Answer:
Alternation of generations (also known as metagenesis) this type of life cycle that occurs in those plants and algae in the Archaeplastida and the Heterokontophyta that will have distinct haploid sexual and diploid asexual stages. A multicellular haploid gametophyte with n chromosomes alternates with a multicellular diploid sporophyte with 2n chromosomes is form in these group, made up of n pairs.
A mature sporophyte will produces haploid spores by meiosis, a process which reduces the number of chromosomes to half, from 2n to n.
In the haploid cell the spores germinate and grow into a haploid gametophyte. At maturity, the gametophyte produces gametes by mitosis, which does not alter the number of chromosomes.
Hydrogen
Iron
Aluminum
Copper
Sodium
Carbon
Silver
Mercury
Gold
Lead
........
Transcription factors are necessary for an initiation of transcription at a regulated gene but not sufficient.
Transcription is the first step of gene expression in which DNA molecule is copied (transcribed) into RNA (mRNA) by RNA polymerase. The process of transcription is divided into three phases:
1. Initiation
• RNA polymerase with transcriptional factors bind to gene promoter Transcription factors can enhance the interaction between RNA polymerase and a DNA sequence- promoter, encouraging the expression of the gene. Such transcription factors are called activators. Otherwise, when the gene expression is inhibited, factors are called repressors and they bind to sequence –operator.
• RNA polymerase unwinds DNA double helix (transcription bubble is formed)
2. Elongation
• RNA polymerases adds nucleotides complementary to DNA
3. Termination
• RNA polymerase gets to stop codon (transcribes a sequence of DNA known as a terminator)
• Formed complementary RNA strand is released from DNA-RNA complex
Answer:
Estimates of historical world population
Year 1400 1600
population (in billions) 0.35–0.40 0.50–0.58
growth p.a. >0% 0.15–0.3%
