Theme B: B2 Cells - B2.2 Organelles and Compartmentalization Flashcards
Cell compartmentalisation
Cell compartmentalization refers to the organization of cellular components into membrane-bound organelles in eukaryotic cells. This separation allows specific biochemical processes to occur in distinct areas, enhancing efficiency and preventing interference between incompatible reactions.
reductionism
studying cells and how they work by reducing it to its component parts and studying each part individually.
biochemical fractionation
fractionation refers to the seperation and isolation of specific chemical and/or structures so that detailed research can be carried out.
chatgpt: A laboratory technique used to separate and isolate different components of a cell (such as organelles, proteins, or nucleic acids) based on their physical and chemical properties, like size, density, or solubility. It often involves methods like centrifugation or chromatography to study the function and structure of specific cellular components.
catabolic process
breaks a large molecule into smaller sub-parts (e.g. respiration - one of the key ways a cell releases chemical energy to fuel cellular activity.)
anabolic process
the reverse reaction of a catabolic process, here sub-parts are combined to form larger moleucles (e.g. photosynthesis)
cell fractionation (centrifugation)
Fractionation refers to the seperation and isolation of specific chemicals and/or structures to carry out detailed research. Cell fractionation allows the extraction of organelles from cells. Centrifuges are used to sepearte components of a cell by spinning it at high speeds. separation occurs because of the different densities of the component parts.
process:
1) cells are first mixed in a tube with the substances that break down the cell membrane
2) sample is then spun at high speeds to isolate the different components by size and shape.
3) once separated, larger and heavier organelles are found at the bottom of the tube
chromotography
very effective at isolating pure subtances like amino acids, proteins, carbohydrates, and plant pigments.
* a mixture of molecules is placed into a separating medium.
* the molecules separate out depending on their size and the speed with which they travel through the medium.
there are several types including:
1) gel and ion exchange chromotography
gel electrophoresis
separates different types of molecules by passing them through a gel using an electrical charge. the molecules are separated based on properties such as size and charge. commonly use din nucleic acid studies.
which cell components are not organelles?
1) cell wall
2) cytoskeleton
3) cytoplasm
examples of cell organelles
1) nucleus
2) vesicles
3) ribosomes
4) plasma membrane
5) cilia/flagella
6) mitochondria
7) Golgi apparatus
8) lysosomes
9) chloroplast
10) Endoplasmatic reticulum
what cell processes are responsible for the production of proteins?
1) transcription
2) translation
transcription
DNA strand serves as a template or copy strand for the formation of messenger RNA (mRNA) (happens in NUCLEUS)
translation
occurs when ribosomes use the code carried by mRNA to produce a polypeptide/protein (happen in CYTOPLASM)
what does the separation of transcription and translation allow?
the separation of thw two processes allows post-transcriptional modification of mRNA to occur in the nucleus (before translation happens). in prokaryotic cells there is no isolation, so mRNA can immediately come in contact with ribosomes and initiate translation without modification. the separation reduces chance of errors from occuring in production of polypeptides. this compartmentalization allows greater cell efficiency.
all eukaryotic cells posses organelles involved with…
1) energy production
2) biosynthesis
3) metabolism
4) degradation
acinar cells
a type of pancreatic cell specialised in secretion of digestive enzymes. they’re essential to human life and have gretaly enlarged Golgi apparatus, ER, and granule storage comaprtments.
benefits of compartmentalisation of lysosomes
lysosomes contain digestive enzymes that could severly damage the cell if not isolated by a membrane.
process of phagocytosis (endocytosis) and formation of phagocytic vacuoles
Phagocytosis is a cellular process for ingesting and eliminating particles larger than 0.5 μm in diameter, including microorganisms, foreign substances, and apoptotic cells (not in textbook). it plays a key role in defending cells against invading pathogens.
1) entrapment
2) formation of phagocytic vacuole
3) fusion with lysosomes (allowing inactviation and digestion of the threat)
4) digestion
the phagotyic vacuole is a meains of protecting the cellular contents from potential damage when phagocytosis occurs, bringing in food particles or pathogens.
challenge of compartmentalisation
the cell must develop a means of integrating ALL separate functions since each organelle carries out specific functions.
to accomplish this some organelles are connected in a functional series, allwoing important chemical pathways to take place.
membrane pumps and carriers have evolved so that the products of one organelle can enter another and important reactions can occur.
adaptions of the mitcohondria to sucessfully produce ATP energy by aerobic respiration
1) outer membrane: sepeartes its contents from the rest of the cell
2) matrix: cytomplasm-like subastance contaiing enzymes for first stages of respiration that take place in mitochondria (e.g. the link reaction and the Kreb’s cycle)
3) cristae: tubular regions surrounded by membranes that increase the surface area for reactions at the end of respiration (e.g. oxidative phosphorylation)
4) inner membrane: contains carrers and enzymes for final stages of respiration (e.g. electron trasnport chain and chemiosmosis)
5) space between the inner membrane and outer membrane: resevoir for hydrogen ions (protons) allowing a high concentration of protons
adaptation of the cholorplast to conduct photosynthesis
1) extensive membrane surface area of the thylakoid: grater absorption of light by photosystems
2) small space (lumen) and low volumes of fluid within thylakoids: faster accumulation of protons to create concentration gradient
3) stroma region simialr to cytoplasm of the cell and mitochondrial matrix: provides region where enzymes for Calvin cycle can work
4) double outside membrane: isolates working parts and enzymes of chloroplast from surrounding cytoplasm
respiration
glucose chemical bonds broken for ATP energy
overall equation for cellular respiration:
C6H12O6 + 6O2 –> 6CO2 + 6H2O + energy
photosynthesis
chemical bonds made for carbon compounds.
overall equation for photosynthesis:
6CO2 + 12H2O + light energy –> C6H12O6 +6H2O + 6O2
occurs in organisms called anotrophs (organisms that make their own food)
similarities between mitochondria and cholorplast structure
- both have extra outer membrane
- their own DNA
- both close in size to a prokaryotic cell
features of the nucleus
1) nuclear envelope: a double membrane providing a area where DNA can carry out its functions without being affected by surrounding reactions. it also breaks down early on in cell division process (mitosis and meiosis) to allow movement of DNA strcutures.
2) has many nuclear pores that extend through both layers of the nuclear envelope. these pores allow ions and small molecules to diffuse between the nuclear material, nucleoplasm, and cytoplasm. pores can also control passage of mRNA, proteins, and RNA-protein complexes (often become ribosomes and produced in the nucleolus) in and out of the nucleus.
3) outer membrane of nuclear envelope: continuous with ER + shares functions with it
4) inner membrane of nuclear envelope: interacts with chromatin (inactive form of DNA) and also maintains nucleus shape
ribosomes structure
made of proteins and RNA and has 2 subunits:
1) the larger subunit has two specialised binding sites (P site and A site) where molecules carrying amino acids can attatch. these sites allow multiple amino acids to be bonded into highly specific proteins
2) smaller subunit has an mRNA binding site
eukaryotic ribosomes are located either:
1) attatched ot the ER 2) free floating in the cytoplasm
free floating ribosomes
they produce proteins used within the cell. e.g. supporting the cytoskeleton, and also used in nucleus, mitochondria and in otehr organelles not derived from the cell’s inner membrane system.
membrane bound ribosomes
produce proteins transported through ER and often exported out of the cell. can produce secretory proteins sent to the Golgi apparatus where they’re packed for cellular exit (e.g. hormones and enzymes)
Golgi apparatus (and its role in processing and secreting proteins)
- transport vesciles (fileld with proteins or lipids) are recieved on the cis side from either the rough or smooth ER.
- as the protein or lipid move through the cisternae they’re modified to carry out specific function needed at the time.
- once modified product is packaged into a vesicle that depart on the trans side.
- often mdoficiation of a vesicle involves the attatchment of a signal chemical that directs the destination of the product
- some vesicles may beocme lysosomes wihtin the cell, others may turn into ER. many will combien with the plasma membrane and undergo exocytosis
vesicles
small membrane-bound sacs in which various substances are transported or stored in the cell
common vesicles:
* peroxisomomes: contain enzymes to break down fatty acids
* lysosomes: contain enzymes necesarry for cellualr digestion and for destroying defective or damaged organelles.
* transport vesicles: move molecules within the cell
* secretory vesicles, contain material to be excreted form the cell, such as neurotransmitters and hormones
clathrins
proteins in cell membrane that anchor certain proteins to specific cites. important example is their presence in plasma membrane in receptor-mediated endocytosis.
receptor-mediated endocytosis
The clathrins line coated pits, allowing recptors to bind to specific molecules. whan an appopriate collection of molecules occcurs in the lined pit, the pit deepens and will eventually seal off forming a vesicle. this process is highly specific where sealing off and the formation of vesicles occurs very rapidly.
different cells need different molecules thus they have specific recpetors on their surface.
