Differentiate is the process by which a cell changes to become
specialised for its job. As the cell changes, they develop different
subcellular structures and turn into different types of cell, this
allows them to carry out specific functions. Most differentiation
occurs as an organism develops, in most animal cells, the ability
to differentiate is then lost at an early stage, after they become
specialised. However, losts of plant cells don't every lose this
ability. the cells that differentiate in mature animals are mainly
used for repairing and replacing cells, such as skin or blood cells.
some cells are undifferentiated cells - they're called stem cells
Sperm Cells are specialised for reproduction - the function of sperm is basically to get the male DNA to the female
DNA. It has a long tail and a streamlined head to help it swim to the egg. There are a lot of mitochondria in the
cell to provide the energy needed. It also carries enzymes in its head to digest through the egg cell membrane.
Nerve Cells are specialised for rapid signalling - The Function of nerve cells is to carry electrical signals from one
part of the body to another. These cells are long and have branched connections at their ends to connect to other
nerve cells and form a network throughout the body.
Muscle Cells are specialised for contraction - the function of a muscle cell is to contract quickly, These cells are long
and contain lots of mitochondria to generate the energy needed for contraction
Root Hair Cells are specialised for absorbing Water and Minerals - Root hair cells on the surface of plant roots, which
grow into long "hairs" that stick into the soil. This gives the plant a bigger surface area for absorbing water as well
as minerals from the soil.
Phloem and Xylem cells are specialised for transporting substances - Phloem and Xylem cells from phloem and
xylem tubes, which transport substances such as food and water around plants. To form the tubes, the cells are
long and joined end to end. Xylem cells are hollow in the center and phloem cells have very few subcellular
structures, so that stuff can flow through them.
Cells
Cells can only be either Prokaryotes or
Eukaryotes. The difference is the Eukaryotic cells
are complex and include all animal and plant cells.
Prokaryotic cells are smaller and made up of
Eukaryotic cells. a prokaryote is a prokaryotic cell,
this is a single celled organism
the different parts of a cell are called subcellular structures. most animals have the
following structures... 1. Nucleus- this contains the DNA and genetic materials
which controls the activities of the cell. 2. Cytoplasm - this is a gel like substance
were most of the chemical reactions take place. Cytoplasm contains enzymes that
control the chemical reactions. 3. Cell Membrane - holds together and controls
what goes on and out of the cell. 4. Mitochondria - where most of the reactions for
aerobic respiration takes place. Respiration transfers energy that the cell needs to
work. 5. Ribosomes - where the protein is made
Plants usually has everything that the animal cell has but, it ha a few extra...
1. Rigid Cell Wall - Made of cellulose. it supports the cell and strengthens it.
2. Permanent vacuole - contains cell sap, a weak solution of sugar and salts.
3. Chloroplasts - Photosynthesis occurs here, this makes food and water.
they contain a green thing called chlorophyll which absorbs light for
photosynthesis.
Microscopy
microscopes are pretty important for biology. 1.
Microscopes - they let us see things that we can't see with
the naked eye, the microscopy techniques we can use have
developed over the years as technology and knowledge have
improved. 2. Light microscpoes - use light and lenses to form
an image of a specimen and magnify it. They let us see
individual cells and large subcellular structures, like nuclei.
3. Electron microscopes - they use electrons instead of light
to form an image. They have a much higher magnification
than light microscopes. They also have a higher resolution
between two points, so a higher resolution gives a sharper
image. Electrons microscopes let us see much smaller things
in more detail, like the internal structure of mitochondria
and chloroplasts. They even let us see tinier things like
ribosomes and plasmids.
Chromosomes and Mitosis
Chromosomes Contains genetic information
Most cells in your body have a nucleus. The nucleus contains your genetic materials in the form of chromosomes. Chromosomes
are coiled up in lengths of DNA molecules. Each chromosomes carries a large number of genes. Different genes control the
development of different characteristics, e.g. hair colour. Body Cells normally have two copies of each chromosome - one from the
organism's 'mother' and one from its 'father'. So, humans have two copies of chromosome 1, two copies of chromosomes 2, etc.
The Cell Cycle Makes New Cells For Growth, Development and Repair
Body cells in multicellular organisms divide to produce new cells as part of a series of stages
called the cell cycle. the stage of the cell cycle when the cell divides is called mitosis.
Multicellular organisms use mitosis to grow or replace cells that have been damaged. The end of
the cell cycle results in two new cell identical to the original cell, with the same number of
chromosomes
Growth & DNA Replication
In a cell that's not dividing . the DNA is all spread out in long strings. Before it divides, the cell has
to grow and increase the amount of subcellular structures such as mitochondria and ribosomes. It
then duplicates its DNA - so there's one copy for each new cell. The DNA is copied and forms
X-shaped chromosomes. Each 'arm' of the chromosomes is an exact duplicate of the other.
Mitosis
Once its contents and DNA have been copied, the cell is
ready for mitosis... The chromosomes line up at the
center of the cell and cell fibers pull them apart. The two
arms of each chromosomes go to opposite ends of cell.
Membranes form around each of the sets of
chromosomes. These become the nuclei of the new cells
- the nucleus has divided. Lastly , the cytoplasm and cell
membrane divide. The cell has the same DNA - they're
identical. Their DNA is also identical to the parent cell