Biology Test 330

The genetic code is universal, for example, from bacteria to human UUU would code for phenylalanine (phe). Some exceptions to this rule have been found in mitochondrial codons, and in some protozoans. The genetic code shows degenerecy, some of the amino acids are coded by more than one codon. One codon codes for only one amino acid, hence, it is unambiguous, specific and the codon is read in mRNA in a contiguous fashion. There are no punctuations.

Phosphate groups are attached to the 5'- and 3'-carbon atoms of each sugar to form the backbone chain of DNA. One end of the chain carries a free phosphate group attached to the 5'-carbon atom, this is called the 5' end of the molecule. The other end has a free hydroxyl (-OH) group at the 3'-carbon and is called the 3' end of the molecule.

Inbreeding results in an increase in the homozygosity. Therefore, a mating of the related individuals of the same breed will increase homozygosity. It is a progeny of single, self-fertilized homozygous individuals.

Any cell which has the ability to develop into a complete organism is totipotent. The concept of tissue culture is based on the property of the totipotency of the plant cells. The ability or potential of any living plant cell or explants to produce all the differentiated cells in an organism is called totipotency.

Consideration of one character at one time contributes to the success of Mendel. Mendel'scontribution was unique because of his methodological approach to a definite problem, use of clear cut variables and application of mathematics (statistics) to the problem. Using pea plants and statistical methods, Mendel was able to demonstrate that traits were passed from each parent inheritance of genes.

GCU indicates alanine but GUU indicates valine. Stop codons are UAG, UGA and UAA. AUG is the most common start codon which also codes for methionine. Stop codons do not have tRNAs. UUA indicates leucine but UAC indicates serine.

When a homozygous dominant individual (AA) is crossed with a homozygous recessive individual (aa) for a single trait, all the offspring will inherit one dominant allele and one recessive allele, making them all heterozygous (Aa).

Down's syndrome is caused by the presence of an extra copy of chromosome 21 (trisomy 21). This chromosomal abnormality leads to a variety of physical and developmental characteristics associated with the syndrome.

Mendel's principle of independent assortment states that the alleles of different genes assort independently of each other during gamete formation. This means that the segregation of alleles for one trait does not affect the segregation of alleles for another trait.

Hemophilia is a sex-linked disorder that is primarily inherited through the X chromosome. It affects the blood's ability to clot properly and is more commonly seen in males, who have only one X chromosome.