1 Section 1 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 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 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 Daughter Father Normal Son Affected Son 2 Sex Linked Colorblindness Fragile X syndrome Sex 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 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 Terms to know and understand DNA RNA gene chromosome transcription translation homozygous heterozygous dominant recessive DNA think double helix contains all of the genetic instructions RNA 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 protein Chromosome 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 enzymes Translation The RNA that was just copied gets read and decoded by a ribosome which translates that information into a protein Dominant Recessive Homozygous Heterozygous Heterozygous Parents G Dominant yellow Homozygous Dominant Heterozygous looks like the dominant trait g Recessive green GG 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 yellow Homozygous recessive 3 What is evolution What types of traits move on to the next generation What is natural selection What is artificial selection Why did Darwin prefer decent with modification to evolution 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 Artificial selection is a process where a certain trait is isolated and bred exclusively Think corn Corn with brown and purple kernels doesn t appeal to buyers so farmers isolate and grow only the true breeding corn that yields big yellow kernels 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 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 inhibited Section 2 Know the different organelles and their functions 4 The cell membrane is a lipid bilayer That is two lipids tail to tail The Tail part is hydrophobic scared of water the outside and inside wall is hydrophilic loves water This water hating region on the inside means water soluble ions Sodium potassium Chloride can t get through They have to be let in through proteins called ion pumps This allows cells to regulate themselves Understand the structure of the cell membrane Know the parts of a neuron and their functions Be able to label the parts of a neuron Dendrite receives info from axon terminal Axon carries nerve signals away from soma Myelin sheath insulates axon makes it faster Axon terminal contains synapses which release neurotransmitters Node of Ranvier gaps in myelin sheath capable of generating electrical activity to keep the action potential moving Compare motor neurons sensory neurons How are they different from each other how are they the same Be able to draw each one Which one is multipolar and which one is unipolar Motor Sensory 5 Soma in Spinal cord Axon is nerve in body Terminals are in muscles MULTIPOLAR Soma outside of Spinal cord Very long axon Special endings in skin Terminals are in Spine
View Full Document
Unlocking...