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81 Cards in this Set
- Front
- Back
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What is a Eukaryotic Cell? |
A cell with membrane-bound organelles |
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Examples of membrane-bound organelles |
Nucleus Chloroplast Mitochondrion Ribosomes Smooth endoplasmic reticulum Golgi body |
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Function of the nucleus |
Contains DNA and controls what goes in and out the cell |
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Function of chloroplasts |
Site of photosynthesis Contains chlorophyll Absorbs sunlight |
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Function of mitochondria |
Site of aerobic respiration. |
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Function of ribosomes |
Site of protein synthesis |
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Function of SER |
Site of lipid synthesis |
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Function of Golgi body |
Packaging large molecules |
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Features of a bacteria/ prokaryotic cell |
Loop of DNA Non cellulose cell wall Peptidoglycan Plasmids Capsule Flagellum Mesosome |
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Describe cell fractionation |
Homogenise Ice cold isotonic ph7 buffer Centrifuge at low speed Makes pellet Centrifuge supernatant at high speed Repeat |
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What does homogenising do? |
Breaks open cells |
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Why does it have to be ice cold? |
To slow down enzymes |
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Why does it have to be isotonic? |
So osmosis is equal in the tissue and solution. |
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Why does it have to have a pH7 buffer? |
To prevent enzymes denaturing. (Balances pH) |
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Why spin it at low speed first? |
Remove cell debris |
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Why spin at higher speed? |
Separate organelles |
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Why do they separate? |
Different densities |
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Inside the nucleus |
Around the nucleus it has: •nuclear envelope •nuclear pores - controls the exit of substances such as RNA. Inside the nucleus it has: •nuclearplasm •Chromatin - DNA •Nucleolus- dark region of chromatin that makes ribosomes. |
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Inside the mitochondria |
•Outer membrane- simple and permeable •Inner membrane - highly folded •Cristae- folds on the inner membrane •Matrix- space in the inner membrane. •inner membrane has stalled particles - site of ATP synthesis |
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Inside the Chroloplast |
• 3 membranes •Third membrane called THYLAKOID membrane. (Contains chlorophyll) •Thylakoid membrane is folded into thylakoid disks. •The stacks of disks are called Grana. •Space between membrane is called Stroma. |
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Ribosomes |
•Made of proteins and RNA. •Made in the Nucleolus. •Found roaming free or studded on the RER. •Found in groups called polysomes. |
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What size ribosomes do Eukaryotes haves? |
80s ribosomes |
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Smooth endoplasmic reticulum |
•Lots of membrane channels •Transports materials, mainly lipids, that the cell needs. |
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Rough endoplasmic reticulum |
•Studded with ribosomes. •Ribosomes synthesis proteins which are processed on the RER. |
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Golgi body |
•Flattens sacs/membranes called Cisternae. •Its formed from the ER. •Transport proteins from RER to the cell membrane to export. |
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Lysosomes |
•Membrane bound vesicles from RER • Contain a "cocktail of digestive enzymes". •Break down toxins or unwanted chemicals and organelles. |
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Vacuole |
Membrane bound sacs containing water or dilute solutions of salt and other dilutes. Filled with cell sap to keep it ridgid. |
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Cytoskeleton |
Network of protein fibres extending through cells for support and transport. |
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Centriole |
Pair of short micro tubes involved in cell division. |
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Micro villi |
Finger like extensions on cell membrane in some cells like epithelial cells. Larger surface area therefore faster absorption. |
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Cell membrane / plasma |
Thin flexible layer round the outside of all cells made of phospholipids and proteins. |
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Cell wall |
Strength and rigidity Networks make it permeable to solutes. Mainly cellulose Fungal cell walls are made of Chitin |
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Explain the role of genes in the differentiation process |
Cells get more specialised. When they do, this means that they can not switch on certain genes to produce certain specialised cell types. Therefore, pluripotent stem cells can turn on and off certain genes to specialise and once they do they can not change. |
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Inside a prokaryotic cell |
Ribosomes- make proteins Nuclear material- controls Mesosome- aerobic respiration Cell wall- structure Plasmid- contains DNA (can object it to other bacteria) Cell capsule - harder to kill and resists water loss Flagellum- moves the cell 70s ribosomes |
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What is a Virus? |
A prokaryote that can only reproduce inside other cells. |
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Name of method in which bacteria reproduce |
Binary fission |
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What is a prokaryotic cell? |
Cell with no membrane bound organelles |
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Equation for calculating the size of something in micrometres |
Image / actual = magnification
Convert millimetres to micro meters by x1000 |
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Changing units |
1m 1000mm 1000000um 1000000000nm |
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What is a light microscope? |
Magnified 1000 times Eyepiece Stage Focusing dial |
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Adv of light microscopes |
Use it on living cells Can explore cell division |
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Adv of light microscopes |
Use it on living cells- Can explore cell division Quick and simple Relatively cheap |
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Disadv of light microscope |
Can't see organelles Often need to be stained- can kill cells Resolving power of only 200nm |
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What is resolution? |
The minimum distance apart that 2 objects can be in order for them to appear separate
The ability to distinguish between 2 separate objects |
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What is magnification? |
How much bigger a sample appears to be under the microscope than it is in real life. |
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Overall magnification = |
Objective lens/ ocular lens (eyepiece) |
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Overall magnification = |
Objective lens X ocular lens (eyepiece) |
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Why can't mitochondria be seen under a light microscope? |
The wave length of light is bigger and can not reflect off the mitochondria |
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What is an artefact? |
Something observed in a scientific investigation or experiment that is not naturally present but occurs due to preparation for a procedure |
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What is laser scanning confocal microscopy ? |
Laser scans an object we want to see. Precise layer |
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What is laser scanning confocal microscopy ? |
Laser scans an object we want to see. Precise layer |
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Adv of master scanning confocal microscopy |
Precise layer 3D Higher resolution Visualise specific proteins and structures and watch them move |
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What is an electron microscope? |
Uses electron beams 2000x better resolution than light microscope |
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What is an electron microscope? |
Uses electron beams 2000x better resolution than light microscope |
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Adv of electron microscope |
Electrons have a very short wavelength so resolution is 2000x better than that of a light microscope |
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What is an electron microscope? |
Uses electron beams 2000x better resolution than light microscope |
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Adv of electron microscope |
Electrons have a very short wavelength so resolution is 2000x better than that of a light microscope
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How does an electron microscope work? |
Electron gun shoots beam of electrons passed down microscope MUST BE A VACUUM so electrons don't bounce of air molecules. Focus electron beam with electromagnetic lenses Passes through specimen Image produced on fluorescent screen on bottom |
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Disadv of an electron microscope |
Must be in a Vacuum so can't view living specimens Careful staining required, often has to be really thin Can get artefacts (false images) |
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2 types of electron microscopes |
Transmission electron microscopes
Scanning electron microscopes |
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Transmission scope |
Electrons pass through specimen Fat 2D images Only if it's very thinly sliced VERY HIGH RESOLUTION |
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Transmission scope |
Electrons pass through specimen Fat 2D images Only if it's very thinly sliced VERY HIGH RESOLUTION |
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Scanning scope |
Electron beam scattered from surface of specimen NOT THROUGH IT. 3D images Doesn't have to be thin LOWER RESOLUTION As to be coated with metal an can lead to artefacts |
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Rules for calculating magnification |
Keep units the same |
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What is a virus? |
A prokaryote that can only replicate inside another cell |
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What is a virus? |
A prokaryote that can only replicate inside another cell |
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Function of DNA in virus |
Carries genetic info |
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What is a virus? |
A prokaryote that can only replicate inside another cell |
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Why do viruses often target specific types of cells? |
Due to the specific chemicals that will make them stick to it and infect them |
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Why do antibiotics kill bacteria but not viruses? |
Viruses reproduce inside cells and antibiotics can't get to it |
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What is apoptosis? |
When a cell kills itself. |
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Why is apoptosis useful? |
It stops invading viruses from spreading |
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Function of DNA in virus |
Carries genetic info |
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Function of capsid |
Protein coat |
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Capsomere |
Individual parts of capsid |
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Glycoproteins |
Attach to other cells |
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Viral envelope |
Lipid bilayer So virus can bind to the host cell |
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Why do viruses often target specific types of cells? |
Due to the specific receptors |
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Why does the capsid of a retrovirus also contain an enzyme called reverse transcriptase ? |
Changes RNA to DNA Injects it into host cell Reproduce |
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Stages of binary fission |
•bacteria copies DNA •2 copies attach to inside walls of bacterial cell •cell divides forming new cell membrane and wall •own DNA |
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Stages of a virus reproducing |
• attaches to specific host cell • hereditary material enters the host cell •causes cell to make more hereditary material and proteins •new viruses form inside the host cell • new viruses burst out and destroy host cell |
