2: GENETIC BACKGROUND OF DEVELOPMENT Flashcards
a slender material inside the nucleus, usually found as colored
bodies during cell division.
Chromosome
Each chromosome is composed of ____ which separate during cell
division
sister chromatids
has a ____ or primary constriction (“waist line”), where the
kinetochore proteins are attached.
centromere
____ the sight of attachment of spindle fibers. The tip of the
chromosome arm, needed for chromosome stability, is called ____.
Kinetochore
telomeres
centromere is at the middle part of the chromosome
Metacentric
centromere is sub-median; (near the middle); long-up & short-down
Sub-metacentric
centromere is at the subterminal portion; (3/4 at tip of chromosome);
short-up & long-down
Acrocentric
centromere is at the terminal end of the chromosome
Telocentric
A sexually reproducing individuals possess ____, one
set coming from the male and another set coming from the female parent
two sets of chromosomes (2n)
complete set of chromosomes coming from either parent
Genome
Each of the chromosome in a genome has corresponding ____
identical
chromosomes or homologue.
Each ____ divides once the cell divides. This is accomplished through
cell division.
chromosome
continuity of life is based upon the reproduction of cells
cell division.
CELL DIVISION purpose
- multicellular organism to grow and
- reach the adult size,
- replaces worn-out or damaged cells, and
- keeps the total number of cells in an adult organism relatively constant.
The Key Roles of Cell Division
- unicellular organisms reproduce by cell division
- necessary for the repair and renewal of the worn-out tissues
- for the formation of new cells
- for cell growth, development and tissue differentiation
involved in in the distribution of the identical genetic materials
(DNA) to two daughter cells
Cell division
The genes are located in a
____ that is found in the nucleus
chromosome
Chromosomes are greatly involved in cell
division and in the reproductive process of an organism.
series of stages in the life of the cell is referred to as
cell cycle.
referred to as the “preparatory stage”
Interphase
▪ it is the longest phase in the cell cycle for most cells
▪ typically, it lasts for at least 90% of the total time required for the cell cycle
Interphase
a cell at interphase may appear resting under the microscope but it actually goes
through a period of ____
very high metabolic activity
- grow in size; cell increases in volume
- cell is preparing the chemicals necessary for DNA synthesis
- ER, golgi apparatus, ribosomes, mitochondria and chloroplast are
formed - chromatin, although it would appear as darkly staining materials, if
stretched would resemble a long chromatin fiber
G1 phase (first growth phase)
- each of the chromosomes is replicated by the cell
- where DNA synthesis or replication occurs
S phase (DNA synthesis)
- cell “double checks” the duplicated chromosomes for error, making any
needed repairs - active synthesis of RNA and proteins (needed for synthesis of
chromosomes) - formation of mitotic spindle occurs
- doubled chromatin fiber folds to form a chromosome
- continue until the onset of mitosis
G2 phase (second growth phase)
the period of nuclear division and cytokinesis
M-phase (Mitotic phase)
the actual division
of the cytoplasm and generation of two new daughter cells
cytokinesis
series of events wherein each cell divides to form to new daughter cells which
are exactly identical to the mother cell
Mitosis
division of the nucleus, with its contents (duplicated chromosomes: 2n), into
two identical nuclei
Mitosis
mitosis occurs in ____ except sex cells or gametes
body or somatic cell and other cells
- Chromatin in the nucleus begins to condense and becomes visible in
the light microscope and now called chromosomes - Chromosomes are thickened and become shortened
- Centrioles begin moving to the opposite ends of the cell
- Fibers extend from the centromeres. Some fibers cross the cell to form
mitotic spindle - Nucleoli and nuclear membrane completely disappear
Prophase
- The chromosomes move along the middle of the cell to ensure that the
next phase, when they separate, each nucleus will receive one copy of
each chromosome - Centrioles reached the opposite end of the nucleus
- Chromosomes become attached to the spindle fibers and move toward
the equator - Chromosomes tightly coiled and discrete; it is very much condensed
Metaphase
- At early anaphase, centromeres are duplicated and start moving apart;
sister chromatids start to separate - At late anaphase, two identical sets of chromosomes move toward the
opposite poles and spindle begins to disappear
Anaphase