week 1 Flashcards
what does the cell theory state?
- the cell is the basic organizational unit of life
- all organisms are comprised of one or more cells
- cells come from prexisting cells
What are the two types of cells?
Prokaryotic and eukaryotic
What are the differences between a prokaryotic and eukaryotic cell?
- Prokaryotic cells have no nucleus
- Prokaryotic cells also have no membrane bound organelles or compartments
- Prokaryotes are also single-celled organisms, but can live in clusters
What is the difference between bacteria and archaea?
Bacteria live everywhere, whilst archaea are found in abnormal places such as volcanic vents and cow stomachs
What is the nucleoid?
This is an area found in prokaryotes – it consists of strings of free DNA complexed with proteins
Why do plant cells have greater sized vacuoles?
It compensates for the lack of a skeletal structure
What does the endosymbiont theory explain
The origin of the eukaryotic cell, and how it is believed that they once emerged from prokaryotic
How did things come about from the early anaerobic eukaryotic cell
There was an early anaerobic eukaryotic cell, and an aerobic bacterium that was assumed to be ancestral. Because the bacteria lives inside the anaerobic cell, it is able to survive.
Explain the engulfing of mitochondria
Mitochondria was believed to have been evolved from aerobic bacteria that was once enguled by an early anaerobic eukaryotic cell, and thus lived in symbiosis with it
Why do mitochondria have double membranes?
It was believed that mitochondria (once existing aerobic bacteria) was engulfed by an ancestral anaerobic eukaryote. It lost its membrane by being engulfed by the eukaryote, and thus the outer membrane is believed to be derived from the host when the bacterium was engulfed
How did chloroplasts evolve?
Similarly, there was an early aerobic eukaryotic cell, and a photosynthetic anaerobic bacterium.
What features of the mitochondria and the chloroplast suggest the endosymbiotic theory?
- They both have 70s ribosomes, that similar to the prokaryotic ribosomes
- Their ribosomes are also sensitive to the same antibiotics of prokaryotic ribosomes
- They have their own DNA and genome, and have kept the double membrane
- They have also kept some of their own protein and DNA synthesis components
What does the fossil record suggest?
That prokaryotes came first, and eukaryotes second
What are the four strong lines of evidence that suggest the endosymbiotic theory?
- Similarity between ribosomes
- Ribosomal sensitivity to antibiotics
- The fossil record
- Double membrane composition
What is information flow?
The flow of information within the central dogma
What are the 3 types of RNA
- Messenger RNA
- Transfer RNA
- Ribosomal RNA
What is the function of mRNA?
It is translated into protein
What is the function of tRNA?
It is used in transporting amino acids and protein synthesis
What is the function of ribosomal RNA?
It is a part of the ribosome, and has a function on structural and cataclyticism
What is the genome?
This is the communication within the cell – all that concerns the genes
What is the transcriptome
When DNA is transcribed, it forms the transcriptome.
It is all the RNA at a given point of time (it is dynamic)
What is the proteome?
This is all of the proteins at one point in time – like a photograph of all the proteins in a cell at a given time
Is the proteome a mirror of the transcriptome/genome
No, because not everything that is transcribed is translated
What is the interactome?
This concerns all the protein-protein interactions within the cell
What is the metabolome?
This concerns all the metabolic reactions between small molecules, like sugars, ATP, fatty acids, etc.
What is the phenome?
This is all of the -omes connected to a phenotype
It is trying to match clinical, observable characteristics with what is occurring internally
What is the anti-parallel mechanism?
Directionality always goes from the 5’ to the 3’ end due to the orientation of the sugar phosphate backbone
What is the structure of DNA?
It has a pentose sugar, which acts as a scaffold for attaching a base. The sugar is also attached to a phosphate
What carbon is the phosphate group and the base attached to?
The phosphate group attaches to the fifth and third carbon, going in the 5’ to 3’ direction, and the nucleotide base is attached to the first carbon 1’
What are the two classes of nitrogenous bases?
Purines have two rings, and they are adenine and guanine
Pyrimidines have one ring, and they are uracil, cytosine, and thymine
What are the differences between DNA and RNA?
- Their pentose sugars. DNA has deoxyribose whilst RNA has ribose. In deoxyribose, the 2’ carbon does not have an -OH group attached
- Their base pairings, RNA has uracil instead of thymine
- DNA is double stranded, RNA is not
What is a nucleoside?
A nucleoside consists of the sugar and the base, but not the phosphate
What is deoxy adenosine?
It is a DNA molecule with an adenine base pairing
What are dNTPs?
Deoxynucleoside triphosphates consist of 3 phosphates, one for each nucleotide base
What bond connects the pentose sugar to the phosphate?
Phosphodiester bond
How does DNA have an energetically favourable conformation?
It has a major grove and a minor groove, formed by the electron heavy backbone and the way the hydrophobic bases are pushed to the middle
Why are the nucleotide bases hydrophobic?
They are aromatic rings, thus they cannot dissolve in water
What is the central dogma?
The flow of information from DNA to RNA to protein
What differentiates viruses from normal cells?
Viruses can contain information in the form of DNA or RNA, but they do not have the ability to replicate. Thus they live off of the processes of the host cell, ultimately like a parasitic zombie
Why aren’t daughter cells exact replicas of their parent?
At times, replication may have mutations that make the daughter cells differ from its originating parent
What can be found inside a bacterium?
No organelles other than ribosomes, and an area of genetic information called the nucleoid
Explain fluorescent microscopy
Fluorescent dyes used for staining cells are detected with the aid of a fluorescent microscope.
What is a fluorescent probe?
Fluorescent molecules absorb light at one wavelength, and emit it at another, longer wavelength. Some fluorescent dyes bind to particular molecules in cells and can reveal their location when the cells are examined with a microscope.
What is a transmission electron microscope?
These use a beam of electrons whose wavelength is very short
What is the scanning electron microscope?
The specimen has been coated with. heavy metal, and is scanned by a beam of electrons brought to a focus by a magnetic coil
How big are prokaryotes?
Some can be a few micrometers long, or even 100 times longer than that
How fast can prokaryotes divide?
As little as 20 minutes
Describe the nucleus
Has a double membrane, forming a nuclear envelope
Contains molecules of DNA
Describe the mitochondria
- They appear as worm shaped structures that form branching from the interior membrane
- Found to be enclosed with two membranes, one of which forms folds into the interior of the organelle
What do mitochondria do?
Generators of chemical energy for the cell; they harness the energy from the oxidation of food molecules, to produce ATP
What does the endoplasmic reticulum do?
It is an irregular maze of interconnected spaces enclosed by a membrane; and is the site where materials destined for export and cell-membrane components are made
What do the golgi apparatus, lysosomes, and peroxisomes do?
- The golgi apparatus modifies and packages molecules made in the ER, destined to be secreted or transported
- Lysosomes release nutrients from ingested food particles and break down unwanted molecules
- Peroxisomes are membrane-enclosed vesicles that provide a sequestered environment for reactions
What is a cytoskeleton?
This is a system of protein filaments
What are the 3 major filament types?
- Actin
- Intermediate
- Microtubules
What are motor proteins?
These use the energy stored in molecules of ATP to carry organelles and proteins
What are protozoans?
These are a class of free-living, motile, unicellular organisms
What is an example of a protozoan?
Didinium, a large carnivorous protozoan with a diameter of about 150 micrometers, and can attach and engulf other cells.
What are the main examples of model organisms?
- E. Coli
- S. Cerevisae (yeast)
- Arabidopsis
- Drosophila melanogaster (fruit fly)
- Nematode worm C. Elegans
