ap biology unit 5

• asexual reproduction 


  single individual or “parent“ organism

  -no fusion of gametes

  -clones

  -mutations are the source of variations

  -can produce asexually through mitosis
• sexual reproduction 


  two parents

  -fusion of two haploid gametes need to make one diploid offspring

  -offspring are unique combinations of genes from parents

  -genetically varied from parents and siblings
• clones

  offspring are exact genetic and phenotypic copies of parents
• homologous chromosomes

  a pair of chromosomes

  -same size, length, centromere position) that carry the same genes
• one homologous chromosomes is inherited from _____ parent and one is inherited from _____ parent

  maternal and paternal parent
• somatic (body) cells


  diploid: two complete sets of each chromosome (full genetic information)
• gametic (sex) cells


  haploid: one set of each chromosome (half of the genetic in

  -human gametes: sperm and egg
• autosomes


  chromosomes that do not determine biological sex
• sex chromosomes


  the combination of x and y will determine the biological sex of the organism
• life cycle

  sequence of stages in the reproductive history of an organism from conception to it’s own reproduction
• fertilization and meiosis ____ in sexual life cycles

  alternate
• meiosis


  a cell division process that creates haploid gamete cells in sexually reproducing diploid organisms
• mitosis process

  -occurs in somatic cells

  -1 division

  -results in 2 diploid daughter cells (somatic)

  -daughter cells are genetically identical
• meiosis process


  -forms gametes

  -2 divisions

  -results in 4 haploid daughter cells (gametes)

  -each daughter cell is genetically unique
• meiosis interphase


  cells goes through G1, S (DNA is copied), and G2

  -chromosomes not actual visual
• meiosis prophase 1


  spindle fibers form, chromatin condense, nuclei disappear

  -synapsis

  -crossing over/recombination

  -every chromatid that is produces has a unique combination of DNA
• synapsis


  homologous chromosomes pair up and physically connect to each other forming a tetrad (4 sister chromatids in two homologous pairs)
• crossing over/recombination

  occurs at the chiasmata or point of contact and physical section of chromosomes and there DNA are exchanged
• meiosis metaphase 1

  independent assortment
• independent assortment


  occurs which is when the tetrads line up at the metaphase plate randomly for increased genetic variation
• meiosis anaphase 1

  pairs of homologous chromosomes seperate

  -sister chromatids are still attached
• meiosis telophase 1

  two nuclei reform and cleavage furrow begins the cell division process
• meiosis cytokinesis 1

  the cytoplasm divides as the cleavage furrow splits the plasma membranes in two

  -there is now a haploid set of chromosomes but still diploid genetic material in each of the 2 daughter cells
• meiosis prophase 2


  spindle fibers form, two nuclei disappear, chromatic condense

  -no crossing over occurs
• meiosis metaphase 2


  chromosomes line up at the metaphase plate

  -because of crossing over in meiosis 1 chromatids are unique
• meiosis anaphase 2


  sister chromatids separate and move to opposite poles
• meiosis telophase 2


  nuclei reappear, cleavage begins
• meiosis cytokinesis 2

  4 haploid cells produced, each daughter cell is genetically unique
• how does meiosis lead to genetic variation

  crossing over, independent assortment of chromosomes, random fertilization
• random fertilization 


  any can fertilize any egg
• meiosis followed by fertilization ensures ______ in sexually reproducing organisms and provides genetic variation that plays a role in _____

  genetic diversity and natural selection
• meiosis is driven by the interaction of ____ components and uses _____ that is required for the ____ and ____ of living systems

  sub cellular components and uses free energy

  -for the growth and reproduction
• common ancestry

  1. DNA and RNA carry genetic information
  2. the genetic code is shared by all living systems
  3. ribosomes
  4. metabolic pathways - ATP
• gregor mendel

  studied inheritance and created two laws that can be applied to the study of genetics
• true breeding


  organisms that produce offspring of the same variety over many generations of self pollination
• example of true breeding

  true breeding purple pea plants will only produce purple offspring with self pollination
• p generation

  true breeding parental generation

  PP x pp
• f1 generation


  (first filial) hybrid offspring of p generation

  100% Pp
• f2 generation

  (second filial) offspring of the f1 generation

  3:1 phenotypic expression
• homozygous


  an organism that has a pair of identical alleles for a character