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Learning Objective and Success Criteria
LO: - Explain what are mitosis and meiosis
Progress Step 1:
Recall the
difference
between mitosis
and Meiosis in
terms of cell
division
Progress Step 2:
Correctly use key
words such as
haploid, diploid,
gametes, mitosis
and meiosis
Increasing Difficulty
Progress Step 3:
Explain the step by
step process of
mitosis and meiosis
Chromosomes
Long strands
of genetic
info (DNA)
found in
nucleus
In cell division chromosomes can be
seen to look like a cross
23 pairs in the human body (46 all together)
- How many from Mum, how many from Dad?
Chromosomes come
as identical
homologous pairs.
(Except sex
chromosomes)
Chromosomes
Making New Cells
New cells are needed for an organism of
part of an organism.
When are new cells needed?
They are needed to replace worn out and repair damaged
cells.
What needs to be achieved from cell division?
The new cells must be the same as the originals, so they can
do they can do the same job.
Mitosis
This is the type of cell division
that happens in normal body
cells.
It results in a cell splitting into
two identical cells. (daughter
cells)
In some parts of a plant or animal
it happens rapidly all of the time
– skin.
Mitosis
The diploid cell has
two sets of
chromosomes
Each chromosome is
copied
When the cell divides in
two each cell gets one
copy of each
chromosome
The nuclei contain two copies of each chromosome.
They are diploid cells!
My
is
Chromosomes
line up ready
for division.
Chromosomes
in nucleus are
copied.
2 identical
diploid
daughter cells
produced.
Cell division
starts and
chromosomes
start to
separate.
Summary...
Learning Checkpoint
Using the worksheet
describe what Mitosis
is.
•Chromosomes
•Nucleus
•Cell division
•Diploid
•Daughter Cells
Differentiation
What does the term mean?
• In early development of animal and plant embryos, cells are very
unspecialised.
• Each type of cell (stem cell) that can turn, differentiate into a type
of cell that is needed.
• Cells become specialised in early life. By the time a human baby is
born, most of the cells are specialised for a particular job, e.g Liver
cells.
• How will liver cells divide?
• What would be produced as a result?
Meiosis is
EVERYTHING to do
with the production of
sex cells!
How many
chromosomes do you
inherit from Mum and
how many from Dad?
Meiosis
This occurs in the sexual
organs to produce
gametes.
The chromosome number is
reduced by half.
Each of the 4 gametes
produced are slightly
different from each other.
Chromosomes are
copied by a cell in the
reproductive organs.
The cell divides into
two new cells
4 gametes
are
genetically
different.
There is
variation.
The cells divide to
produce 4 haploid
daughter cells
(gametes)
Meiosis is
EVERYTHING to
do with the
production of sex
cells!
Learning Checkpoint
Using the worksheet
describe what meiosis
is.
•Sexual reproduction
•Gametes
•Haploid
•Chromosomes
Comparison: Mitosis vs. Meiosis
Feature
Where in the
body it takes
place
Number of
chromosomes in
daughter cells
compared to
original cell
Variation?
Mitosis
Meiosis