Cell Structure and Organisation Flashcards
(22 cards)
What are cells?
Cells are the simplest functioning units of life
What are the two types of microscopes?
Light Microscopes - magnify objects up to 1000x
Electron Microscopes - magnify objects up to more than 200 000x
What are micrographs?
(Do not over stress on this as it is least likely to come out in exams.)
Micrographs are a camera fitted to a microscope:
Light Micrographs - images come out coloured
Electron Micrographs - images come out black and white, can be artificially colourised.
What do cells consist of?
Living matter called protoplasm
Protoplasm
A jelly-like substance where many chemical activities take place
Note: Protoplasm and Cytoplasm are different. Protoplasm is a broader version of cytoplasm (basically encasing it)
What is inside the protoplasm?
The Protoplasm of a cell is made up of the cell (surface) membrane, cytoplasm and nucleus.
What is the Cell Membrane?
The cell membrane
* - is made up of lipids and proteins
- is partially permeable
* - controls the movement of substances in and out of the cell
What is the Cell Wall
The cell wall
- is only present in several plant cells (e.g. leaf cells)
* - is made of cellulose
* - protects and gives the cell a fixed shape
- is fully permeable
What is the Cytoplasm?
The cytoplasm
- is a jelly-like substance
* - is where most cell activities occur
* - contains organelles [Nucleus, Endoplasmic Reticulum, Ribosomes, Golgi Body, Mitochondrion, Chloroplasts, Vacuoles]
What are organelles?
Organelles are cellular structures that perform a specific job in the cell
What is the Nucleus?
The nucleus
* - contains genetic material in the form of chromosomes (to be explored further in Molecular Genetics)
* - controls cell activities (e.g. cell growth)
* - Essential for cell division
What is the Endoplasmic Reticulum?
There are two types of endoplasmic reticulum, the
Rough Endoplasmic Reticulum which:
* - have ribosomes attached on its outer surface
- is directly connected to the nuclear membrane
* - transports newly synthesised proteins to the Golgi Body, and the Smooth Endoplasmic Reticulum, which:
- has no ribosomes attached
* - synthesises fats and steroids
* - is the site for detoxification
What is the Golgi Body?
The Golgi Body
- is Disc-shaped
- has vesicles fusing into and tearing off on the opposite side
* - chemically modifies substances made by the ER
* - stores and packages substances in vesicles for secretion in and out of the cell through the cell membrane by diffusion
What are Ribosomes?
Ribosomes attached to the RER make proteins that are usually transported out of the cell
Ribosomes laying freely in the cytoplasm make proteins that are used within the cytoplasm of that cell
What are Mitochondrion?
The Mitochondrion
- is sausage-shaped
* - is where aerobic (cellular) respiration takes place
* - releases energy for the cell to perform cell activities
* Several cells have more mitochondria than others (e.g. Sperm Cell)
What are Chloroplasts?
Chloroplasts
- are found only in several plants
- are oval structures
* - contain a green pigment called chlorophyll
* - are essential for photosynthesis
What are Vacuoles
Vacuoles
- store substances
* Animal cells have multiple small vacuoles which are temporary. They mostly store food and water substances.
Plant cells have a large central permanent vacuoles that contains cell sap which contains dissolved substances (e.g. amino acids, mineral salts)
What are the differences between a plant and animal cell?
Animal | Plant
Cell Wall Absent | Cell Wall Present
Presence of many small temporary vacuoles | Presence of large central vacuole
Chloroplasts absent | Chloroplasts Present
What is differentiation?
Differentiation is the process in which a cell becomes specialised for a specific function (e.g. Red Blood Cell, Muscle Cell)
What are the adaptations of a red blood cell that allow it to function efficiently?
Red Blood Cell
- contain haemoglobin (red pigment) which binds to oxygen and transports it to the rest of the body
* - has a circular, biconcave shape which increases surface area-to-volume ratio, thus oxygen diffuses in and out at a higher rate
* - lacks a nucleus, which allows the cell to store more haemoglobin, thus more oxygen transported
* - is flexible and can squeeze through capillaries easily
What are the adaptations of a muscle cell which allows it to function efficiently?
Muscle cells
- are elongated and cylindrical in shape
* - contains many mitochondria and nuclei to provide energy for contraction of the cell
What are the adaptations of the root hair cell that allows it to function efficiently?
Root Hair cells
* - has long and narrow root hair which increases surface area-to-volume ratio and increases rate of diffusion of water and mineral salts
