Bio Exam 3
experts estimate that approximately ______ of the US population (nearly 90 million people) is colonized by S. aureus
30-40%
an individual inheriting the genotype aaBbCc falls in the ____ foot phenotype
5
A mating of two people of medium height (where three genes control height): AaBbCc x AaBbCc produce _____ distinct phenotypes determined by the number of genes inherited.
7
if a person with AB- blood is in need of a transfusion, people with that blood types will be able to donate blood for them
A-
you have type B blood. therefore, you can accept blood donations from people with a
BB and BO genotypes
a wife is heterozygous for DMD alleles and her husband has a dominant allele on his X chromosome. What percentage of their sons and what percentage of their daughters will have DMD
DMD is X-linked recessive. 50 % of their sons will have DMD and 0% of the daughters will have DMD
thich of the steps of bacterial reproduction occurs first
DNA is replicated
If a man has an X-linked recessive disease, can his sons inherit that disease from him? Why or why not?
If a male has an X-linked recessive disease he cannot pass it to his son because the father must pass the Y chromosome to his son. The X chromosome in males will always come from the mother
Why are more males than females affected by X-linked recessive genetic disorders?
Males have only X chromosomes, whereas females have two X chromosomes. Recessive traits occur when only recessive alleles are present. Males have only one allele of each X-linked gene because they have one X chromosome; therefore, if they have the recessive genetic disease. Females are less likely to be affected because their recessive allele can be masked by a dominant allele.
the term "MRSA" as it is used today refers to
S. aureus bacteria that are resistant to many antibiotics
If you are a female, will your brother and your son have essentially identical Y chromosomes?
The brother and son of a female will not have identical Y chromosomes because the Y chromosome is inherited from the father. The exception is if the brother is the son's father
which sex chromosome is present in a typical male
XY
early in development, a human embryo resembles
a car embryo
antibiotics
a chemical that can slow or stop the growth of bacteria; many antibitotics are produced by living organisms
estrogen
a class of sex hormones, including estradiol, that are higher in women than in men and support female sexual development and function
androgens
a class of sex hormones, including testosterone, that are present in higher levels in men and cause male-associated traits like deep voice, growth of facial hair, and defined musculature
which two people would have the most different Y chromosomes
a father and his daughter's biological son
incomplete dominance
a form of inheritance in which heterozygotes have a phenotype that is intermediate between the two homozygotes
codominance
a form of inheritance in which the effects of both alleles are displayed in the phenotype of a heterozygote
population
a group of organisms of the same species living together in the same geographic area
which of these was an adaptation observed in Tiktaalik
a jointed elbow. wrist, and fingerlike bones
which couple could have a boy with Duchenne muscular dystrophy (DMD)?
a male with DMD and a carrier female
which feature of Tiktaalik is not shared with other bony fish
a mobile neck
x-linked traits
a phenotype determined by an allele on an X chromosome
amniocentesis
a procedure that removes fluid surrounding the fetus to obtain and analyze the chromosomal makeup of fetal cells
in the presence of penicillin: what happens to a resistant strain of S. aureus
a resistant strain will not be affected by penicillin and will continue to grow
in the presence of penicillin: what happens to a sensitive strain of S. aureus
a sensitive strain will eventually burst (lyse) and die because of its weakened cell wall
polygenic trait
a trait phenotype is determined by the interaction among alleles of more than one gene
diversifying selection
a type of natural selection in which organisms with phenotypes at both extremes of the phenotypic range are favored by the environment
stabalizing selection
a type of natural selection in which organisms with phenotypes at one end of a spectrum are favored by the environment
directional selection
a type of natural selection in which organisms with phenttypes at one end of a spectrum are favored by the environment
pedigree
a visual representation of the occurrence of phenotypes across generations
as a woman ages, the risk of giving birth to a baby with any chromosomal abnormalities increases because
a woman is born with all the eggs she will ever have, all her eggs ages as she ages, older eggs have more chance of acquiring mutations, older eggs have a greater chance of making errors during meiosis
the change in foot structure of horses from ancestral species to modern species is indicative of
adaptation to a prairie environment
when a population shows an adaptation, it means that a population responds to an environmental pressure such that the presence of ____ trait ____ over time
advantageous;increases
if a nondisjunction occurs in meiosis I
all four resulting cells will be aneuploid
what conclusions are drawn from Darwin's proposal of descent with modification, now known as the theory of evolution
all living things are related
a trait with polygenic inheritance is influenced by
alleles of multiple genes
aneuploidies
an abnormal number of one or more chromosomes (either extra or missing copies)
multifactorial
an interaction between genes and the environment that contributes to a phenotype or trait
a person with 47 total chromosomes has a karyotype that can best be described as
aneuploid
chemicals that either kill bacteria or slow their growth by interfering with the function of essential bacterial cell structures are
antibiotics
binary fission is asexual. What does this mean? how could two daughter cells end up with different genomes at the end of one round of binary fission
asexual reproduction involves only one parent. the parent passes on a copy of all its genetic material to its offspring. this means that the offspring are copies of the parent. The two daughter cells that are the products of binary fission could be genetically different if a mutation occurred during replication of the parent genome before division. One copy of the genome would contain the mutation and one copy would not, and each daughter cell would inherit one of the two different copies
In what sense do bacteria "eveolve faster" than other species
because bacteria divide very rapidly, they have a very short generation time. As evolution is a change in allele frequency over time, it doesn't take long for bacterial populations to accumulate many generations. As there is a chance of one or more mutations to arise with every generation, there is a wealth of genetic diversity for natural selection to act on
MRSA is most likely to be problematic of found in the
bloodstream
in codominance wha tphenotype does heterozygotes display
both the homozygous dominants and homozygous recessive phenotypes
how do b-lactam antibiotics kill sensitive bacteria
by destabalizing the cell wall
how do beta-lactam antibiotics kill sensitive bacteria
by destabilizing the cell wall
what are the two major mechanisms by which bacterial populations generate genetic diversity
by gene exchange and mutation
evolution
change in allele frequencies in a population over time
amniocentesis can detect
chromosome abnormalities in the fetus
A black dog is bred with a brown dog, and all the puppies have patches of black and brown. The color coat alleles for black and brown are an example of
codominance
a form of inheritance in which both alleles contribute equally to the phenotype is
codominance
if you carry staph of any strain but aren't sick, you are
colonized
which step is not involved in bacterial reproduction
daughter cells stay attached
natural selection
differential survival and reproduction of individuals in response to environmental pressure that leads to change in allele frequencies in a population over tome
a sensitive S. aureua bacterium acquires acquires a new genre that allows it to resist the effects of beta-lactam antibiotics. what might the protein encoded by that gene do
digest beta-lactam antibiotics
the evolution of antibiotic resistance is an example of
directional selection
a woman is born with the BRCA1 breast cancer susceptibility allele. This is a "strike" against her in terms of her risk of developing breast cancer. Which of these will reduce her risk
eating a healthy diet, exercising, and not becoming obese
a highly resistant antibiotic strain of S. aureus would reproduce
equally in the presence or absence of antibiotic
the discovery of transitional fossils is important because it supports
evolution and natural selection
a person with type B blood makes antibodies against the "B" anitgen
false
methicillin is currently used to treat staph infections
false
what are the two major mechanisms by which bacterial populations generate gentic diversity
gene transfer and mutation
When looking at a karyotype, for example to diagnose Trisomy 21 in a fetus, is it possible to use that anlysis also tot ell if the fetus has inherited a cystic fibrosis allele from a carrier mother
genotypes cannot be deduced from karyotype analysis. Karyotype analysis is used to determine the number of chromosomes present
trisomy 21
having an extra copy of chromosome 21; Down Syndrome
what is one human system that protects us from most infections
immune system
for incomplete dominance, what is the phenotype of heterozygotes
in between homozygous dominants and homozygous recessive
what is the difference betweena n S. aureua colonization and an S. aureus infection
in colonization, the bacteria are growing on or in the body without causing disease. infections are associated with disease
how does incomplete dominance differ from co-dominance
incomplete dominance describes traits in which heterozygous individuals have an intermediate phenotype between that if the homozygous dominant and homozygous recessive phenotypes. Traits that are co-dominant produce heterozygotes that display both the dominant and recessive phenotypes. traits that are co-dominant produce heterozygotes that display both the dominant and recessive phenotypes
if you have a genetic predisposition to a disease such as cancer, you will eventually get cancer. Is this a true statement?
it is not necessarily true; it may be dependent on the environment
some of the middle ear bones of humans are homologous with the
jaw bones of reptiles
which inheritance patterns includes an environmental contribution
multifactorial
two people with the same genotype for a condition such as asthma have different phenotypes. this results from what type of inheritance pattern?
multifactorial inheritance
differential survival and reproduction of individuals in response to environmental pressure that leads to changes in allele frequencies in a population over time is called
natural selection
the most severe disease that can result from MRSA is
necrotizing fascitis
If we take the most fit bacterium from one environment--one in which the antibiotic amoxicillin is abundant, for example--and place it in an environment in which a different antibiotic is abundant, will it retain its high degree of fitness?
not necessarily, fitness depends on the ability of an organism to survive and reproduce, and it may not do this as well in a different environment
which hypothetical antibiotic would treat bacterial infections by interfering with bacterial reproduction
oe that decreases cell membrane synthesis
In sedimentary rock, the _____ fossils tend to be found _______
older; in the deeper layers
autosomes
paired chromosomes present in both males and females; all chromosomes except the X and Y chromosomes
sex chromosomes
paired chromosomes that differ between males and females. Females have XX and males have XY
beta-lactam include
penicillin, cephalosporins and methicillin
fitness is determined by the interaction between ____ and the environment
phenotype
the combination of alleles a person inherits predicts a distinct phenotype. we call this type of inheritance
polygenic
a group of organisms of the same species living together in the same geographic are is called a
population
the us of radioactive isotopes as a easure to determine the age of rock or fossils is termed
radiometric dating
a wife is heterozygous for DMD alleles and her husband has a dominant allele on his X chromosome. What percentage of their sons and what percentage of their daughters will have an X-linked dominant form of rickets
rickets is X-linked dominant. 50% of their sons will have rickets and 100% of the daughters will have rickets
which of these is a harmful bacterium
salmonella
people with depression have lower levels of ____ in their brain
serotonin
gonads
sex organs: ovaries in females, testes in males
X-linked traits are most typically inherited by _____ from their _______
sons; mothers
in humans, very large birth weight and very tiny babies do not survive as well as midrange babies. What kind of selection is acting on human birth weight
stabalizing selection
MRSA and drug-resistant syaph refer to
staph strains that are resistant to penicillins, cephalosporins, and beta-lactams
MRSA is caused by a drug-resistant form of
staphylococcus aureus
what is the evolutionary meaning of the term "fitness"
the ability of an individual to survive and reproduce in a given environment. Individuals that are more fit leave more offspring and more of their alleles in the next generation relative to individuals that are less fit
Which of the following most infuence the development of a female fetus?
the absence of a Y chromosome
If you are male, will your brother and your son have essentially identical Y chromosomes?
the brother and son of a male will have essentially identical Y chromosomes because the Y chromosomes is inherited from the father. The two brothers will have received essentially the same Y chromosome from their father and then pass that Y chromosome to their sons
karyotype
the chromosomal makeup of cells. analysis can be used to detect chromosome disorders prenatally
Y-chromosome analysis
the comparison of sequences on the Y chromosomes of different individuals to examine paternity and paternal ancestry
when amniotic fluid is tested for chromosome anaylsis, whose karyotype is being examined
the embryo's
nondisjunction
the failure of chromosomes to separate accurately during cell division; nondisjunction in meiosis leads to aneuploid gametes
If you are blood type A+, to whom can you safely donate blood? who can safely donate blood to you?
the only possible recipient for an A+ door is type A+. The possible donors to an A+ patient are types A+, A-, O+, and O-
what is the environmental pressure in the case of antibiotic resistance
the presence or absence of antibiotics in the environment
gene transfer
the process by which bacteria can exchange segments of DNA between them
adaptation
the process by which populations become beteer suited to their environment as a result of natural selection
which of these is decreased when there is stabalising selection
the range of phenotypic variation
fitness
the relative ability of an organism to survive and reproduce in a particular environment
a male has a son and a daughter. both the son and the daughter have one son and one daughter. which grandchild has a Y chromosome that is identical to the grandfather in this question
the son's son
why do the beta-lactam antibiotics affect sensitive bacterial cells but not eukaryotic cells
they interfere with the syntheis of peptidoglycan-containing cell walls. Humans (and other animals) do not have cell walls at all, and while plant cells do have a cell wall, it is made if cellulose and not peptidoglycan. Eukaryotic cells therefore do not have the structure that is the target of penicillin (and other beta-lactam antibiotics)
an organism's fitness depends on its environment
true
even though mutation rates for bacteria and humans are identical, bacteria are able to adapt more quickly to their environment than are humans
true
binary fission
type of asexual reproduction in which one parental cell divides into two
which situation puts a healthy person at greater risk for a MRSA infection
undergoing a medical procedure that weakens the immune system, undergoing a procedure that causes a break in the skin, being a child whose immune system is still maturing, and being elderly
continuous vatiation
variation in a population showing an unbroken range of phenotypes rather than discrete categories
a homologous structure is one that
was inherited from a common ancesotr
tracing a paternal (male) line of ancestry is best accomplished by examining genes on the ___ chromosome
y
can S. aureus be present in or on a person who has no evidence of an infection
yes; S. aureus is a common skin bacterium