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Cell division and growth
B2 5.1P.186
http://www.bbc.co.uk/learningzone/clips/cell-division-by-mitosis/4189.html
Homework
To show the stages in mitosis:-
• EITHER Make a mitosis flick book (animate)
• OR mitosis poster
This link may helphttp://tinyurl.com/mitosis-hwk
Link to a short movie made for homework
Objectives Copy and fill the gaps
• … results in the production of additional cells for growth, repair and replacement.
• Before each cell division, the genetic information on the … is … so that the new cells have the same genes as the parent cells.
• Most animal cells differentiate at an early stage but most … cells have the ability to differentiate throughout life.
copied / Mitosis / chromosomes / plant
Card sort (recap of B1)
• DNA– The chemical from which chromosomes are made.
• Cell – The basic building block of a living organism.
• Gene – A small packet of information controlling a
characteristic.• Chromosome
– Thread-like structures holding genes.• Nucleus
– The part of a cell that contains genetic information.
Fastest?
What’s the order? (use p.202 Fig 1 to help)
My toes (non-sexy)
Cell division to produce normal cells is called MITOSIS
Time lapse pictures of a cell undergoing mitosis.
What is Mitosis? (Don’t copy yet)• Mitosis begins with a single
cell. How many chromosomes does this cell contain?
original cell
cell division
2 new cells
4. Each new cell has a full set of chromosomes and is identical to the original cell.
1. First the cell makes a copy of each chromosome….
2. The copies remain joined at the middle for a bit…
3. then it divides.
Mitosis animation
Mitosis video in amphibian lung cellJohn Kyrk mitosis animation
What is Mitosis? (Copy down)• Mitosis begins with a single
cell. This cell contains 46 chromosomes.
original cell
cell division
2 new cells
4. Each new cell has a full set of chromosomes and is identical to the original cell.
1. First the cell makes a copy of each chromosome to make 92 in total….
2. The copies remain joined at the middle for a bit…
3. then it divides.
Q 1,2,3 p. 187Early-finishers can do the activitiesOn the next two slides
Mitosis activity
Stages of mitosis activity
Answers text p.2031. Growth, replace, genetic information, nucleus, genes,
chromosomes, mitosis2. a) cells die and need replacing, cells are damaged,
cells needed for asexual reproduction in some organisms
b) cells need to be identical to do the same job3. a) differentiation is the process by which cells become
specialised b) in animals it occurs in the embryo and in bone
marrow, and in some other tissues and organs. It is permanent, in plants it occurs throughout life in stem tips, buds and root tips.c) plants can be cloned more easily, differentiation can
be reversed, mitosis induced, cells re-differentiate into new tissues. In animals differentiation cannot
be reversed so to make clones embryos have to be made
DNA and cell divisionWhat happens to the chromosomes when a cell divides during mitosis?
cell division
chromosomes are copied
What must happen to DNA during this same process?
Why must chromosomes be copied before a cell divides?
Centriolesmake ‘spindle
fibres’
What is mitosis?
• Each new cell can keep on dividing by mitosis.
• Mitosis makes new cells for growth and repair in all living things. That’s how you get from one cell to 50 billion!
• Mitosis is also called copying division. What does this mean?
Observing the stages in mitosis
• Use the prepared slides and complete the worksheets
• These are cells in a plant root tip
Differentiationalso covered in stem cell lesson
• Non-specialised cells are called stem cells• These stem cells, in animals, differentiate to
become specialised cells – e.g. liver/hair• Some genes have been switched on and others
switched off• Liver cells can only produce liver cells by mitosis.
Hair cells can only produce hair, etc…• At certain growth points, undifferentiated plant
cells are always being produced. In this way, plants can produce stem cells all through their lives.
• Once an animal cell has differentiated it stays that way.
Cloning a cauliflower
(recap from B1)
Syllabus
• In body cells the chromosomes are normally found in pairs. Body cells divide by mitosis.
• The chromosomes contain the genetic information.
When a body cell divides by mitosis:
■ copies of the genetic material are made
■ then the cell divides once to form two genetically identical body cells.
The cells of the offspring produced by asexual
reproduction are produced by mitosis from the
parental cells. They contain the same alleles
as the parents.
