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NAS 161
Exam 4 Unit 4 (chapt 4, 6, 13, 5, 10)
Question | Answer |
---|---|
Gene | Part of DNA molecule that encodes the information to synthesize a protein, a control sequence for tRNA or rRNA the unit of inheritance. The portion of a DNA molecule that contains the genetic information from making a print |
Genetic code | Information for synthesizing proteins encoded in nucleotide sequence of DNA molecules. The correspondence between a unit of DNA information (3 nitrogenous bases or a "triplet") and a particular amino acid |
Genome | Complete set of genetic instructions of an organism (cell). 3.2 billion DNA bases long |
Describe the chemical structure of a nucleic acid | A molecule that is composed of bonded nucleotides; RNA or DNA |
Describe the chemical structure of a nucleotide | 5 carbon sugar (ribose and deoxyribose), a phosphate group and one of several nitrogenous bases |
What are the four nucleotides of DNA | Adenine (A) Cytosine (C) Guanine (G) Thymine (T) |
What are the four nucleotides of RNA | Adenine (A) Cytosine (C) Guanine (G) Uracil (U) |
Purines | Double organic ring structures Ex: A & G |
Pyrimidines | Single organic ring structures Ex: T & C |
What is meant by base pairing | Rungs are formed by bonding of complementary bases by weak hydrogen bonds. Ex: A-T, C-G, T-A, G-C |
RNAs main location is in the | Cytoplasm |
DNAs main location is in | Part of chromosomes, in nucleus |
Deoxyribose is 5 carbon sugar of RNA or DNA molecules | DNA |
Ribose is a 5 carbon sugar of RNA or DNA molecules | RNA |
What is the basic molecular structure of DNA molecules | Double-stranded |
What is the basic molecular structure of RNA molecules | Single-stranded |
What are the nitrogenous bases in DNA | Cytosine, guanine, adenine, thymine |
What are the nitrogenous bases in RNA | Cytosine, guanine, adenine, uracil |
What are the major functions of DNA molecules | Contains genetic code for protein synthesis, replicates prior to mitosis |
What are the major functions of RNA molecules | Messenger RNA carries transcribed DNA information to cytoplasm and acts as template for synthesis of protein molecules; transfer RNA carries amino acids to messenger RNA; ribosomal RNA provides structure for ribosomes |
Define hydrogen bond | Bond that holds double-stranded DNA together |
Define nitrogenous base | Project from the sugar-phosphate backbone of one strand of DNA and bind to the other nitrogenous base on the second strand of DNA |
Define double helix | Formed when double-stranded molecules twists |
Covalent bond | Chemical bond formed by electron sharing between atoms |
Describe DNA replication | When a cell divides, the process that creates an exact copy of a DNA molecule. This happens during "interphase" of cell cycle |
Steps in DNA replication | -DNA helix unwind -DNA separates into its 2 nucleotide chains -each strand acts as a templet (set of instructions) -end result: 2 DNA molecules that are identical to original DNA helix; each DNA molecule now consists of 1 "old" strand and 1 "new" stran |
Define triplet | code consisting of sequences of 3 nucleotide Ex: C,G,T or G, C, A |
mRNA "condon" | Messenger RNA, Carries the "message" containing instructions for proteins synthesis from the DNA in the nucleus to the ribosomes out in the cytoplasm |
rRNA | Ribosomal RNA, Forms part of the "ribosomal" structure and helps coordinate the protein building process |
tRNA "anticondon" | Transfer RNA, "Transports" an amino acid to the ribosome site; recognizes the mRNA Condons |
RNA differs from DNA in that | -single-stranded -contains ribose -has uracil (U) as one of its 4 bases |
DNA differs from RNA in that | -double-stranded -contains deoxyribose -has thymine (T) as one of its 4 bases |