Topic 3A- Cells Flashcards
(22 cards)
What is the functuon of the rough endoplasmic reticulum?
Folds and processes proteins which have been produces by the ribesomes attached to them.
What is the function of the nucleolus?
It produces ribesomes.
What is the function of nuclear pores?
They allow movement of mRNA between the nucleus and the cytoplasm.
What is the function of lysozomes?
They contain digestive enzymes, lysozyme, which can digest invading cells, or digest worn out components inside cells.
What are ribesomes composed of?
Proteins and RNA.
What are the functions of smooth endoplasmic reticulum?
Synthesises and processes lipids.
What is the function of the golgi apparatus?
It processes and packages new proteins and lipids.
What are the functions of mitochondria?
They are the site of aerobic respiration, where ATP is produced
What is the function of centrioles?
They’re small hollow cylinders composed of microtubules which are involved in the separation of chromosomes during Anaphase in mitosis.
Describe the pathway in a cell to produce and transport a protein.
Proteins are produced in the ribesomes. If theyre extracellular proteins, ribesomes on the surface of the rough endoplasmic reticulum synthesise them, and if theyre intracellular proteins, free floating ribesomes produce the proteins.
These proteins are then folded and processed (for example sugar chains are added) in the rough endoplasmic reticulum.
The proteins are then transported from the rough endoplasmic reticulum to the golgi apparatus in vesicles.
At the golgi apparatus, the proteins may undergo more processes, for example the sugar chains may be trimmed or more may be added.
The golgi apparatus then packages the new proteins into a vesicle (or lysozome if lysozyme is being produced), and the vesicles move around the cell to their required destination. If the proteins are extracellular, the vesicle will move to the cell surface membrane and will pinch onto the surface and will leave the cell by exocytosis, where they are secreted.
What are cell walls on prokaryotic cells typically made of, and what is it?
Murien, it is a glycoprotein.
What is the function of a slime capsule/
It protects the cell from immune cells by making them harder to be digested during phagocytosis im assuming as this is why TB is so good at evading the immune system.
Compare and contrast light microscope and electron microscopes.
light microscopes-
Can view live specimens
have lower resolutions than electron microscopes
are cheaper than electron microscopes
are mobile/can be transported
They use light to form images
can get resolutions of up to 0.2 micrometers
have a maximum magnification of around 1500x, which can view most organelles like the nucleus, and parts of the mitochondria
electron microscopes-
very high resolutions of around 0.0002 micrometers, so more detailed images
very high magnification of up to 1500000x
use electrons to form images
cannot view live specimens
What are the different types of electron microscopes?
Transmission-
Focus beams of electrons on thin specimens. They work by the specimen absorbing different amounts of electrons based on the thickness of them. The denser the part of the specimen is, the more electrons are absorbed and the darker it appears, vice versa. It is good because it provides high resolution 2D images of internal structures, of for examples mitochrondria, where their matrixes and cristae can be seen.
scanning-
Then scan a beam of electrons across a specimen, where electrons are knocked off the specimen. These electrons are gathered in a cathode ray tube which forms an image. This image can be 3D. It can be used on thicker objects, the resolutions are not as high in scanning than they are in transmission electron micrographs.
How to use an eyepiece graticule and a stage micrometer to calculate scales to measure specimens on a light microscope?
At a given magnification, place an eyepiece graticule on the eyepiece lens and place a stage micrometer on the stage. Line up the eyepiece graticule and the stage micrometer. Calculate the number of divisions of the eyepiece graticule which fit within one division of the stage micrometer. The stage micrometer has units for its divisions, whilst the eyepiece graticule does not, so you calculate the value of each division of the eyepiece graticule by dividing the measurement of one division of the stage micrometer by the number of divisions of the eyepiece graticule which fit within the stage micrometer. This gets the value for the length of each division of the eyepiece graticule. You can then replace the stage micrometer with the specimen and measure the length of the specimen.
Describe the different stages within interphase.
Gap Phase 1-
The cell grows and new organelles and proteins are made.
Synthesis-
The cell replicates its DNA here
Gap Phase 2-
further cell growth, and proteins required for cell division are made.
What occurs interphase as a whole?
The DNA is uncoiled from histone proteins, and is replicated so there is now double the DNA content. The organelles are replicated so there is now double the organelles, enough to make a new cell. The ATP content is also increased as cell division requires lots of ATP.
What occurs in Prophase?
The chromosomes condense (re wrap around histone proteins), getting shorter and fatter. Hollow protein tubes called centrioles begin to migrate to opposite poles of the cell. They start to spindle fibres between them. The nuclear envelope disintegrates, leaving the chromosomes lying free in the cytoplasm.
What occurs during metaphase?
The chromosomes attach to the spindle fibres at their centromeres, and line up at the centre/equator of the cell due to spindle fibre action.
What occurs during Anaphase?
Chromosomes split at the centromere, leaving two pairs of sister chromatids. The spindle fibres contract and pull each sister chromatid to each opposite pole of the cell.
What occurs during Telophase?
The sister chromatids uncoil to form long and thin chromosomes again. They are now at complete opposite poles of the cell, and a nuclear envelope begins to develop around each set of chromosomes, so there is now two nuclei. The cytoplasm begins to divide (by cytokinesis). There are now two genetically identical daughter cells. Cell division has finished and each daughter cell begins interphase again in preparation for further cell division.
Devise and experiment on how to observe mitosis.
Cut 1cm of meristem/root tip from a plant (this is the part of the cell which undergoes cell division).
Prepare a boiling tube with 1mol hydrochloric acid, and heat it in a water bath at 60 degrees.
Transfer the root tip into the boiling tube and leave it to incubate for 5 minutes.
Then remove the root tip, and rinse with cold water to remove the hydrochloric acid, and leave the root tip to dry on a paper towel.
Then place the root tip on a microscope slide and cut 2mm of the very tip of the root tip.
Use a mounted needle to macerate the root and break it apart/spread it out thinly.
Add a small amount of toluidine blue to stain the DNA of the plant, this makes the chromosomes easier to see.
Place a cover slip over the sample and press down firmly to remove any excess dye. It will also make the sample thinner and easier for light to pass through subsequently.
Now you can observe the stages of mitosis under the light microscope.
Calculate the mitotic index:
Number of cells with visible chromosomes/
The total number of cells.
