, by splicing the resulting mRNA differently (i.e., removing different exons)
What does it mean when we say a gene is “turned off”?
The gene cannot be transcribed and translated into a protein
Puberty is caused by the release of follicle stimulating hormone and luteinizing hormone from the pituitary gland. These hormones are delivered to the ovary in girls and initiate the monthly release of mature egg cells. This is an example of what mechanism of regulation of gene expression?
A typical signal transduction pathway
The signal transduction pathway allows ____
one cell to regulate the gene expression of another cell.
Which gene are responsible for your overall structure, such as how many legs you have and where they develop?
Homeotic genes
Which of the following mutations is LEAST likely to result in harmful changes to cellular proteins?
Silent mutation
The type of mutation that alters the nucleotide sequence of a gene but does not alter the amino acid sequence of the protein produced that gene is called _____ mutation
silent
What are carcinogens?
Physical or chemical factors that can lead to mutations causing cancer
What type of mutation leads to a frameshift in the reading of DNA?
Both insertions and deletions
A normal gene, that, if mutated, can lead to cancer is called an
proto-oncogene
A gene that causes a cell to become cancerous is called an
oncogene
an _________ ______ is a gene that encodes proteins that inhibit cell division. Such proteins normally help prevent cells from becoming cancerous
tumor-suppressor gene
An ____ ___ is a protein that promotes cell division. In excess, such a protein may lead to cancer.
growth factor
How does a cell typically know when to divide?
Proto-oncogenes code for growth factor that initiate cell division
Cancer is ____
uncontrolled cell growth
A ____ ___ is a lump of abnormal cells that, although growing out of control, remains at its original site
Benign tumor
A _____ _____ is an abnormally growing mass of cells that is actively spreading through the body
malignant tumor
______ is the spread of cancer cells from their site of origin to other sites in the body.
Metastasis
An individual with a malignant tumor is said to have _____
cancer
Which of the following is TRUE concerning benign tumors?
Do not spread to other parts of the body
According to the American Cancer Society, what is the single best lifestyle choice that you can make to reduce your risk of cancer?
Don’t smoke tobacco products
what is a “benign” tumor?
A mass of cells that grows out of control and spreads to other tissues
The spread of cancer cells from their site of origin to sites distant in the body is called ______
metastasis
what is the main cause of cancer?
Exposure to carcinogens in the environment
Are there ways to prevent cancer?
yes, there are many ways cancer can be prevented, including through a healthy diet and exercise
A ____ cuts DNA only at a specific nucleotide sequences.
restriction enzyme
Why can a person who is unable to produce insulin be successfully treated with insulin derived from genetically modified bacteria?
The gene that produces insulin in humans was inserted into the bacteria where it continues to produce human insulin
What is recombinant DNA?
A segment of DNA containing sequences from two different sources
Which of the following could you be certain is NOT a GMO at the grocery store?
steak
Genetically modified organisms that acquire genes from a different species are called ____ organisms
transgenic
PCR is used to copy just a relatively small region of DNA, not the entire genome. How do researchers specifically target the region of interest?
They use two primers, each about 15 to 20 nucleotides long, that flank the region of interest
which of the following is an example of a transgenic organism?
a bacterium with human gene for producing insulin
restriction enzymes ______
cut DNA at specific nucleotide sequences
The process of accurately amplifying a sample of DNA is called ______
the polymerase chain reaction
Gel electrophoresis separates pieces of DNA based on ____
size
A supplemental appendix is to a book as a ____ is to a bacterial chromosome
plasmid
Gel electrophoresis separates DNA fragments according to their ______
length
DNA profiling relies on an individual’s _____, no two of which are the same between different people, except identical twins
unique set of short repeats within DNA
Through mapping the entire human genome researchers have learned that what percentage of the human genome codes from proteins?
1.5%
How would you describe the current status of gene therapy research?
Gene therapy has had limited success in a few cases. However, there is still a long way to go before gene therapy is deemed safe and effective enough for widespread use in curing genetic diseases
How does a scientist get the corrected version of a gene into the cells of a gene therapy patient?
It is delivered with a modified virus
Which of these characteristics affects the diffusion oxygen into the icefish’s blood?
Icefish have transparent, scale-less skin
icefish live in very cold water where temperatures are below blood’s freezing point. Which statements are true about icefish adaptations for cold water?
-icefish have antifreeze proteins, which prevent blood from freezing.
- icefish lack red blood cells, which reduces the viscosity (thickness) of blood, allowing it to flow more freely at cold temperatures
which statement is true of the Notothenioids?
Notothenioids can live in very cold, nutrient-rich waters where other fish species cannot
How did the icefish antifreeze gene arise?
An existing gene was accidentally duplicated. It then acquired mutations, which caused it to have a different function
which of the following are true of the “death” of the icefish globin gene?
mutations destroyed the function of the icefish globin gene
A strong selective pressure (like very cold water) can _____
cause a reproductive advantage for an individual with an advantageous mutation
compare the “birth” and “death” of icefish genes.
The “birth” of the antifreeze gene and the “death” of the globin gene are both caused by mutation
Translation begins when a ___ molecules binds to a _____
mRNA; small ribosomal unit
In the 1950s, when Watson and Crick were working on their model of DNA, which concepts were well accepted by the scientific community?
-chromosomes are made up of protein and nucleic acid
- genes are located on chromosomes
- chromosomes are found in the nucleus
what are the chemical components of a DNA molecule?
-nitrogenous bases
- phosphate groups
- sugars
In the early 1950s, many researchers were racing to describe the structure of DNA using different approaches. Which of the following statements is true?
Jim Watson and Francis Crick built theoretical models, incorporating current knowledge about chemical bonding and X-ray data
Early, flawed DNA models proposed by Watson and Crick and by Linus Pauling correctly described which property of DNA
DNA is composed of sugars, phosphates, and bases
What did Rosalind Franklin’s famous photo 51 show?
DNA is a helix
What did the structure of DNA’s double helix suggest about DNA’s properties?
-DNA stores genetic information in the sequence of its bases.
- DNA can change. Errors in copying can result in changes in the DNA sequence that could be inherited by future generations
- DNA can be replicated by making complementary copies of each strand
Before the publication of Charles Darwin’s On the Origin of Species, what was the prevailing public consensus regarding species evolution?
That species were permanent and unchanging
How did Darwin’s ideas on evolution conflict with contemporary religious dogma?
In contrast to biblical teaching. Darwin argued that the earth was very old, and that species are constantly changing
What contribution did Charles Lyell make?
He provided the first evidence that the Earth is much older then was previously thought
What prompted Darwin to publish his book decades after he began writing it?
Wallace, a colleague, was about to publish a similar transcript
Individuals with variations that make them best suited to their environment are, on average, more likely to _____
survive and reproduce
Can you inherit physical traits that your parents acquired during their lifetime?
No
How might global warming result in most grizzly bears having fur that is less dense in the future?
In any population of bears, some individuals have thick fur, some have thin fur, and some are in between. As temperatures increase with the passage of time, the survival of bears with thin fur will increase, and the number of bears in the population with thick fur will decrease
Which two observations led Darwin to conclude that there is competition for survival?
Overproduction of organisms and limited food resources
Before Darwin published his work, Lamarck and other had suggested mechanisms for evolution. By what means did Darwin propose species evolved over time?
natural selection
Natural selection acts on ____, and ____ evolve
individuals;populations
a weed exhibits resistance to an herbicide ________
inherited the gene that made it resistant to the herbicide
Evolution can be best defined as ______
change in the gene pool of a population
Cauliflower, broccoli, Brussels sprouts, cabbage, and kohlrabi are all the same species of plant. What is responsible for the differences in these vegetables?
Artificial selection
Which of the following is evidence for evolution in action?
All are evidence for evolution
In the Grand Canyon, fossils in rock layers at the bottom of the canyon are _____ than those in layers closer to the top
older
What is radiometric dating?
The process of determining the age of a fossil from radioactive isotopes
What is radiometric dating?
The process of determining the age of a fossil from radioactive isotopes
The oldest fossils are typically found in the sediments _______
located deep under the surface
Which of the following are considered fossils?
All of the above are considered fossils
What is the name for the study of the geographic distribution of species?
Biogeography
Comparing the body structures of organisms to find evidence of a shared evolutionary history is called ______
comparative anatomy
the approach that consists in comparing DNA sequences to find evidence of a shared evolutionary history is called ____
bioinformatics
If two organisms of different species share more similar DNA sequences with each other than with other species, we can conclude that ______
these two species are very closely related
Human embryos have a developmental stage during which they have a tail and pharyngeal pouches. How can we explain these characteristics of human embryos
human embryos share a common ancestor who had gills
what is the smallest unit that can evolve
the population
The modern evolutionary synthesis of the 1930s and 1940s melded together Darwin’s findings with _____
genetics
What defines a population in evolution
interbreeding members of the same species that share a common space
Which of the following best defines microevolution
changes in genes within a population over times
habitat loss has driven the population of the florida panther to extremely low numbers. which mechanism of microevolution is likely at play in this species
Genetic drift: the bottleneck effect
What does fitness mean when speaking in terms of evolution
how many offspring an individual produces
What events can lead to offspring having a unique arrangements of their parent’s genes
both crossing over and independent assortment
What is the leading hypothesis for what might have brought about the extinction of dinosaurs
an asteroid impact
Which process of evolution does not change the total number of species?
nonbranching evolution
when did life first appear on the planet
3.5 billion years ago
how long ago were the organisms that produced the oldest fossil records alive?
3.5 billion years
The slow drifting of sections of the earths crust sometimes separating, other times colliding, is known as ___
plate tectonics
in many ways, a mule is a superior animal to the horse or donkey. Mules are often stronger ad can jump higher than either of their parent. Why, then, are mules considered to be a “weak hybrid”?
They are sterile
What is an exception to the standard biological species concept used to define a species?
asexual species cannot be distinguished using this concept
what term describes the failure of one species to fertilize the egg of a different species?
gametics incompatibility
the eastern meadowlark and the western meadowlark are two bird species that look very similar to each other. why do biologists not consider them the same species?
all of the above
due to differences in mating times, two sub-populations of frogs form into separate species, even though they occupy the same pond. this overall process is known as ______
sympatric speciation
The rapid diversification of species seen in the fossil record followed by long periods of statis is part of the ____ model of evolution
punctuated equilibrium
which model of evolution is closest to what was originally suggested by charles darwin
the graduated model matches best the reasoning of charles darwin
which of the following most leads to allopatric speciation?
habitat isolation
