Genetics Flashcards
What are the Hardy-Weinberg assumptions?
Large population, random mating, no mutation, no migration, no natural selection
What are the Hardy Weinberg equations?
p+q= 1
p² + 2pq + q² = 1
What is the fitness equation?
Fitness= mean # offspring for specific genotype/ mean # offspring for most prolific genotype
Fitness will be between 0 and 1
What is the selection coefficient and what does it represent?
Selection coefficient= 1-Fitness
Selection coefficient is the intensity of selection against a genotype.
What is epigenetics?
How a genotype is transduced to produce a phenotype
“Heritable” but does not involve changes to the DNA
What is the thrifty phenotype?
Assumes that when environmental conditions are poor for the
parent, they are likely also to be poor for the offspring. Therefore, when the parent experiences food shortage, biochemical modifications allow pre-adaptation to produce offspring that are metabolically thrifty, eating as much as possible, minimizing energy expenditure, and hoarding/conserving calories.
What is evolution?
∆ in gene (ƒ) frequency over time in a population, leads to speciation & divergence, success measured by offspring.
What is a population?
Group of interbreeding, sexually reproducing individuals w/ common set of genes.
What does DNA methylation do?
gene repression, addition of methyl groups to nucleotide bases, cytosine to 5-methylcytosine, maintained through DNA replication
What do acetylated histones do?
Generally associated with gene activation.
What is Behavioral epigenetics:
Life experiences, especially early in life, have long-lasting effects on behavior.
An example of epigenetic changes induced by maternal behavior?
Increased licking and grooming as pups led to changes in DNA methylation which changed stress response and made less fearful adult rats.
An example of X-inactivation?
Xist RNA coating an X chromosome to inactivate it, one X-chromosome randomly inactivated throughout female cats body leads to calico cats
What can differentiated adult cells be reprogrammed to as induced pluripotent stem cells (iPSCs)?
Endoderm (internal layer): lung cells, thyroid cells, pancreatic cells
Ectoderm (outer layer): neurons, skin cells of epidermis, pigment cells
Mesoderm (middle layer): cardiac muscle cells, skeletal muscle cells, tubule cells of the kidney, red blood cells, smooth muscle cells
What is genomic imprinting?
The epigenetic phenomenon by which genes are expressed in a parent-of-origin-specific manner, eg. Prader-Willi syndrome (paternal) and Angelman syndrome (maternal). May be due to differential male/female imprinting due to male waning increased fetal growth vs female wanting to have decreased fetal growth.
What are epigenetic effects of environmental chemicals?
Pb change’s DNA methylation, eg. Agouti mouse as a test for epigenetic mutagens
Totipotent Cell
Ability of single cell to divide and produce all of the differentiated cells in an organism (only the morula’s cells are totipotent able to become placenta and all )
What is determination?
When a cell becomes comitted to a praticular cell fate (unipotentcy)
What is pluripotent?
Embryonic stem cells originate as inner mass cells within a blastocyst. These stem cells become any tissue in the body except a placenta
What are hematopoietic stem cells?
They are an example of multipotency. When they differentiate into into myeloid, or lymphoid progenitor cells, the lose potency and become oligopotent cells with the ability to give rise to all cells of its lineage
What cell type is needed for animal cloning and what are the steps involved?
To clone an animal totipotence must be reestablished.
1) donor cell taken from sheep’s udder and fused via electric shock to an egg cell
2) fused cell begins dividing normally and becomes an embryo
3) embryo is placed in the uterus of foster mother
What determines the dorsal-ventral axis?
Dorsal gene
Determination of the anterior-posterior axis is by what?
Biocid gene, nanos gene, hunchback gene
What is apoptosis?
Controlled programmed cell death
What is necrosis?
Injured cells dying in an uncontrolled matter
What are the steps of apoptosis?
1) DNA is degraded
2) cell and nucleus shrink; nucleus fragments
3) macrophage phagocytizes apoptotic cells
What are the steps of necrosis?
1) cell swells
2) cell lyses and releases cytoplasmic material
How does natural selection lead to enviornmental specialization?
It is caused primarily by changing of expression levels of calmodulin
Natural selection leading to enironmental specializaton has what affect on genes?
It regulates the expression of many other developmental genes
What patterns and process of evolution arE revealed via development?
1) common genes in a developmental pathway
2) Evolution through change in gene expression
What is an antigen?
A molecule that elicits an immune reaction
What is an Antibody?
A protein that binds antigens and marks them for destruction by phagocytic cells
What is the organization of the immune system?
Humoral immunity, cellular immunity, clonal selection
What are the steps in activation of humoral immunity?
Antibodies are produced by B cells → the circulating antigens are identified and targeted → the cells producing these antigens are then targeted for destruction by macrophages.
What is cellular immunity?
Cellular immunity is produced by T cells and is direced against cells infected with a pathogen and expressing the pathogen’s protein, i.e. the antibody on the host cell surface
What are the steps of humoral immunity?
1) lymphocytes originate from stem cells in the bone marrow
2) B-cells mature in the bone marrow
3) B-cells encounter antigens they mature into plasma cells which secrete antibodies that bind to antigen (this is known as humoral immunity)
What are the steps in cellular immunity
1) lymphocytes originate from stem cells in the bone marrow 2)T cells mature in the thymus and enter circulation
3) they attack by binding host cells and lysing them (this is cellular immunity)
An immune response to a specific antigen is produced through clonal selection. List the steps of clonal selection.
1) in a large pool of B-lymphocytes each is specific for one antigen
2) when an antigen binds to a B-cell the B-cell divides
3) dividing B-cells give rise to a clone of Bcells that are all specific for the same antigen
4) the proliferation of lymphocytes is the PRIMARY immune response 5) some cells differntiate into antibody-secreting plasma cells 6) antibodies are spcific for the antigen
7) memory cells remain in circulation
8) if second exposure of the same antigen occurs
9) the antigne binds to a memory cell
10) this will rapidly give rise to a secondary immune response