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Society and Genetics


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What are HOX genes and why are they important in development?
set up basic axes of body orientation, responsible for development controls whether or not anatomical parts develop in the appropriate places.
What are highly conserved genes?
genes that do not vary from species to species and stay relatively the same throughout species.
How is the human body segmented? (3 answers)
1. The body is segmented along its length; each segment has its own embryologic somite 2. These are retained in the adult as dermatomes and mytomes 3.The head is also segmented as an embryo and has gills, which become various structures like the ear and glands.
What is intrinsic in relation to development
part of the original cell
What is extrinsic in relation to development
egg has mRna pieces distributed randomly throughout the cell. After Fertilization it divides and the mRna is unevenly distributed through out the egg
How do protein gradients direct development? (6 answers)
1. Maternal mRNA coded proteins set up gradients in the embryo which can be used to determine body orientation. 2.Having multiple genes gives a more precise location by setting up latitutes and longitudes. 3. Refines the longitudes and Latitudes in modules. 4.Defines identities of different modules. 5. Specific coordinates turn into new world form. 6.Set up the 3rd axis.
what are somites?
a muscle group and neurovascular bundle
What are dermatomes?
(skin associated with spine
What are mytomes?
(segments of muscles)
What is situs inversus and how is it caused?
Inverted position of the internal organs and is caused by cilia traveling in the opposite direction of which it should.
In Kartengeners Syndrome cilia is (fill in the blank)
How does development relate to stem cells?
Cells start out totipotent and embryonic stem cells have the potential to become pluripotent and differentiate into any three germ layers (meso, ecto, endo)
What is an antigen?
molecules,viruses, bacteria, etc.. that stimulate the immune system
What are self antigens?
antigens present on self tissue that notify the body not to provoke an immune response, thus keeping the body from attacking itself.
name the five non-specific defenses.
1. physical barrieers 2. cytokines 3. interferons 4. interleukens 5. compliments
what do physical barriers do in non-specific defenses
creates mucus and inflamation.
What are Cytokines? (non-specific defense)
proteins that attack foreign antigens and alert the immune system.
What are Interferons? (non-specific defense)
tell the immune system when the body is effected with virus.
What are Interleukens? (non-specific defense)
triggers fever and raises body temperature.
What are compliments? (non-specific defense)
blood proteins and inflammation and can lyse cells.
What are the five types of white blood cells.
1.Macrophages 2.Neutrophils 3. Basophils/mast cells 4.lymphocytes 5. Natural Killer T cells
What do macrophanges do?
They are large phagocytes that present MHC molecules on the surface, which tells helper T-cells to carry to B-cells to create antibodies.
Describe the lifespand of neutrophils and their activation.
neutrophils live for less than five days. They are activated in the blood stream and become active and indiscriminate killers outside the blood stream.
Pus is a sign of..?
What are Basophils/mast cells and what do they do?
types of blood cells. Mast cells release histamines to induce inflammation.
Lymphocytes consist of what three types of cells, and what do they do?
lymphocytes consist of t-cells, b-cells, and natural killer t-cells. They are adaptive or specific immune response.
What are Natural killer t-cells?
are non-specific immune response that kill cancer cells and cause them to destroy themselves.
What does a chemotaxic blood cell do?
sends out chemicals that attract other WBC to the site of the infection.
What does a phagocytotic blood cell do?
WBC engulfs and ingests bacteria or other foreign bodies.
What are the three functions of the Lymphatic system?
1. Transports lymphocytes 2.Recovers excess interstitial fluid and return it to circulatory system 3. Fat absorption in intestine via lacteals
Name the four parts of the lymphatic system
1. vessels 2.Nodes and Lymphoid tissues 3.Thymus 4.Spleen
Name two functions of the Nodes and Lymphoid tissues.
1.filter lymph by removing antigens 2. warning system by activating lymphocytes Thymus
What does the thymus produce?
mature lymphocytes.
What are the two functions of the spleen?
1. Blood reservoir 2. Contains lymphoid tissue to remove pathogens
What are T-cells and what do they do?
Respond to phagocytes that present the antigen infected cells, goes to B cell and finds the proper b cell that matches that antigen, than stimulates it using cytokine, b cells multiply and spew out antibodies
what do cytoxic antigens do?
finds specific antigen and kills them
What do plasma b-cells do?
produce antibodies which either directly inactivate antigens or stimulate other immune responses
What do memory b cells do?
remember antigen for the next time so they don’t have to be stimulated by the helper t-cell (known as secondary response)
What are antibodies?
- Are proteins which bind to the bacteria and viruses to stop its function
How are antibodies coded in the genome?
1.There is a heavy and light chain; the lower portion of these chains are constant while the amino acid sequence on the upper portion of the polypeptide change is variable 2. The V,D, J genes for heavy chains are on chromosome 14; light is on 2 and 22 3. Since each polypeptide is encoded by more than 1 gene, can produce millions of possible antigens 4.Alternative splicing : during maturation of b-cells, these are whittled down to a few combos in each antibody group, allowing same genes to code for multiple antibodies
What is active acquired immunity?
- body makes own antibodies, natural exposure to antigen, artificially (eg. Vaccines)
What is passive acquired immmunity?
transfer antibodies from another individual (mother&child through placenta or breast milk) or inject antibodies
What are some possible causes of autoimmune diseases?
1. A virus incorporates parts of self antigens to its own surface during replication (basically camouflage) 2.Poor selection for immune cells – doesn’t select against those that attack self-cell 3.Similarity of self and non-self antigens 4.Fetal cells and mosaicism
How can fetal cells trigger an autoimmune reaction?
Fetal cells are transferred from the infant to the mother, but it is attacked by the mother’s immune system
What is Mosaicism?
x inactivation in mother causes 2 types of cells illicit immune response
What does Hardy-Weinberg Equilibrium (HWE) allow us to predict?
Allows us to predict the portions of genotypes in a population if it is in equilibrium
How can HWE be used to predict probabilities in genetic fingerprinting?
1.Genetic fingerprinting uses variable number tandem repeats (VNTR) 3.HWE can be applied to parts of genome that do not affect the phenotype (therefore not subject to natural selection), forensic scientists use these VNTR of junk DNA to do genetic fingerprinting 4.Samples are either heterozygous or homozygous for VNTR – use HWE to calculate probability that it will match another random match
What are the five conditions for HWE to hold true?
1. Random mating 2. large populations 3. no migration 4. no mutation 5. no natural selection
How does consanguine mating affect HWE?
increases the chance that alleles are more common by descent, more homozygotes.
What is genetic drift
Genetic drift is random changes in allele frequency due to the effect of limited genetic sampling with each generation.
Why is genetic drift more common in small populations.
Small populations tend to have less genetic diversity, more susceptible to random events.
What is Founder effect?
an unrepresentative sampling of the original population due to moving to another place
What is population bottleneck?
An event that occurs to prevent a significant portion of populations from reproduce (ie. Death)
What does genetic drift and population bottleneck have in common?
Both deal with small population, so the majority of genetic info comes from a small sampling of the original group
What is the ‘Extinction Vortex’?
a class model used to categorize extinction into context
Descibe the Extinction Vortex of Florida Panthers
1.Small, isolated, fragmented population from things such as habitat loss, overhunting, or exotic species 2.Due to inbreeding there is a loss of genetic diversity (small population may be affected by genetic drift) 3.Reduced adaptability, survival, and reproduction caused by increased homozygosity (inbreeding) 4.Combined with catastrophes, environmental variation can lead to reduced numbers => further extinction
How does migration affect HWE?
migration introduces new genes by bringing in genes that are different from original population, therefore new introduction of genes and alleles change HWE frequencies
How is migration being used to help florida panthers?
Researchers mating Texas cougars with nearly-extinct Florida panthers to introduce new alleles into their gene pool and increase genetic diversity
How does mutation affect HWE?
Since mutations change an allele into another allele, as humans we have some mutated alleles that would be harmful if we were homozygous for it. Therefore it can be passed on to the next generation. Also mutation can kill before reproductive age and change frequencies for next generation
What is Fisher’s Fundamental Theorem?
The amount of possible selection is proportional to the amount of genetic variance.
What is Eugenics?
is a scientific field involving the controlled breeding of humans to get desirable traits.
What are the 4 steps for natural selection?
1) More individuals are produced than can survive. Consequently ⬦ 2) There is a struggle for existence, and because 3) Individuals vary in features that influence their survival and reproduction (no two individuals are exactly the same, and some will do better than others i.e. natural selection), 4) There will be EVOLUTION if those features that favor some individuals over others are heritable.
How does resistance and natural selection coincide?
1. Resistance evolves via mutation, then natural selection 2.Bacteria can laterally transfer genes spreading the resistance quicker 3.Prophylactic use of antibiotics increases resistance.
What are the four limits on natural selection?
1)Constraints imposed by phylogenetic history. Evolution builds on what is there. We descended from a quadrupedal ancestor, so some aspects of our anatomy such as our backs, knees, and feet are adequate but often fail. 2) Lack of appropriate genetic variation. -Fisher’s Fundamental Theorm 3) Natural selection cannot act on traits that appearpost-reproductively. The deleterious genes have already been passed to the next generation. 4) Developmental interactions among organs or structures that necessitate trade-offs. For example, having larger babies might compromise female pelvic and hip structure.
What are some characteristics of human genetic diversity?
1Population diversity in humans throughout the world 2.Diversity within populations such as the diversity within one race rather than comparing two races
In terms of the molecular clock, to calculate the divergence of species you must do what to the overall variation?
Divide by 2
Name three differences between polymorphism and mutation.
1.mutation occurs in less than 1% of the population while polymorphism occurs in more than 1% of the population. 2. Polmorphism is induced from within the cell while mutation is induced from outside the cell. 3. polymorphism is heritable mutation is not.
How does mutation occur?
Mutations can occur through - Exposure to mutagen, radioactive material, sunlight - Spontaneous mutation, higher for mitochondrial genes because they do not have repairing enzymes.
Why do mutations persist in the future?
Mutations can persist in future generations: - Germline mutations occurring before meiosis - Genetic load: all humans carry a number of deleterious alleles that can be harmful if homozygous
Name three reasons why not all mutations are bad.
1.CCR5 gene prevents HIV infection 2.mutations are a source of natural genetic diversity and variation 3. not all mutant phenotypes are abnormal or unusual
What is a ‘molecular clock’?
1.the observation that some genes and other regions of genomes appear to evolve at average constant rates. 2. The more time between the species' divergence from their common ancestor, the greater the difference in genes (e.g. number of nucleotide substitutions).
What is the mode of inheritance for achondroplasia?
Autosomal Dominant
Name 4 symptoms ofachondroplasia.
1. short limbs 2. narrow trunk 3. large head 4. motor problems 5. chronic ear infections 6.obesity 7. neurological problems
What are the possibilities for achondroplasia surviving in the gene pool?
1. De Novo mutations 2. social acceptance 3. Dwarfs mating with one another
Where are the mutational hotspots?
1.Repetition of single bases may result in “spelling errors” 2.Repeated sequences can cause a strand to loop around itself during replication 3. Palindrome can be confusing 4.Crossing over
How are mutational hotspots useful in thinking about genes of major effect in fatal diseases?
1. If there is an area that is important but also subject to a lot of mutations, 2. A condition that is fatal before adult, but you see it in a lot of places it may be because it is a rapidly evolving area that is subject to de novo mutations. If it is dominant and fatal, it will wipe itself out unless it is caused by de novo, but recessive and fatal can remain in the gene pool because it can be carried by heterozygous

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