Meiosis
What is meiosis and why is it important in
reproduction?
Starter
Choose a key word from the list below and
describe it in your own words.
Done? Find out what you neighbour did.
Try another.
Double
helix
Scientific paper
Nuclear
membrane
mitosis
cytoplasm
mitochondria
Meiosis
What is meiosis and why is it important in
reproduction?
Starter
Complete your revision card for mitosis
Learning Outcomes
1) Recall that meiosis is a type of cell division that produces
gametes.
2) Explain why gametes only contain half the chromosome number
of the parent cell.
3) Recall that a zygote contains a set of chromosomes from each
parent.
4) Outline how sexual reproduction gives rise to variation.
Call my Bluff
Work in teams to come up with 2 alternative
definitions for your key word. You win, if no one
guesses the right answer.
Call my Bluff
•
•
•
•
•
Gamete:
Meiosis:
Zygote:
Chromatid:
Organelle
Call my Bluff
• Gamete: these are sex cells i.e. Sperm and eggs. They have half the
number of chromosomes compared to normal body cells.
• Meiosis: the process by which sex cells are formed with half the
number of chromosomes to a normal cell.
• Zygote: a cell produced by the joining of an egg cell and sperm cell.
• Chromatid: each of the pair of the chromosomes that are made
when DNA doubles during mitosis.
• Organelle – a specialised structure within a cell.
Genetic information
Inside each cell is a nucleus.
Inside the nucleus are 46 chromosomes.
Each chromosome contains thousands of genes.
Each gene codes for a protein.
Chromosomes are made of a chemical called DNA.
Largest
Smallest
In a normal body cell you have 23
PAIRS of chromosomes
Downs Syndrome
Fertilisation
• What happens in fertilisation?
• If 2 complete cells combined how many
chromosomes would the zygote (embryo)
have ?
46
46
92
What is a zygote?
92 chromosomes is FAR too many
• The embryo has to have 46 chromosomes .
• To get this the egg and sperm must have 23
each.
23
23
46
BUT the question is...
• If our cells all have 2 sets of chromosomes
how do we make gametes (sex cells) with only
1 set? THINK – PAIR – SHARE
Gametes have 23 chromosomes
Stages of Meiosis
• Meiosis only happens in the testes and
ovaries to produce eggs and sperm.
• During Meiosis as in mitosis, all the genetic
information doubles.
• In meiosis the parent cells then split twice.
• This produces 4 daughter cells which have 23
chromosomes from the parent. (half the
normal number) These are either sperm cells
or egg cells.
Tasks:
• 1) complete the
meiosis cartoon, cut
and paste exercise.
8 mins
2) Complete the mix
and match card sort
for mitosis and
meiosis. 5 mins
3) Complete the past paper questions on
mitosis and meiosis. 5 mins
• 4) Create a concept
map comparing
meiosis and mitosis.
5) Write your own
exam style question for
mitosis and meiosis
Plenary
Mitosis or Meiosis
Produces clones
Mitosis or Meiosis
• Produces gametes
Mitosis or Meiosis
• Makes 4 daughter cells
Mitosis or Meiosis
• Important for repair of damaged parts of the
body
Mitosis or Meiosis
• Used by bacteria to reproduce.
Mitosis or Meiosis
• Makes 2 daughter cells
If all our cells are genetically identical,
why do we have so many different
organs?
THINK, PAIR, SHARE
Stem cells and differentiation.
What is a major difference between plants and
adult humans?
Key Word Card Sort
Mitosis & Meiosis
solve the anagrams by rearranging the letters
clue
1. things you find in a cell
2. where the chromosomes are
3. type of cell division
4. type of cell division
5. joining of egg and sperm
6. sex cell
7. how new cells are made
8. the new cell
9. the original cell
10. found in the nucleus
letters
a gel loner
clue sun
i miss to
some i is
airline fist to
eat gem
sliced violin
cat hurdle leg
all percent
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