Unit 2: Non-Mendelian Inheritance Flashcards
The genes responsible for the traits that Mendel studied in pea plants were
on different chromosomes.
Linkage
When genes are close to each other on the same chromosome, they
usually do not segregate at random during meiosis and therefore their
expression does not support Mendel’s predictions.
Instead, genes close on a chromosome are packaged into the same gametes and are said to be “linked”
Linkage
in genetics refers to the transmission of genes on the same chromosome.
Linkage
idk ano meron pero pls remeber:
William ______ and R. C. ______
William Bateson and R. C. Punnett
This do not assort independently and do not produce Mendelian ratios for crosses tracking two or more genes.
Linkage
Thomas Morgan’s Research
Morgan identified more than ____ genes on Drosphila’s 4 pairs of chromosomes
He discovered that many seemed to be “linked” together
- They are almost always inherited together & only rarelt become seperated
- - GRouped genes into 4 linkage groups
50 genes
Groupes genes into 4 linkage groups
History of linkage mapping
Linkage maps were first developed by whom?
student of Thomus Hunt Morgan
Linkage mapp is a map based on the frequencies of recombination between markers during crossover of homologous chromosome
Alfred Sturtevant
It is a map of the genes on a chromosome based on linkage analysis.
This does not show the physcial distance betweengenes but rather their relative position, as determined by how after two Gene loci are inherited together
Linkage mapping
Genetic maps derived from percent recombination between linked genes accurately reflect the order of the genes on the chromosome, but the distances are estimates because crossing over is not equally likely across the genome.
Linkage Disequilibrium
Some DNA sequences are nearly always inherited together, like two inseparable
friends. This nonrandom association between DNA sequences is called
linkage
disequilibrium (LD).
The human genome consists of many LD blocks, where stretches of alleles stick
together, interspersed with areas where crossing over is prevalent. LD blocks, called
____________, could be used to track genes in populations.
haplotypes
Greek name of haplotype
Haploos = simple
It is a combination of alleles at multiple linked loci that are transmitted together
May prefer as two loci or to an entire chromosome depending on the number of recombination events that have occured between a given set of loci..
Haplotype
The term haplotype is a portmanteau of __________
Haploid genotype
Set of single nucleotide polymorphisms (SNPs) on a single chromatid that are statistically associated. It is thought that these associations, and the identification of a few alleles of a _______ block, can unambiguosly identify all other polymorphic sites in its region
Haplotype
Such information is very valuable for investigating the genetics behind common diseases, and is collected by the IHP (what does it mean?)
International HaMap Project
Sex determination in humans
An oocyte has a single X chromosome. A sperm cell has either an X or a Y chromosome. If a Y-bearing sperm cell with a functional SRY gene fertilizes an oocyte, then the zygotes is a ________(male/female)
Male (XY)
Sex determination in humans
If a X-bearing sperm cell fertilizes an oocyte, then the zygotes is a ________(male/female)
Female (XX)
‘It’ extensively controls physical, psychological, and behavioral traits which are also influenced by genetic information.
Sex-linked traits
Sex-linked Traits
Sex-related genetics may be categorized by how sex affects
phenotypic traits, including sex itself as a trait (i.e., sex determination), sex-____ trait, sex-_____ trait, and
sex-_____ trait.
sex-linked trait
sex-limited trait
sex-influenced trait.
Males with translocation of the gene can have chromosomes of ______.
XX
Females with mutation of the gene can have chromosomes of _____.
XY
Genes on the Y chromosome are ______ and genes on the X chromosome are ______.
Y-linked;
X-linked
___-linked traits are rare because the chromosome has few genes, and many of its genes have counterparts on the X chromosome.
a. Y-linked
b. X-linked
Y-linked
___-linked traits are passed from male to male, because a female does not have a
chromosome.
X or Y
Y
T/F: No other Y-linked traits besides infertility (which obviously can’t be passed on) are yet
clearly defined.
True
Some traits at first attributed to the Y chromosome are actually due to genes that have been inserted into that chromosome from other chromosomes, such as a _______ gene.
deafness/blindess
deafness
ANatomy of the Y chromosomes
Y chromosome has 2 pseudoautosomal regions
PAR1
PAR2
Anatomy of the Y chromosomes
it determines male sex
SRY
Anatomy of the Y chromosomes
A large central area that comprises about 95% of the chromosone and has only 22 genes
MSY (Male-specific region)
Anatomy of the Y chromosomes
It encodes a protein essential to producing sperm; mutations in it cause infertility
AZF - Azoospermia factor
Sex-linked traits are more likely X-linked
In males, however, a single copy of an X-linked allele causes expression of the trait or illness
because there is no copy of the gene on a second X chromosome to mask the effect. A man inherits an X-linked trait only from his ________ (father/mother)
Mother
The human male is considered ________ for X-linked traits, because he has only one set of X-linked genes.
hemizygous
Always expressed in the male
a. X-linked Recessive Trait
b. X-linked Dominant Trait
a
Expressed in a female homozygote and vert rarely in a female heterozygote
a. X-linked Recessive Trait
b. X-linked Dominant Trait
a
Affected male inherits trait from heterozygote or homozygote mother
a. X-linked Recessive Trait
b. X-linked Dominant Trait
a
Affected female inherits trait from affacted father and affected or heterozygote mother
a. X-linked Recessive Trait
b. X-linked Dominant Trait
A
Expressed in females in one copy
a. X-linked Recessive Trait
b. X-linked Dominant Trait
b
traits that is due to genes on autosomes, and the expression of these traits are limited so that normally only one sex is affected.
An example of this is with lactation. In females, the mammary glands mature during puberty due to hormones. Then, during pregnancy, different genes involved in lactation become activated. In males, the mammary glands normally don’t mature because males don’t produce the right hormones. So, even though they contain the right genes for lactation, males don’t normally lactate.
Sex-limited traits
Much more severe effects in males
a. X-linked Recessive Trait
b. X-linked Dominant Trait
b
Passed from male to all daugthers but to no sons
a. X-linked Recessive Trait
b. X-linked Dominant Trait
b
High rates of miscarriage due to early lethality in males
b
The X-linked recessive trait, the
blood-clotting disease hemophilia B is
also known as __________ and
factor IX (“FIX”) deficiency.
Christmas disease
Syndrome that is rare neurodevelopmental disorder. Cannot speak, use her hands, walk, eat, or breathe easily
1 in 10,000 female babies affected
Longevity well into adulthood
No FDA approved treatments
Rett Syndrome
Hemophilia B
This X-linked recessive disease susually passes from a heterozygous woman (designated XhXh, where h is the hemophilia-causing allele) to heterozygous daugtheror hemizygous sons. The father has normal blood clotting.
Basahin mo lang
Affects a structure or function of the body that is present in only males or females.
The gene for such a trait may be autosomal
Sex-limited trait
Although an inherited disease that causes symptoms associated with pregnancy is
obviously sex-limited, the male genome may play a role by contributing to the development
of supportive structures, such as the _______.
placenta
It is a sudden rise in blood pressure late in pregnancy. It kills 50,000 women
worldwide each year. A study of 1.7 million pregnancies in Norway found that if a man’s
first wife had preeclampsia, his second wife had double the risk of developing it.
Preeclampsia
Another study found that women whose mothers- in-law developed preeclampsia when pregnant with the women’s husbands had twice the rate of developing the condition themselves. Perhaps a gene from the father affects the placenta in a way that elevates the pregnant woman’s blood pressure.
Traits that may be expressed in both sexes but occurs more frequently on one sex
Sex-influenced traits
are autosomal traits that are influenced by
sex. If a male has one recessive allele, he will show that trait, but it will take two recessive for the female to show that same trait. One such gene is baldness.
one recessive allele sa male ay magpapakita na
two recessive allele naman para magpakita sa female
Sex-influenced traits
