patterns of inheritance Flashcards
what is synapsis, when does it occur, and how does it occur?
-occurs during prophase 1 of meiosis
-Homologous chromosomes pair together during the process of synapsis forming a tetrad
Non-sister chromatids from each homologous chromosome exchange genetic information which results in crossing over
how many viable eggs does oogenesis produce and why?
Produces one viable ovum (egg cell) and three un-viable polar bodies as a result of uneven cytokinesis
what is the differnece between primary and secondary oocytes?
primary oocytes are egg cells that have not gone through meiosis 2, and are therefore still diploid. Seondary oocytes are egg cells nad are haploid, created after meiosis 2.
how many viable sperm cells are produced via spermatogenesis?
Produces four viable spermatozoa (Sperm cells)
what is the law of segregation?
homologous allele pairs from the initial diploid cells of mitosis separate randomly into the 4 gametes produced after mitosis 2. This is because each gamete only receives one allele, and because of synapsis and independent assortment in metaphase 2, which one is received is random.
what is the law of independent assortment?
-each allele pair seperates indpendently into different cells during gamete formation when they are unlinked (two different characteristics) and on different pairs of homologous sister chromatids.
-If two traits are controlled by genes on different chromosomes, the way one trait is inherited doesn’t affect the way the other trait is inherited.
-If genes are on different chromosomes, they don’t “stick together” when passed down—each gene is inherited independently.
how are the laws of independent assortment and segregation different?
the law of indepndent assortment refers to how two different genes are inherited on different chromosomes, and that they are always inherited separately if they are on different chromosomes (not “sticking” together)
-however, the law of segregation states that an allele for a gene on homologous chromosomes (sister chromatids) goes randomly into one of the 4 gametes produced.
what is nodisjunction, when does it occur, and what does it lead to?
- it leads to aneuploidy (having an abnormal number of chromosomes)
-When homologous chromosome pairs during Meiosis I or sister chromatids during Meiosis II do not divide correctly
The resulting gametes have too many or too few chromosomes
what are autosomes?
Any of the chromosomes not involved in determining sex (Chromosome pairs 1-22 in humans)
what aneuploid causes down syndrome?
Trisomy 21(Aneuploid Condition)
Characterized by an extra 21st chromosome
what aneuploid causes turner syndrome?
Monosomy at the X chromosome
Characterized by having one X chromosome
and no y chromosome
what aneuploid causes klinefelter syndrome?
XXY
Characterized by a male having an extra X chromosome
what are the three forms of fetal genetic testing?
Fetal Testing
Amniocentesis
Chorionic Villus Sampling
Newborn Screening
what are homologous chromosomes and how are they different from sister chromatids?
Chromosome pairs that possess the same genes containing variations of the same trait.
(one from your mom and one from your dad)
- sister chromatids are from the same parent and form during prophase of meiosis or mitsosis. There are duplicated forms of the same chromosome
what is genomic inprinting?
an epigenetic process where certain genes are expressed based on whether they were inherited from the mother or father. One allele is silenced through chemical modifications like DNA methylation, so only the other parent’s allele is active
-the silencing marker is passed from parent to child, ensuring that only the mother’s or father’s gene is active. However, during egg and sperm formation, these marks may be erased and re-established based on the individual’s sex.
what is a gene?
A unit of DNA which carries the genetic information necessary to synthesize specific proteins which represent heritable features.
what is a trait?
Each variant for a heritable feature
what are the p1, f1, and f2 generations?
P:Parental Generation
True Breeding Parents
F1: First Filial Generation
Hybrid offspring from the P generation
F2: Second Filial Generation
The result of the F1 hybrids crossing
what is dosage compensation/x inactivation adn what does it result in?
In female mammals, a random x-chromosome is inactivated in every individual cell
The inactivated chromosome condenses into a compact object called a barr body
Females are a mosaic of their parents because the paternal x/maternal x is activated/inactivated in different cells
what is the condition multiple alleles?
A genetic trait that has more than three phenotypes
why is blood that is not your blood type rejected?
Antibodies against the antigens on incompatible blood types are produced naturally as a defense mechanism against foreign substances
If a transfusion takes place with an incompatible blood type, the two blood types will agglutinate (clump) together in the blood vessels which can halt circulation and kill the individual.
what is rh factor and what can it cause in pregnancy?
Indicates the positive or negative designation of your blood type
As depicted in the image to the right, if an Rh- mother mates with an Rh+ father complications such as destruction of the fetal red blood cells can arise in the second offspring
what is epistasis?
One gene altering the expression of another gene
