CELL AND CHROMOSOME Flashcards
are complex structures located in the cell nucleus.
Chromosomes
components of Chromosomes
DNA, Histone and non -histone proteins, RNA, and polysaccharides
the “packages” that contain the DNA.
Chromosomes
Normally chromosomes cannot be seen with a light microscope but during cell division, they become
condensed enough to be easily analyzed at ________.
1000x
To collect cells with their chromosomes in this condensed
state they are exposed to a _________________ which blocks formation of the spindle and arrests cell division
at the ___________ stage.
mitotic inhibitor, metaphase
Chromosomes are Discovered by______________________ after staining techniques were developed that made them visible
Karl von Nageli (1842)
coined the term chromosome (means “colored body”)
Heinrich Wilhelm Waldeyer (1888)-
a sequence of DNA or RNA that codes for a molecule that has a function of the transmission of genes to an organisms offspring is the basis of inheritance of phenotypic traits
GENE
is a molecule composed of two chains which coil around each other to form a double helix carrying the genetic instructions used in the growth, development, functioning of all known living organisms
DNA
linear eukaryotic chromosomes are composed of a complex double-stranded DNA and protein called
Chromatin
two forms of Chromatin
- Euchromatin
- Heterochromatin
found in a loosely packed state; involved in gene duplication, gene transcription
and phenogenesis or phenotypic expression of gene through some type of protein synthesis
Euchromatin
highly condensed and readily visible organization; exist both in the region of centromere and in sex chromatin and is late replicating one
Heterochromatin
The unique structure of chromosomes keeps DNA tightly wrapped around spool-like protein called
“____________________”
histones
Under the microscope, chromosome appear as thin, thread-like structures. They all have a short arm designated as “___” meaning petite and a long arm designated as “__”, they are separated by a primary constriction called the “_____________”
P, Q, centromere
is the location of spindle attachment and is an integral part of the chromosome;
essential for the normal movement and segregation of chromosomes during cell division
Centromere
these chromosomes have short and long arms of equal length with centromere in the
middle
METACENTRIC
these chromosomes have short and long arms of unequal length with the
centromere more towards one side
SUB-METACENTRIC
These chromosomes have a centromere very near to one end and have very small
short arms. They frequently have a secondary constrictions on the short arms that connect very small pieces of DNA, called “Stalks” and “Satellites”, to the centromere. The stalks contain genes which code for ribosomal RNA
ACROCENTRIC
the proteinaceous structure on the surface of
the centromere to which the microtubules attach
Kinetochore
refers to the regular and repetitive physical and chemical process taking place within the cell
Cell Cycle
A cell cycle is a cycle which means there is _____________________
no fixed starting point
The first major phase of the cell is the
_____________. Then, the second major phase- the ____________.
interphase, M Phase
cells are not actively
dividing.; chromosomes are uncondensed throughout this phase
INTERPHASE
During _____ Interphase, cells undergo a period of
rapid growth, and the chromosomes are unduplicated
G1 Phase
During _______ Interphase cells begin to prepare for division
during interphase by duplicating its chromosomes
S Phase
During _______ Interphase the cell again grows and complete the preparation for division (mitosis
or M Phase)
G2 Phase
First stage of interphase
The protein synthesis and RNA synthesis within the cell resumes that was interrupted
during the process of mitosis
Growth and young cell maturation occurs, which accomplish the physiological function
The phase during which the cell cycle starts with synthesis of RNA and protein required by
the young cells for their growth and maturity. G1 phase is usually termed as the prior to
DNA Synthesis phase.
G1 (First Gap Phase)
The second stage of Interphase
DNA synthesis takes place; S stands for synthesis
Replication of cellular DNA begins which when gets duplicated with the
cell containing nearly double the amount of chromosomes, the cells from the S phase move
into the G2 Phase
S Phase
The third stage of interphase
There is an increase in the synthesis of the RNA and the protein, which is followed by
another round of proof reading and subsequent repair among the newly synthesized DNA
sequences before the cell cycle transits to the mitotic cycle
The mitotic spindle formed from the cytokinetic fibers start forming and the cell ensures
the number of chromosomes and the organelles present, which further leads the cell cycle
from the interphase to the mitotic phase.
G2 Phase (Second Gap Phase)
