1.3 Flashcards
how many chromosomes in a adult haploid egg?
23
how many chromosomes in sperm?
23
how many chromosomes in diploid cell (zygote)
46
the cells of the zygote divid, giving rise to more and more diploid cells through the process of mitosis that form the multicellular diploid indiv
broad def of meiosis
cell division process in which the # of chromosomes is reduces during cell division in order to counterbalance the doubling that occurs during fertilization. only specialized cells called germ cells located in the gonads are capable of meiosis
can plants undergo meiosis
yes
what is different about the haploid stage of the life cycle of plants compared to humans?
plant haploid is usually a multicellular organism
dominant trait
‘stronger’ trait that masks the ‘weaker’ (recessive) trait
recessive trait
‘weaker’ trait that is ‘masked’ by the dominant trait
allele
alternate versions of a gene
how does a diploid organism inherit two alleles?
for ea character, an organism inherits 2 characters (allele) of a gene, one from ea parent
if the two alleles in a diploid indiv differ (aka heterozygote) what is the relationship of the two alleles to the organisms phenotype?
the dominant allele determines the organisms appearance, the recessive allele has no noticeable effect on the organism appearance
phenotype
The observable characteristics in an individual resulting from the expression of genes; the clinical presentation of an individual with a particular genotype.
organisms appearance/observable trait
genotype
the genetic makeup of an organism
homozygote
an organism with identical pairs of genes (or alleles) for a specific trait.
heterozygote
presence of two different alleles at a particular gene locus. A heterozygous genotype may include one normal allele and one mutated allele
law of segregation
explains that the pair of alleles segregate from each other during meiosis cell division (gamete formation) so that only one allele will be present in each gamete.
the 2 allels for a character separate during the formation of gamete cells and end up in diff daughter cells
daughter cell
A cell produced by reproductive division of a cell during mitosis or meiosis
complete dominance
when one allele is fully dominant over the other
incomplete dominance
when both alleles are partially expressed
codominance
when allels are expressed equally
Tray-Sach’s allele
Tay-Sachs is an autosomal recessive disease caused by mutations in both alleles of a gene (HEXA) on chromosome 15. HEXA codes for the alpha subunit of the enzyme β-hexosaminidase A. This enzyme is found in lysosomes, organelles that break down large molecules for recycling by the cell.
-homozygous
T/F - ea gene has only two alleles
F
pleiotropy
when a gene has multiple phenotypic effects
in inheritance of recessive traits, ppl who are affected with recessive disorders are born to parents who are…
carriers
what does the word carrier mean when we talk about recessive inherited disorders?
that they carry the allele with the recessive gene but do not phenotypically display it bc they are heterozygous
T/F - you can tell an allele is dominant bc it is more common in a population
F
autosomal dominant
- rare (often unusual to see homozygous dominant individuals if severe phenotype)
- males and females equally affected (autosomal)
- affected individuals have an affected parent (dominant)
- doesnt skip generations (dominant)
x-linked recessive
- rare
- males affected more frequently
- skips generations
- unaffected generations have affected children
- never have father to son transmission
autosomal recessive
- rare
- males and females equally affected
- unaffected individuals have affected individuals
- skips generations
- becomes more common with inbreeding
mRNA is —- stranded
single stranded
