Cell structure Flashcards
What is the cytosol ?
It is the aqueous environment inside of the cell.
What is the cytoplasm ?
It refers to both the cytosol and the organelles in the cytosol.
What are the some of the propreties of prokaryotic cells ?
Smaller than eukaryotic cells (so large surface area to volume ratio)
No membrane-bound organelles
No nucleus
They generally reproduce asexually
Of what is made a prokaryotic cell ?
Ribosomes Plasmids Nucleoid Cell wall Flagellum Pilus
What are ribosomes ?
The molecular machine that convert RNA into protein through translation.
Of what are made ribosomes ?
It is made of a specific mixture of proteins and ribosomal RNA (rRNA)
What is the large dsDNA molecue in bacteria cells ?
It is the large, complete set of genes (chromosomes and proteins) of the bacteria. It folds up on itself to form the nucleoid.
What are the plasmids ?
They are additional small circular dsDNA molecules that some bacterias have. Plasmids contain additional genetc information that can be transfered to other bacteria through the pilus.
Of what is made the cell wall ?
It is composed of peptidoglycan.
What is the function of the cell wall ?
It is a defensive layer that protects the prokaryotic cell from outside materail (it is outside the cell membrane).
What do prokaryotic cells have to move ?
They have a flaggelum that whips around its protuding part and pilus.
What are the advantage of compartmentalization within an eukaryotic cell ?
Each compartment can have a specific microenvironment (different concentrations, pH,…)
What is the nucleus ?
It is a membrane-bound organelle that stores and protects the DNA of a cell. It also produces mRNA and rRNA.
What is the nuclear envelope ?
It is the double- membrane surrounding the nucleus.
What is the nucleolus ?
A specific region within the nucleus where rRNA is produced.
How is messenger RNA produced ?
mRNA is produced by recopying regions of DNA in a short term format.
Of what is composed the endomembrane system ?
the nucleus the endoplasmic reticulum (ER) the Golgi apparatus Vacuoles Lysosomes
How is called the inside of the endoplasmic reticulum ?
It is called “Lumen”
What does smooth ER ?
It focuses on the formation and the maturation of lipids. such as steroids and phospholipids. It can also help develop certain polysaccharides.
Whaat does rough ER ?
It produces new proteins. Many ribosomes are bound to it.
What is the function of the Golgi apparatus ?
It is the sorting center of various proteins and lipids. it also futher modifies proteins and lipids.
What does the lysosome ?
It helps to destroy the cell or other paricules. It has a pH of 5.
Of what is made the lysosome ?
It is made of special enzymes, specifically lipases, proteases, nucleases and carbohydrases.
What are vacuoles ?
They are large membrane-bound sacs that can contain a variety of substances.
What are central vacuoles ?
Vacuoles that contain water.
What are food vacuoles ?
Vacuoles that contain the particles taken up by the cell through endocytosis.
What are contractile vacuoles ?
Vacuoles that can pump water out of a cell.
What can the Golgi apparatus send proteins and lipids to ?
It can send proteins and lipids to vacuoles, to the lysosome or to the cell membrane.
What are peroxisomes ?
An organelle that contains special enzymes to break down hydrogen peroxyde or degrade other chemicals such as alchool.
Where are found cells with the most peroxisomes ?
In the liver and the kidney.
What is the mitochondria ?
A organelle with a double-membrane that synthesises ATP (adenosine triphosphate). The mitochondria also contains circular DNA and RNA.
By what process is the ATP within the mitochondria produced ?
By respiration. It is in the mitochondria that the respiration reaction is performed.
What cells have the most mitochondria ?
Cells that need the most energy (there is a tight correlation between the number of mitochondria and the energy needs of a cell).
What are the chloroplasts ?
Organelles with a double-membrane and the thylakoid space. It is where photosynthesis is performed. It also contains circular DNA and RNA.
Where are found chloroplasts ?
Only in plant and plant-like protists cellss.
What are the thykaloids?
Further compartment within the thykaloid space that have a third phospholipid bilayer (the first two form the membrane).
What is chlorophyll ?
A specialised molecule that allows the capture of light. It is also what gives plants their green color.
What is a symbiotic relationship ?
A relationship in which noth participants benefit.
How is the relationship between the mitochondria / chloroplast and the cell called ?
An endosymbiotic relasioship.
What is the cytoskeleton ?
A set of structural biomolecules within a cell, more specifically microtubules, microfilaments and intermediate filaments.
What are microtubules ?
Long hollow tubes that are composed of alpha-tubulin and beta-tubulin (which are proteins).
Where are microtubules found ?
In the flaggelum of eukaryotic cells, the cilia and within the cell. It acts as a “highway”.
What are the two motor proteins that move along microtubules ?
kinesins (moves towards positive) and dyneins (moves towards negative).
What is the centrosome ?
A pair of tube-like structures composed of 9 triplets of microtubules.
Of what are microfilaments made ?
They are made of actin (a protein).
What motor protein moves along microfilaments ?
Myosin which only moves towards positive.
What are microvilli ?
Small “hairs” that increasde the surface area of the cell, thus allowing a greater absorption of nutrients accross the cell membrane.
How is called the simultaneous removal and growth of actin (for microfilaments) or tubulin (for microtubules) ?
It is called dynamic instability.
Of what are motor proteins responsible for ?
They are responsible for vesicular transpost (the movement of vesicles or even organelles within the cell.
How do motor proteins move ?
By “walking”. They use ATP to change the position of their “feet”.
What is the cytoplasmic streaming ?
A flow in the cytosol caused by the movement of motor proteins. It can help motor proteins to push vesicles and organelles along.
Of what is responsible the movement of myosin along micofilaments ?
it is responsible for muscle contraction.
What are propreties of intermediate filamentss ?
They are “in between” sized
They are structural proteins
They do not demonstrate dynamic instability
THey are not made of a specific protein
What does intermediate filaments ?
They provide structural support to the cell, especially the nucleus.
What is one of the most important roles of the extracellular matrix (ECM) of animal cells?
It is for the ECM proteins to provide a form of anchoring for the different cells (to hold them in place).
What are proteoglycans ?
A “mixture” of sugars and proteins that capture and retain water.
What is collagen ?
A strong hellical protein .
What is elastin ?
A loose protein that gives elasticity to the skin, the intestines and the lungs.
What are integrins ?
Integral membrane proteins.
What are fibronectins?
Peripheral membrane proteins that connect integrins to other ECM components.
How are called the points of contact between two cells ?
Junctions
What are demosomes ?
Junctions where two cells connect at a SPECIFIC point of contact thanks to their cadherins (which are integral membrane proteins).
What are tight junctions ?
Junctions that are in contact along a LARGE surface of two cells.
What are gap junctions ?
Junctions that form when two cannels (one on each cell) connect. The channels are integral membrane proteins.
