This document provides an overview of sexual reproduction in flowering plants and mammals. It discusses how gametes are produced through meiosis, containing half the number of chromosomes. Fertilization occurs when the male and female gametes fuse, restoring the full chromosome number and allowing for genetic variation in offspring. The document also describes DNA and genes, how genetic information is passed down, and sex determination in humans based on X and Y chromosomes.

1. 6.1 Sexual Reproduction in Flowering Plants
Today’s Learning Objectives:
 State the meaning of the term ‘gamete’.
 Name the parts of a flower that produce pollen.
 Name the parts of a flower which produce egg cells.
 State two differences between the pollen and
ovules of a flowering plant.
 State the meaning of the term ‘fertilisation’.
 State the meaning of the term ‘zygote’.
 Describe how fertilisation occurs in flowering
plants.
 Explain how fertilisation produces variety in the
offspring.

2. Reproduction
AsexualSexual
Only ONE organism
producing offspring.
Offspring identical
to parent plant.
No variety
within species
Two organisms
producing offspring.
Promotes variety
and therefore
biodiversity.

3. Flowering Plants
Most flowers have both male and female parts.
These sexual parts produce sex cells called
gametes.
Male gamete= POLLEN
Female gamete= EGGS

4. Flower Structure
Petals
Anther
Filament
Nectary
Sepal
Ovary
Style
Stigma
Stamen}

5. Fertilisation
Pollen Tube

6. 6.2 Sexual Reproduction in Mammals
Today’s Learning Objectives:
 Name the gametes produced by mammals.
 Name the sex organs in mammals which produce
gametes.
 Describe where fertilisation occurs in humans.
 State what genetic information a zygote contains.
 Explain how gametes are genetically different.
 Explain how sexual reproduction produces variety in
the offspring.

7. As with flowering plants, mammals need to
produce gametes for reproduction.
Male gamete= SPERM
Female gamete= EGG

8. Male and Female Gametes
Nucleus – contains information
in chromosomes
Cytoplasm – contains food store
Head
Tail – allows
sperm to swim to
egg

9. Fertilisation
Fertilisation is when
the two nuclei fuse

10. Early Human Development
After fertilisation the egg divides to form a zygote.
The zygote cell begins to divide to produce a large
ball of cells.
This will develop into an embryo.

11. 6.3 Genetic Information
Today’s Learning Objectives:
 State the meaning of the term ‘chromosome’.
 State the location of the chromosomes in a cell.
 State the number of chromosomes present in a
human body cell.
 State the meaning of the term ‘gene’.
 Describe the structure of DNA.
 Describe an experiment to isolate DNA from tissue.

12. The nucleus of a cell carries all the genetic
information.
Chromosomes inside the nucleus contain all
the genetic information.

13. Every nucleus in every cell of an organism
contains identical copies of these chromosomes.
The number of chromosomes present in an
organisms’ cells depends on its species.
e.g Human Male
46 Chromosomes

14. Chromosomes and Genes
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.

15. 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.

16. A A C T G C C G T A T G
The Genetic Code!

17. 6.4 Genes and Proteins
Today’s Learning Objectives:
 Describe the function of DNA.
 State what an amino acid is in relation to protein
structure.
 Describe protein structure.
 Explain the genetic code in terms of bases and
amino acids.
 Solve problems related to the genetic code.
 State the importance of the three-dimensional
shape of proteins such as enzymes.

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

19. 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.

20.  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)
 The amino acids are linked together to make a protein
Amino acidAmino acid Amino acid Amino acid
Protein molecule

21. 6.5 Gamete Production
Today’s Learning Objectives:
 Give the meanings of the terms ‘chromatid’ and
‘centromere’.
 Name the process which produces gametes.
 Name the cell from which a gamete is produced.
 Compare the total number of chromosomes in
gametes and other cells.
 Describe the process of meiosis.
 Identify diagrams of cells undergoing gamete
production and put them in the correct sequence.
 Explain the importance of chromosome shuffling
during gamete production.

22. Chromosome
Chromatid
Chromatid
Centromere

23. Sperm
Mother cell
Egg
Mother cell
Cell ready to
divide againSperm cell Egg cell
MEIOSIS
zygote
FERTILISATION

24. A Closer Look at Meiosis
Gamete Mother cell.
4 double chromosomes.
Matching chromosomes pair.
Line up cross cell
Pairs separate.
Cell divides.
Chromosomes line up.
Each cell divides again.
Centromeres split
Chromatids pulled apart

25. 6.6 Sex Determination
Today’s Learning Objectives:
 Draw or identify the male and female gamete
symbols.
 Name the the two different sex chromosomes in
humans.
 Name the sex chromosomes present in a) male body
cells, and b) sperm cells.
 Name the sex chromosomes present in a) female
body cells, and b) egg cells.
 State the theoretical ratio of males to females in a
human population.
 Explain why the actual ratio of males to females can
be different from the theoretical one.

26. The sex chromosomes of an individual are
the chromosomes which determine their
sex.
In humans this is chromosome 23.
There are two types of sex chromosome:
X chromosome (large)
Y chromosome (small)
An individual inherits one sex chromosome
from each parent.

27. Males
X and Y Chromosome
Females
X and X Chromosome

28. XX XY
Female
Female Male
Egg SpermX X X Y
XX XYXY XX
FemaleMale Male

29. 6.7 Genes and Alleles
Today’s Learning Objectives:
State what is meant by an ‘allele’.
 Give examples of genes and alleles.
 State the number of alleles of a gene in a gamete.
 State the number of alleles of a gene present in a
body cell.
 Describe fertilisation in terms of alleles.
 Describe fertilisation in terms of chromosomes.
 Explain how different alleles could be inherited
from parents.

30. Variations between individuals are due to the genes
they inherit from their parents.
These variations occur due to genes having different
forms. These forms are called alleles.
Alleles are different forms of
a particular gene.
e.g. Humans have a gene for blood group.
The alleles are Group A, Group B etc.
Labradors have a gene for coat colour.
The alleles are golden or black.