BIO 311C FINAL REVIEW

• Karyotype

  Arrangement of chromosomes in pairs starting with the longest chromosome
• Stages of the cell cycle

  • Interphase
  • Mitotic phase
• Interphase

  1. G1 - cell growth, accumulates materials for DNA synthesis

  2. S - DNA synthesis occurs and DNA replication results in duplicated chromosomes

  3. G2 - cell synthesizes proteins needed for cell division
• Stages of mitosis

  • Prophase
  • Prometaphase
  • Metaphase
  • Anaphase
  • Telophase
  • Cytokinesis
• If a cell had 4 chromosomes before entering the cell cycle, it would have 2 chromatids after prophase
• Cytokinesis in animal cells

  1. Involves a cleavage furrow-a shallow groove in the cell surface near the metaphase plate

  2. Just below this groove there is a contractile ring of actin filaments along myosin causing the ring to contract

  3. This contraction causes the cleavage furrow to deepen until the parent cell is pinched into 2 forming 2 daughter cells
• Cytokinesis in plant cells

  1. Vesicles from golgi move along microtubules to the middle of the cell where they coalesce producing a cell plate

  2. Cell wall material carried in the vesicles collects inside the cell plate as it grows

  3. The cell plate enlarges until its surrounding membrane fuses with the plasma membrane along the perimeter of the cell resulting in 2 daughter cells
• Law of Segregation

  • The 2 alleles for a heritable character separate(segregate) during gamete formation and end up in a different gametes
  • An egg/sperm gets only 1 of the 2 alleles that are present in the organism
  • The segregation of alleles corresponds to the distribution of homologous chromosomes to different gametes in meiosis
• Law of Independent Assortment

  • Crossing 2 true-breeding parents differing in 2 characters produces dihybrids in the F1 generation, heterozygous for both characters
  • A dihybrid cross(a cross between F1 dihybrids) can determine whether 2 characters are transmitted to offspring as a package or independently
• Alleles

  Alternative versions of genes
• Dominant allele

  Determines the organism's appearance
• Recessive allele

  Has no noticeable effect on appearance
• Genotype

  Genetic makeup
• Phenotype

  Physical appearance
• Monohybrid cross

  Individuals that are heterozygous for 1 character
• Dihybrid cross

  Crossing 2 true-breeding parents differing in 2 characters(heterozygous for both characters)
• Checkpoints in cell cycle regulation

  • G1/S checkpoint
  • G2/M checkpoint
• G1/S checkpoint


  • If cell receives a go-ahead signal, cell will continue cell cycle
  • In absence of a go-ahead signal, cell exits cell cycle and enters G0(nondividing state)
• G2/M checkpoint

  • A cell in mitosis receives a stop signal, when any of its chromosomes are attached to spindle fibers
  • When all chromosomes are attached to spindle fibers from both poles, a go-ahead signal allows the cell to proceed into anaphase
• Cyclins

  Family of structurally and functionally related proteins required for cell cycle function(eukaryotes)
• CDKs (cyclin-dependent kinases)

  Various kinases that bind to a specific cyclin and add phosphate groups to targets
• Kinases

  Add phosphate to target proteins which changes protein activity
• Cyclin

  Dictates which target protein will be phosphorylated by the CDK
• MPF (maturation promoting factor/M-phase promoting factor)

  Promotes entry into mitosis
• Characteristics of cancer cells

  • Uncontrolled cell growth
  • Accumulation and propagation of mutants
  • Ability to invade and disrupt local/distant tissue
  • Loss of density dependent inhibition and anchorage dependence
• Oncogenes

  Genes that contribute to cancer
• Proto-oncogenes

  Normal cellular genes that are responsible for normal cell growth/division
• Tumor suppressor genes

  Normally inhibit cell division
• Tumor suppressor proteins

  • Repair damaged DNA
  • Control cell adhesion
  • Act in cell-signaling pathways that inhibit the cell cycle
• How mutation in Ras can lead to cancer

  1. Ras is a proto-oncogene

  2. Ras is activated by tyrosine kinase receptor, signal transduction occurs, last molecule activated is a transcription factor leads to turning on gene expression to form proteins that stimulate the cell cycle

  3. Ras has ability to remove the phosphate group from GTP converting it back to GTP, when this occurs pathway stops

  4. When Ras is mutated, GTP is always bound to mutant Ras-making Ras always active(hyperactive) this leads to a constant activation of the pathway(even in the absence of the signal) resulting in uncontrolled cell division
• How mutation in p53 can lead to cancer


  1. P53 is a transcription factor that binds DNA and activates genes to make proteins that halt the cell cycle

  2. When p53 is mutated, it can't function as a transcription factor, so if there is damage in the DNA no proteins are made that will pause the cell cycle

  3. The DNA damage is propagated that increases the likelihood of more mutations and damage to DNA- this leads to loss of cell cyle regulation and cancer
• Phases of meiosis

  • Meiosis I & Prophase I
  • Metaphase I
  • Anaphase I & Telophase I
  • Meiosis II
• Meiosis I & Prophase I

  Chromosome duplication; pair of duplicated homologs held together by chiasma(site of crossing over) and sister chromatid cohesion
• Metaphase I

  Pair of homologous chromosomes line up at the metaphase plate
• Anaphase I & Telophase I

  • Homologs separate during anaphase I; sister chromatids remain attached at the centromere
  • Haploid n=3; daughter cells of meiosis I
• Meiosis II

  Sister chromatids separate during anaphase II
• PCR (Polymerase Chain Reaction)

  • A technique that allows us to replicate a target sequence in a test tube- application of DNA replication
  • 3-step cycle that brings about a chain reaction that produces an exponentially growing population of identical DNA molecules
  • The 3 steps are carried out at different temperatures in a thermocycler
  • Key to PCR is the use of heat-stable DNA polymerase Taq-heat is used to separate the DNA strands, then cooled to allow annealing of short, single stranded DNA primers complementary to sequences at the ends of the target segment
  • A DNA polymerase extends the primers in the 5' to 3' direction- the cycle of heating and cooling with the help of enzymes/primers increases the amount of DNA
• Nuclear transplantation used to make Dolly


  1. The nucleus of an unfertilized egg cell/zygote is replaced with the nucleus of a differentiated cell

  2. Mammary cell donor- egg from ovary and egg cell donor- nucleus removed are fused, nucleus from mammary cell is grown in culture, early embryo is implanted in uterus of a 3rd sheep(surrogate mother), embryonic development occurs until lamb is born
• arrange the following from LOWEST to HIGHEST order in hierarchy

  mitochondria, organism, oxygen, protein, cell, water, tissue

  
  

  oxygen, water, protein, mitochondria, cell, tissue, organism
• Which of the following is an example of a NONPOLAR covalent bond

  formed by sharing electrons between H and H in H2