Chapter 1: Cell Structure and Organisation Flashcards
What are the 2 things that cells described as?
- The basic building blocks of life
- The simplest structural and functional units of life
What are the 2 apparatuses that we use to see cells?
Light and electron microscopes
How much does a light microscope magnify objects up to?
1000x
How much does an electron microscope magnify objects up to?
200 000x
What is special about light micrographs?
They can come out as colour images
What is special about electron micrographs?
They are black-and-white images but can be artificially colourised.
What does the protoplasm contain?
Cell membrane, nucleus and cytoplasm
What are the 8 organelles that can be found in cytoplasm?
- Nucleus
- Rough Endoplasmic Reticulum (RER)
- Ribosomes
- Smooth Endoplasmic Reticulum (SER)
- Golgi body
- Mitochondria
- Chloroplasts
- Vacuoles
Describe all the features of the cell membrane?
- It surrounds the cytoplasm of the cell
- It is made up of only lipids and proteins
- It is a partially permeable membrane
What is the function of the cell membrane?
It controls the movement of substances in and out of the cell
Describe the features of a cell wall.
- It encloses the entire plant cell
- It is made of cellulose
- It is fully permeable
What is the function of a cell wall?
It protects the cell from injury and gives the cell a fixed shape
Describe the features of cytoplasm.
- It is a jelly-like substance that fills the inside of the cell
- it is enclosed by the cell membrane
- It contains organelles
- It is the part of protoplasm between the cell membrane and nucleus
What is the function of cytoplasm?
It is the site where most cellular activities happen.
Which apparatus can the organelles be seen by?
Electron microscopes
Describe the features of the nucleus.
- It is surrounded by a membrane called the nuclear membrane
- It contains genetic information in the form of chromosomes
What is the function of the nucleus?
It controls cell activities and is essential for cell division
What will happen if a cell (except for RBC) does not have a nucleus?
The cell will die as it will be unable to undergo cell division
Describe the features of the RER.
- It consists of a network of flattened spaces lined with a membrane.
- Its surface appears rough when viewed under the electron microscope as ribosomes are attached to its outer surface.
- Its outer surface is continuous with the nuclear membrane
What is the function of the RER?
It allows the ribosomes to attach to it and it transports proteins made by the ribosomes to the Golgi body for secretion out of cell.
Describe the features of ribosomes.
- They are small, round structures.
- They are either attached to the RER or lie freely in the cytoplasm
- Ribosomes lying freely in the cytoplasm make proteins that are used within the cell
- Ribosomes attached to the RER make proteins that are transported out of the cell
What is the function of the ribosomes?
They are needed to synthesise the proteins in the cell.
Describe the features of the SER.
- It does not have ribosomes attached to its membrane.
- It is more tubular than RER
- It is connected to the RER
What are the functions of the SER?
- It synthesises substances such as fats and steroids.
- It is the site for detoxification.
Dsescribe the features of the Golgi body.
- It is shaped like a disc
- It consists of a stack of flattened spaces surrounded by membranes
- Vesicles can be seen fusing with one side of the Golgi body and pinching off from the opposite side.
What are the functions of the Golgi body?
- It chemically modifies substances made by the ER
- It stores and packages these susbtances in vesicles for secretion out of the cell.
How are substances made by the ER moved out of the cell?
- Small vesicles containing substances made by the ER are pinched of from the ER.
- These vesicles then fuse with the Golgi body and release their contents into the Golgi body. The substances made by the ER may be modified inside the Golgi body
- Secretory vesicles containing these modified susbtances are pinched off from the Golgi body. Thye then move to the cell membrane
- The secretory vesicles then fuse with the cell membrane and their contents are released out of the cell.
Describe the feature of mitchondria
They are small, oval-shaped organelles
What is the function of mitochondria?
Aerobic respiration occurs here.
What is aerobic respiration?
During aerobic respiration, food substances are broken down to release energy
What can the energy released by the mitchondria be used for?
The energy may used by the cell to perform cell activities such as growth and reproduction.
What are the features of chloroplasts?
- They are oval structures found in plant cells.
- They contain chlorophyll
What is the function of chloroplasts?
They are essential for photosynthesis.
Describe the feautres of a vacuole.
It is a fluid-filled space enclosed by a partially permemable membrane.
What is the function of a vacuole?
They store substances within a cell.
What is the type of the vacuole in plant cells?
Large central vacuole
What is special about plant cell vacuoles?
They contain cell sap.
What is type of vacuole is in animal cells?
Many small vacuoles
What is special about animal cell vacuoles?
- The vacuoles contain water and food substances.
- These vacuoles usually exist temporarily.
What is the cell structure of a red blood cell?
They have thinner central portion and have a biconcave shape.
What are the RBC’s adaptations + explanation for these adaptations.
- It contains haemoglobin which bind to oxygen and transports it around the body
- Its circular, biconcave shape increase the RBC’s surface area-to-volume ratio so that oxygen can diffuse in and out at a higher rate.
- By lacking a nucleus, it enables the cell to store more haemoglobin for transport of oxygen.
- It is flexible, allowing it to squeeze through capillaries easily.
What are the adaptations of a muscle cell + explanation for adaptation.
- It is elongated and cylindrical in shape, containing many nuclei and mitchondria.
- Has more mitchondria to release more energy for the contraction of muscle cell.
What are the adaptations of a root hair cell + explanation for adaptations.
Has a long and narrow cellular extension to increase surface area-to-volume ratio to absorb water and mineral salts at a higher rate.
