E2: Describe the purpose of DNA replication.
DNA replicates in order for cells to divide, withy a parent cell divides giving each daughter cell the full DNA string in each nucleus. Without cell division, an organism cannot grow into a plant, a human or an animal. DNA replication allows all cells to contain the full genetic code for the body.
E3: Identify the roles of DNA replication within a cell.
Investigating how the distinct activities required for DNA synthesis are organized within the cell nucleus relates to the larger issue of understanding how DNA replication is regulated on a cellular level. A cell must duplicate its entire genome once and only once every time it divides.
E4: Identify the roles of DNA, messenger RNA, transfer RNA and ribosomes in the process of transcription and translation.
Messenger RNA (mRNA) carries the genetic information copied from DNA in the form of a series of three-basecode “words,” each of which specifies a particular amino acid.
2.Transfer RNA (tRNA) is the key to deciphering the code words in mRNA. Each type of amino acid has its own type of tRNA, which binds it and carries it to the growing end of a polypeptide chain if the next code word on mRNA calls for it. The correct tRNA with its attached amino acid is selected at each step because each specific tRNA molecule contains a three-base sequence that can base-pair with its complementary code word in the mRNA.
3.Ribosomal RNA (rRNA) associates with a set of proteins to form ribosomes. These complex structures, which physically move along an mRNA molecule, catalyze the assembly of amino acids into protein chains. They also bind tRNAs and various accessory molecules necessary for protein synthesis. Ribosomes are composed of a large and small subunit, each of which contains its own rRNA molecule or molecules.
Translation is the whole process by which the base sequence of an mRNA is used to order and to join the amino acids in a protein. The three types of RNA participate in this essential protein-synthesizing pathway in all cells; in fact, the development of the three distinct functions of RNA was probably the molecular key to the origin of life. How each RNA carries out its specific task is discussed in this section, while the biochemical events in protein synthesis and the required protein factors
E5: Determine the sequence of amino acids coded for a specific DNA sequence, given a table of mRNA codons.
1) A tRNA molecule with the anticodon GCU would be carrying which amino acid
2) GGAGTTTTCGCT.
E6: Identify the complementary nature of the mRNA codon and the tRNA anti-codon.
Each transfer RNA has an anticodon whose bases are complementary to a codon on the mRNA strand. The ribosome positions the start codon to attract its anticodon, which is part of the tRNA that binds the next codon and its anticodon
E7: Give examples to explain of 2 environmental mutagens that can cause mutagens in humans.
E8: Use examples to explain how mutations in DNA change the sequence of amino acids in a polypeptide chain.
At the DNA level, there are two main types of point mutational changes: base substitutions and base additions or deletions. Base substitutions are those mutations in which one base pair substitutes for another. They, again, can be divided into two subcategories: transitions and transversions. To describe these subcategories, we consider how amutation alters the sequence on one DNA strand (the complementary change will take place on the other strand). Atransition is the replacement of a base by another base of the same chemical category (purine replaced by purine: A → G or G → A; pyrimidine replaced by pyrimidine: C → T or T → C). A transversion is the opposite—the replacement of a base of one chemical category by a base of the other (pyrimidine replaced by purine: C → A, C → G, T → A, T → G; purine replaced by pyrimidine: A → C, A → T, G → C, G → T). In a description of the same changes at the double-stranded level of DNA, both members of a base pair must be stated: an example of a transition is GC → AT; that of a transversion is GC → TA.
Addition or deletion mutations are actually of nucleotide pairs, but nevertheless the convention is to call them base-pair additions or deletions. The simplest are single-base-pair additions or single-base-pair deletions. There are examples in which mutations arise through simultaneous addition or deletion of multiple base pairs.
Each transfer RNA has an anticodon whose bases are complementary to a codon on the mRNA strand. The ribosome positions the start codon to attract its anticodon, which is part of the tRNA that binds the next codon and its anticodon
E7: Give examples to explain of 2 environmental mutagens that can cause mutagens in humans.
- Radiation (x-rays, UV rays, radioactive elements)
- Organic chemicals (cigarette smoke, pesticides -only if mutagen is in gametes)
E8: Use examples to explain how mutations in DNA change the sequence of amino acids in a polypeptide chain.
At the DNA level, there are two main types of point mutational changes: base substitutions and base additions or deletions. Base substitutions are those mutations in which one base pair substitutes for another. They, again, can be divided into two subcategories: transitions and transversions. To describe these subcategories, we consider how amutation alters the sequence on one DNA strand (the complementary change will take place on the other strand). Atransition is the replacement of a base by another base of the same chemical category (purine replaced by purine: A → G or G → A; pyrimidine replaced by pyrimidine: C → T or T → C). A transversion is the opposite—the replacement of a base of one chemical category by a base of the other (pyrimidine replaced by purine: C → A, C → G, T → A, T → G; purine replaced by pyrimidine: A → C, A → T, G → C, G → T). In a description of the same changes at the double-stranded level of DNA, both members of a base pair must be stated: an example of a transition is GC → AT; that of a transversion is GC → TA.
Addition or deletion mutations are actually of nucleotide pairs, but nevertheless the convention is to call them base-pair additions or deletions. The simplest are single-base-pair additions or single-base-pair deletions. There are examples in which mutations arise through simultaneous addition or deletion of multiple base pairs.