Topic A: Basics: Cells and classification Flashcards
The Cell concept?
All living organisms are made from cells. A simply organism may have different types of specialized cells which all do different jobs. Different types of organisms contain different cells.
What are Plants?
- Multicellular organisms
- Their cells contain chloroplasts- able to carry out photosynthesis
- Their cells have cellulose cell walls
- They store carbohydrates as starch or sucrose.
What are Animals?
- These are multicellular organisms
- They have no cell walls
- They usually have nervous coordination and are able to move from one place to another
- They often store carbohydrate as glycogen.
What are Fungi?
-Usually organised into a mycelium made from thread-like structures called hyphae, which contain many nuclei
-Some examples are single-celled
-Their cells have walls made of chitin
-They feed by extracellular secretion of digestive enzymes onto food material and absorption of the organic products (saprotrophic nutrition)
-They may store carbohydrate as glycogen.
DON’T CONTAIN CHLORPLASTS
What are Protoctists?
These are microscopic single-celled organisms
Some, like Amoeba, that live in pond water, have features like an animal cell
Some like Chlorella, have chloroplasts and are more like plants
A pathogenic example is Plasmodium, responsible for causing malaria.
ALL HAVE NUCLEUS
SOME HAVE CELL WALL
What are viruses?
- These are small particles, smaller than bacteria
- They are parasitic and can reproduce only inside living cells
- They infect every type of living organism
- They have a wide variety of shapes and sizes
- They have no cellular structure but have a protein coat and contain one type of nucleic acid, either DNA or RNA
- Examples include the tobacco mosaic virus, the influenza virus (causes ‘flu’) and the HIV virus (causes AIDS)
What is a pathogen?
-A pathogen is anything that causes a disease. Pathogens include:
- Bacterium (example: bacterial meningitis or strep throat)
- Virus (example: hepatitis A, hepatitis B, and hepatitis C)
- Fungus (example: athlete’s foot)
What are the main characteristics that all living organism share?
Movement Respiration Sensitivity Growth Reproduction Excretion Nutrition
Function of the nucleus?
Controls what the cell does. It contains instructions to make new cells.
Function of Cytoplasm?
Chemical reactions take place inside the cytoplasm, to keep the cell alive.
Function of the Cell membrane?
This is a thin layer of skin around the cell membrane, it gives the cell its shape and controls what comes in and out of the cell.
Function of Mitochondrion?
The cell’s power station. they convert energy into forms that are useful for the cell.
Function of the cell wall?
Covers the thin cell membrane. it is made of tough cellulose that strengthens the wall.
Function of chloroplasts?
These are found in cells that carry out photosynthesis. they contain chlorophyll to trap light energy.
Function of Large permanent vacuole?
a plant cell has a large permanent vacuole filled with a liquid called cell sap.
Level of organisation?
Atom, smallest unit that a chemical element is made of.
Molecule: 2 or more atoms (same different) chemically combined.
Organelle, structures in the cell that perform a particular job.
Cell, Unit of all living organism.
Tissue: Many cells of the same kind with a particular function.
Organ, Several tissues combined to perform a particular task.
Organ system: several organs which act together to perform a general function
Organism: An independent organism.