Chapter 3 Notes
Genetics- the study of how genes work and how traits are passed from one generation to the next
Cells are the fundamental units of life in all organisms
Multicellular forms: plants, insects, birds, and mammals are composed of billions of cells
Proteins- 3 dimensional molecules that serve a wide variety of functions through their ability to
bind to other molecules
Nucleus- a structure (organelle) found in all eukaryotic cells. The nucleus contains chromosomes
Molecules- structures made up of two or more atoms; molecules can combine with other
molecules to form more complex structures.
DNA(deoxyribonucleic acid) - the double stranded molecule that contains the genetic code;
DNAis a main component of chromosomes.
RNA(ribonucleic acid) - a single-stranded molecule similar in structure to DNA; Three forms
of RNAare essential to protein synthesis: messenger RNA(mRNA), transfer RNA(tRNA), and
Cytoplasm- the portion of the cell contained within the cell membrane, excluding the nucleus.
The cytoplasm consists of a semifluid material (gel-like substance) and contains numerous
structures involved with cell function.
Protein Synthesis- the assembly of chains of amino acids into functional protein molecules; the
process is directed by DNA.
Mitochondria- structures contained within the cytoplasm of eukaryotic cells that convert energy,
derived from nutrients, to a form that can be used by the cells.
Ribosomes- structures composed of a form of RNAcalled ribosomal RNA(rRNA) and protein;
ribosomes are found in a cell’s cytoplasm and are essential to the manufacture of proteins.
Mitochondrial DNA(mtDNA)- DNAfound in the mitochondria; mtDNAis inherited only from
Somatic cells- basically, all the cells in the body except those involved with reproduction.
Gametes- reproductive cells (eggs and sperm in animals) developed from precursor cells in
ovaries and testes. 2
Zygote- a cell formed by the union of an egg cell and a sperm cell. It contains the full
complement of chromosomes (in humans, 46) and has the potential of developing into an entire
DNA is the very basis of life because it directs all cellular functions
James Watson and Francis Crick- developed a structural and functional model of DNA
Nucleotides- basic units of the DNAmolecule composed of a sugar, a phosphate, and one of four
DNAbases (adenine, guanine, thymine, and cytosine).A T G C
Replicate- to duplicate; the DNAmolecule is able to make copies of itself
Enzymes- specialized proteins that initiate and direct chemical reactions in the body
Complementary- in genetics, referring to the fact that DNA bases form pairs (called base pairs)
in a precise manner. For example, adenine can bond only to thymine. These two bases are said to
be complementary because one requires the other to form a complete DNAbase pair.
Hemoglobin- a protein molecule that occurs in red blood cells and binds to oxygen molecules
Hormones- substances (usually proteins) that are produced by specialized cells and that travel to
other parts of the body, where they influence chemical reactions and regulate various cellular
Amino acids- small molecules that are the components of proteins
Protein synthesis takes place outside of the cell nucleus
Messenger RNA- a form of RNAthat’s assembled on a sequence of DNAbases; it carries the
DNAcode to the ribosome during protein synthesis.
RNA is DIFFERENT than DNA in several ways