Cell Biology
Prokaryotes and eukaryotes
Prokaryotes and Eukaryotes:
- Cells can either be prokaryotes or eukaryotes. Eukaryotic cells are Bacteria, animal and plant cells
complex and include all animal and plant cells. Cell definitions
- Prokaryotic cells are smaller and simpler, e.g. bacteria
Cell specialisation
o The genetic material is not enclosed in a nucleus
o The genetic material is a single loop of DNA, and there may be Microscopy
one or more small rings of DNA, called plasmids. Chromosomes
o They do not contain mitochondria or chloroplasts Cell Cycle
- Eukaryotes are organisms made up of eukaryotic cells, and a prokaryote
is a prokaryotic cell (a single-celled organism). Stem cells
Diffusion
Bacteria, Animal and Plant Cells:
Bacteria Cells: Osmosis
- In bacteria cells, the roles of mitochondria and chloroplasts are taken Active transport
over by the cytoplasm.
- Plasmid DNA is a small circular section of DNA
which can replicate independently of the
chromosomal DNA.
- Chromosomal DNA is not found within a nucleus
and is usually found as one circular chromosome.
- The cell wall provides support for the cell (not
made of cellulose).
- The flagella are tail-like structures that rotate to
help some bacteria move.
Animal Cells:
- The nucleus contains genetic material that controls the activity of the cell.
- Cytoplasm is a gel-like substance where most of the chemical reactions
happen. It contains enzymes that control these reactions.
- Mitochondria are where most of the reactions for aerobic respiration take
place. Respiration transfers energy that the cell needs to work.
- The cell membrane holds the cell together and controls what goes in and out.
- Ribosomes are where proteins are made in the cell.
Plant Cells:
- Chloroplasts are needed to make their own food through photosynthesis. They contain a
green substance called chlorophyll, which absorbs the light needed for photosynthesis.
- The cell wall, made of cellulose, supports the cell and strengthens it.
- Permanent vacuole contains cell sap, a weak solution of sugar and salts.
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, Cell Definitions:
- Nucleus – Contains genes on chromosomes. Controls the activities of the cell.
- Cytoplasm – Where most of the chemical reactions (metabolism) of the cell occur (including some parts
of respiration). These reactions are controlled by enzymes.
- Cell Membrane – A selectively permeable barrier that controls the movement of substances into and
out of the cell.
- Mitochondria – Where aerobic respiration occurs to release energy.
- Ribosomes – The site of protein synthesis.
- Cellulose Cell Wall – Provides strength and support for the cell. Prevents it from bursting due to
osmosis.
- Chloroplasts – The site of photosynthesis.
- Permanent Vacuole – Contains cell sap (which may contain dissolved substances). Important for keeping
the cell rigid (turgid) and providing support for the plant.
Cell Specialisation:
Sperm Cells – Sperm cells are found in the reproductive system. The nucleus contains 1
set of genetic material (haploid). The acrosome at the front contains enzymes to digest
its way into the egg. There are mitochondria behind the nucleus to provide energy for
movement. It has a flagellum (tail) that can move, so it can swim to the egg. The sperm cell is the
male sex cell (gamete).
Nerve Cell - Nerve cells are found in the nervous system. Dendrites
allow this cell to synapse with many other nerve cells. The fatty (myelin)
sheath insulates the axon and speeds up the nervous impulse. The nerve
cell’s job is to send action potential (nerve impulses) around the body to
allow nervous coordination.
Muscle Cell – Muscle cells are found in your muscles. Muscle cells can contract
(get smaller). The muscle cells contain many protein fibres that ratchet over each
other to make the muscle cell smaller. Muscles cause movement. Causing
movement requires a lot of energy. Muscle cells will contain a lot of mitochondria,
so they can do a lot of respiration.
Root hair Cell – The root hair sticks out from the surface of the root. Root hairs
are found in the roots of plants. This gives a very large surface area. The root
hair absorbs water from the soil by osmosis. They also absorb minerals, often using
active transport.
Xylem Cell – Xylem tissues are usually stained red or pink in prepared slides. Different vessels have
different patterns of lignification. Xylem vessels are found in the root stems and leaves of
flowering plants. Xylem vessels are dead. They have been waterproofed and strengthened with
a chemical called lignin. They have lost their cell contents, and the end walls have broken down
to make open tubes, so water can flow with less resistance. They transport water from the
roots to the leaves of the plant.
Phloem cells – Phloem vessels are alive. The cells are highly elongated for transporting material
around the plant. They have fewer organelles than most cells, so that liquids can move through
the phloem easily. Their end walls are perforated so that material can flow through the cells. They
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Prokaryotes and eukaryotes
Prokaryotes and Eukaryotes:
- Cells can either be prokaryotes or eukaryotes. Eukaryotic cells are Bacteria, animal and plant cells
complex and include all animal and plant cells. Cell definitions
- Prokaryotic cells are smaller and simpler, e.g. bacteria
Cell specialisation
o The genetic material is not enclosed in a nucleus
o The genetic material is a single loop of DNA, and there may be Microscopy
one or more small rings of DNA, called plasmids. Chromosomes
o They do not contain mitochondria or chloroplasts Cell Cycle
- Eukaryotes are organisms made up of eukaryotic cells, and a prokaryote
is a prokaryotic cell (a single-celled organism). Stem cells
Diffusion
Bacteria, Animal and Plant Cells:
Bacteria Cells: Osmosis
- In bacteria cells, the roles of mitochondria and chloroplasts are taken Active transport
over by the cytoplasm.
- Plasmid DNA is a small circular section of DNA
which can replicate independently of the
chromosomal DNA.
- Chromosomal DNA is not found within a nucleus
and is usually found as one circular chromosome.
- The cell wall provides support for the cell (not
made of cellulose).
- The flagella are tail-like structures that rotate to
help some bacteria move.
Animal Cells:
- The nucleus contains genetic material that controls the activity of the cell.
- Cytoplasm is a gel-like substance where most of the chemical reactions
happen. It contains enzymes that control these reactions.
- Mitochondria are where most of the reactions for aerobic respiration take
place. Respiration transfers energy that the cell needs to work.
- The cell membrane holds the cell together and controls what goes in and out.
- Ribosomes are where proteins are made in the cell.
Plant Cells:
- Chloroplasts are needed to make their own food through photosynthesis. They contain a
green substance called chlorophyll, which absorbs the light needed for photosynthesis.
- The cell wall, made of cellulose, supports the cell and strengthens it.
- Permanent vacuole contains cell sap, a weak solution of sugar and salts.
1
, Cell Definitions:
- Nucleus – Contains genes on chromosomes. Controls the activities of the cell.
- Cytoplasm – Where most of the chemical reactions (metabolism) of the cell occur (including some parts
of respiration). These reactions are controlled by enzymes.
- Cell Membrane – A selectively permeable barrier that controls the movement of substances into and
out of the cell.
- Mitochondria – Where aerobic respiration occurs to release energy.
- Ribosomes – The site of protein synthesis.
- Cellulose Cell Wall – Provides strength and support for the cell. Prevents it from bursting due to
osmosis.
- Chloroplasts – The site of photosynthesis.
- Permanent Vacuole – Contains cell sap (which may contain dissolved substances). Important for keeping
the cell rigid (turgid) and providing support for the plant.
Cell Specialisation:
Sperm Cells – Sperm cells are found in the reproductive system. The nucleus contains 1
set of genetic material (haploid). The acrosome at the front contains enzymes to digest
its way into the egg. There are mitochondria behind the nucleus to provide energy for
movement. It has a flagellum (tail) that can move, so it can swim to the egg. The sperm cell is the
male sex cell (gamete).
Nerve Cell - Nerve cells are found in the nervous system. Dendrites
allow this cell to synapse with many other nerve cells. The fatty (myelin)
sheath insulates the axon and speeds up the nervous impulse. The nerve
cell’s job is to send action potential (nerve impulses) around the body to
allow nervous coordination.
Muscle Cell – Muscle cells are found in your muscles. Muscle cells can contract
(get smaller). The muscle cells contain many protein fibres that ratchet over each
other to make the muscle cell smaller. Muscles cause movement. Causing
movement requires a lot of energy. Muscle cells will contain a lot of mitochondria,
so they can do a lot of respiration.
Root hair Cell – The root hair sticks out from the surface of the root. Root hairs
are found in the roots of plants. This gives a very large surface area. The root
hair absorbs water from the soil by osmosis. They also absorb minerals, often using
active transport.
Xylem Cell – Xylem tissues are usually stained red or pink in prepared slides. Different vessels have
different patterns of lignification. Xylem vessels are found in the root stems and leaves of
flowering plants. Xylem vessels are dead. They have been waterproofed and strengthened with
a chemical called lignin. They have lost their cell contents, and the end walls have broken down
to make open tubes, so water can flow with less resistance. They transport water from the
roots to the leaves of the plant.
Phloem cells – Phloem vessels are alive. The cells are highly elongated for transporting material
around the plant. They have fewer organelles than most cells, so that liquids can move through
the phloem easily. Their end walls are perforated so that material can flow through the cells. They
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