Answer: 1) Recessive allele is unable to express its effect in the presence of dominant allele WHILE a dominant allele is able to express itself even in the presence of its recessive allele.
2) Recessive allele produces its phenotypic effect only in the presence of a similar allele. E.g; tt is dwarf. WHILE a dominant allele does not require another similar allele to produce its effect on the phenotype. E.g; Tt is tall.
3) Recessive allele forms a defective polypeptide or enzyme so that the expression consists of absence of the effect of dominant allele. E.g; white flower colour in Pea. WHILE a dominant allele can form a complete polypeptide or enzyme for expressing its effects. E.g; red colour of flower in Pea.
Explanation:
a. The error rate of DNA replication is 1.0 × 10^-8 per base pair. This is considering that a human has approximately 3 billion base pairs where mutations can occur. However, this mutation is kept low by the proof-reading mechanism of DNA polymerases which are 99% efficient.
b. Given that the human genome is 3.2 × 109 bp, this means that there are on average 0.32 new substitutions every time the complete genome is replicated. In humans, there are about 30 cell generations between zygote and egg cells and about 400 cell divisions between a zygote and mature sperm. Thus, in males, the sperm cells have about 128 new mutations and the haploid egg genome has about 10 new mutations for a total of 138 new mutations in every new zygote.
c. Considering the above-mentioned mutation rates of approximately 1 and 2 mutations per 100 million base pairs between generations, then there will be approximately 130 mutations per generation. This means I will probably have about 130 different nucleotide bases from that of my parents.
<span>d. Siblings at an average of 50%, grandparents at an average of 25%; aunts/ uncles at an average of 25%; and first cousins at 12.5%.
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<span>f. You are approximately different from the other random person by one SNP per 1000 bases. The human genome is about 3 Gbps long and therefore about 3 million SNPs among two random people.</span> With about 20,000 genes each having a coding sequence (exons) about 1.5 kb long (i.e. about 500 amino acids long protein on average), the human coding sequence covers 30 Mbp or about 1 percent of the genome. If SNPs were randomly distributed along the genome that will suggest about 30,000 SNP across the genome coding sequence or just over 1 per gene coding sequence.
g. Humans carry on average one to two mutations that, if inherited from both parents, can cause severe genetic disorders or death before reaching reproductive age. These mutations are what are referred to as recessive alleles of a gene.
<span>h. Mosaicism refers to individuals with genetically distinct cell lines that originated from a single zygote, whereas chimerism refers to those who originated from more than one zygote. Microchimerism is the co-existence of two genetically different cell populations in one organism, of which one occurs in a very low number. </span>
Enveloped viral membranes are generally (C)lipid bilayers with associated virus-specific (C)glycoproteins.
Viruses are intracellular parasites that hijack the cellular machinery for their own replication. Therefore, an essential step in the viral life cycle is the transfer of the viral genome into cells. Enveloped viruses (viruses with a lipid envelope) use a two-step process to release their genetic material into the cell.
It first binds to specific surface receptors on target cell membranes and then fuses with these. Viruses and cell membranes. This last step can occur at the cell surface or after internalization of the virus particle by endocytosis or another pathway (such as micropinocytosis).
Strikingly, the virus-cell-membrane fusion process proceeds along essentially the same intermediate steps as other membrane fusions that occur, for example, in vesicle fusion at neural synapses or cell-cell fusion in yeast mating. Fusogens, special viral proteins, facilitate the fusion of viruses and cell membranes.
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They use different genetic codes
