Unit 3: Bioenergetics Flashcards

Cell Division

• Mitosis: Division of body (somatic) cells.
  • Diploid (2N) to diploid (2N).
  • Asexual reproduction.
  • Identical offspring.
• Meiosis: Division of sex cells (gametes).
  • Diploid (2N) to haploid (1N).
  • Sexual reproduction.
  • Genetically different offspring.

Mitosis Stages

• Prophase:
  • Chromosomes shorten and become visible.
  • Nuclear membrane disappears.
  • Spindle fibers form.
• Metaphase:
  • Chromosomes line up in the middle.
• Anaphase:
  • Spindle fibers attach to centromeres.
  • Sister chromatids move to opposite poles.
• Telophase:
  • Nuclear membrane reappears.
  • Chromosomes begin to disappear.
  • Cleavage furrow/cell plate develops.
• Cytokinesis:
  • Division of cytoplasm.
  • Two identical daughter cells form.

Meiosis Stages

• Interphase:
  • G_1: Cell grows.
  • S: DNA duplicates/replicates.
  • G_2: Cell grows and gets ready for division.
  • G_0: No change/growth; chromosomes are invisible.
• Prophase I:
  • Chromosomes form a tetrad (4 chromatids).
  • Synapsis occurs (crossing over). Chromosomes exchange genetic information, increasing genetic diversity.
  • Tetrads move to poles.
• Metaphase I:
  • Chromosomes line up randomly along the equator (Independent Assortment), leading to more genetic diversity.
• Anaphase I:
  • Homologous chromosomes (tetrads) move to opposite poles.
• Telophase I:
  • Nuclear membrane develops; reverse of prophase.
• Cytokinesis I:
  • Two genetically different haploid cells are formed.
• Meiosis II:
  • No Interphase II.
  • Identical to Mitosis.
  • Four genetically different haploid cells.

DNA

• DNA (Deoxyribonucleic Acid):
  • Double-stranded (double helix).
  • Contains genetic information in the nucleus.
  • Made of nucleotide bases: A, T, G, C. A pairs with T, and G pairs with C.
  • DNA Replication: DNA Helicase unzips the DNA; DNA Polymerase adds new bases and proofreads; DNA ligase zips it back up; makes an identical copy!
• Central Dogma: DNA → RNA → Protein

RNA

• RNA (Ribonucleic Acid):
  • Single-stranded.
  • Bases: A, U, C, G. A pairs with U.
  • Types: mRNA, tRNA, rRNA.

Protein Synthesis

• Transcription:
  • DNA → mRNA.
  • Occurs in the nucleus.
  • Creates mRNA ("recipe").
• Translation:
  • mRNA → Protein.
  • mRNA-tRNA-ribosome.
  • Codon (three mRNA bases) specifies an amino acid.
  • Anticodon (tRNA).
  • START codon: AUG.
  • STOP codons: UGA, UAA, UAG.

Genetics

• Genotype: Genetic makeup (e.g., Hh).
• Phenotype: Physical characteristics (e.g., brown hair).
• Alleles:
  • Dominant allele.
  • Recessive allele.
  • Homozygous (e.g., HH or hh).
  • Heterozygous (e.g., Hh).
• Monohybrid/Dihybrid crosses: Used to predict offspring genotypes and phenotypes.
• Punnett Square: Diagram used to predict genotypes and phenotypes of offspring.
• Pedigrees

Mutations

• Point Mutations:
  • Silent: No change in amino acid sequence.
  • Missense: Change in amino acid sequence.
  • Nonsense: Premature stop codon.
• Frameshift Mutations:
  • Insertion: Addition of a nucleotide.
  • Deletion: Removal of a nucleotide.
• Chromosomal Mutations:
  • Inversion: Section of chromosome is reversed.
  • Translocation: Section of chromosome moves to another chromosome.
  • Nondisjunction: Failure of chromosomes to separate properly during meiosis.

Other Genetic Concepts

• Incomplete Dominance: Blending of traits (e.g., red + white = pink flowers).
• Codominance: Both traits are expressed (e.g., black + white = black and white speckled chickens).
• Multiple Alleles: More than two alleles for a trait (e.g., blood type).
• Sex-Linked Traits: Genes located on sex chromosomes (e.g., colorblindness, XX, XY).

Gametogenesis

• Spermatogenesis (males):
  • Creates four genetically different sperm cells.
• Oogenesis (females):
  • Creates one egg and three polar bodies.

Blood Types

• Blood Types: A, B, AB, O
• AB: Codominant
• O: Recessive
• Universal Donor: O