Lecture 7 Flashcards
Homozygous
The two alleles at a particular locus are the same. Eg. PP purple allele and purple allele
Heterozygous
The two alleles at a particular locus are different.
Dominant
An allele that is fully expressed in a heterozygote. (Controls what the trait would actually look like). Dominance has to do with the expression of the allele in the heterozygote.
Recessive
An allele that is not expressed at all in the heterozygote.
Genotype
The specific alleles that an organism has.
Phenotype
The character that the organism has (due to genotype and environment) ex tanning (the sun changing traits, the env affecting traits).
Pea plant
diploid, they have two alleles at each locus. Like the flower color locus. The purple allele (dominant) and the white (recessive) allele.
Phenotype
observable trait. Genotype: invisible trait.
Are animals haploid or diploid?
Diploid
What is to be known of the parents to predict the offspring traits?
Knowing the genotypes of the parents will give an idea of the offspring
Codominant
Both alleles are fully expressed in the heterozygote.
Incomplete dominance
It means no dominance, where both alleles contribute partially to the phenotype in the heterozygote. They both influence the phenotype but not completely. Example: pink flower with allele for red flower and allele for white flower.
Pleiotropy
Refers to a situation where a genotype at a single locus influences more than one trait. Eg. osteogenesis imperfecta: at a single locus there are two known alleles and on of the alleles is a recessive allele.
Dihybrid Cross
Hybridization experiment in which the inheritance of two traits is studied. eg . pea color and pea shape are two different traits and each of the traits are determined at different locus.
The two competing hypothesis
the hypothesis of dependant vs independent assortment.
Dependent assortment: The allele inherited at one locus is dependent on the allele inherited at the other locus.
Independent assortment
The allele inherited at one locus is independent of the allele inherited at the other locus.
Diploid
Two alleles at each locus!
Polygenic traits
The flipside of pleiotropy, polygenic traits: the phenotype is influenced by many loci. Eg. skin colour in humans: Many loci determine skin colour.
What are alleles carried by in sexually reproducing organisms ? explain
In sexually-reproducing organisms, alleles are carried by gametes. These gametes are haploid, which means they carry one allele for each locus. Through fertilization, each zygote gets one allele (for each locus) from each gamete, and is therefore diploid.
What is inside the punnet square?
Inside the punnet square are the genotypes of the zygotes.
Where are the loci and the alleles physically found?
The loci and the alleles are physically found in the chromosomes.
Human sex determination
There is a homologous pair of sex chromosomes. The two XX chromosomes develop into female. The XY is male.
Gametogenesis
The genesis of gametes, how gametes are produced
Oogenesis
This is a modified version of meiosis
What is discarded during oogenesis?
Polar bodies are discarded and have the least amount of cytoplasm
Ootid
an egg cell that results from the second meiotic division of an oocyte and that develops into a mature egg
Oogenesis cell developement
1st oocyte, 2nd oocyte, Ootid and produces the Ovum
Spermatogenesis
is gametogenesis in males: Less modified version of meiosis
What does primary spermatocytes start?
Primary spermatocytes starts spermatogenesis
What do secondary spermatocytes go through?
Secondary spermatocytes goes through meiosis two and produces 4 spermatids that become spermatozoa
