Biology Chapter 5: Nucleic Acids

Nucleic acids

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Gene
- programs the amino acid sequence of a polypeptide
Nucleic acids
- genes consists of DNA, which belong to the class of compounds called nucleic acids- nucleic acids are polymers made of monomers called nucleotides
What are the two types of nucleic acids?
- desoxyrinonucleic acid (DNA)- ribonucleic acid (RNA)
What are the roles of DNA and RNA?
- enable living organisms to reproduce their complex components from one generation to the next
What does DNA do?
- provides directions for its own replication- directs RNA synthesis and through RNA, controls protein synthesis
What is DNA?
- the genetic material that organisms inherit from their parents- each chromosome contains one long DNA molecule, usually carrying several hundred or more genes - when a cell reproduces itself by dividing, its DNA molecules are copied and passed along from one generation of cells to the next- encoded in the structure of DNA, is the information that programs all the cell's activities- DNA however is not directly involved in running the operations of the cell; proteins are required to implement programs
What does RNA do?
- each gene along a DNA molecule directs synthesis of a type of RNA called messenger RNA (mRNA)- the mRNA molecule interacts with the cell's protein-synthesizing machinery to direct production of polypeptide
The flow of genetic information
DNA>RNA>protein
Ribosomes
- the sites of protein synthesis
What happens in eukaryotic cells?
- ribosomes are in the cytoplasm- but DNA resides in the nucleus- mRNA conveys genetic instructions for building proteins from the nucleus to the cytoplasm
What happens in prokaryotic cells?
- cells lack nuclei but still use mRNA to convey a message from the DNA to ribosomes and other cellular equipment that translate the coded information into amino acid sequences
Polynucleotide
Nucleic acids are macromolecules that exist as polymers called polynucleotides
Nucleotides
- each polynucleotide consists of monomers called nucleotides- composed of three parts: 1. a nitrogen containing base 2. a five-carbon sugar 3. one or more phosphate groups
Polynucleotide and phosphate groups
In a polynucleotide, each monomer has only one phosphate group
Nucleoside
- the portion of a nucleotide without any phosphate group- nitrogenous base and a sugar