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.
Kingdoms are subdivided into Phyla……..
Phylum - classes class - orders order - families family - genera genus - species
Examples of Plants?
-Examples include flowering plants, such as a cereal (for -example maize), and a herbaceous legume (for example peas or beans).
Examples of Animals?
-Examples include mammals (for example humans) and insects (for example mosquito).
Examples of Fungi?
-Examples include Mucor (hyphal example) and yeast (single cell example).
Define Diffusion?
The movement of particles form an area of high concentration to an area of low concentration, down a concentration gradient until equilibrium is reached. Substance that the cells need are diffused through the membrane.
Define Osmosis?
Movement of water from an area of high water potential to a low water potential down a water potential gradient through a semi-permeable membrane, this requires no energy. Used root hair cells to absorb water.
Define Active Transport?
The movement of particles against the concentrating gradient (low-high) THIS REQUIRES ENERGY. Used to transport proteins into and out of the cell.
Structure of Fungi?
- Usually organised into a mycelium made from thread-like structures called hyphae, which contain many nuclei.
- Some are single celled.
What are Fungi cell walls made of?
Chitin.
Experiment to investigate Diffusion?
Using Agar jelly with phenolphthalein and dilute sodium hydroxide. Fill a beaker with dilute hydrochloric acid. To investigate the rate, these cubes can be cut into different sizes. You can then record the rate at which the cubes turn colourless as the acid diffuses into the agar jelly and neutralizes the sodium hydroxide.
Experiment to investigate Osmosis - potato cylinders?
Cut potato into cylinders, and put them into beakers with different sugar solutions (one should be pure and another saturated) Then some in between. You can measure the length of the cylinders then leave them and then after an hour take measurements again . if the cylinders have drawn water in by osmosis we know that the water concentration of water in the potato is less than the water concentration in the beaker and visa versa.
Experiment to investigate Osmosis - Visking Tubing?
(Explain setup) Pour some suger solution down the glass tube into the visking tubeing. Put the visking tubing in a beaker and measure where the sugar solution comes up to on the glass tube. Leave this overnight, then measure where the liquid is in the glass tube. Water should be drawn into the visking tubing by osmosis and this will force the liquid up the glass tube. Inside the visking tubing the water concentration is low, outside it is high.
The Main factors effecting the movement of substances?
Surface are to volume ratio.
Temperature.
Concentration gradient.
Example of a Protoctists?
Amoeba
Example of Bacteria?
Salmonella
What is a Bacteria?
Bacteria are living cells and, in favourable conditions, can multiply rapidly. Once inside the body, they release poisons or toxins that make us feel ill.
NO NUCLEUS
Ways structure of virus differs from bacteria?
no cell wall
no cell membrane
smaller
Example of a Virus?
HIV virus
Example of a disease caused by a virus?
AIDS
Which organisms have a protein coat?
Virus
Are all pathogens?
Virus
Contain DNA in nucleus?
Fungus
Respire?
Bacteria and Fungus
What is Saprotrophic nutrition
Normally used by Fungi, they feed by extracellular secretion of digestive enzymes onto food material and absorption of the organic products (saprotrophic nutrition)
