Genes and environment pg 140 Flashcards
What is Phenotype
characteristic of an organism etc. sex size and shape
What is Genotype
genetic makeup of organism etc. height and freckles
What is continuous variation
Are the characteristics affected by both genotype and environment. etc. height
Charactistic have a average human range etc. height size
Are controlled by genes at many loci such as polygenetic inheritance and influcense gene expression
What is discontouonous variation
Organsims genotype is expressed without environment being involved.
Genes are controlled at a single locus
Locus
position of gene on chromosome
What does polygenic inheritance mean? and examples
More than one gene with many loci, which interacts with each other, coding for a single feature (contionuous variation). Height, weight and skin pigment
Why is their an increase in human height
taller men have more children
Greater movements of people = less inbreeding
Better nutition and improved health
end of child labour
How is mealin made
MSH are recoptors on melanocytes and signal melain to be placed into melanosomes In the melanocytes. Melanosomes and transfereed to skin and hair.
Lots of UV light effect on melain and low
Lots of UV light
more MSH produced
More MAH receptors forming on melanocytes so more melain produced
more melanosomes collected around nucleus of the skin
How do animals make melain
animals use an enzyme called tyroysinase which catalyses amino acid tyrosine to mealin.
Enzyme is unstable and inactivated at normal body temperatures
How does the environment influence the epigneeome of two identical mice?
Healthy brown mouse
agouti gene is methylated and no isn’t expressed
Obese yellow mouse
agouti gene isn’t methylated so is expressed and binds to MSH rectors on skin preventing it from being brown.
How does behavior cause epignemome changes?
High licking and grooming causes no methylation of GR gene so GR gene is expressed and high stress hormone glucocorticoid binds to GR receptors = low anxiety
Vice versa for bad parents, but their is no methlaytion of GR gene so isn’t expressed and high glucocorticoid has no GR receptor to bind to it so high anxiety
What is cancer
when cell multipcation is faster than the rate of cell death causing development if a tumor
Describe the two genes that have a role in triggering cancer
Oncogenes
These code for the next stage in cell cycle and dna mutations can cause cell cycle to be continuously active=to much cell divison=tumour
Tumor suppressor genes
Porduce proteins which stop the cycle. more methylation causes no brake on cycle
How can environement cause canacer
UV light damages DNA in skin cells and etc. can cause a mole to grow bigger
Diet whereby vegatlbes causes lots of antiotoxidants which kill free radicals and radicals contriube to cancer through DNA damage
Can be triggered by virus infections whereby a virus’s RNA may contain an oncogene
Smoking increases chance of lung cancer
