2406824
Description
Mind Map by Uzair Arif, updated more than 1 year ago
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Created by Uzair Arif
about 9 years ago
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B5
- DNA
- A double helix of
paired bases
- Each strand is made up
of little nucleotides
- Each nucleotide
contains a base:
A, T, C, G
- A-T and C-G
- A-T and C-G
- A double helix of
paired bases
- Proteins
- Genes are sections of DNA
that contain instructions for
particular proteins
- Cells make proteins by
joining amino acids in a
particular order
- The order of the bases in a gene
tell the cell in what order to put
the amino acids together
- They are made in
the cytoplasm by
ribosomes
- DNA cannot move out of the nucleus
because it is too big, so a copy of the
DNA is made using mRNA
- mRNA is shorter and
only has one strand
- 1, The two DNA strands unzip and a
molecule of mRNA is made using one
strand of DNA as a template
- 2. The mRNA moves out of
the nucleus and joins the
ribosome In the cytoplasm
- 3. The ribosome sticks the amino
acids together in a chain to make
a protein, following the order of
the bases in the mRNA
- mRNA is shorter and
only has one strand
- Genes are sections of DNA
that contain instructions for
particular proteins
- Cell Division
- Mitosis
- 1. The cell has two copies
of its DNA all spread out in
long strings
- 2. Before the cell divides, the DNA forms
X-shaped chromosomes. The two arms
are duplicates of each other
- 3. The chromosomes line up at the centre
of the cell and their fibres pull them
apart; the two arms of each chromosome
go to opposite ends of the cell
- 4. Membranes form around each sets
of the chromosomes; these become the
nucluei of the two new cells
- 5. Finally, the cytoplasm divides
- You now have two new cells containg
exactly the same DNA - they're genetically
identical to each other and the parent cell
- 1. The cell has two copies
of its DNA all spread out in
long strings
- Meiosis
- 1. The cell duplicates its DNA -
one arm of each chromosome is
an exact copy of the other
- 2. The chromosome
pairs line up in the
centre of the cell
- 3. The pairs are pulled
apart so each new cell
only has one copy of
each chromosome
- 4. The chromosomes line
up again in the centre of
the cell and the arms of
the chromosomes are
pulled apart
- 5. You get four gametes
with only a single set of
chromosomes in it
- After two gametes join
at fertilisation, the zygote
grows by repeatedly
dividing by mitosis
- 1. The cell duplicates its DNA -
one arm of each chromosome is
an exact copy of the other
- Mitosis
- Animal Development
- Embryonic stem cells can
be divided to produce ANY
type of specialised cell
- Used to replace
faulty cells in
sick people
- Used to replace
faulty cells in
sick people
- Adult stem cells can be
divided into SOME but
NOT all types of cells
- Used to cure sickle-cell
anaemia (blood disease) by
bone marrow transplants as
it contains stem cells that can
turn into new blood cells to
replace the faulty ones
- Used to cure sickle-cell
anaemia (blood disease) by
bone marrow transplants as
it contains stem cells that can
turn into new blood cells to
replace the faulty ones
- Genes can be switched
on if they're needed
during development
- Cloning
- 1. Remove a nucleus
from an egg cell
- 2. A nucleus from a body cell
of the adult you're cloning is
inserted into 'empty' egg cell
- 3. Under correct conditions, inactive
genes in the nucleus of the body cell
can be reactivated (switched on) so
that an embryo forms
- 4. Embryonic stem cells can
then be extracted from the
embryo - these stem cells could
then be controlled to form any
type of specialised cell
- 1. Remove a nucleus
from an egg cell
- Embryonic stem cells can
be divided to produce ANY
type of specialised cell
- Meristem Cells
- The only cells that are
mitotically active are
found here
- Found in areas
of a plant that
are growing -
roots and shoots
- Produce
unspecialised cells
that are able to
divide and form
any cell type
- Unspecialised cells become
specialised to form tissues like
xylem and phloem (the water
and food transport tissues)
- These tissues can group
together to form organs
like leaves, roots, stems
and flowers
- The only cells that are
mitotically active are
found here
- Phototropism
- A certain
direction in which
a plant responds
to light
- Positive Phototropism -
plants grow towards
sunlight for photosynthesis
- Negative Phototropism - plants
grow away from light so the
roots travel down into the soil
where they can absorb water
- A certain
direction in which
a plant responds
to light
- Auxins
- Chemicals that control
growth near the tips of
shoots and roots
- Produced in the tips
and diffuse backwards
to stimulate the cell
elongation process
- If the tip of a shoot is
removed, no auxins are
available and the shoot
may stop growing
- When a shoot tip is exposed to
the light, more auxins accumulate
on the side that's in the shade
than the side that's in the light
- This makes the cell grow
(elongate) faster on the
shaded side, so the shoot
grows towards the light
- Chemicals that control
growth near the tips of
shoots and roots
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