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| Question | Answer |
| What is the cell theory? | All living cells are made up of cells. |
| Define unicellular. | An organism made up of one cell only. |
| Define multicellular. | An organism made up of many cells. |
| What does specialised mean and give examples. | A specialised cell is a cell that has adaptations which allow it to carry out its specific function. E.g. red blood cells, lymphocytes, etc. |
| Define prokaryotic cell. | A cell without a nucleus, and they have much simpler structures without membrane bound organelles. |
| Define eukaryotic cells. | Cells that have a nucleus bound by a membrane and complex membrane bound organelles. |
| Describe the structure of the cell membrane. | - It is a double membrane. - Made up of two layers of phospholipids/ phospholipid bilayer. - It is embedded with proteins. |
| What is the function of the cell membrane. | - Controls the entry and exist of substances in and out of the cell. - Helps maintain different conditions on either side of the cell. |
| Difference between plasma membrane and the cell membrane. | - Plasma membrane is found around organelles, cell membrane is found around the cell. |
| Describe the structure of the nucleus. | - Large and round in shape. - Has a dark staining region called the nucleolus. - They have a double membrane called the nuclear envelope. - Nuclear envelope has pores which allows the exchange of substances between the cytoplasm and the nucleus. |
| What is the function of the nucleus? | - It contains protein bound linear DNA. DNA holds all of the genetic information needed to control the activities of the cell. |
| what is the function of the nucleolus? | - These produce ribosomes. - Also produces ribosomal RNA |
| Describe the structure of the mitochondria. | 1. They have a double membrane - their inner membrane is folded into a cristae - this increases the surface area for respiratory enzymes. 2. They have an oval shape. 3. Have a matrix. |
| what is the function of the mitochondria? | - site of aerobic respiration. - They respire aerobically to produce ATP which releases energy. |
| What are lysosomes ? | - A type of golgi vesciles - speherical organ and it contains hydrolytic/ digestive enzymes called lysozymes within a single membrane. |
| What is the function of the lysosomes? | - They digest protein molecules and other structures inside the cell. |
| What is the structure of ribosomes. | - Made up of two subunits of proteins and Ribosomal RNA rRNA. - They have no membrane - Usually attached to the rough ER. |
| What is the function of ribosomes? | Site of protein synthesis, from amino acids by condensation reaction, releasing a water moelcule and forming a peptide bond. |
| Describe the structure of the endoplasmic reticulum. | - These membranes that form a series of tubes in the cytoplasm of the cell. - They can originate from the nucleus. |
| What are the 2 types of ER? | 1. Rough ER. 2. Smooth ER. |
| What is the function of the rough ER? | 1. Provide a larger surface area for the synthesis of proteins. 2. provide a pathway for transport of substances espically proteins in the cell. |
| What is the function of smooth ER? | 1. Synthesis of lipids. 2. Transport of lipids. 3. Synthesis and transport of carbohydrates, |
| What is the structure of the golgi apparatus? | It is a stack of flattened sacs each surrounded by a membrane. vesicles are continuusly being pinched off the ends of the sacs. |
| What is the function of the golgi apparatus? | - It packages and processes molecules such as proteins. Also forms lysosomes, glycoproteins, etc. |
| What is the structure of microvilli? | Tiny finger like projections of the cell surface membrane. |
| What is the function of the microvilli? | - increase the surface area to maximise the rate of absoption. |
| Describe the structure of the cell wall. | - Thin layer made from cellulose found outside the cell surface membrane. |
| Function of the cell wall. | - Provides strength and support. - Stops cell from bursting when it is in a dilute solution by preventing cell from bursting. |
| What is the function of the middle lamella? | It marks the boundary between the neighbouring cell walls in plant cells. |
| Describe the structure of chloroplasts. | 1. Grana - a stack of round 100 thylakoids. 2. Thylakoid - contain the pigment chlorophyll which absrob light for photosynthesis They have disc shape structures. 3. Stroma - fluid filled matrix. Also have a double plasma membrane. |
| Which 2 cells contain chloroplasts? | 1. plant 2. Algal. |
| function of the chloroplasts | Photosynthesis. |
| What is the vacuole? | A sac filled with fluid surrounded by a membrane called the tonoplast. Found in plant cells' cytoplasm. The fluid inside is called cell sap and it is water dissolceved in other substances. |
| Function of the vacuole. | 1. Keep plant cells turgid. 2. Amino acids and sugars act as a temp food store. 3. pogments may colour petals and attract pollinating insects. |
| Give examples of eukayotic cells. | 1. Fungi 2. Algae 3. Plant cells. 4. Animal cells. |
| What does it mean for a cell to differentiate? | The cell becomes speciliased? |
| How do cells differentiate? | By reading different parts of the same genetic material and ignoring the other parts. |
| What are the 4 types of mammlian tissues? | 1. Nervous tissue. 2. Connective tissue 3. Muscular tissue 4. Epithelial tissue. |
| What are tissues, organs and organ systems? | 1. Tissues are a group of similar cells that have the same functions. 2. Organs are a group of tissues which work towards the same function. 3. Organ system are a group of organs which work together to carry out a specific physiological function. |
| What is the difference between eukatyotic cells and prokaryotic cells? | 1. prokayotic cells are smaller than eukryotic cells. 2. Prokayoritc cells do not have membrane bound organelles. 3. Prokyatoic cells do not have a true nucleus. - they have a single cirucular DNA strand free in the cytoplasm. (circular DNA) 4. Prokaytoic cells have smller ribosomes. 5. Prokyarotic cells have a murein cell wall. 6. pro have plasmids - tiny ciruclar loops of DNA 7. pro have flagellum- it propells it llowing it to move through fluids, 8. pro have capsules - those store toxins nd prevent bacterium from drying out and being attacked by white blood cells. 9. Pro have no nuclelous. |
| What are viruses? | small simple structures. |
| what are the 2 ways that viruses are described? | 1. acellular - they cannot reproduce outside host cells. 2. non liviing have no ode of metabolism. |
| describe the 3 main structures of viruses. | 1. genetic material which could be DNA or RNA. (HIV have RNA) BUT NOT BOTH. 2. attachment proteins 3. capsid / protein shell |
| gIVE 3 EXAMPLES OF VIRUSES. | 1. adenovirus 2. influenza virus 3. HIV 4. Polio |
| what is an object? | the material put under a microscope. |
| what is an image? | the appearance of the material put under the microscope when viewed uder the microscope. |
| what is magnification? | This is how many times bigger / larger is the image is compared to the actual object/ |
| how is magnification calculated? | image / actual size |
| what is resolution? | the minimum distance that two objects can be apart for them to appear as two seperate items. |
| what does an electron microscope have a better resolution than 1 ligh microscope. | - A beam of electrons will have a shorter wavelength than light. |
| what does it mean to have a greater resolution. | greater resolution = greater clarity = cleaer and more precise image. |
| how to calculate the resolution. | resolution = wavelength / 2 |
| what are the two types of microsocopes. | 1. light microscope / optical 2. electron |
| what are the 2 types of electron microscope. | 1. transmission electon microscope 2. scanning electron microscope. |
| which microsocpe gives a higher magnification? and better resoltuion. | an electron microscope. |
| hhow does a transmission electron microscope work ? | This works by absorbing the elecrons tht pass through the organeles and so the desner organeles will absorb more electrons and appear darker. Electrons pass through the speimen. |
| main advantages of using TEM instead of SEM. | 1. Higher magnification can be achieved with TEM 2. Better / higher reslutn can be achieved using TEM and so more detail of small structures / organellescan be seen. |
| disadvnatges of using TEM instead of SEM | 1. Long prep method. 2. Specimen is in a vacuum, cannot look at living materil 3.artefacts present 4. image is not in 3d 5. specimen must be very thin so electrons can pass through it. |
| how does a scanning electron microscope work? | the electrons bounce off the structure, |
| advantages of using SEM rather than TEM | 1. can view surface of specimen 2. image in 3D 3. thin sections do not need to be prepared. |
| How would we understand the function of the organelles? | 1. obtain a pure sample containing lots of the organelles you want to investigte, 2. sepeprate the organelles by cell fractionation. |
| Describe cell fractionation | - a process in which the cells are broken up and the different organelles they contain are seperated out. 1. tissue is cut up and put in a cold isotonic buffered soltion. - cold to reduce enzyne activity - isotonic to prevent osmosis so prevent shrinkig and brusting of organelles. - buffered to prevent damage to enzymes and maintain a constant pH. 2. The tissue is then placed in a homogeniser to release the organelles, the homogenate is removed a filteretd to remove complete cells and cel debris. 3. homognetae placed in an ultracentifuge and spun at high speed, first pellet/ thin sediment is nucleibcs most dense. then supernatant is removed and spun at a higher speed. |
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