6.sex cells and fertilisation

1. Sex Cells and Fertilisation
Sexual Reproduction

2. Sexual Reproduction
Copy the following definition:
Reproduction is the method by which
the members of a species produce
offspring. Sexual reproduction
involves the fusion of two gametes
(sex cells) during fertilisation.

3. Sexual Reproduction (plant)
Petals
Anther
Filament
Nectary
Sepal
Ovule
Style
Stigma
Ovary
Stamen}

4. Sexual Reproduction (plant)
Pollen Tube

5. Sexual Reproduction (mammal)
Nucleus – contains information
in chromosomes
Cytoplasm – contains food store
Head
Tail – allows
sperm to swim to
egg

6. Sexual Reproduction (mammal)
Fertilisation is when
the two nuclei fuse

7. Sexual Reproduction
Note:
Fusion of nuclei forms a zygote
containing genetic material from both
parents.

8. Sexual Reproduction Notes
Answer Tp163-164 ‘Testing Your
Knowledge’ in sentences.
Collect cut-outs and
label the parts
draw an ‘X’ where fertilisation occurs
Extension work – Success Guide p36-37

9. Sex Cells and Fertilisation
Genetics

10. Genetics Notes
Copy the definition below:
Chromosomes are thread-like
structures found inside the nucleus of
every living cell. They contain genetic
information which gives rise to an
organisms characteristics.

11. Genetics
The number of chromosomes present in an
organisms’ cells depends on its species.
e.g Human Male
46 Chromosomes

12. Genetics
The thread-like chromosomes
are made of a chemical
substance called DNA.
DNA has two strands which
form a twisted structure
called a helix.
DNA carries coded genetic
information.
Each piece of information is
called a gene.

13. Genetics Notes
Copy the definition below:
A gene is a section of a chromosome
which contains a separate piece of
genetic information.

14. Genetics
Adenine (A)
Thymine (T)
Guanine (G)
Cytosine (C)
 Rows of four different
bases make up a
strand of DNA.
 The order of the bases
makes the DNA code.
A A C T G C C G T A T G

15. Genetics
A A C T G C C G T A T G
The genetic code found in genes gives the
cells instructions to make protein
molecules.
The proteins produced have a variety of
jobs e.g.
• structural (muscle tissue),
• controlling cell activities (enzymes)

16. Genetics Notes
Answer Tp167 Q2 in sentences.
Label the cut-out and stick it in.

17. Genetics
Protein molecules are made from
combinations of 20 available amino
acids, linked together in a long chain.
The DNA molecule tells the cells which
amino acids to use when making a
specific protein.

18. Genetics
Three bases (e.g. ATG) carry the code for one
amino acid.
Each amino acid is different depending on the
combination of bases (e.g. CGT, TGC, AAG
etc)
Amino acidAmino acidAmino acidAmino acid

19. Genetics
Amino acidAmino acidAmino acidAmino acid
Protein molecule
The amino acids are linked together to make a protein.
The sequence of amino acids dictates the structure and
function of the protein.

20. Genetics Notes
Complete the cut-out and stick it in.
Answer Tp167 Q3.
Use the passage ‘Proteins’ on Tp165 to
make a note about the relationship
between proteins present in a cell and
an organism’s characteristics.
Extension work: Success Guide p38-39.

21. Fertilisation Mini Essay
Describe how and where fertilisation
occurs in a flowering plant.
For Wednesday 15
th
December

22. Sex Cells and Fertilisation
Gamete Production

23. Gamete Production Notes
Note:
Body cells have two matching sets of
chromosomes. Gametes have one set of
chromosomes.
The reduction in number of
chromosomes to a single set occurs
during meiosis (gamete formation).

24. Gamete Production
Chromosome
Chromatid
Chromatid
CentromereCentromereCentromere

25. Gamete Production Notes
Copy these definitions:
A chromatid is the name given to each
single strand of a double chromosome
A centromere is part of a single
chromosome. In double chromosomes, it
holds the two chromatids together.

26. Gamete Mother cell.
4 double chromosomes.
Matching chromosomes pair.
Line up across cell
Pairs separate.
Cell divides.
Chromosomes line up.
Each cell divides again.
Centromeres split
Chromatids pulled apart
4 gametes produced.

27. Gamete Production Notes
Answer Tp173 Q2+3 in sentences.

28. Sperm
Mother cell
Egg
Mother cell
Cell ready to
divide again
Sperm cell
Egg cell
MEIOSIS
Zygote
FERTILISATION

29. Sex Cells and Fertilisation
Sex Determination

30. Sex Determination Notes
Every normal body cell in a human being
contains 46 chromosomes as 23 pairs.
Of these, one pair makes up the sex
chromosomes.
Females have two large X
chromosomes, while males have a large
X and a small Y chromosome.

31. Sex Determination Notes
Complete and stick in the sex
chromosomes cut-out.

32. Gamete Production
Note:
In humans, each male gamete has an
X or a Y chromosome, while each
female gamete has an X chromosome.
Now fill in the sex determination grid to
work out the expected ratio of boys:girls.

33. Gamete Production
Look at Tp175 Q5 (you don’t need to
write anything down – just think about
the question.)

34. Sex Cells and Fertilisation
Genes and Alleles

35. Genes and Alleles Note
Chromosomes are made up of smaller
units called genes. Each gene is a unit
of heredity that controls an inherited
characteristic (e.g. wing type, hair
texture, flower colour, etc.)

36. Genes and Alleles Note
Alleles are different forms of a particular
gene. At least two forms of each gene
normally exist among the members of a
species. For example in pea plants, the
gene controlling flower colour can
produce lilac or white coloured flowers.
The alleles of a gene are found at the
same location on each member of a pair
of chromosomes.

37. Genes and Alleles Note
Using the green booklets, make notes
on 6.7 section 2 only (The Segregation
of Alleles)
Read through 6.7 section 3
Finally, attempt the check test for 6.7.