Chedrese Lecture 2-3.1

Question 1

What are chromosomes composed of in eucaryotic and prokaryotic cells?

Answer 1

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

Question 2

During what stage in the cell cycle are chromosomes visible under a light microscope/condensed?

Answer 2

Metaphase

Question 3

What are dryads?

Answer 3

A pair of sister chromatids

Question 4

During mitosis how do spindle fibres attached the centromere?

Answer 4

By the kinetichore

Question 5

What is a karyotype?

Answer 5

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

Question 6

How are chromosomes classified?

Answer 6

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

Question 7

How do you prokaryotic cells divide

Answer 7

Binary fission

Question 8

What are the three periods (B, C, and D) of the cell cycle of prokaryotes

Answer 8

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

Question 9

How does DNA replication in prokaryotes

Answer 9

DNA replication begins at a single site called Ori through reaction catalyzed by enzymes located in the middle of the cell

Question 10

What is Ori?

Answer 10

A discrete DNA sequence in a genome at which replication is initiated

Question 11

The cell cycle of eukaryotes is dividing to what two main stages?

Answer 11

Mitosis or M phase and interphase

Note interphase lasts at least 91% of the total time required for the cell cycle

Question 12

What goes on in the cell during interphase?

Answer 12

The cell grows, accumulates nutrients needed for mitosis and replicates it’s DNA and some of its organelles

Question 13

What are the four distinct periods of interphase?

Answer 13

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

Question 14

What are two other terms for mitosis?

Answer 14

Karyokinesis or nuclear division

Question 15

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

Answer 15

True

Question 16

What’s the difference between open mitosis and close mitosis?

Answer 16

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

Question 17

What is Mitotic cell rounding?

Answer 17

A shape change to adopt the nearest spherical morphology at the start of mitosis

Question 18

What is the microtubule organizing centre or MTOC

Answer 18

A structure found in eucaryotic cells from which microtubules emerge

Question 19

What is a centriole and centrosome?

Answer 19

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

Question 20

What are the two main functions of the microtubule organizing center?

Answer 20

The organization of eucaryotic flagella and Celia. The organization of the mitotic and meiotic spindle apparatus, which is separate the chromosomes during cell

Question 21

How do you kinetochore are proteins work?

Answer 21

Each chromatid has its own kinetochore which face in opposite directions and attached to opposite poles of the mitotic spindle apparatus

Question 22

How do kinetochore microtubules pull the chromosomes to the poles?

Answer 22

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

Question 23

What is non-kinetochore microtubules movement?

Answer 23

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

Question 24

What to proteins are responsible for forming the cleavage furrow

Answer 24

Actin and myosin

Question 25

Difference between gametogenesis, spermatogenesis, and oogenesis

Answer 25

Gametogenesis is the process whereby a haploid cell is formed from a diploid cell through meiosis in cell differentiation.
Spermatogenesis occurs in the testes to produce sperm and all for nuclei from meiosis for a separate sperm cell
Oogenesis occurs in the ovaries and produces eggs. Only one out of four nuclei produced become an egg

Question 26

What is chromosome crossover?

Answer 26

Chromosome crossover is the exchange of genetic material between two nonsister chromatids that results in recombinant chromosomes. During synapsis nonsister chromatids of homologous chromosomes crossover at points called chiasmata forming bivalents

Question 27

How does meiosis prophase one differ from mitosis prophase

Answer 27

Sister chromatids are held together all along their length and share a joint kinetochore. Different than mitosis in which each chromatid forms its own Kinetichore