Answer:
C)Parental: 41% Dr, 41% dR; recombinant: 9% DR, 9% dr.
Explanation:
The notation Dr/dR for genotypes means that one homologous chromosome has the alleles Dr and the other homologous chromosome has the alleles dR.
The heterozygous plant Dr/dR will produce 4 types of gametes: two identical to the chromosmes the individual has in its somatic cells (called parental), and two gametes which will be a mix of the alleles in the homologous chromosomes (called recombinant).
- Dr: parental
- dR: parental
- DR: recombinant
- dr: recombinant
To calculate the frequency of each type of gamete, we must use the formula:
Distance (map units) / 100 = frequency of recombination.
18 mu / 100 = 0.18.
The total frequency of recombination between the genes D and R is 0.18, but every time crossing over happens, two recombinant gametes are generated. Therefore, each recombinant gamete will have a frequency of 0.18/2=0.09 = 9%.
The frequency of parental gametes will be:
1 - frequency of recombinant gametes
1 - 0.18 = 0.82
But there are 2 parental gametes, so each of them will have a frequency of 0.82/2=0.41 = 41%.
Answer:
A=2 B=4 C=3 D=1
Explanation:
Identifying the stages of succession assignment
natural gas or coal or nuclear power
Answer:
- One spermatogonium produces 4 spermatids FALSE. One primary spermatocyte produces 4 spermatids.
Explanation:
Germ cells are diploid reproductive cells in charge of gamete production. Germ cells divide by mitosis and meiosis. Through mitosis, they originate more sexual cells, but through meiosis, they produce gametes -sperm and egg cells-. This process is known as gametogenesis.
Gametes´destiny is to merge during fecundation, and a new diploid cell called zygote emerges through fertilization. The zygote is a complete cell and suffers successive mitosis to form the new organism.
Spermatogenesis is the process of production and maturation of sperm cells. Spermatogonia are the masculine diploid germ cells, carrying 46 chromosomes. These germ cells suffer mitosis to reproduce. Some of them stay as spermatogonia, and some others become primary spermatocytes, which are in charge of gamete production. Primary spermatocytes are also diploid cells, meaning that they still carry 46 chromosomes.
Each primary spermatocyte replicates its genetic material and then goes through meiosis I to produce two daughter haploid cells called secondary spermatocytes, each of them carrying 23 chromosomes. Each secondary spermatocyte will produce two other haploid daughter cells by meiosis II.
The total result from the two cellular divisions of each primary spermatocyte is four haploid daughter cells called spermatids.
During spermiogenesis, spermatids mature into spermatozoa or sperm cells. Each sperm cell characterizes by being composed of a head, midpiece, and tail.
- DNA replicates once, but cells divide twice TRUE
- The products are spermatozoa that each have a head, midpiece, and tail TRUE
- Spermatids containing 23 chromosomes (1n) are produced TRUE
- One spermatogonium produces 4 spermatids FALSE. One primary spermatocyte produces 4 spermatids.
- Genetically diverse spermatids are created TRUE
