CHAPTER 3 Part 1

ORGANELLE

  • Membrane-bounded structure with specific cell functions.

  • Example: Chloroplast

CELL

  • Fundamental unit of life; multicellular organisms consist of many cells; unicellular organisms consist of one.

  • Example: Leaf cell

TISSUE

  • Collection of specialized cells functioning in a coordinated manner (only in multicellular life).

  • Example: Epidermis of leaf

POPULATION

  • Group of the same species living in the same place and time.

  • Example: Multiple acacia trees

ORGANISM

  • Single living individual.

  • Example: One acacia tree

ORGAN

  • Structure of tissues organized to interact for specific functions (only in multicellular life).

  • Example: Leaf

ORGAN SYSTEM

  • Physically or chemically connected organs functioning together (only in multicellular life).

  • Example: Aboveground part of a plant

COMMUNITY

  • All populations occupying the same region.

  • Example: All populations in a savanna

ECOSYSTEM

  • Living and nonliving components of an area.

  • Example: The savanna

BIOSPHERE

  • Global ecosystem; parts of the planet and atmosphere where life exists.

DNA AND GENETICS

  • DNA manipulated in technology; undergoes mutations.

  • Proteins carry out functions; replication produces variation.

  • Meiosis yields gametes (sex cells); mitosis and binary fission also pass on DNA through inheritance.

DNA STRUCTURE

  • DNA structure: Double helix confirmed in 1953 by Watson, Crick, Wilkins, Franklin.

  • Composed of nucleotides: sugar (deoxyribose), phosphate, nitrogenous base.

  • Strands are antiparallel; complementary base pairing: A-T, G-C.

TRANSCRIPTION

  • Process where RNA polymerase synthesizes mRNA from a DNA template; includes a promoter to initiate and a terminator to end transcription.

  • In eukaryotes, mRNA is capped, spliced, and has a polyA tail added before exiting the nucleus.

TRANSLATION

  • mRNA translated into protein; uses tRNA to bring amino acids based on codon sequence.

  • Ribosome facilitates translation: initiation, elongation, and termination with stop codons marking end of protein synthesis.

MUTATIONS

  • Mutations can be beneficial, harmful, or neutral, involving changes in nucleotide sequences.

  • Occur during DNA replication, affecting proteins in various ways: substitutions, deletions, etc.

VIRAL INFECTION

  • Steps for viral propagation: attachment, entry, synthesis, assembly, and release.

  • Some animal viruses can undergo latent infections, remaining inactive until reactivated.