7D- nature vs nurture Flashcards
• proportionate influences of genetic material, and environmental and epigenetic factors, on phenotypes
environment
the conditions and resources external to an organism with which that organism typically interacts
proportionate heritability
the amount of phenotypic variation that can be explained by genes in a given population
epigenetics
changes to an organisms phenotype resulting from modifications to gene expression
gene expression
the process of reading the information stored within a gene to create a functional product, typically a protein
transcription
the process whereby a sequence of DNA is used to produce a complementary sequence of mRNA
translation
the process whereby an mRNA sequence is used to produce a protein
DNA methylation
the process by which methyl (-CH3) groups are added to particular nucleotides in a DNA segment so as to modify the expression of a gene
somatically heritable
genetic traits or alterations to a cell which are inherited by daughter cells during the course of regular mitotic cell division
what is an organisms phenotype explained by
partly by genes and partly by environmental factors
what does proportionate heritability tell us
an organisms phenotype can be entirely due to the environment (dying hair) or genes can play the main role in phenotype determination (blood type)
how do environmental factors impact phenotype
they will typically act in ways that influence the performance of an organisms proteins. they modify the functions of proteins rather than affecting the creation of the proteins themselves
what is transcription and translation
transcription involves reading and copying out a gene sequence from a DNA molecule. the copy- mRNA- moves out of the nucleus to ribosomes in the cytosol or on the RER for translatoin
translation is where the mRNA instructs the ribosome how to build the specific protein for which the DNA sequence codes
what is the process of gene expression
DNA -transcription> copy of gene (mRNA) -translation> protein
what does epigenetics alter
they alter the process of transcription.
how can epigenetics regulate expression
they can increase or decrease the amount of transcription of a particular gene and therefore alter the amount of protein produced. epigenetics regulate the expression of specific proteins, which changes growth and development
show how the presence or absence of an epigenetic factor can produce a different genotype
epigenetic factor X present → gene Z turned on → protein produced → phenotype A
epigenetic factor X present → gene Z turned off → protein not produced → phenotype B
what are 2 types of epigenetic changes
DNA methylation and histone modification
what is DNA methylation
methyl groups attach to nucleotides within the DNA sequence of a particular gene
they then alter levels of gene expression, typically by silencing it
what is DNA demethylation
removal of methyl groups from a DNA sequence
gene is expressed
what is histone modification
when histone methyltransferases HMT join methyl groups to histone tails and modify how tightly a DNA molecule is wrapped aruond it
if the DNA is condensed tighter around the histone, it makes it more difficult for genes to be transcribed and less likely to be expressed
if the DNA is less tightly packed, it is easier to transcribe and more likely to be expressed
what are methyl groups like
they are like a light switch. when they attach to parts of our DNA sequence, they tell our cells to read or to not read this section, which in turn means that the associated proteins aren’t created
what is the importance of epigenetics
helping to control cell differentiation → despite containing the same DNA, not all of the cells inside an organism are the same. different cell types are regulated largely by epigenetic mechanisms that turn off unneeded genes and promote expression of required genes
provide an environment response mechanism→ epigenetic modifications act as a rapid feedback mechanism by which an organism can respond to changes in their environment. the genes for these proteins are stimulated by high temperatures to demethylate, activating transcription and ensuring more of these useful proteins are synthesised
are epigenetics heritable
they are somatically heritable although some epigenetic changes may also be passed onto offspring during reproduction
why do identical twins become increasingly different as they age
genes are being switched on or off by exposure to different environmental factors, but these are being passed onto new cells as they grow and regenerate- somatically heritable
