Chedrese Lecture 2-3.1 Flashcards
What are chromosomes composed of in eucaryotic and prokaryotic cells?
In eucaryotic cells chromosomes are composed of chromatin fibres are made of a linear relax DNA strand attached a basic histone proteins. And prokaryotes the chromosome is single circular structure
During what stage in the cell cycle are chromosomes visible under a light microscope/condensed?
Metaphase
What are dryads?
A pair of sister chromatids
During mitosis how do spindle fibres attached the centromere?
By the kinetichore
What is a karyotype?
A karyotype is a collection of chromosomes in an individual.
Karotyping is a photographic representation of all the chromosomes in an organism viewed under a microscope
How are chromosomes classified?
They are classified by number and microscopic appearance based on the length, position of the centromere’s, banding pattern and identification of the sex chromosomes
How do you prokaryotic cells divide
Binary fission
What are the three periods (B, C, and D) of the cell cycle of prokaryotes
B. Extends from the end of cell division to the beginning of DNA replication (rest)
C. DNA replicates
D. The stage between the end of DNA replication and the splitting of the bacteria cell into two daughter cells
How does DNA replication in prokaryotes
DNA replication begins at a single site called Ori through reaction catalyzed by enzymes located in the middle of the cell
What is Ori?
A discrete DNA sequence in a genome at which replication is initiated
The cell cycle of eukaryotes is dividing to what two main stages?
Mitosis or M phase and interphase
Note interphase lasts at least 91% of the total time required for the cell cycle
What goes on in the cell during interphase?
The cell grows, accumulates nutrients needed for mitosis and replicates it’s DNA and some of its organelles
What are the four distinct periods of interphase?
G1 is when a daughter cell from previous division cycle enters initial period of cytoplasmic growth or first growth
G0 is the period that cells temporarily or reversibly stop dividing and enter the state of Dormancy
S stage or DNA synthesis is when DNA synthesis commences and ends when all of the chromosomes have been replicated
G2 is the period after DNA replicates in the cell prepares for nuclear division.Protein synthesis and rapid cell growth. Microtubules begin to re-organize to form spindles
What are two other terms for mitosis?
Karyokinesis or nuclear division
True or false? Mitosis is followed by cytokinesis or division of the cell. Mitosis is not necessarily followed by cell division because it is in multi nucleated cells
True
What’s the difference between open mitosis and close mitosis?
Open mitosis in animal cells is when the nuclear envelope breaks down before the chromosome separates. Closed mitosis in fungi such as yeast is when the chromosomes divide within an intact cell nucleus
What is Mitotic cell rounding?
A shape change to adopt the nearest spherical morphology at the start of mitosis
What is the microtubule organizing centre or MTOC
A structure found in eucaryotic cells from which microtubules emerge
What is a centriole and centrosome?
A centriole is a cylindrical structure Composed mainly of tubulin only found in animal cells and not present in plant cells. The centrosome is formed by an association of a pair of centrioles
What are the two main functions of the microtubule organizing center?
The organization of eucaryotic flagella and Celia. The organization of the mitotic and meiotic spindle apparatus, which is separate the chromosomes during cell
How do you kinetochore are proteins work?
Each chromatid has its own kinetochore which face in opposite directions and attached to opposite poles of the mitotic spindle apparatus
How do kinetochore microtubules pull the chromosomes to the poles?
The kinetic or microtubules connected to the kinetochore that connect chromosomes to the spindle poles become shorter by the polymerization of tubulin subunits, lessening the distance from the chromosomes to the poles
What is non-kinetochore microtubules movement?
Kinesin is a motor protein That move along microtubule filaments powered by the hydrolysis of ATP. Non-kinetochore microtubules exert force by the traction of the kinesin transport molecules that walk along microtubule tract
What to proteins are responsible for forming the cleavage furrow
Actin and myosin
