Slides in this set
· Most cells in our body have a nucleus and it's the nucleus that contains our genetic
· The human cell nucleus contains 23 pairs of chromosomes. They're always in pairs, one
from each parent.
· Chromosomes are made of long DNA molecules, the DNA is coiled up to form the arms of
·A gene is a short length of the chromosome. Different genes control the development of
· Genes can exist in different versions, each version gives a different characteristic like blue
or brown eyes, The different versions of the same gene are called alleles.…read more
Reading our genes
· Genes are a section of DNA which gives instructions for
a cell about how to make a certain kind of protein.
· Genes are inherited by parents.
· Features can be influenced by genes, the environment or
· PROTEINS: A zygote (fertilised egg cell) has the
instructions for making every protein inside of us.
· Structural: Builds the body e.g. collagen
· Functional: Takes part in chemical reactions.…read more
What makes us all different?
Organisms inherit information from their parents. This
controls how they develop, so children look a lot like
their parents. People share many common features and
the differences between people are very small. These
differences make us unique.
Chromosomes are made
Most features are also affected by the
of DNA molecules
environment e.g. Weight, height, skin colour
All living things
are made of cells
Different proteins in the body do
different jobs. H: They can be Genes are instructions
structural (to build the body) or which tell the cell how
functional: enzymes (to speed up to make proteins
chemical reactions in the body)…read more
Reproduction It involves the fusion of male and
female genes. There are two parents, so
their genetic information combine to
produce offspring which contain a
mixture of their parents genes which
are genetically different from the
1) The mother and father produce
gametes e.g. egg and sperm in animals.
2) Each gamete contain half the number
Asexual Reproduction of chromosome in a normal cell, instead
There is only one parent and the offspring has of having two of each chromosome they
identical genes to the parent. Organisms like just have one.
bacteria and certain plants produce offspring 3) The egg from the mother and the
using asexual reproduction. Also this is how all sperm from the father then fuse
plants and animals grow and produce together (fertilization) to form a cell
replacement cells. with the full number of chromosomes.
1) X shapes chromosomes have two identical
halves and so they split down in the middle.
2) It forms two identical sets of half
3) The DNA replicates itself to form two identical
cells with complete sets of X shaped
· When twins are born, they
· But there is some
· This is because of
variations in environment.
Environment can affect
· During fertilisation, the
zygote cell divides by
mitosis to form 2 babies
instead of one.
· The 2 babies have the
same genetic information.…read more