CD-1
LET’S GET DOWN TO THE NITTY-GRITTY…
AND LEARN THE HOWS AND WHYS OF CELL DIVISION AND MITOSIS (“CELLICATION”).
GET OUT YOUR PENCILS AND WARM UP YOUR DRAWING SKILLS…
IT’S TIME TO MAKE YOUR VERY OWN…
“ALL ABOUT ‘CELLICATION’” BOOK!
SCIENCE – THE CELL
MRS. P - TEAM E - MAY 2008
NAME: ________________________________________________
IMPORTANT INFORMATION:
REMEMBER: IN PROPER MITOSIS ALL THINGS “CELLICATE”!
(Interphase, Prophase, Metaphase, Anaphase, Telophase, Cytokinesis)
1) Cell Division – The process in which a cell divides to make two identical cells. The cell
makes two nuclei and splits into two identical cells that are also identical to the original
cell (a.k.a. “cellication”).
2) Mitosis – The part of cell division in which a cell copies all of its genetic information so
that the two new cells are identical to the original cell.
3) Growth and Development and Reproduction – The life processes that cell division
and mitosis are most connected with.
4) Stage or Phase– a step of cell division.
5) DNA – the structure in cells that stores the hereditary material (info about an organism).
6) Chromosome – the structure that contains DNA (info about an organism).
Chromosomes always come pairs.
7) Gene – the hereditary unit that codes for a trait category (e.g. gene for hair color).
8) Allele – the specific expression of a gene (e.g. BROWN hair). For every gene in an
organism, there are two alleles present – each allele is present on its OWN chromosome in
the chromosome pair (this explains why chromosomes must come in pairs!).
9) Sister Chromosomes – the original chromosome and its duplicated form. They attach to
each other during cell division at the centromere.
10) Chromatin – the threadlike coils of chromosomes (i.e. what makes up DNA).
11) Chromatid – the condensed form of chromatin that appears at the beginning of cell
division; either of the two “rod-like” sister chromosomes that are connected at the
centromere.
12) Centromere – the connecting point for the identical sister chromosomes.
13) Parent Cell – The cell that is going through cell division. During mitosis it will have
DOUBLE the amount of chromosomes or genetic information units in it
14) Daughter Cell – One of the two identical cells that comes from the parent cell in cell
division. After cell division is complete, it will have EXACTLY THE SAME amount AND
type of chromosomes or genetic information as the other daughter cell AND the original
parent cell.
PHASE/STAGE #1
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CHROMSOMES GET COPIED
- All life functions are occurring, but the cell is NOT dividing yet.
- Chromosomes are called CHROMATIN (thread-like coils).
- Centrioles (except in plant cell!) appear outside nucleus to help out in division.
- At end of this phase, chromatin gets copied. Pairs of chromatin threads attach
at centromere are are now called “sister chromosomes.”
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PHASE/STAGE #2
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MITOSIS BEGINS
- Chromatin of sister chromosomes shortens and forms rod-like structures that are
still joined at the centromere. These structures are called chromotids.
- Centrioles (except in plant cell!) separate and spindles form.
- Nuclear membrane and nucleolus breaks down.
PHASE/STAGE #3
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CHROMOSOMES ATTACH TO SPINDLE
- The chromosomes get attached to the spindle by the centromere.
- Spindle threads span entire cell length.
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PHASE/STAGE #4
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CHROMOSOMES SEPARATE
- Centromere of each chromatid pare splits and sister chromatids separate.
- Chromatids move along spindle (the “bridge”) to opposite sides of the PARENT
cell.
PHASE/STAGE #5
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TWO NUCLEI FORM
- Chromatin of chromosomes uncoils and becomes thread-like again.
- Nuclear membrane forms around EACH chromatin set and nucleolus reappears.
- Mitosis ends.
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PHASE/STAGE #6
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THE CELL SPLITS
(“cell-splitting”)
- Cell membrane (and cell wall in plants) pinches inward at center of cell.
- Cytoplasm splits.
- Cell membrane closes in and forms two DAUGHTER cells, each with their own
nuclei and COMPLETE set of DNA that is the same as the PARENT cell.
- Cell division is complete.
REVIEW FOR THE TEST…
Part I. Fill out the following chart with the correct information about the phases of mitosis and cell division.
When listing the general event(s), please write it/them IN YOUR OWN WORDS.
PHASE
GENERAL EVENT(S)
SKETCH
PART II. Answer the following questions in the spaces provided. Place
1. What is the difference between cell division and mitosis? How are they related to one another?
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2. Which of the life processes are most connected with cell division and mitosis?
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3. If a cell is going to divide into two IDENTICAL cells and it has 4 chromosome pairs before cell
division or mitosis begins how many chromosomes in ALL will each daughter cell have?
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4. Why do multi-cellular organisms need the processes of cell division and mitosis? Why do unicellular
organisms need these processes?
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5. Write the letters of the parts that match the terms in the box to the right of the diagram.
_____ CHROMATID
_____ CENTROMERE
_____ SPINDLE
_____ CHROMATIN
_____ ALLELE/GENE PAIR
____ SISTER CHROMOSOMES
_________ F__________
6. What is a difference between CHROMATIN and CHROMATID and DNA? When and why are each of
these substances present?
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7. What roles do the centromere and the spindle play in cell division? What organelle produces the
spindle?
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