Chapter 1: Cell structure and organisation 🧫 Flashcards
What is a cell?
- A cell is a basic unit of life as it is the simplest unit of life, which makes up a living thing (an organism).
- A cell also requires air, water, and food to survive and live for a longer period of time.
- Cells also take in raw materials, which include undigested food molecules, they break them down and digest them to make new molecules. The cells either use these molecules or transport them to other body parts.
- Most cells are too small to be seen with the naked eye. Hence, the light and electron microscopes allow us to see cells and their parts at a much closer view.
What is a light microscope?
- A light microscope can magnify an object up to 1000 times its original size.
- It produces coloured light micrographs (diagrams/pictures).
What is an electron microscope?
- An electron microscope can magnify an object up to 200000 times its original size.
- It produces black and white electron micrographs.
What is a protoplasm?
- A protoplasm is a living material found in a cell and the protoplasm of a cell is made up of the cell membrane, cytoplasm and nucleus.
What are the main parts of a plant and an animal cell?
ACRONYM: MVCCN (My Very Close Cousin Named)
- The main parts of a plant and an animal cell include the mitochondrion, vacuole, cytoplasm, cell membrane and the nucleus.
What are the descriptions and functions of the cell wall?
The cell wall is:
- The outermost part of the cell.
- Made up of cellulose (sugar).
- Fully permeable to small molecules, so it does not allow ANY small molecules to pass through it.
The cell wall:
- Protects the cell from injury.
- Gives the cell its shape.
What are the descriptions and functions of the cell membrane?
The cell membrane is:
- A partially permeable membrane that surrounds the cytoplasm.
- Is made up of lipids (fats) and proteins.
The cell membrane:
- Controls substances entering or leaving the cell.
What are the descriptions and functions of the cytoplasm?
The cytoplasm is:
- A jelly-like substance embedded with organelles, which are specialised structures in the plant. (so, the cytoplasm contains organelles)
In the cytoplasm:
- Each organelle is specialised for a particular function
(e.g.) The cell wall helps to protect the cell from damage, and it gives the cell its shape because it is very rigid and hard.
- It is a site where most cellular activities occur and take place.
(e.g.) Cellular respiration, photosynthesis.
What are the descriptions and functions of the nucleus?
The nucleus:
- Is surrounded by the nuclear membrane.
- Contains genetic material in the form of chromosomes.
The nucleus:
- Controls cell activities such as growth, and tissue repair.
- Is important for cell division.
What is a nuclear membrane?
The nuclear membrane:
- Is a double-layered membrane that separates the nucleus from the cytoplasm in eukaryotic cells
- Is made out of two lipid bilayer membranes.
- Is selectively (not always) permeable, so it allows only certain molecules to pass through it.
- Contains nuclear pores that allow for the exchange of materials between the nucleus and the cytoplasm.
- Plays a crucial role in protecting the genetic material of the cell from the chemical reactions that occur outside the nucleus.
- Contains many proteins that are used in organizing DNA and regulating genes.
What is an organelle?
- An organelle is a tiny structure embedded in the cytoplasm that carries different and specific functions.
Does a plant cell have a cell wall?
- Yes
Does an animal cell have a cell wall?
- No
Does a plant cell have chloroplasts?
- Yes in leaves, but No in roots.
Reason: There are chloroplasts in leaves so that they can take in sunlight during the day to photosynthesize and make food. However, there are no chloroplasts in the roots as they do not need to photosynthesize and make food for the plant, they only need to absorb water and mineral salts from the soil, anchor the plants to the soil, and to support the plant.
Does an animal cell have chloroplasts?
- No
Does a plant cell have vacuoles?
- Yes, it has one large central vacuole.
Does an animal cell have vacuoles?
- Yes, it has small and many vacuoles.
What are the descriptions and functions of the mitochondrion?
The mitochondrion is:
- A small oval or sausage-shaped structure.
- Enclosed by a double membrane.
- An inner membrane that is highly folded
The mitochondrion:
- Is a site where aerobic respiration occurs.
- Provides energy for cell activities like growth and reproduction.
What is aerobic respiration?
- Aerobic respiration is a metabolic process that occurs in the presence of oxygen, where glucose and other food molecules are broken down into simpler molecules such as carbon dioxide and water.
- Afterwards, it releases energy that can be used by the body’s cells.
What are the descriptions and functions of the endoplasmic reticulum (ER)?
- Rough endoplasmic reticulum (RER):
The Rough endoplasmic reticulum is:
- A network of flattened spaces lined with a membrane.
- Connected to the nuclear envelope.
- Looks ‘rough’ as the ribosomes, small round structures are attached to its outer surface.
The Rough endoplasmic reticulum:
- Uses vesicles to transport proteins made by the ribosomes to the Golgi body.
- (extra point, not the function of the Rough endoplasmic reticulum): Ribosomes found freely throughout the cytoplasm synthesize and make proteins for use within the cell. - Smooth endoplasmic reticulum (SER):
The smooth endoplasmic reticulum:
- Is a tube-like structure.
- Is connected to the rough endoplasmic reticulum (RER)
- Looks ‘smooth’ as no ribosomes are found on its surface.
The smooth endoplasmic reticulum:
- Synthesises fats and steroids (sex hormones in mammals).
- Converts harmful substances to harmless substances through detoxification.
What is detoxification?
- Detoxification is a process of removing toxic substances from the body.
- It can refer to the medical treatment of an alcoholic, or a drug addict involving abstention from drinks or drugs until the bloodstream is free of toxins.
- It is also the process of removing toxic substances from the environment
What are the descriptions and functions of the Golgi body?
The Golgi body is:
- A stack of flattened spaces surrounded by membranes.
- Surrounded by numerous spherical body vesicles.
The Golgi body:
- Processes fats and proteins made in the rough and smooth endoplasmic reticulum.
- Stores and packages them in vesicles which transports them out of the cell.
What are the descriptions and functions of a vacuole? (present in plants and animals)
The vacuole:
- Is a fluid-filled space.
- Is large and central in a plant cell, which is enclosed by a partially permeable membrane.
- Contains cell sap.
- (This point only applies to the vacuoles in animal cells) Is small and numerous in animal cells, which are enclosed by a membrane, and it exists temporarily.
The vacuole:
- In a plant contains cell sap, which contains dissolved sugars, mineral salts, and amino acids. (starch + minerals + proteins
- In animal cell, they store water and food substances.
What are the descriptions and functions of chloroplasts?
Chloroplasts:
- Has an oval structure.
- Contains chlorophyll, a green pigment that is present in stacks of membranes.
Chloroplasts:
- Is the site of photosynthesis which is a process whereby plants make food and photosynthesize.
- Contains chlorophyll which is essential for photosynthesis.
