BIOL 2500

• Genes are the physical units of heredity, as originally posited by Mendel; now known to be defined as DNA sequences
• Chromosomes are long molecules of double-stranded DNA and protein, which contain genes
• Sexually reproducing organisms usually have homologous pairs (or homologs) of chromosomes, which carry genes for the same traits
• Plant and animal cells contain mitochondria, only plant cells contain chloroplasts. These organelles contain one or more copies of their own circular chromosome and are transmitted in the cytoplasm during cell division.
• Complete sets of nuclear chromosomes are transmitted to identical daughter cells via mitosis
• Reproductive cells, or gametes, are produced by the cell division process called meiosis. Genes are transmitted to offspring in predictable patterns.
• Phenotype: the observable traits of an organism
• Genotype: the genetic makeup of an organism
• Alleles: alternative (variant) forms of a gene
• Genome: the complete set of genetic information carried by a species
• Eukarya have a true nucleus + multiple chromosomes
• Bacteria/Archaea have no true nucleus + single chromosome
• DNA replication precisely duplicates the DNA duplex prior to cell division
• In transcription, one DNA strand is used to direct RNA synthesis
• Messenger RNA (mRNA) undergoes translation to produce proteins at structures called ribosomes
• Mitosis produces two identical daughter cells that are genetic replicas of the parental cell.

  • It is controlled to prevent either an excess or insufficient number of cells.
• • Most body cells are somatic cells (non-reproductive), usually with chromosomes present in pairs, which is the diploid number (2n) of chromosomes.
  • The haploid number of chromosomes includes one of each chromosome pair (n)
• Meiosis produces gametes that have half the number of chromosomes as the original cell. The gametes are not genetically identical to one another.