Introduction, Chromosome Structure, Mitosis (Lec 1) Flashcards
Oculocutaneous albinism type 2 is due to a defect in what gene on chromosome 15?
OCA
What did Archibald Garrod discover?
Alkaptonuria
What is a genome?
set of genetic instructions for any organism
Pangenesis theory stated what?
specific particles (gemmules) carry information from various parts of the body to reproductive organs, from which they are passed to the embryo at the moment of conception
Inheritance of Acquire Characteristics theory stated what?
traits acquired in a person’s lifetime become incorporated into that person’s hereditary information and are passed on to offspring
note: made famous by Lamarck
What did the Blending Inheritance theory state?
offspring are a blend of parental traits; genetic material itself blends; once blended, genetic differences cannot be separated out in future generations
What are some common characteristics of model organisms for genetic testing?
short generation time, production of numerous progeny, the ability to carry out controlled genetic crosses, the ability to be reared in a laboratory environment, the availability of numerous genetic variants, an accumulated body of knowledge about their genetic systems
What are alleles?
multiple forms of a gene
How do prokaryotes reproduce?
a process that is called binary fission. The DNA in such cells is contained in a single circular chromosome called a plasmid within the cytoplasm. The reproductive process starts with the replication of the chromosome. The new chromosome attaches itself to the plasma membrane and the two chromosomes migrate to opposite ends of the cell. The plasma membrane in the middle of the cell grows inward until it closes to separate the cell into two compartments, each with a full complement of genetic material. The cell then “fissions” at the center, forming two new daughter cells.
What are some characteristics of prokaryotes?
Nucleus is absent, single circular DNA molecule, no histones in eubacteria (some in archaea), membrane-bound organelles are absent, cytoskeleton is absent
What are some characteristics of eukaryotes?
membrane-bound nucleus is present, multiple linear DNA molecules, histones pack DNA molecules, membrane-bound organelles are present, cytoskeleton is present
DNA + Histones = ?
chromatin
True or False?
Eukaryotic DNA must separate from histones before genetic information can be accessed
true
What is the function of the centromere, in regards to eukaryote chromosome structure?
serves as the attachment point for spindle microtubules, used for chromosome classification
What is the function of the centromere?
location where the kinetochore forms and the spindle microtubules attach
What are telomeres and what do they do?
natural ends of a chromosome, provide chromosome stability, may limit cell division
What is telomerase?
Enzyme that adds DNA sequences to the chromosome so telomeres do not lose length
What are the major functions of mitosis?
stockpile of cells for embryogenesis, provides mechanism for the replacement of damaged or worn-out cells
What happens in the S phase of the cell cycle?
DNA synthesis, chromosome replication, G-1(S)-cyclins degraded, inactive cdc2 kinase, B(M)-cyclin concentration begins to increase toward end of S phase, take about 7 hours
What happens in the G2 phase of the cell cycle?
further preparations for mitotic division, B(M)-cyclins bind to cdc2 kinase, activated MPF leads to activities necessary for mitosis, takes about 2 hours
What happens in the M phase of the cell cycle?
Mitosis, B(M)-cyclin is degraded toward end of phase, cdc2 kinases becomes inactivated, takes about 0.7 hours
What happens in interphase of mitosis?
chromosomes uncoiled
What happens in prophase of mitosis?
centrioles move to opposite poles, spindle apparatus is organized, nuclear membrane begins to disintegrate, chromosomes become condensed
What happens in metaphase of mitosis?
chromosomes are located at center of cell along equatorial plate, spindle fibers are attached to kinetochores, centromeres divide at end of metaphase, chromosome number has doubled
What happens in anaphase of mitosis?
daughter chromatids separate
What happens in telophase of mitosis?
chromosomes begin to uncoil, nuclear membranes reform, cytokinesis usually occurs and two daughter cells are separated
What happens in the G1 phase of the cell cycle?
first gap/growth phase, concentration of G-1(S)-cyclins increases, G-1-cyclin binds to inactive cdc2 kinase, MPF is activated at end of this phase and leads to activities needed for DNA synthesis, highly variable with regard to time
What happens in G0 phase of the cell cycle?
condition of a cell that has been taken out of the classical cell cycle
What are embryonic cells?
cells that proceed immediately to the next cell cycle with little time in the G1 phase; do not grow or differentiate
What are Labile cells?
cells that spend more time in the G1 stag and grow and become differentiated; ex: epithelial cells, hematopoietic cells
Non-dividing cells are permanently locked in what phase of the cell cycle?
G1 phase; ex: skeletal muscle cells, cardiac muscle cells, neurons
What is karyokinesis?
physical division of nuclear material
What is cytokinesis?
physical division of cytoplasmic material
What is endomitosis?
karyokinesis is not followed by cytokinesis which results in an increase in ploidy (increase in complete sets of chromosomes)
