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95 Cards in this Set
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What is the purpose of meiosis? What is the end product of meiosis? Where in the body does it occur?
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Purpose: create 4 haploid (sex cells) from 1 diploid cell
Product: 4 haploid cells (not identical). Have half the number of chromosomes Where: Occurs in sex cells |
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What is the difference between diploid and haploid cells?
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Diploid- full number of chromosomes (mitosis)
Haploid – half the number of chromosomes for the organisms (meiosis) |
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What are homologous chromosomes? Sister chromatids?
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Homologous Chromosomes- same length and same genes but different versions of those genes; One from mom and one from dad
Sister Chromatids- identical to each other (x’s split) |
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What is a karyotype?
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Karyotype – characteristics of cell chromosomes
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What are alleles?
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Alleles – different versions/ forms of the same gene
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Why does an individual look similar but different from their siblings? How does crossing over and independent assortment increase genetic variation?
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Sibling look similar but different b/c of crossing over and independent assortment.
Crossing over – homologous chromosomes pair up and exchange equivalent segments of DNA. Independent assortment – how the homologous chromosomes line up (on the right or left) is random * Both result in many of different genetic combinations among gametes |
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What are common mistakes in the meiosis process? What genetic disorders are associated with each of these meiosis mistakes?
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look at #7 on meiosis
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Why is it important for humans to have exactly 46 chromosomes for normal development?
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It is critical for normal development
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What are the three potential places in meiosis that mistakes can happen?
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1. Crossing over: homologous chromosomes don’t make an equal swap
2. Meiosis I: A pair of homologous chromosomes don’t separate 3. Meiosis II: Sister chromatids fail to separate resulting in egg or sperm with extra or missing chromosome |
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What is a chromosomal deletion? What are the symptoms of Cri du Chat?
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Chromosomal deletion- during crossing over, a piece of chromosome is lost
Cru du Chat Symptoms: • Rare: 1 in 50,000 births • Part of chromosome 5 is missing • High pitched cry at birth • Mental retardation & slow development |
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What is translocation?
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Translocation- crossing over occurs between non-homologous chromosomes
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What is the most common cause of Down Syndrome?
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Chromosome 21 mistakes (3 of chromosome 21)
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What is a more rare cause of Down Syndrome?
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Translocation- 4% of cases
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What are some of the effects of Down Syndrome?
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Mental retardation, reduced life span (55 years), 40% have heart defets
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Why are older mothers more likely to have a child with Down Syndrome?
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The likelihood that a reproductive cell will contain an extra copy of chromosome 21 increases dramatically as a woman ages.
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What is non-disjunction?
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Non-disjunction – When homologous chromosome OR when sister chromatids fail to separate
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What is Turner’s Syndrome? XXX Syndrome?
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Turner’s Syndrome – whole chromosome mistake (XO) females tend to be short, sterile; occurs in 1 in 2500 birhts
XXX Syndrome- whole chromosome mistake; females, symptoms vary from none to delayed motor skills, speech and maturation. Slightly taller |
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What is Klinefelter’s Syndrome? Super Male Syndrome?
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Klinefelter’s Syndrome – (XXY) whole chromosome mistake in males; results in failed or late puberty, delayed speech and/or motor function, taller, most are infertile; occurs in 1 in 750 births
Super Male Syndrome (XYY) – whole chromosome mistake in males; they will have a taller stature, may have mild learning disabilities, may have no symptoms, fertile, excess testosterone; occurs in 1 in 1000 newborns |
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What is the big idea about the number of chromosomes in human cells?
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In humans, having exactly 46 chromosomes is critical to normal development!!
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What is IVF? Explain the basic steps.
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In vitro fertilization – “test tube baby”
Step 1: Develop and monitor follicles in ovaries Step 2: Collect Eggs Step 3: Eggs and sperm are mixed in a petri dish Step 4: Between 4-6 days later, up to 4 embryos are transferred into uterus |
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What is PGD? What is it used for?
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Preimplantation genetic diagnosis – a genetic screening test. Can test for over 100 genetic disorders.To detect genetic disorders
Doctors select mutation free embryos to implant in the uterus OR embryos of the preferred gender |
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What are some disorders that can be screened with PGD?
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• Aneuploidy- incorrect number of chromosomes
o Down syndrome, turner’s syndrome • Single gene disorders- cystic fibrosis, muscular dystrophy, and sickle cell anemia • Translocations that lead to mental retardation • HLA Matching – for bone marrow matching • Sex selection |
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What are embryonic stem cells?
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Inner cell mass is removed from the blastocyst and grown in lab
Blastocyst is destroyed in the process Cell line is cultured in lab |
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What are their characteristics?
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Pluripotent: can develop into many different kinds of cells
Can self-renew / keep dividing |
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Why are scientists interested in ESC?
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Stem cell therapies could replace damaged or dying cells
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What are some ethical issues associated in ESC?
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Destroying life
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What is SCNT (therapeutic cloning)?
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Somatic Cell Nuclear Transfer-
Diploid donor cell is fused to an empty egg cell → blastocyst Inner cell mass is harvested, cultured to create cell lines Result: Clone of donor cell |
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What is the difference between embryonic and somatic (adult) stem cells?
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Embryonic stem cells are pluripotent- can develop into many different kinds of cells
Somatic (adult cells) are multipotent – limited in type of cells that can develop |
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What are some potential therapeutic uses for stem cells?
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• Stem Cell-based therapies could replace damaged or dying cells:
o Heart attack: replace damaged heart muscle o Parkinson’s disease: replace damaged brain cells o Diabetes Type I: replace pancreas cells o Spinal cord injuries: replace damaged nerve cells o Burn Victims: replace skin cells o Alzheimer’s: replace damaged brain cells |
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What is the difference between ESC and SCNT?
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SCNT (Somatic cell nuclear transfer) is used to create ESC (embryonic stem cells) to treat diseases
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What are multipotent stem cells? How do these differ from pluripotent stem cells?
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Multipotent stem cells – limited in type of cells that can develop
Pluripotent- can develop into many different kinds of cells |
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What are Induced Plutipotent stem cells (iPSC)?
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a. In 2007, Scientists announced they could reprogram skin cells to be pluripotent
b. Skin Cells+4 genes→Induced Pluripotent Stem Cells-->fat cells, neurons, macrophages, smooth muscle cells, etc. c. Custom cells lines that can make all tissues d. Patient-specific stem cells e. Can be great models for studies of disease and drug therapy |
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What is the difference between ESC and iPSC?
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iPSC are changed into ESC.
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How does the history of the production of stem cells illustrate the nature of science (how science works)- hint there are 5 ways we talked about in class?
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• Scientific knowledge is durable, yet tentative
o Old idea: Genes control cells, once a cell differentiates, that’s it o Revised Idea: Scientist can manipulate genes to have specialized cells revert back to stem cells. • Scientific knowledge builds over time o IVF → grows ESCs→ SCNT→ iPSCs o Originally, embryos had to be destroyed to harvest stem cells o Now, Adults cells can be reprogrammed • Peer Review Process & Empirical Evidence o (226) S. Korean scientist who claimed to have cloned a human was disproved • There are general accepted ethical principle in the conduct of science o Scientist are against human cloning • Science & societies influence each other o Federal & state policies drive research funding |
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How can XY females and XX males get the SRY gene?
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Accidentally get it during crossing over
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What does the SRY gene do?
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SRY gene is turned on → protein causes gonads to develop into testes → testes produce testosterone → development of a penis
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What is the genotype and phenotype of an organism?
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Genotype: the genetic makeup of an organism
Phenotype: what the organism looks like |
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What is an allele?
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Allele: different versions/ forms of the same gene
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What is a dominant allele?
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Dominance: the version that is seen in the phenotype
A dominant allele is expressed and A LOT of protein is made to cause the trait SO only one allele is needed to see that trait |
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A recessive allele?
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Recessiveness: when an organism has different versions/alleles, it is the version that is NOT expressed and makes no protein, OR makes an inactive protein, or a small amount of protein, * Often a mutated, non-functioning version of the original gene.
So two copies of the recessive allele are needed to see that phenotype |
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How do these relate to the expression of certain traits, i.e. white Bengal tigers?
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White is a recessive allele trait.
Must have 2 of the recessive alleles to see the white trait |
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Are dominant alleles more common in the population?
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YES
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What are some examples of autosomal dominant traits that we discussed in class?
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Only 1 allele is needed to have disorder
1.) Polydactlyl (extra finger) 2.) Huntington’s Disease * Degenerative brain disorder, jerky movements * Lose coordination, develop dementia, no cure * Develops between 35-45 years of age 3.) Marfan’s Syndrome *Tall individuals * Weakened aorta |
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What are some examples of autosomal recessive human traits we discussed in class?
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2 recessive alleles required
1.) Cystic fibrosis – mucus build up in lungs 2.) Albinism 3.) Phenylketonuria (PKU) * can’t break down phenylalanine (aa) which can lead to mental retardation * Early detection and special diets prevent retardation * Screen at birth for PKU 4.) Sickle Cell Anemia |
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What is incomplete dominance?
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Incomplete dominance: neither allele is completely dominant
Dominant allele does not make enough of the protein *Heterozygote is an intermediate phenotype |
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Co-Dominance?
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Co-dominance: Proteins produced from each allele are seen in the phenotype
Ex: ABO blood |
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What are some examples of each of these?
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Heterozygote: is an intermediate phenotype (combination of the two)
Co-Dominance: ABO blood type (all shown) |
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Why are more males than females colorblind?
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It is an X linked recessive trait. Since females have two X chromosomes it is less likely they will show colorblindness whereas males only have one X chromosome
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What are some examples of polygenic inheritance?
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Polygenic Inheritance: more than one contributes to a trait
Ex: Height, skin color (3-6 genes), eye color (at least 6 genes), hair color, face shape, body shape, allergies, baldness |
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What is a scientific theory and how is it different from a scientific law?
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Scientific Theory – Explains how nature works. General set of principles that have explanatory power. Scientists are in the business of theory building
THEORIES DO NOT BECOME LAWS Scientific Law – Describes how nature acts under certain conditions, without explaining why Ex: Law of Gravity, Law of Segregation |
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How is science different from religion as a way of understanding the world?
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Look at #2 under evolution
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What is the theory of evolution?
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• Descent with modification
• Related species share a common ancestor • For example: perch, smallmouth & largemouth bass, and walleye descended from a common bony fish ancestor • On a bigger scale, all life on earth shares a common ancestor |
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How does the theory of evolution explain why do snakes have internal small leg bones and why all life shares the same genetic code?
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Descended from a common ancestor
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What is natural selection? How does this fit into the Theory of Evolution?
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Natural Selection: is the primary mechanism of evolution
Some variations are selected in particular environment Ex: brown bugs more camouflage = advantage Survivors reproduce and pass on their alleles (adaptive trait) Over time, the populations change (evolve) Ex: Brown survives more than green; Survivors have babies so next generation is shifting and there are more brown made; Eventually all will be brown |
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How does the theory of evolution explain the high frequency of sickle cell anemia in some populations? The high frequency of cystic fibrosis in some populations?
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NN = Normal RBC’s and good hosts for malaria parasite → die from malaria
nn = sickle RBC and poor hosts for parasite → die from sickle cell anemia Nn = no sickle AND poor host for malaria → survive and reproduce Most fit in this environment but comes with a cost: 25% of offspring die from sickle cell and 25% die from malaria Populations will evolve over time- Higher frequency of carriers (Nn) |
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Some of the processes involved in evolution are random and some are not. Which processes are random and which are not random.
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Mutations are random
Natural Selection is not. It is based on need |
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One misconception is that evolution gives organisms what they need. Why is this a misconception?
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Genetic variation must be present in the population for natural selection to act on… selects among variants
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Organisms do not ‘try’ to adapt. What evidence do we have that disproves this misconception?
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Involves genetic variation within a population and selection among variants
Some variations are better suited to the environment. THIS IS NOT RANDOM! Survivors then pass on their favorable traits to offspring |
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How does the theory of evolution explain why human skin color varies across the globe? Be able to explain different environmental pressures at the equator and at higher latitudes?
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Toward equator – too much sun destroys folic acid
- light colored skin is at disadvantage – not as fit Toward poles – not enough sun; not enough vitamin D -dark colored skin not as fit; not able to absorb enough vitamin D According to Jablonski, what role does Vitamin D and folic acid play? Folic acid – making RBCs, cell division, sperm development, and spinal cord development in embryo. Folic acid is destroyed at high levels of sunlight Vitamin D – helps body absorb calcium → strong bones - lack of vitamin D → rickets (deformed bones, “bow-legged”) • In regions with lots of sunlight, making enough vitamin D is not a problem. The challenge is protecting folic acid levels, so it’s an advantage to have dark skin. • In regions with little sunlight, protecting folic acid levels is not a problem. The challenge is making enough Vitamin D, so it’s an advantage to have light skin to allow limited UV rays to penetrate skin to make Vitamin D. |
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How does MRSA and antibiotics give support for evolution? Remember: Look for big ideas!
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• Variation among bacteria. Some produce proteins that block certain antibiotics
• Low doses or incomplete doses of antibiotics kill the bacteria that lack these antibiotic resistant genes • Surviving bacteria are resistant to certain antibiotics • Population of “Superbugs” evolve |
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Why should you finish the entire bottle of antibiotics?
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If you stop the treatment before your prescribed medication is scheduled to finish, you could actually be doing more harm than if you had never even begun taking the antibiotic at all. The reason for this is that once antibiotics start to destroy the specific bacterial infection that you are trying to treat, that it will take a specific dose and number of days to completely eliminate the bacteria. If you start a dose and stop it before your doctor has instructed you to do so, you are giving remaining bacteria a chance to grow again, and since the remaining bacteria have not been completely killed, and have been "exposed" to a less than full course of antibiotics, they can now be resistant to antibiotic treatment and can multiply in your body and wreak even more havoc than they did prior to your starting the medicine
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Be able to explain the following mechanisms for evolution:
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Mechanisms of Evolution: Evolution occurs when there is a change in the frequency of alleles in a population
a. Natural selection • Variation within a population • Some variations are better suited to the environment. THIS IS NOT RANDOM!! • Survivors pass on their favorable traits to offspring b. Gene flow: migration • Individuals migrate c. Genetic Drift: distinguish between bottleneck effect and founder effect • Happens in small populations, allele frequency changes b/c of chance o a.) Bottleneck Effect: an event that greatly reduces the population, survivors don’t represent the original gene frequency • Cause: excessive hunting, disease, natural disaster • Examples: Northern Elephant Seals, Cheetahs o b.) Founder Effect: a small sub-set of the population migrates to a new area. This small sub-set has a different allele frequency • Amish and Mennonite populations tend to be isolated gene pools started by a small group • a.) Ellis –van Creveld Syndrome • Form of dwarfism & polydac |
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What is the difference between macroevolution and microevolution? Do scientists use this distinction?
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Microevolution: change in an allele frequency within a population. Can occur in a relatively short period of time.
Ex: Shift to more brown varieties of beetle than green in a population Macroevolution: when new species evolve (organisms that can mate with each other and produce fertile offspring) |
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What is a species? Why is a mule not a new species?
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Species: organisms that can mate with each other and produce fertile offspring
This is why a mule is not really a new species. When a donkey and a horse get together, they produce a mule. The mule, though, is sterile -- it cannot have or make new mules |
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Be able to explain the following reproductive isolating mechanisms:
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a. Ecological isolation
Two species use different habitats. Lions and tigers interbreed but they don’t in the wild Ex: Lions prefer open grassland Tigers prefer deep forests b. Temporal isolation They don’t’ mate/bloom during the same time frame Ex: Flowers of two species that bloom at different time c. Behavioral isolation Individuals don’t recognize courtship rituals, mating displays and songs Ex: eastern and western Meadowlarks d. Mechanical isolation Individuals have to be physically compatible Ex: Reproductive organs in different species of alphine butterflies are incompatible e. Gamete isolation Egg and sperm are incompatible, don’t fuse together f. Hybrid inviability Embryo does not develop normally OR the offspring is infertile Ex: mules |
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When is speciation more likely to occur?
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a. Speciation: development of new species through evolution
i. Occurs when two populations stop interbreeding ii. Speciation require that: 1. Gene flow between two populations is interrupted 2. Significant time (Depends on lifespan of organism) 3. Genetic Difference gradually accumulate between the two populations 4. Reproductive isolation occurs between the two populations |
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What misconception does a person have when they say that humans evolved from apes?
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That we morphed from apes
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What is a shared derived trait? Where would it be placed on a phylogenetic tree?
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at the nodes
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What is artificial selection? What are some examples of organisms that have been artificially selected?
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Artificial Selection: intentional breeding for certain traits
Ancestral wolf pups were domesticated intentionally by early humans |
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What is a clade of organisms?
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Organisms with a common ancestror
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What are some characteristics of the family Canidae?
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• Primarily prey on other mammals, also eat insects, berries, carrion, garbage
• Live in packs ruled by male partner • Teeth adapted for slashing flash |
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What evidence is used to create phylogenies?
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Phylogeny: evolutionary history of a group; study of evolutionary relationships
Phylogenies can be based on morphology (form): -Similarity of many morphological characteristics are used (color, size, structure, etc.) Most recent phylogenies are based on molecular similarities: -E.g., similarities of mitochondrial DNA sequence (mtDNA) -More similarities = a closer relationship |
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Be able to identify a phylogenic tree that best represents the relationship between wolves, fox, dogs, and jackals.
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Jackal → fox → wolf → African wild dogs
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Be able to explain the two competing hypotheses explaining the speciation of domestic dogs, and the supporting evidence for each.
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How did dogs evolve from wolves? (2 hypothesis)
• Ancestral wolf pups were domesticated intentionally by early humans – Artificial selection o Arguments for: • It makes intuitive sense that ancestral wolves could be domesticated easily since they are so dog- like. Early humans would have intentionally bred ancestral wolves o Arguments against: • Why would any human want to deal with an animal that avoids humans? • Modern wolves cannot be “domesticated” by training alone. It takes intensive and sophisticated selective breeding • Ancestral wolf populations experienced natural selection forces that favored dog-like characteristics o Canidaes are very resourceful & would have found human waste piles good foraging – wolves were living close to humans o Wolves are shy skittish animals – only “adventurous” wolves (smaller flight distances) would have stayed close to the waste piles while humans were around o The “adventurous” wolves were the best fed hence had high fitness |
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Describe different types of evidence supporting that whales evolved from land animals?
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• Seems impractical for a mammal to live exclusively in the ocean
• Environmental challenges: o Cold o Danger of drowning o Lack of fresh water o Reproduction is more difficult Fossil evidence: • Ancient wolf ear identical to modern whale ear • Pelvis, knee cap, toes, leg bones, despite aquatic environment Fossil intermediates can be traced from ancestors up to modern whales Vestigial Limbs • Some modern whales have vestigial leg bones and pelvis • Why would a whale have genes to make a femur and pelvis • An ancestor that lived on land The way whales move is different than fish and sharks Mammals swim by undulating spin up and down (not right and left) |
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In general, what is the sequence of events that would produce changes due to natural selection in whales?
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Mutation→ Environmental pressure→ Time→ Change in population
Whales w/ little blubber OR whales w/ lots of blubber → Environmental pressure (warm water)→ Time → Mostly low-blubber whales survive |
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What adaptations allow whales to live in cold water?
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• Whales w/ little blubber OR whales w/ lots of blubber → Environmental pressure (warm water)→ Time → Mostly low-blubber whales survive
• Over time, random mutations favorable to environmental challenges were selected for: o Cold: Blubber (fat) o Lack of fresh water: Kidney adaptations o Danger of drowning: nostrils to top of head • Adaptation for breathing air when surround by water • Air and mucus comes from nostrils o Sex is more difficult: Prehensile penises |
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What misconception about whales does Emily really hate? Why is this a misconception? How could you use your knowledge of whale evolution to dispel this misconception?
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Misconception: out of blowhole comes water
Actually- mucus and water- can’t have water in lungs!! Whales have adapted nostrils on the top of their heads because of the danger of drowning |
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Which of the four types of isolation mechanisms could be responsible for a possible speciation even between northern and southern humpback whales?
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Temporal Isolation – don’t mate at same time- different migrating patterns
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Know the different levels of organization that we used as a framework throughout the course: atoms to biosphere
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Atom→ molecule→ cell organelle→ cell→ tissue→ organ→ organism→ population→ community→ biosphere
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What is a food web? How are food webs different than food chains?
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Food webs have 4-5 “trophic levels” – multiple species can take up each trophic level
Chains: single chain |
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What is a tropic level? Why are there only 3-4 trophic levels in a food web?
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Trophic Level: position an organism occupies in a food chain/web
There are only 3-4 trophic levels because there is a loss of sunlight energy between levels |
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What is an apex predator? Why are there only a few of them in each food web?
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Apex predator: predators with no predators of their own
Producer→ Primary Consumer→ Secondary Consumer→ Tertiary Consumer→ Apex Predator |
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Why are producers at the base of ecological pyramids? What are consumers?
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Because there are many producers (more than apex predators)
Consumers eat the producers and are eaten by the apex predator |
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What is a niche? Can two organisms occupy the same niche? Why or why not?
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Niche- the unique way a species uses it non-living and living resources
-Each species has an ecological niche -Gain/loss of niches can cause speciation Yes two organisms can occupy the same niche- For example, a tree can be a niche for hundreds of different species. Not only can 4 different species of beetles occupy one tree, but you can also have different kinds of species of ants, moss, birds and spiders living in that same tree, and for all these species, that tree is a niche. |
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How does energy move through an ecosystem? Is this a unidirectional path?
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• Energy moves one direction in an ecosystem and is lost between trophic levels
• Arrows represent energy (get smaller on down the line) |
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How are raw materials recycled through an ecosystem? Is this a unidirectional path?
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• Raw materials (like CO2, H2) are recycled in a food web
• Big molecule stored in organisms decompose upon death o Into monomers o Done by decomposers (bacteria, fungi, etc.) * Energy flows one-way BUT raw materials are recycled throughout |
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How much energy is available to the next tropic level in a food web? Recall the sea otter example.
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10% available; 90% lost
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What is a keystone species? What are some examples of keystone species?
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Keystone species: last piece to put in; supports all others; is a species that has a disproportionately large effect on its environment relative to its abundance.
Ex: Sea otter (prevent urchins from massing and mowing down kelp), sea star (prey on sea urchins), feral cats (control rodent populations) |
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What happens if a keystone species is removed or goes extinct?
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Ecosystem could crash
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What is exponential growth? How are humans an example of exponential growth?
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Exponential Growth: Rapid increase, doubles each time
The human population has doubled twice in the past hundred years |
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What is the approximate current human population on earth?
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7 billion
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What is carrying capacity?
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Carrying capacity: the max population that the environment can support indefinitely
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In what ways has human population growth affected the environment?
Be sure to be able to relate human effects to topics covered earlier in the semester. |
• Limited Resources
• The Earth can only support a certain amount of life based upon its resources • We don’t know the Earth’s carrying capacity • Tree harvesting → decrease # of trees→ decrease in photosynthesis → increase levels of CO2 →greenhouse gas increase greenhouse effect → global warming • Land Degradation o 25% of land is degraded (cannot be used anymore) • Due to combination of global climate change and poor farming practices • Ogallala Aquifer o Large underground water reserve which runs from South Dakota to Texas o Recharge very slowly o Increases in human population put a strain on this resource • Non-renewable resource due to rate of recharge |
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How does human population growth affect global warming?
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• Increase tree harvesting to make room for populations→ decrease # of trees→ decrease in photosynthesis → increase levels of CO2 →greenhouse gas increase greenhouse effect → global warming
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