Cell Structure
What is cell theory?
Cells are the smallest unit of life, Cells can only come from other cells, Cells must grow and divide on their own
What is the arrangement of microtubules in a flagellum?
9+2 arrangement of nine double microtubules and two central microtubules.
Cell structure and function are primarily determined by what four factors?
Matter, energy, organization, and information.
How many mitochondria are in a cell?
It varies from a couple hundred to a couple thousand. They exist more in muscle cells and increases with exercise.
What types of sorting are there and what organelles are associated with each?
Co-translational- ER, golgi, lysosomes, vacuoles, PM, or secretion
Post-translational - nucleus, mitochondria, chloroplasts, peroxisomes
What are the main differences between eukaryotes and prokaryotes?
Prokaryotes- no nucleus, no organelles, binary fission, appendages, cell wall, small size
Eukaryotes- complex and large, has what pro's don't
Why is it important that protein synthesis from an mRNA has to occur in the cytosol?
The cytosol is responsible for protein sorting. There are specific pathways that allow for translation of RNA strands.
What is responsible for determining the structure and function of a cell?
The proteome is defined as the complete set of proteins that a cell is currently making or an organism can make.
What similarities exist between bacteria, chloroplasts, and mitochondria?
Single circular DNA, size, two membranes, divide by binary fission, own ribosomes and transcription machinery.
What is the role of signal peptidase?
To cleave signal sequences.
Why have bacteria evolved without a membrane bound nucleus?
It saves energy during processes such as transcription and translation, serves a protective function during viral attack, and aids in effective horizontal gene transfer.
What three things would happen if there was no cytoskeleton in a cell?
The cell shape would be deformed, motor proteins could not transport ions/molecules, and the cell would have a difficult time adjusting to its environment.
Why is compartmentalization important in eukaryotic cells?
Compartmentalization of metabolic processes makes eukaryotic cells very efficient and allows them to organize specific reactions.
If plants have chloroplasts, why do they have mitochondrion as well?
Chloroplast converts energy that can be used to make glucose for mitochondria since plants get their energy from light.
What three roles does the ER SRP take on?
Recognizes signal sequence, stops translation, and docks ribosome to ER Membrane.
A specific virus requires host cell machinery to replicate its genome. Is it considered living?
No, to be living it must be able to divide and replicate on its own.
How does the cytosol organize proteins?
Protein sequences have a sorting signal at the end of a polypeptide recognized by recognition particles that takes it to the correct place.
How do materials from the ER transport out the cell?
The materials get transported in vesicles that get pushed out of the cell by passing through the Golgi Apparatus to be processed.
Let’s say the mitochondrion of a cell didn't have an inner membrane, what would happen to the cell?
The cell would die. The inner membrane is needed to synthesize ATP.
What sorting method would ATP synthase take?
Post translational, it goes to the mitochondria.
What factors influence cell differentiation?
Which proteins are expressed, the levels of proteins expressed, subtypes of proteins expressed, and protein modifications.
How does a single microtubule work with other microtubules to allow “dynamic instability”?
Microtubules connect in a long strand that switches from growing and shortening phases.
Why do plants lack lysosomes and centrioles?
Lysosomes are not needed in plant cells because they have cell walls that are tough enough to keep the large/foreign substances. Plant cells without centrioles build special vesicles from their Golgi apparatus.
What benefits did purple bacteria and cyanobacteria give to eukaryotic cells in their proposed endosymbiotic relationship?
Purple bacteria - mitochondria, gave cell more ATP
Cyanobacteria - chloroplasts, gave photosynthesis
What would happen to cellular proteins if no chaperones were present in the cell?
Prevent polypeptide from folding so it can be threaded through. It won’t be able to make it to target organelles.