What three features do you find in plant cells that are not in animal cells?
Plant cells have rigid cell walls, permanent vacuoles and chloroplasts
Topic B1 Cell Biology
Cells are the building blocks of life
Cells are the building blocks of every organism on Earth. In this video we find out about the huge range and different types of plant and animal cells and various specialised cells.
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Cells can be either Prokaryotic or Eukaryotic.
Eukaryotes are organisms which contain eukaryotic cells. Organisms containing prokaryotic cells are called prokaryotes . these are single cell organisms.
Bacteria are prokaryotes
Taking a (much) closer look...
Watch this video and use it to answer the questions
1. What does a microscope do?
2. What is meant by the term resolution?
3. Which objective lens should you use first?
4. How do you work out the total magnification used ?
5. What is the magnification formula
6. In the video they show an image of a red blood cell which is 1.0cm in diameter. The actual "real" blood cell has a diameter of 0.001 cm . What is the magnification used in this example?
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Inside cells... (subcellular structures)
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Most animal cells have:
Nucleus
In both plant and animal cells and contain the genetic material that controls the activities of the cell.
Cytoplasm
Chemical mixture (gel-like) liquid which fills the cell. It is composed of water, salts, and various organic molecules and is where most of the cell reactions take place.
Cell membrane
Separates the inside of the cell from the outside environment. It hold the cell together, containing the cytoplasm and controls what enters or leaves the cell
Mitochondria
These are where most of the reactions for aerobic respiration happen. This releases energy which is needed by the cell.
Ribosomes
Where proteins are made in the cell.
Plant cells have the all the above but also have...
Permanent Vacuole
Contains - a weak solutions of sugar and salts - cell sap
Rigid cell wall
This gives the cell strength and supports it . It is made of cellulose
Chloroplasts
Where photosynthesis occurs. This process makes glucose . The chloroplasts contain the green pigment called chlorophyll. Found in most plants.
Specialised cells
1. What are stem cells ?
2. what can stem cells turn into?
3. What is the difference between adult and embryonic stem cells?
4. What can stem cells be useful for?
5. Why is the use of stem cells controversial?
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Chromosomes and Mitosis
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Use the video to make a copy of the image below to explain the processes involved in Mitosis
Active transport
- How does active transport differ from diffusion and osmosis?
- Why is active transport into cells sometimes needed?
- Give an example of where active transport happens in humans
- Give an example of where active transport happens in plants.
Exchanging substances : Lungs
Oxygen moves from the inside of the alveolus into the blood and attaches to the haemoglobin of the red blood cells. It moves by a process called diffusion.
Carbon dioxide, made during respiration, leaves the blood plasma and enters the air inside the alveolus ready to be exhaled.
The alveolus has some special features that enable gas exchange to occur more easily:
- Large surface area - Each alveolus is like a balloon. When you have many of them together it is like having a bunch of balloons rather than one big one, there is more surface area this way for gas exchange.
- Moist surface - If the surface of the alveolus is moist it makes it easier for the gases to diffuse and prevents the inner surfaces sticking together.
- Thin walls - Like capillaries, the walls of the alveolus are thin so that the diffusing gases can move in and out of the blood more quickly and easily.
- Capillary network - This ensures a good blood supply. The blood takes away oxygen that has diffused from the air inside the alveolus. This maintains the concentration gradient that is needed for further diffusion.
- What function do the alveoli perform?
- Explain the ways in which the Alveoli are specialised to maximise the diffusion of CO2 and O2
- What is the approximate surface area of the alveoli in a human
Exchanging substances : Guts
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The partly digested food exits the stomach and enters the small intestine. In the first part of the small intestine bile, from the gall bladder, and pancreatic juices , from the pancreas, are added.
Both the bile and pancreatic juices help to neutralise the acid from the stomach providing the optimum pH conditions (approximately pH6 to pH8) for the enzymes to work.
Bile also emulsifies any fats present in the part digested food.
This provides a greater surface area for the digestive enzymes to work on. The pancreatic juices contain enzymes to digest carbohydrates, fats and proteins.
Exchanging substances : Leaves
- By what process does carbon dioxide and oxygen enter or leave a leaf?
- What structure in the leaf allows the gases to enter or leave?
- What do the guard cells do?
- In what ways are leaves adapted to maximise gas exchange?
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