TEST 1

CH2: CHROMOSOME AND CELLULAR REPRODUCTION

Prokaryotes: no real nucleus, 1 circular DNA molecule, DNA not complex, small amount of DNA, non membrange organelles.

Eukaryotes: real nucleus, multilinear DNA molecule, complex DNA, large DNA, membrenae organelles present.

Histones: proteins that organize DNA.

Virus: not prokaryote or eukaryote, complex structures.

Prokaryotes Binary fission: a) replicate info, distribute/ separation, division of cell= 2 identical prok. cells.

Eukaryotes replication and homologous pairs:

(n) females=23 pairs

(n) males=22 pairs

=zyote, diploid (2n)


Chromosome structure:

Cell cycle:

  1. Interphase:

    1. G1: cell grows

    2. 1st checkpoint: info is accurate

    3. S: DNA replication

    4. G2: cell prepares for mitosis/ continues growing

    5. 2nd checkpoint: surveillance/ cell is commited to divide.

  2. M phase: nuclear and cell division

    1. Mitosis and Cytokinesis take place.

Mitosis: almost all cell go through this process=somatic cell in body

  1. Interphase: nuclear membrane is present and relaxed chromosomes

  2. Prophase: chromosomes condense, 2 chromatids, mitotic spindle forms

  3. Pro-metaphase: nuclear membrane desintegrates

  4. Metaphase: chromosomes line up on center plate (vertically0

  5. Anaphase: sister chromatids separate, start moving to opposite poles

  6. Telophase: chromosomes arrive at spindle pole, nuclear membrane reforms

Genetic consequences in mitosis:produce 2 identical cells genetically

Sexual Reproduction and genetic variation:

Meiosis 1: homologous chrom. separate reducing the chrom. # by half

Meiosis 2: sister chromatids separate, resulting in 4 haploid cells with the same chromosome # as the starting cell in meiosis 2.

Product of meiosis= gametes (n), corssing over prodices genetic variation

Spermatogenesis→Spermatogonium (2n) 24 chrom.→Primary spermatocyte (2n) divides in to 2 12 chrom.→seocndary spermatocyte (n) divides into 4→ spermatids (n)→maturation=sperms

Oogenesis→Oogonium (2n)→Primary Oocyte (2n) divides into 2→Secondary oocyte (2n) and first polar body→Ovum (n) and secondary polar body on the other side

Principles of heredity:

Locus: specific location, for specific trait

Pea Plant Experiment: Study of heredity (Mendel) When 2 different plant traits aere crossed.

  1. Mendel removed anthers (male) to prevent self-fertilization

Principle of segregation: 3:1 ratio Monohybrid cross: cross between 2 parents that differ ina single chromosome

dominant (RR) vs recessive (rr) zygote


Multiplication rule: 2 independent events ocurring together “and”

Addition rule: P of 2+ mutually exclusive event ocurring “or”

Binomial expansion: (a+b)^n

n=event occurs

a= P of event 1

b= P of event 2


Dihybrid cross: ration 9:3:3:1 examine 2 traits at a time

  1. P generation

  2. F1 generation:

  3. F2 generation:


Formula to observe and expectance: x²=sum (O-E)²/E