Midterm 1 Flashcards

Question

Sickle cell anemia is a balanced polymorphism. What does this mean and why does it occur? Briefly explain the relationship between sickle cell anemia and malaria that leads to this balanced polymorphism in some human populations. Your answer should include the genetics of sickle cell anemia, selection pressures, the geographic relationship and the biological relationship between the diseases, and what human populations are at risk for sickle cell (2 main ones).

Answer 1

Balanced polymorphism: stabilizing selection produces incomplete/partial dominance 2 different versions of a gene are maintained in a population of organisms because individuals carrying both versions are better able to survive than those who have two copies of either version alone There is a higher frequency of people carrying sickle cell anemia in regions where there is malaria. This is because those with heterozygous or homozygous sickle cell gene have protection against malaria. Malaria became a stabilizing selective pressure as swidden agriculture opened up tropical forested ecosystems. (expand with more information)

Answer 2

Epigenome: set of instructions sitting on top of the genome and acting as a switch to turn genes on and off - Separate from, and in addition to, regulatory genes - Affects how genes are read 3 Examples: agouti mice, mothers in famine, stressed out rats Agouti mice: agouti mice who ate a diet rich in methyl groups grew up to be brown, lean, and not prone to disease, whereas the mice which ate a normal diet grew up to be yellow, fat, and prone to disease. Mom’s food insecurity -> child’s adult obesity: pregnant women were followed during the Dutch Hunger Winter (a famine) in the 1940’s. Infants later in life experienced different health issues based on what period of gestation their pregnant mother had experienced the famine. Stressed out rats: Some rat mothers lick their offspring to comfort them and others do not. The rats who had mothers that licked them a lot became calmer, more healthy rats, whereas the rats who did not were more nervous and had more health problems. To see if this effect was genetic, they swapped out the offspring between the two kinds of rats to be raised by the other mother. The rats born of unaffectionate mothers, but raised by affectionate mothers saw the same health benefits as the ones born of the affectionate mothers.

Answer 3

DNA methylation is an epigenetic mechanism that occurs by the addition of a methyl (CH3) group to DNA, which alters the gene expression.

Answer 4

Yes, some epigenetic marks are reversible. Some ways to positively impact epigenetics: Stay healthy and nourished your entire life, especially while with child. Avoid drinking and smoking. Not all marks are reversible, if a mother was malnutritioned, this can follow the child for their entire life as well.

Answer 5

Genome - an organism’s entire set of hereditary instructions coded into DNA Epigenome - set of instructions sitting on top of the genome and acting as a switch to turn genes on and off

Answer 6

Lamarck came up with the theory of Transformational Evolution (aka Uniformitarianism), which asserts that traits became more or less common over just a few generations through their use or disuse. He pointed to the longer neck of giraffes compared to their ancestors as evidence, since the ones with longer necks could reach more leaves. This carries over well to epigenetics, in which genes may be switched on or off for generations due to environmental factors of just one.

Answer 7

1. Sexual selection - One trait, for instance having coarse, full body callaces, deemed so unattractive as to produce no viable offspring. 2. Mutation - A rare, volatile allele could be particularly prone to mutation, and disappear. Alternatively, a new allele could mutate which is superior in any of the other four categories. 3. Genetic drift - An entire population with a few distinct alleles could be wiped out in a famine or volcanic eruption. 4. Gene flow - A group which had been preserving a homozygous recessive phenotype could begin breeding with a population with a dominant allele 5. Adaptation - One trait could simply prove beneficial over the course of natural selection. For instance, in a grasslands transitioning into dessert, creatures which require a lot of water to survive will die off.

Answer 8

It is out of equilibrium, which means evolution is occurring. Evolution is always occurring. If the population is out of equilibrium, the equation does not add to equal 1.

Answer 9

1. Mutation has happened. - > Would have to be not occurring 2. There is selection for certain variants. - > Would have to be truly random 3. There is a small population. - > Would have to be infinitely large 4. Few members of the population breed. - > Every member would have to breed 5. Parents choose their children’s reproductive partners. - > This is non-random 6. Everyone produces the same number of offspring. There is only migration out of the population, not in. -> No migration at all

Answer 10

Adaptation is the long term result of natural selection. Natural selection accounts for adaptation, which is a series of beneficial adjustments.

Answer 11

Prenatal- Timing: Fertilization to birth Milestones: Embryo, organ development, rapid growth in length, rapid weight gain Energy directed towards GROWTH Postnatal- Timing: birth to 10 years following puberty Milestones: neonatal, infancy, childhood, juvenile, puberty, adolescence, Energy directed towards GROWTH (and reproduction at puberty) Adult- Timing: 20 years to end of life Milestones: Prime, senescence Energy directed towards REPRODUCTION

Answer 12

Because the grandmothers are not busy reproducing themselves, they have more time available to devote to helping out the mother take care of their kids, which leads to healthier, better offspring, and the ability to have more offspring. Elder males are important because they can pass on knowledge. They can still help with child rearing too. And if they’re not frail, they can protect the tribe

Answer 13

Genetic Adaptation – population level, permanent & inherited Developmental Adaptation – individual level, nonreversible •Capacity to change inherited, change not inherited Acclimatization – individual level, reversible •Capacity to acclimatize inherited, changes not inherited Cultural Adaptation – individual & population level, learned

Answer 14

An example of clinal variation is the frequency of yellow-brown hair in Australia. The populations near the coast are less likely to have yellow-brown hair, and as you gradually move closer to the center, the frequency of yellow-brown hair gradually increases. Another example is the percentage of people in England with red hair. The distribution of red hair is non-continuous, and seems almost entirely contained within one or two discrete regions.

Answer 15

Skin pigmentation is a global cline Ancestral skin pigmentation was light-colored under body hair/fur (compare with contemporary chimp & bonobo) Skin pigmentation via melanin and melanocytes are a natural sunblock that protects us from UV radiation, which can cause sunburn or cancer. -> Climates with more UV exposure naturally select for more pigmentation Vitamin D is synthesized in skin when exposed to UV radiation. Lack of vitamin D can cause rickets (soft, bendy bones). -> too much melanin -> not enough UV radiation -> lack of vitamin D -> rickets Melanin protects folate/folic acid which is important for synthesizing DNA and cells in the body, including sperm production and fetal development. -> Melanin protects folic acid -> ability to reproduce

Answer 16

4 Primary Kinds of adaption: 1. Genetic change (themoregulation - according to Bergmann's law, people living in cold climates are naturally selected to have shorter limbs, stockier builds to conserve warmth, and vice versa for hot climates) 2. Developmental adjustment (nutrition - children with protein deficiency result in kwashiorkor, symptoms are swollen abdomen, stick-like arms and legs, other symptoms, and will have retarded growth as an adult). 3. Acclimatization (high altitudes - more red blood cells and capillaries are made to carry oxygen, lungs increase in size) 4. Culture practices and technology (workload - tools are made to allow more work to be done more efficiently)

Answer 17

Wolff’s Law: Bone mass produced where needed, taken away where not needed. For example, physical activity results in loss of bone density. Useful for archaeologists because they are able to see what people did when they were living there, and be able to construct a more compelling argument to how their life may have gone and what their duties entailed.

Answer 18

People in hotter climates -> shorter limbs, stockier builds to conserve heat through less surface area in comparison to mass People in colder climates -> longer, leaner builds to release heat through more surface area in comparison to mass

Answer 19

``` Selective environmental pressure No variation in gene pool Variation in gene pool “Arms Race” predation, parasitism, bacteria/virus We need to maintain genetic variation Mutation Sexual reproduction ```

Answer 20

Compare K and r life history strategies. K-selected: Adapted for more stable environment, high intraspecific competition. Few offspring, who are born helpless and heavily invested in. Ex: Primates R-selected: Adapted for unstable environment, live long lives if they survive, produce many offspring with low survival rates. Ex: Trees

Answer 21

Predictability of the environment (randomly occurring hurricanes or no), availability of resources (how many houses, foods, and mating partners), and environmental stressors (number of predators).

Answer 22

Generally much smaller than host Able to travel between hosts Able to survive for time outside of any host May require different hosts for each stage in life cycle STDS - Small, travel between, survive outside host, different hosts different stages

Answer 23

Microbiome! Ten times more non-human cells in/on a human. Bacterias, viruses, fungi, tiny little animals, other single celled organisms.

Answer 24

Predation - Mostly interspecific. One species eats other species. Predator benefits at the expense of prey. Humans & chickens. Parasitism - Interspecific. One species lives off of other species’ energy, but usually does not kill it. Parasite benefits at expense of host. Tape worm & human. Mutualism - Interspecific. Both species engage in behaviors which benefit the other. The bird that eats the gunk on crocodile teeth. Competition - Inter/intraspecific. Two species or organisms in the same species rely on shared resource. Both suffer. The perpetual antagonism between Egypt and Ethiopia/Eritrea over use of the Nile. Commensalism - Interspecific. When one species benefits off of shared community while other neither benefits nor suffers. Elements of the human microbiome. Cooperation - Intraspecific. When members of same species work together for common goal. Group hunting of buffalo herd. CCCMPP - Commensalism, cooperation, competition, mutualism, parasitism, predation.

Answer 25

Red Queen Hypothesis - Evolution is a perpetual arms race of competing species, through non-symbiotic competition, predation, and symbiosis. Microevolution scale, always occurring. Court Jester Hypothesis - Macroevolution occurs due to random events of mass disaster.

Answer 26

A disturbance process is a temporary but significant change to the environment as part of a natural cycle. Biotic example: The black plague Abiotic example: Hurricane

Midterm 1 Flashcards

(50 cards)