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B5 Growth and Development
- Cell specialisation in animals
- Cells of the same
type are grouped as
tissues
- Organisms begin
life as a zygote
and divides
through mitosis
- Embryonic stem cells
will produce any cell
type in the body
- Adult stem cells
can differentiate
into a limited
number of cell
types
- Only genes are needed to
enable the cell to function, as
that type of cell is switched on.
- Cells of the same
type are grouped as
tissues
- Cell specialisation in plants
- Xylem transports water
and mineral salts
- Phloem transports
the products of
photosynthesis
- Cells in regions
called meristems
are unspecialised
- When meristem cells divide
into two, the new cell
produced can differentiate
into different cell types.
- When meristem cells divide
into two, the new cell
produced can differentiate
into different cell types.
- Unlike animal cells plants keep
growing for their whole lifetime
- Xylem transports water
and mineral salts
- Plant clones
- Pieces of plants that have
plant cells and are used to
produce clones are called
cuttings
- Cuttings can be used to
produce new plants with
the same desirable
features as the plant
- Or to produce clones that
are genetically identical to
the parent plant
- Or to produce clones that
are genetically identical to
the parent plant
- Root growth in cuttings
is promoted by plant
hormones
- Another method is called tissue culture-
a small piece of tissue, or a few cells are
placed on agar jelly containing nutrients
and plant hormones. Each will grow into
a small plant
- Plant hormones called auxins
are included in the agar for
tissue culture and in hormone
rooting powder
- Auxins increase cell division
and cell enlargement,
promoting growth of the plant
tissue
- Auxins increase cell division
and cell enlargement,
promoting growth of the plant
tissue
- Pieces of plants that have
plant cells and are used to
produce clones are called
cuttings
- Plant growth and development
- Plant growth and
development is affected by
the environment
- Plants response to light is called
phototropism
- Plants grow towards the light, so they
are positively phototropic
- Plants grow towards the light, so they
are positively phototropic
- If a plant is illuminated from one side:
- The auxin produced in the tip is
distributed towards the shaded side, the
auxin produces growth on the shaded
side and therefore the shoot grows
towards the light.
- The auxin produced in the tip is
distributed towards the shaded side, the
auxin produces growth on the shaded
side and therefore the shoot grows
towards the light.
- Plant growth and
development is affected by
the environment
- Cell Division
- Mitosis
- Mitosis is the type of cell
division that takes place
when an organism grows
and cells divide to repair
tissues
- results in 2 daughter cells
that are genetically identical
- Before mitosis, the DNA in each
chromosome is copied. Each
chromosome is now a double
chromosome with two DNA
molecules
- During Mitosis, each
double chromosome
separates so that two nuclei
and two cells are produced
- Mitosis is the type of cell
division that takes place
when an organism grows
and cells divide to repair
tissues
- Meiosis
- Meiosis is the type of cell
division used to produce
gametes
- In humans, gametes contain
half the number of
chromosomes (23) as body cells
(which contain 46 or 23 pairs)
- Produces 4 daughter cells
with half the number of
chromosomes
- Meiosis is the type of cell
division used to produce
gametes
- Mitosis
- Chromosomes, genes and DNA
- Chromosomes are made
from a DNA molecule
- DNA molecule is a double helix
- There are four bases -A and T,
G and C.
- The order of the bases in a gene
makes up the genetic code. This
is the code that gives instructions
for the assembly of a protein (the
amino acids that are in the
protein and the order in which
they're arranged.
- Chromosomes are made
from a DNA molecule
- Protein synthesis
- Protein synthesis
occurs in the
cytoplasm
- Genes do not leave the nucleus, so in
order to carry the genetic code to the
cytoplasm, mRNA is produced in the
nucleus, using DNA as the template.
- Proteins are assembled
on organelles in the
cytoplasm called
ribosomes
- The number and sequence of
amino acids determines the type
of protein and its properties
- The sequence of amino acids in
the protein is determined by the
genetic code
- The bases work in
threes to code for
amino acids
- The sequence of amino acids in
the protein is determined by the
genetic code
- Protein synthesis
occurs in the
cytoplasm
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