Eukaryotic cells (2.1) Flashcards
Who designed and put together one of the first working optical microscopes?
Robert Hook
What is magnification?
A measure of how much bigger the image you see is than the real object.
What is resolution?
A measure of how close together two objects can be before we see them as one
What does haematoxylin stain do?
stains the nuclei of plant and animal cells purple, blue or brown
What does methylene blue stain do?
stains the nuclei of animal cells blue
What does acetocarmine stain do?
stains the chromosomes in dividing nuclei in both plant and animal cells
What does iodine stain do?
stains-starch containing material in plant cells blue black
What are the advantages of using a light microscope?
-Can see living plant and animal- compare slides with living tissue.
-Relatively cheap
-Relatively light and portable so we can use them almost anywhere. e.g. identifying malaria in the field.
What are the disadvantages of light microscopes?
-Preservation and staining tissue can produce artefacts in the tissue being observed, so what we see may be the result of preparation rather than a true representation of living tissue.
-limited powers of resolution and magnification.
What are the different types of microscope
optical ( light)
scanning electron
transmission electron
ultrastructure
What is the optical microscope
A beam of light through the object, objective lens and eyes piece lens magnifies the sample.
What is a scanning electron microscope
a beam of electrons scans back and forth over the surface of the sample, producing a 3D image
What is a transmission electron microscope
-Electron beam
-Electrons pass through the specimen
-Harder for electrons to pass through thicker parts of the specimen, causing contractions in 2D image
- Electrons have smaller wavelenght so higher resolution
What is a ultrastructure microscope
structure only visible through a TEM. Electron microscopes have shorter wavelengths so higher resolution.
What does staining do ?
provide contrast between organelles and the cytoplasm, so they are observable.
What are some advantages of the electron microscopes?
-Huge powers of magnification and resolution. Many details of cells structures have been seen for the first time since they were developed.
Disadvantages of electron microscope?
-All specimens are examined in a vacuum- air would scatter the electrons and make the image fussy so impossible to look at living specimen.
-specimens undergo severe treatment that is likely to result in artefacts.
- requires skill
-Extremely expensive
-Large and have to keep at a constant temperature and pressure and need to maintain an internal vacuum.
What is the Fluid Mosaic Model ?
-Each consist of hydrophobic tails ( 2 fatty acids) and hydrophilic head (phosphate)
-Arranged with tails pointing inwards.
-Oily, giving membrane flexibility and fluidity
-Allows the passage of certain lipid soluble substances
What is the job of the cell surface membrane?
-control what substances enter and leave the cell
-allow recognition by other cells e.g. by the immune system
-Allow cells to communicate
What do the membranes within the cell do?
- membranes around organelles divide the cell into different compartments, making their different functions more efficient
-The membranes of some organelles are folded increasing surface areas, making chemical reactions more efficient.
What is the function of the plasma membrane? (7)
- The plasma membrane forms a barrier between a cell and the external environment.
-Offers mechanical support
-Has too be flexible to allow cells to move, grow and divide.
-must be self sealing to stop cells from bursting .
-Control passage of materials
-Recognition of other cells
-Receptor sites for hormones and neurotransmitters
What is the function of the intracellular membrane? (3)
- Similar structure to plasma membranes.
-Acts as a reaction surface
-Acts as an intracellular transport system
-Provides intracellular compartments so isolating different chemicals reactions
What is the Fluid Mosaic Model made up off?
-Phospholipid Bilayer
-Proteins
-Carbohydrates
-Cytoskeleton
What are intrinsic proteins and they’re properties/ function? (2)
-They span the width of the membrane.
- Act as protein channels to transport substances across the membrane or at routes for passive movement of material
-Carrier proteins bind to ions or other molecules ( like glucose) then change shape to move molecules across
What are extrinsic proteins and they’re properties/ function? (4)
-They are confined to the outer and inner surfaces.
-Gives mechanical support if alone and by attaching with cytoskeleton to anchor the membrane in place
- Many combine with carbohydrates groups to form glycoproteins
- Some lipid molecules join with carbohydrates molecules to form glycolipids.
-Glycolipids act as chemical receptors of the cell.
What is Cholesterol and its function? (5)
-strengthens bilayer
-Is hydrophobic so prevents water loss
-Helps decrease permeability
- Makes membrane less fluid at high temps
-Reduces lateral movements of other molecules
What do Glycolipids do ?
-Act as recognition
- Helps maintain stability
-Helps cells to attach to one another
- Act as chemical receptors
What are glycolipids made up of?
lipid molecules and carbohydrate molecules
What do Glycoproteins do?
- Act as recognition sites
- Helps cells to attach to one another
- Allows cells to recognise one another
What are Glycoproteins made up off?
extrinsic protein and carbohydrate.
Who proposed the Fluid mosaic model?
Gorter and Grendel
Why is the membrane describes as fluid and mosaic?
-Fluid = flexible.
-Mosaic= studded with proteins and other molecules.
What is Magnification?
How much bigger the image is than the object.
What is the plasmodesmata?
- Cytoplasmic bridges between cells.
-The interconnected cytoplasm of cells is called the symplast.
What is the function of the nucleus? (3)
- Acts as a control centre.
-contains genetic material in for of RNA and DNA.
-Manufactures ribosomal RNA and assembles ribosomes.
What is the Nucleolus?
Ans extra dense part of the nucleus that is made up of almost pure DNA and proteins.
what are ribosomes mad up off?
Ribosomal RNA and proteins and consists of one large and one small subunit.
What are 80 Ribosomes?
- Made up of 2 unequal subunits ( 40s and 60s)
-Ratio of RNA: proteins in 80s ribosomes is 1:1
What are 70 ribosomes ?
- Found in mitochondria and chloroplast of plant cell.
-Made up of 30s subunits and 50s larger subunits.
What do mitochondria consist of? (3)
- Double membrane ( inner one folds inwards to from critae)
- Cristae provides large area for attachment of enzymes involved in respiration.
-The rest is made up of the matrix, which contains lipids, proteins, ribosomes and DNA.
- Cristae provides large area for attachment of enzymes involved in respiration.
What is the function of the mitochondria?
Where respiration occurs and production of ATP.
What do Lysosomes consist of/do?
- Contain a powerful mix of enzymes
-Fuse with each other and with the membrane- bound vacuole that either contains food or absolute organelle. - Their enzymes break down the contents into reusable molecules.
What is the function of Lysosomes?
- Break down food
-Destroy worn out organelle - May fuse with cell membrane to release extracellular enzymes to kill bacteria.
-They can self destruct, releasing their enzymes, and causing apoptosis( controlled cell death)
What is the rough endoplasmic reticulum?
- RER id covered with granules, which are 80s Ribosomes
-Main function is to provide as a large surface area for synthesis of proteins.
What is the smooth endoplasmic reticulum?
- SER has no ribosomes
-Synthesises, stores and transports lipids and carbohydrates.
What are centrioles?
- In each cell there is a pair on centrioles near the nucleus.
-Each is made up of a bundle of tubules
What are centrioles function?
- The centrioles are involved in cell division
-The centrioles pull apart to produce a spindle of microtubules that are involved in the movement of chromosomes.
What is the Golgi/ what does sit do?
- Made up of flatterned discs called cisternae
-Proteins and lipids made up in ER are passed to the Golgi apparatus.
-Golgi modifies the proteins and lipids and then transfers them to other parts of the cells in Golgi transport vesicles.
-They also forms Lysosomes
What is the function of the Golgi?
Transforms, modifies and packages proteins and lipids.
What does the cell wall consist ?
- Mostly made up of insoluble cellulose
-Permeable to most substances dissolved in water
-Some additions to the cell wall effect permeability
-Is mostly made up of pectins
What is the function of the cell wall?
- Provides tensile strength and protection against mechanical and osmotic stress.
-Provides rigidity and strength
What does the chloroplasts consist of?(4)
- Envelope
-Grana= stacks of discs structure called thylakoids.
-Chlorophyl= is contained in the thylakoids (where 1st stage of photosynthesis takes place)
-Stroma= the fluid filled matrix (where the 2nd stage of photosynthesis take place )
What is the function of the chloroplast?
Produce energy through photosynthesis and oxygen.
What does the plant vacuole consist of ?
- A vacuole isa fluid filled space inside the cytoplasm surrounded by the membrane.
- The vacuole is filled with cell sap, a solution of various substances water.
What is the function of the vacuole?
- The solution causes thew water to move by osmosis so cytoplasm is kept pressed against wall= Turgid cell.
-stores pigments
-Stores proteins
-Stores waste products
What is the tonoplast?
- The specialised membrane that surrounds the vacuole
- Has many different protein channels and carrier systems in it.
-It controls the movement of substances into and out of vacuole.
-It controls the water potential of the cell
What is the Cytoskeleton?
- 3D web like structure that fills the cytoplasm.
- Made up of microfilaments and microtubules.
-The microtubules can be found singularly or in bundles and consist mostly of globular protein tublin.
What is the function of the cytoskeleton ?
- Give the cytoplasm structure and keeps organelles in place.
-Also closely linked with cell movements and transport within cells
What is the structure and subunits of microfilaments?
Structure= Protein fibres
Subunits= Actin and mycsin
What is the structure and subunits of microtubules?
Structure= Protein tubules
Subunits= tubulin
Example= Spindle fibres involved in cell division.
How does protein transport from the RER to the surface membrane?
1) ERE vesicles containing proteins which have been synthesised in RER. Pinch off and fuse with the flattened discs of the Golgi.
2) Golgi apparatus is stacks of flattened cisternae which modify proteins.
3) Vesicles containing the modified proteins pinch of the Golgi and fuse with the surface membrane.
What are the three components of cell theory?
1) Everything is made up of cells
2) Everything is made from the another cell
3) Cells are the basis of all life
What is the definition of tissue ?
The tissues are groups of similar cells carrying out a particular function.
What are the four types of tissue ?
-Epitheal
- Connective
-Muscles
-Nervous
What is epitheal tissue and the four types?
Found on the lining of surfaces inside and outside the body.
1) Squamous= found the lining of blood vessels
2) Cuboidal= lining different tubes in the body
3) Ciliated= containing goblet cells so produce mucus
4) Compound= Found on surfaces that are continuously scratched
What is the definition of an organ?
Made up of several different tissue that work to carry out a particular function
What are the different types of organ systems? (6)
-Skeletal system
- Muscular system
-Digestive system
- Respiratory system
-Nervous system
- Circulatory system
