Clear and orderly summary of Chapter 20 of the book "Genetics: Analysis and Principles, 6th Edition by Robert Brooker". Together with all my other summaries of Genetics I got an 8,5 for this course.
Genetics Summary Chapter 3 – Chromosome transmission during cell
division and sexual reproduction
3.1 General Features of chromosomes
Prokaryotic cells are simple and lack cell compartmentalization, whereas eukaryotic
cells contain a cell nucleus and other compartments
- Lysosomes; role in degradation of macromolecules
- Endoplasmic reticulum and Golgi; role in protein modification and trafficking
(handel)
- Mitochondrional (ATP synthesis) and chloroplast (photosynthesis) also consist
DNA
Microscope and karyotype
Chromosomes can be examined under the microscope (cytogenetic is involve with
this). Cell prepared to divide, chromosomes become more tightly coiled (strak
gewikkeld), they become visible
What happens: cells removed from body. Treated with
- Chemical that stimulate to begin cell devision
- Chemical that halts cell division during mitosis.
- Hypotonic solution, make cells swell chromosomes spread out easier to
see individual chromosomes.
- Fixative, that freezes the chromosome no longer move
- Chemical dye, binds the chromosomes and stains (kleuren) them banding
pattern
Karyotype; organized representation of the chromosomes.
Eukaryotic chromosomes
Chromosomes are found in sets. Eukaryotic cells are often
diploid, which means that each type of chromosome occurs in
a homologous pair.
Homologous similar to each other; in size, banding pattern
and types of genes
Homologous different to each other; alleles may be different
3.2 Cell division
Purpose of cell division
- Asexual reproduction; does not involve union of gametes. Cell divides
to produce two new cells
- Multicellularity; organism consist of more than one cell. Produce more
cells
Bacteria cell division—asexual
Bacteria divide by binary fission; bacterial cell divides into 2 daughter cells. 2
daughter cells become divided by the formation of a septum.
FtsZ, assembles (monteert) ring. It recruits other proteins to process a new
cell wall between the daughter cells
, Eukaryotic cell division
Eukaryotic divide by going through the cell cycle
- G; gap. Process more proteins etc.
- S; synthesis of DNA (DNA-replication).
- M; mitosis and cytokinesis
- G0; a cell which is not advancing through the cell cycle. Nerve
cells
Interphase; G1, S and G2
Metaphase; M
G1 phase
Restriction point; point in G1 that causes a cell to progress to cell division
S phase
After replication copies of chromosome are called chromatids.
Dyad; pair of sister chromatids
Monad; single chromatid
Kinetochore; proteins that attached to centromere during meiosis and mitosis
Cell has twice as many chromatids as it has chromosomes in G1 phase.
Homologs or sister chromatid?
Homologs one from father one from mother
Sister chromatids exactly the same
3.3 Mitosis and cytokinesis
Mitotic spindle
Mitotic spindle apparatus (mitotic spindle; short chromosomes.
Microtubule-organizing centers (MTOCs); structures in cells
which microtubules grow from.
- Aster microtubules; outward from centrosome to the
plasma membrane
- Polar microtubules; toward the region where chromosomes will be found
during mitosis.
- Kinetochore microtubules; between centromeres and kinetochores
Mitosis
- Prophase; nuclear membrane dissociates. Chromatids become more compact.
Mitotic spindle starts to form
- Prometaphase; nuclear membrane vesiculates (weg) and mitotic spindle is
formed
- Metaphase; chromosomes align along the center of the mitotic spindle and
formation of spindle is complete
- Anaphase; sister chromatids separated and sent to opposite
poles
- Telophase; chromosomes reached the poles and
decondense. Nuclear membrane is re-formed.
- Cytokinesis; two nuclei are segregated into separate
daughter cells. It segregates also cell organelles. Begins
shortly after anaphase.
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