[GENBIO1] Q1M4 Membrane-bound Organelles

cell organelles

specialized entity present inside a particular type of cell that performs a specific function

nucleus, endoplasmic reticulum, golgi apparatus, mitochondria, lysosomes, peroxisomes, vacuoles, vesicles, chloroplast

[9] membrane-bound organelles

nucleus

Found majority on eukaryotic cells and considered as the largest organelle, accounting for around 10% of the cell’s volume. This contains the genome. And through gene expression, it coordinates the activities of the cell.

nuclear envelope, chromatin, nucleolus

[3] parts of the nucleus

cell compartmentalization

the process of selectively permeable nuclear envelope separates the contents of the nucleus from that of the cytoplasm

first transcription

the mechanism by which DNA is transcribed to mRNA

gene expression

involves first transcription, which is the mechanism by which DNA is transcribed to mRNA

pre-mRNA molecules

newly synthesized mRNA molecules

post-transcriptional modification

molecules are added or removed from the structure (processing of pre-mRNA)

endoplasmic reticulum

major site of synthesis in the cell

cisternae

flattened sac network

rough endoplasmic reticulum

takes proteins from the cytosol and continues its production in the golgi apparatus until completion

post-translational modifications

undergone by the proteins that pass across the RER's membrane including inserting signal sequences to guide them to the cell's proper portion

secretion into the extracellular matrix like mucus and enzymes, association with the cell membrane-like receptors and channels, membrane-bound vesicle-like enzymes and lysosomes

The RER plays an important role in the synthesis of proteins that are destined for [3]

incorrectly folded proteins

processed inside the cell and eventually destroyed

smooth endoplasmic reticulum

important in lipid, phospholipid and steroid synthesis

steroidogenic cells and muscles

certain specialized tissues that have extensive SER

cytochrome p450 enzymes

found in the SER, essential to some drugs and toxins, such as alcohol and barbiturates, in the metabolism

hepatocytes

store glycogen in SER-rich regions

golgi apparatus

Mostly present in eukaryotic cells which is responsible for packaging of macromolecules into vesicles so that is can be sent out to their site of action.

golgi apparatus

modifies proteins and lipids which are obtained from the endoplasmic reticulum

exocytosis

The biochemicals leave the golgi by this method until they are transported to different intracellular and extracellular destinations.

protein processing

the carbohydrate regions of glycoproteins are altered by addition, removal or modification of carbohydrates

lipid processing

adds phosphate groups and glycoproteins to lipids from ER (like cholesterol) to create the phospholipids that make up the cell membrane

biochemicals

chemically labelled in the golgi to ensure appropriate delivery to the correct site

lysosomal proteins

packaged into vesicles specific to it (e.g. enzymes)

mannose-6-phosphate

usually labels the proteins within the golgi

secretory proteins

packaged into exocytosis-ready secretory vesicles (e.g. hormones)

cell surface proteins

enter constitutive secretory pathway present in all cells (e.g. phospholipids)

mitochondria

It has inner and outer membrane with an intermembrane space in between.

outer membrane of the mitochondria

contains proteins known as porins that enable ion movement to and from mitochondrion

porins

proteins that enable ion movement to and from mitochondrion

fatty acid elongation, adrenalin oxidation

[2] processes whereas the enzymes involved can be found on the outer membrane

inner membrane of the mitochondria

includes a number of enzymes such as ATP synthase that produces ATP in the matrix and carries proteins that control metabolite movement into and out of the matrix

ATP synthase

enzyme that produces ATP in the matrix and carries proteins that control metabolite movement into and out of the matrix

enzymes of the Krebs and fatty acid cycles, DNA, RNA, ribosomes, calcium granules

[5] materials in the mitochondrial matrix

mitochondria

site of ATP synthesis for the cell

cristae

increases the surface area available for energy production within the mitochondria

lysosomes

acidic membrane-bound organelle that contain numerous hydrolytic enzymes which catalyze hydrolysis reactions

membrane that surrounds the lysosome

important for ensuring that these enzymes do not flow into the cytoplasm and destroy the cell from within

hydrolytic enzymes

contained within the lysosome allow foreign particles to be destroyed

lysosomal membrane

allows protons to be transported into the lysosome to maintain its acidic pH

phagolysosome

formed when phagosome then attaches to a lysosome

phagosome

where foreign materials are held when phagocytosed by macrophages

endocytosis

how lysosomes also help to defend against pathogen entry by degrading pathogens before they enter reach the cytoplasm

peroxisomes

consists of single membrane and granular matrix scattered in the cytoplasm; assembled from proteins that are synthesized on free ribosomes and then imported into peroxisomes as completed polypeptide chains

catalase

enzyme which decomposes hydrogen peroxide either by converting it to water or by using it to oxidize another organic compound

plasmalogens

family of phospholipids in which one of the hydrocarbon chains is joined to glycerol by an ether bond rather than an ester bond

vacuoles

It acts as a storage for nutrients as well as waste materials to protect the cell from toxicity

tonoplast

membrane that encloses fluid containing inorganic materials like water and organic materials like nutrients and enzymes

vesicles

facilitate the storage and transport of materials in and outside the cell

lamellar phase

outer layer enclosing the liquid (vesicles) similar to the plasma membrane

chloroplast

a type of plastid that involved in photosynthesis in plants and algae

grana, stroma

two distinct regions of the chloroplast

chlorophyll

any of a group of green pigments found in photosynthetic organisms; traps sunlight

grana

consist of the chlorophyll pigments and are the functional units of chloroplasts; site for the process of light-dependent reactions of the photosynthesis process

thylakoids

disc-shaped structures that make up the grana

stroma

the homogenous matrix which contains grana and is similar to the cytoplasm in cells in which all the organelles are embedded; contains various enzymes, DNA ribosomes and other substances

stroma lamellae

function by connecting the stacks of thylakoid sacs