1Exam 2 Study GuidePSB2000Genetics1. What is heritability, how do we study it (what are twin and adoption studies…what do their results tell us?), and what are the problems with studying it?Heritability is the amount of phenotypic variation(physical expressed characteristics such as eye color or height) in a population that is due to genetic variation among individuals. This is studied through twin studies. There are two types of twins, Monozygotic(identical=come from the splitting of the same zygote) and Dizygotic(fraternal=come from the separate simultaneous fertilization of two eggs). It makes sense that if twins came from the same zygote that they should be very similar. Twins from different zygotes will have similarities, because they are related, but will still be unique. If MZ twins resemble each other more for a given trait then a pair of DZ twins that trait is said to be highly heritable.IF MZ and DZ twins show the same amount of resemblance for that trait it is said to have a low heritability.Same thing goes with adoptions. If the kid resembles the real parents more, chances are it has to do with the genes they got rather than the environment they were raised in.There is discussion that the prenatal environment of the children may also play a role in a child’s characteristics. Is it Prenatal Environment or Genetics?2. What are examples of environmental influences on traits with otherwise high heritability?Just because a trait was inherited doesn’t mean it cannot be changed! Cautious mice that prefer the safe enclosed part of the maze can become more adventurous. Environment such as smell and lighting can alter how you react.3. What is a sex-linked gene? Understand the heritability of sex-linked genes. What is a sex-limited gene? What are examples of each (sex-linked and sex-limited)?Sex linked-a gene that is located on either the X or the Y chromosome (M=XY)(F=XX) A male can give an X or a Y to offspring, a female can give either of her two X’s. For example, a son gets the Y from dad and an X from mom who is a carrier for Fragile X syndrome(unaffected because she also has a normal Dominant X). Since the son only gets ONE X chromosome, the affected x, he will have Fragile X syndrome. Normal Daughter Mother (Xc is affected) Carrier DaughterFatherNormal Son Affected SonSex Linked= Colorblindness, Fragile X syndrome2Sex Limited= Characteristic present in both sexes but usually one or the other. Chest hair, breast size (can be turned on by sex hormones Testosterone/Estrogen.)4. What is the multiplier effect? When heritability is OVERESTIMATED. Genetics made Shaq tall but not good at basketball. Being tall gave him potential so his environment nurtured him into a star using that advantage. His skill is then blamed on he’s genes, when in fact it was the thousands of hours spent practicing.5. Terms to know and understand: DNA, RNA, gene, chromosome, transcription, translation, homozygous, heterozygous, dominant, recessiveDNA- think double helix, contains all of the genetic instructionsRNA-A single strand, is an exact copy of DNA made during transcription(COPYING)Gene- A unit of heredity. One specific stretch of DNA that codes for a particular proteinChromosome- humans have 46, they contain your genetic information tightly coiled up with different proteins and structures.Transcription- transcribe is to write, the DNA is copied into RNA by different enzymesTranslation- The RNA that was just copied gets read and decoded by a ribosome which translates that information into a protein.Dominant, Recessive, Homozygous, HeterozygousHeterozygous Parents G=Dominant (yellow) g=Recessive(green)6.Homozygous DominantGG is Dominant homozygous (same allele). gg is Recessive homozygous. GG offspring is yellow, gg offspring is green. Heterozygous is Gg. It has one dominant allele and one recessive. Therefore the dominant trait will be expressed. Gg will appear yellowHeterozygous- looks like the dominant traitHomozygous recessive37. What is evolution? What types of traits move on to the next generation? What is natural selection? What are adaptive characteristics?Evolution is a very long process. With each new offspring from each parent comes a new combination of genes, genetic variation. Some might have weird mutations and be blue. However, if that blue mutation allows you to get away from predators more easily. You will be able to have children. These children can also have this trait that made you so successful. The successful traits and traits that increase survival make it to the next generation. Adaptive characteristics are the process by which inherited traits that increase an animals’ likelihood to service/reproduce become more prevalent in a population. Ie.) A owl butterfly that has adapted to displaying eyespots on its wings when approached by a bird. Prevent birds from preying on them as much.Evolution implies it just happened randomly. Evolution arises from these modifications (from genetic variation) that are more successful. Those are passed on to the next generation.8. What is epigenetics? Why does this new field of research “blur the line between environment and genetics”?Anything other than DNA sequence that influences the development of an organism. The cells of a multicellular organisms are genetically identical but are functionally different due to what region of DNA is being expressed or inhibitedDrug Actions**In general, all drugs of abuse cause dopamine release in the nucleus accumbens. Okay, not a question, but KNOW THAT!1. Stimulants: know some examples of stimulant drugs. What neurotransmitters do they increase? What are some behavioral effects?Amphetamine, Cocaine, Ritalin, Ecstasya) Cocaine: what is its method of action (ie, what does it do at a synapse)? Blocks the reuptake of dopamine, serotonin, and norepinephrine. b) What does Ritalin do at the synapse? How is it different from cocaine? Blocks the reuptake of dopamine like cocaine. Not as sudden as cocaine.c) What does ecstasy do at the synapse? What are the effects of long-term use neurons? What are some psychological/cognitive effects? Know examples of hormones that ecstasy affects and the behavioral result. Ecstasy increases dopamine release. Hallucinogenic at high doses. Large injections destroy neurons
View Full Document
Unlocking...