Chromsomes In Motion
I.
Sketch a chromosome and label its parts.
One chromsome
Two chromatids
Two copies of DNA
One chromsome
One chromatid
One copy of DNA
Chromsomes In Motion
II.
Sketch and label each phase of mitosis.
Spindle
forming
Centrioles
Chromatin
Nuclear envelope
Centromere
Centriole
Chromosomes (paired
chromatids)
Interphase
Prophase
Cytokinesis
Centriole
Telophase Individual chromosomes
Nuclear envelope
reforming
Spindle
Anaphase
Metaphase
Mitosis Questions:
1. What are the two main purposes of mitosis?
Growth of organism, decrease cell volume, repair after
injury, asexual reproduction
2. An organism has 20 types of chromosomes. How many
chromosomes would be found in a body (somatic) cell? How
many chromosomes would be found in a gamete?
40 chromsomes in somatic (body) cell (2N)
20 chromsomes in gametes (sperm and egg cells) (N)
Mitosis Questions:
3. Name a specific cell type in your body where you would
expect mitosis to be occurring right now (an area with a
high mitotic rate).
Skin, intestines, cells in bone marrow that produce
blood cells
Chromsomes In Motion
III.
Sketch and label each phase of meiosis.
spindle
centrioles
chromosomes (DNA)
Meiosis I
Meiosis I
spindle
centrioles
chromosomes (DNA)
Prophase II
Metaphase II
Anaphase II
Meiosis I results in two
The chromosomes line up in a The sister chromatids
haploid (N) daughter cells,
similar way to the metaphase separate and move toward
each with half the number of stage of mitosis.
opposite ends of the cell.
chromosomes as the original.
Telophase II
Meiosis II results in four
haploid (N) daughter cells.
Meiosis Questions:
a. What is the main purpose of meiosis? What type of cells are
produced?
Purpose - To produce 4 cells that are genetically different from
each other and the original cell – ensures genetic variation in
offspring.
Type of cell - Gametes (sex cells) are produced
b. Why do sexually reproducing organisms need to carry out meiosis?
Meiosis has to occur in order for gametes to have a haploid
number of chromosomes. Fertilization requires two haploid
cells in order to make a diploid zygote.
(body)
(sperm or egg)
1.
What happens to the chromosomes during interphase
prior to mitosis and meiosis beginning (specifically, the
S phase)?
Copied/Replicated/duplicated
2.
What happens to the cell during cytokinesis?
The cytoplasm is divided between the daughter
cells as the cell membrane pinches in.