Chapter 3 - Cell Structure Flashcards
What similiraities do eukaryotic and prokaryotic cells have?
They both have a cell membrane
They both contain genetic information (DNA)
They both have ribosomes
They both have cytoplasm
Cell wall (plants and bacteria)
Differences between eukaryotes and prokaryotes
Eukaryotes have their DNA stored in a nucleus in chromosomes whereas prokaryotes instead have a DNA loop which is not assosciated with proteins (unlike the histones in eukaryotes)
prokaryotes have murein (glycoprotein) cell walls whereas eukaryotes have cellulose
prokaryotes can have capsules on the outside to protect them from harsh environments, as well as one or more flagella
Prokaryotes have plasmids
eukaryotes are significantly larger
eukaryotes have larger organelles (mitochondria, chloroplasts, golgi body, smooth and rough ER) but prokaryotes don’t
What is the structure of a virus?
They contain a capsid and attachment proteins to attach to other cells. They also contain genetic materials and proteins which they insert into their attached host
What is the benefit of using an optical microscope?
It is easy and relatively cheap to use and does not require specialists to operate. It is quick and provides coloured pictures without a lengthy preparation process for the sample as well as the sample having the potential to be alive
What are the drawbacks of optical microscopes compared to electron microscopes?
Electron micrscopes have significantly higher magnification and resolution, allowing you to see things such as individual organelles.
What are the drawbacks of electron microscopes?
The preparation process of slides is long as expensive, requiring mediums such as heavy metals. An incorrect preparation can also result in artefacts which are easily mistook for organelles. Furthermore the sample must be dead and only makes black and white images
How can you calculate the size of a sample on an optical microscope?
You would use a eyepiece graticule and then a stage micrometer to calibrate the eyepiece graticule. After it has been calibrated, you can use the intervals on the eyepiece graticule with their known size to calculate the size of the sample
What is the difference between magnification and resolution?
Magnification is how much greater the the sample size is compared to how large it actually is, whereas resolution is the detail image, and the ability to distinguish two different details
What equation is used to calculate the actual size of a sample based on the magnified size?
Actual size = image size / magnification
What are the three different stages of the cell cycle?
Interphase, mitosis and then cytokinesis
What happens during interphase?
All organelles and DNA is replicated
What are the four stages of mitosis?
Prophase, metaphase, anaphase and then telophase
Describe what happens during the first two stages of mitosis:
In prophase the nuclear envelope breaks down, the chromosomes condense or “supercoil” and the centrosomes begin to form
Then, in metaphase the chromosomes arrange themselves in the equator of the cell and the spindle fibres move towards them
What happens in the last two stages of mitosis, as well as cytokinesis?
In anaphase, then spindle fibres attach to the centromeres of the chromosomes and each pull one chromatid to each pole of the cell.
In telophase, the chromsomes reach each pole and the spindle fibres break down and the nuclear envelope reforms around the two groups of chromosomes. Finally, in cytokinesis cell cleavage occurs resulting in two genetically identical daughter cells
Describe the process of binary fission:
The plasmids replicate as well as the DNA loop, and then the DNA loops both move to different poles of the cells which become the two daughter cells with a random number of plasmids
