DNA+biology+DB

Chapter 21 DNA Biology



Define complementary paired bases- Hydrogen molecules bonds between particular bases T pairs with A, G pairs with C in DNA, and U pairs with A and G pairs with C in RNA

template- A strand of DNA is the guide to make new strands

mutation- alteration in chromosome number or structure or in a gene because of a change in DNA makeup

messenger RNA- type of RNA that has information for amino acids to be able to form polypeptide

DNA replication- a new DNA double helix is made

transcription- DNA strand stands as a template for mRNA to be made

translation- Ribosomes use pattern of codons in mRNA to make a polypeptide with a certain pattern of amino acids

codon-a three base sequence of mRNA that brings about the insertion of a paricular amino acid into a protein

Questions 1. How does the structure of DNA allow it to be replicated? DNA is a double helix. The double helix allows DNA strands to unwind so that each original strand may stand as a template for the formation of a new strand. The structure of DNA allows the replication process to be semiconservative.

2. How is the structure of RNA similar to, but also different from DNA? (THIS IS A LONG ANSWER SEE TABLE 21.1 RNA is like DNA in that they are both nucleic acids and made up of nucleotides. They also both have a sugar-phosphate component and have four different base types. RNA, unlike DNA, has bases A,U,C, and G and is single-stranded. RNA is found in the nucleus as well as the cytoplasm, and finally, RNA differs from DNA in that it is tranlsated to give proteins and aids DNA.

3. If a strand of DNA was GCCATGACC what would the complementary DNA strand be? CGGTACTGG

4. If a strand of DNA was GCCATGACC what would the complementary mRNA strand be? CGGUACUGG

5. What is the structure of a protein? Protein structure is divided into three parts. Its primary structure is the sequence of amino acids. The secondary structure is a helix or pleated sheet and the tertiary structure is any three dimensional shape.

6. What functions do proteins perform? Proteins dictate the structure and function of many cells in the body. Hemoglobin, for example, makes blood red and gives them the ability to carry oxygen molecules.

7. If a mRNA had the codon sequence AUU GCG UGG, name the three amino acids that would be linked. Isoleucine, Alanine and Tryotophan

8. What evidence with respect to DNA suggests that all living things are related and share a common ancestor? All living things have DNA in the double-helix form that humans have.



9. Where does transcription occur and what is the product? Transcription occurs at the DNA double helix in the nucleus as mRNA nucleotides are joined by RNA polymerase. A complementary strand of DNA is formed.

10. Where does translation occur and what is the product? Translation occurs in the cytoplasm at the ribosomes, and tRNA fits with amino acids to form polypeptide chains.