1- name 4 basic transport method by which the cell uses to import/export molecul

Question

1- name 4 basic transport method by which the cell uses to import/export molecules

2- what is the role if eukaryotic cilia ?

3- name 3 types of protin that help to traffic vesicles and origin destination of the vesicles

4- what is the elongation stage of transcription

5- what happens during the major steps of the cycle cell

6- what is the problem with supercoiling of DNA during DNA replication

7- Name 3 event that occur during the elongation stage of protin production

"" Answer ALL of them please ""

Explanation / Answer

1. active transport , passive transport , diffusion, endocytosis and exocytosis.

2. In humans, for example, motile cilia are found in the lining of the trachea (windpipe), where they sweep mucus and dirt out of the lungs.
In female mammals, the beating of cilia in the Fallopian tubes moves the ovum from the ovary to the uterus.
Ciliates are microscopic organisms that possess motile cilia exclusively and use them for either locomotion or to simply move liquid over their surface.

3.

4. elongation stage of transcription ----------- it involves the movement of the transcription bubble by a disruption of DNA structure. The enzyme moves along the DNA and extends the growing RNA chain . AS the enzyme moves , it unwinds the DNA helix to expose a new segment of the template in single stranded condition. Nucleotides are covalently added to teh 3' end of the growing RNA chain , forming a RNA-DNA hybrid . During elongation when RNA polymerase transcribes DNA.

5.   INTERPHASE --- The cell is engaged in metabolic activity and performing its prepare for mitosis (the next four phases that lead up to and include nuclear division). Chromosomes are not clearly discerned in the nucleus, although a dark spot called the nucleolus may be visible. The cell may contain a pair of centrioles (or microtubule organizing centers in plants) both of which are organizational sites for microtubules.
PROPHASE --- Chromatin in the nucleus begins to condense and becomes visible in the light microscope as chromosomes. The nucleolus disappears. Centrioles begin moving to opposite ends of the cell and fibers extend from the centromeres. Some fibers cross the cell to form the mitotic spindle.
METAPHASE --- Spindle fibers align the chromosomes along the middle of the cell nucleus. This line is referred to as the metaphase plate. This organization helps to ensure that in the next phase, when the chromosomes are separated, each new nucleus will receive one copy of each chromosome
ANAPHASE --- The paired chromosomes separate at the kinetochores and move to opposite sides of the cell. Motion results from a combination of kinetochore movement along the spindle microtubules and through the physical interaction of polar microtubules.
TELOPHASE --- Chromatids arrive at opposite poles of cell, and new membranes form around the daughter nuclei. The chromosomes disperse and are no longer visible under the light microscope. The spindle fibers disperse, and cytokinesis or the partitioning of the cell may also begin during this stage.
CYTOKINESIS --- In animal cells, cytokinesis results when a fiber ring composed of a protein called actin around the center of the cell contracts pinching the cell into two daughter cells, each with one nucleus. In plant cells, the rigid wall requires that a cell plate be synthesized between the two daughter cells.

6. supercoiling of DNA will lead to the coiling of the DNA , so the opening of the DNA strand will face a problem hence there will be a difficulty in DNA replication.

7. Elongation is a cyclic process on the ribosome in which one amino acid at a time is added to the nascent peptide chain . Elongation takes place in three steps

1. decoding

2. transpeptidation

3. translocation

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