Activities Key Terms Quizzes Art Chapter 15 Self-Quiz
Unit 3: Genetics From Gene to Protein Review
  1. The bulk of the DNA sequence in most genes codes for the production of . A protein is made of one or more , which are linear polymers of , and which are folded into specific shapes. In other words, the DNA sequence specifies the sequence of proteins. RNA is an important component in this process. Proteins ultimately determine an organism's .
  2. RNA is structurally similar to DNA, but differs in three key respects.
    1. Most RNA is , unlike the double-stranded structure of DNA.
    2. RNA nucleotides contain a sugar rather than the deoxyribose of DNA.
    3. RNA does not contain the base thymine (T), but instead contains the base (U), which base-pairs with adenine (A) of DNA.
  3. The flow of information from genes to proteins involves a two-step process of followed by .
  4. The DNA message of a gene is first transcribed into within the cell nucleus using the enzyme starting at the and ending at the . Similar to DNA replication, the direction of transcription is 5' to 3'.
  5. Other enzymes remove noncoding sequences of RNA called and splice the to produce the final (mRNA), which exits the nucleus through the .
  6. The mRNA is then translated within the cytoplasm using the to form the sequence of that makes up a polypeptide. The genetic code is made of triplets of bases called that code for amino acids. The code is : many amino acids can "wobble": they are encoded by more than one codon.
  7. The actual assembly of proteins occurs in the cytoplasm on , which consist of many proteins and (rRNA). A 3rd kind of RNA, (tRNA), forms an initiation complex at the start codon. The tRNA carries a specific amino acid and an which binds to the codon on the mRNA. The complex forms bonds between amino acids, until a stop codon terminates the process, releasing the completed polypeptide.
  8. Genetic mutations are either or or of one or more wild-type DNA bases. Since many tRNAs can "wobble", some substitution mutations are and do not exhibit a change in amino acids, but many substitution mutations do result in changed proteins and are called mutations. Insertions and deletions cause a of the decoding sequence and usually result in a protein.

Activities Key Terms Quizzes Art Chapter 17 Self-Quiz
Unit 3: Genetics DNA Technology Review
  1. Knowledge about the molecular nature of genes provides tools for genetic .
  2. DNA sequences can be studied by cutting DNA into specific segments using enzymes. The ends can be used to insert fragments of DNA from other sources.
  3. The segments can then be sorted by using gel . These technologies can be combined in Length Polymorphism (RFLP) to detect genetic diseases such as sickle-cell anemia.
  4. Alleles can also be identified by DNA , using radioactively labeled, single-stranded DNA segments called DNA that can base-pair with specific DNA sequences.
  5. Segments of DNA can be isolated and by two techniques.
    • Use enzymes and DNA to construct a DNA in bacteria with vectors such as and , then identifying and culturing the bacteria in the carrying the desired gene.
    • Use the enzyme DNA and known DNA in Chain Reaction (PCR) to synthesize large quantities of a gene in vitro.
  6. Cloned DNA can be used as DNA tool in identifying individuals.
  7. Isolated genes can be modified and then inserted back into organisms through a process called genetic .
  8. Other applications of DNA technologies include screening and therapy.
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