genetics & brain development Flashcards
the human genome is a set of ______ for _________ a human being.
instructions; constructing
what is a genotype?
23 pairs of chromosomes someone has
a chromosome is a _______-like structure made of _______ and ___ molecule(s) of DNA.
thread; protein; 1
a gene is a segment of ________ that produces ___________ protein(s).
a gene can have multiple ________, each representing a ____ in the sequence of DNA for that gene.
DNA
alleles; variation
what do histones do for a chromosome?
provide structural support
gene expression is the translation of _________ into __________.
genotype; phenotype
what is an imprinted gene?
how much of a human’s genes are imprinted?
copy of gene expressed that belong to either father or mother but not both
~1%
epigenetics is the science of how ____________ and _________ can cause ________ to how you genes work.
gene _________ can be switched on and off, depending on _______ and ____________.
behaviours; environment; changes
expression; behaviours; environment
can epigenetics be passed on to offspring?
yes
give 1 example of epigenetic change.
smoking causes genome-wide methylation where chemical groups are added to DNA to block the transcription process, switching the genes off.
can be reversed and resolved when smoking ceases.
what are the 5 stages of gene expression?
- epigenetics
- transcription
- post-transcription
- translation
- post-translation
imprinted genes are crucial for _________ development and ____________ in these processes lead to _________ disorders.
it is regulated by _______ modifications which __________ gene expression but not the _______ sequence.
normal; disruptions; genetic
epigenetic; alter; DNA
**epigenetic mods include DNA methylation & histone modifications
paternal vs maternal imprinting.
paternal imprinting - paternal allele silenced, only maternal allele expressed.
maternal imprinting - maternal allele silenced, only paternal allele expressed
1) what is an SNP?
2) SNP results in different versions of a gene, aka ______, which may affect traits.
3) when SNP occurs (at least __% frequency), it contributes to genetic ________ in that gene, influencing things like disease susceptibility and responses to treatment.
1) Single Nucleotide Polymorphism - variation in a single nucleotide (A, T, C, or G) at a specific location in the DNA sequence.
2) alleles
3) 1; diversity
huntington’s disease is inherited as an autosomal _______ trait. it only requires ______ copy(ies) of the dominant huntingtin (____) allele to develop the disease.
dominant
single
HTT
there are a pair of sex chromosomes (XX or XY) and ___ pairs of autosomal chromosomes (aka autosomes) in humans.
X is always present in the _____ and either X or Y is present in the _________.
When ovum (X) is fertilized by sperm (X or Y), resulting combination determines sex of the offspring:
either female (XX) or male (XY)
22
ovum (egg cell); sperm
sex-linked characteristics are ________ resulting from gene expression on the ___ chromosome.
phenotypes; X
1) hemophilia is a __________ condition. it is an example of a sex-linked characteristic. it is typically inherited in an X-linked _________ manner. This means that the gene responsible for the disorder is located on the ___ chromosome. Males (XY) have one X chromosome, while females (XX) have two.
2) Males have only 1 X chromosome. If they inherit an X chromosome carrying the hemophilia allele (Xh), they will express the condition. Their chromosome will look like _____.
3) Females have 2 X chromosomes. They can be ______ of the hemophilia gene if one of their X chromosomes has the hemophilia allele (Xh). They have another healthy X chromosome to mask the effect of the faulty gene, so they typically do not express the disorder unless both X chromosomes carry the allele (XhXh).
1) blood-clotting; recessive; X
2) XhY
3) carriers
XHXH: Both X chromosomes carry the normal allele, so the female is not affected and does not carry the hemophilia gene.
XHXh: One X chromosome carries the normal allele, and the other carries the hemophilia allele. This female is a carrier but typically does not express the condition.
XhXh: Both X chromosomes carry the hemophilia allele. In this case, the female would express hemophilia.
what is CNV?
- associated with _______ and _______ where there are more frequent ________ of _____ genes.
copy-number variation - number of gene copies differs from person to person
autism; schizophrenia; repeats; rare
heritability is the contribution of _________ to the _________ of a _____ observed in a _________.
cannot be assessed without taking __________ into account. (nature + nurture)
what study is associated with heritability?
genetics; variation; trait; population
environment
twin and adoption studies
*minnesota study of twins reared apart where 81 out of 137 twins are reared apart.
is Alzheimer’s disease a cause of nature or nurture?
both.
how is nature responsible for development of Alzheimer’s disease?
inherited APOE4 allele, increasing baseline risk
how is nurture responsible for development of Alzheimer’s disease?
nurture modifies risk that nature (APOE4 allele) presents
- sedentary lifestyle, unhealthy diet –> increase risk
- regular exercise, cognitive stimulation –> increase brain plasticity and cognitive reserve –> protects against AD
