|
|
|
|
Biology H- Mr. Willets
Chromosomes
Read page 145-146
1) Chromosomes are made of DNA and _______________________
2) The DNA wraps around proteins called _____________________ These help keep the __________ of the chromosomes and aids in the ______________________________________
3) Look at pictures on bottom of page 145 to see how the DNA double helix is coiled and coiled etc to form the chromosome.
4) Look at the chromosome shown on page 146.
5) The chromosome consists of two _________________________
6) Each half of the chromosome is called a ______________________
7) Chromatids formed as a result of what process? __________________________________
8) What holds the two chromatids together? ________________________
***********************************************************************
Mitosis is the division of a cell's nucleus such that each new nucleus gets a full set of chromosomes (DNA). This means that the DNA must replicate before mitosis. Once the nucleus has divided, the rest of the cell can then divide to form two cells. In multicellular organisms, this leads to an increase in the number of cells which can be used for growth, repair or reproduction. In unicellular organisms, this is a method of reproduction. In either case, the new cells formed have the same amount and kind of chromosomes (DNA) as the original cell.
Pg 149
1) The three main phases of the cell cycle are ______________________ , ___________________
and _________________________
2) The time between cell divisions is called _____________________, the ______phase or mitosis is when the __________________divides. The division of the cytoplasm is called ___________________
3) Interphase has 3 stages- the G-1 phase when the cells _____________________________
The S phase when the _______________________ and the G-2 phase when the cell prepares for
___________________________________
Pg 149-150
4) Mitosis can be divided into 4 phases- Name them in order: _________________ , ______________,
____________________ , _____________________
5) During prophase: a) the chromatin coils and becomes ____________________________
b) the ___________________ and ___________________ disappear
c) Two types of ________________fibers begin to form. These are made of _________________ of protein. (other things happen that we will ignore)
6) During metaphase, the chromosomes are moved to the _____________________ of the cell. Each chromosome is held in place by spindle fibers.
7) During anaphase, each chromosome (made of two identical _________________) divides and each chromatid moves towards the __________________ of the cell. At this point, each chromatid is considered to be a ________________________
Pg 151
8) At the beginning of telophase, the chromosomes have reached ___________________________.
9) During telophase, the ______________________ disappear and the ________________ and
____________________ reappear. The chromosomes uncoil and become ___________________
10) The process by which the cytoplasm of the cell divides is called _______________________.
11) In animal cells, cytokinesis occurs when the cell membrane pinches in. The area of the membrane that pinches in is called the ___________________________ See picture pg 151
12) In plant cells, cytokinesis occurs when a cell __________________ forms at the equator.
See picture pg 151
13) On page 150, there are 4 drawings of the phases. Examine them
In Lab, you will examine slides of the tip of the root of an onion plant. This part of the root has many cells that are dividing. When it was killed, there should have been cells in all phases of division. You will find an example of each phase and make a diagram of how it looks under the scope. Bring a pencil!!!
|
|
|
|