Test 5

• Binary fission: division of a single bacterial cell into 2 daughter cells
• Genes: discrete segments of coiled DNA molecules that contain instructions for building proteins and regulating cell processes
• Cell cycle: process that provides each new cell with a complete set of chromosomes
• Chromosomes: structure of nucleic acids and protein found in the nucleus, carries genetic information
• Chromatin: DNA, RNA, and protein material that eukaryotic chromosomes are made of
• Centromeres: region of chromosomes where the microtubules of the spindle attach
• Telomeres: region of repetitive DNA at the end of a chromosome
• Cytokinesis: division of the contents of acell into two
• Gamete: reproductive cells that generate genetic diversity

  Haploid: single set of unpaired chromosomes present in a cell

  Diploid: two sets of chromosomes, one from each parent
• Binary Fission

  • Allows bacteria to rapidly colonize new environments
  • High levels of adaptation to changing conditions
  • Quick and efficient reproduction
  • Asexual
• Cell Cycle

  • Important for DNA replication and cell division
  • Includes interphase and mitosis
  • Interphase
  • G1
  • S
  • G2
• Mitosis: proper distribution of chromosomes into daughter cells to preserve genetic integrity and diversity

  • Prophase
  • Metaphase
  • Anaphase
  • Telophase
• Prophase

  • Prepares the compacting and condensing of chromosomes
  • Cell nucleus dissolves
  • Mitotic spindle (protein apparatus) starts to guide the separation of genetic materia
• Metaphase

  • Part of the cell cycle that aligns chromosomes along the cell equator
  • Alignment in the middle makes sure that each daughter cell gets an equal genetic amount
• Anaphase

  • Bonds that hold sister chromatids together are broken
  • Separated chromatids are pulled towards opposite poles of the cell
  • Each new cell will get a complete set of chromosomes
• Telophase

  • Cell almost done dividing
  • Starts to remake normal structures
  • Cytokinesis: division of the contents of the cell
• • Steps of Mitosis
  • PMAT
  • Prophase
  • Metaphase
  • Anaphase
  • Telophase
  • Steps of Meiosis
  • prophase
  • prometaphase
  • metaphase
  • anaphase
  • telophase
  • cytokinesis.
• Steps of Interphase:

  • G1 - Cell growth
  • S - DNA Replication
  • G2 - Preparation for Mitosis

  
  

  • G0 - Nothing yet
• • Chromosomes: structure of nucleic acids and protein found in the nucleus, carries genetic information
  • Genes: sequence of nucleotides that form part of a chromosome
• • Chromatin: DNA, RNA, and protein material that eukaryotic chromosomes are made of
  • Centromeres: region of chromosomes where the microtubules of the spindle attach
  • Telomeres: region of repetitive DNA at the end of a chromosome (protect DNA)

  
• Interphase

  • G1 phase: responsible for growth and preparation
  • S phase: DNA replication
  • Enzymes unzip the DNA double helix
  • Expose underlying genetic code, synthesizes(duplicates) 2 identical copies
  • G2 phase: final preparations (fixes errors)
• Mitosis

  • Goal: proper distribution of chromosomes into daughter cells
  • Chromosomes undergo
  • Condensation
  • Alignment
  • Separation
  • Rearrangement
  • All to preserve genetic integrity and diversity
  • Includes prophase, metaphase, anaphase, and telophase
• • Cancer: disruption in cell growth
  • Uncontrolled growth
  • Impaired DNA repair
• • Only Gametes go through Meiosis
  • Gametes are Haploid cells
• Mitosis - Two diploid daughter cells

  Meiosis - Four haploid daughter cells

  
• Meiosis

  • Consists of 2 cell divisions

  1. Meiosis 1
  2. Meiosis 2

  • Each division is followed by cytokinesis
  • Results in the formation of 4 haploid daughter cells
• Meiosis 1 and 2

  • M1: replication of chromosomes
  • M2: No replication of chromosomes
• Meiosis – Prophase 1

  • Similarities to Mitosis: DNA coils and becomes visible
  • Differences:
  • Homologous (equivalent) chromosomes find each other “pairing”
  • Cross-over between homologous chromosomes that are close
  • Allows for the exchange of DNA between non-sister chromatids
  • After cross-over: sister chromatids are no longer
• Meiosis – Alignment

  • Differences:
  • Mitosis is getting half of each kind
  • Meiosis remains haploid
• Meiosis – between M1 and M2

  • Interkinesis: the time between meiosis 1 and meiosis 2
  • Time is takes is variable
  • No DNA replication is occurring between M1 and M2
• Meiosis M1 vs M2

  Metaphase 1 - binding to 1 side

  Metaphase 2 - binding to both sides
• Reproduction in Humans

  • Each parent has 46 chromosomes
  • Gametes (egg and sperm) each have 23 chromosomes
  • 23 chromosomes + 23 chromosomes = 46 total chromosomes in child
• Asexual reproduction: inherit all chromosomes from one parent

  • Next generation has ALL the chromosomes from a single parent

  
  

  Organisms that primarily use asexual reproduction

  • Prokaryotes: binary fission
  • Protists: use except when under conditions of high stress
  • Plants: very common
  • Animals: less common, budding off of localized mass of cells
• Meiosis 2

  • No replication of chromosomes
  • Prophase II: nuclear envelope breaks down and new spindle forms
  • Metaphase II: spindle fibers bind to both sides of centromere
  • Anaphase II: spindle fibers shorten, and sister chromatids move to opposite poles
  • Telophase II: nuclear envelope re-forms
  • Result: 4 haploid cells
• Meiosis 1

  • Replication of chromosomes
  • Prophase 1: DNA coils and becomes visible, chromosomes that are close start crossing over to allow for exchange of DNA
  • Metaphase 1: Chromosomes meet in the middle and the nuclear envelope goes away, joined pairs line up on the metaphase plate
  • Anaphase 1: the whole centromere with both sister chromatids will move towards the poles and each pole will receive a homologous pair
  • Telophase 1: nuclear membrane re-forms around each daughter cell and sister chromatids are no longer identical due to crossing over