PHSC1212 Biochemistry - Lecture 3 Membranous Organelles

endoplasmic reticulum, golgi apparatus, lysosomes, peroxisomes, mitochondria, nucleus

membranous organelles

cisternae

storage chambers within membranes of the ER (flattened stacked membrane folds)

synthesis and modification of peptides and proteins, synthesis of carbohydrates and lipids, storage of synthesized molecules and other materials, detoxification of drugs or toxins

functions of the ER (including both smooth and rough)

calcium

important material stored in the ER, released in cell signaling circumstances

covered with fixed ribosomes

appearance of rough ER

fold polypeptides into functional protein structures, chemically modifies some proteins, packages into transport vesicles

functions of rough ER

adds carbohydrates to produce glycoproteins

How does the rough ER chemically modify some proteins?

glycoproteins

proteins modified by rough ER to have carbohydrates

transport vesicles

What does the rough ER package proteins into?

secretion, membrane incorporation, lysosomes

Rough ER is the primary site for synthesizing proteins destined for what?

proper protein structure and folding

ensured by the rough ER

no ribosomes present

What gives the smooth ER its smooth appearance?

lipid and carbohydrate synthesis, calcium storage, and drug metabolism and detoxification

smooth ER functions

phospholipid, cholesterol, steroid hormone, triglyceride, and glycogen

synthesized by smooth ER depending on cell type

to maintain plasma membranes

Why does the smooth ER synthesize phospholipid and cholesterol?

reproductive organs and adrenal glands

Where would cells have the smooth ER synthesize steroid hormones?

liver and fat

cells where smooth ER synthesizes triglycerides

skeletal muscle and liver

cells where smooth ER synthesizes glycogen

muscle contraction and neurotransmitter release

cell signaling processes calcium can be released for

cytochrome P450s

important enzymes that break down drugs, toxins, and other molecules that are foreign to the body

break down drugs, toxins, other foreign materials

What do cytochrome P450s do?

liver

Where are there high levels of CYP and therefore drug or toxin detoxification?

bound to smooth ER membranes

Where are CYPs in the cell?

golgi apparatus

receives transport vesicles from the rough ER and modifies and packages for secretion outside of the cell as well as membrane modification and lysosome packaging

forming or cis face

Where do vesicles enter the golgi apparatus from the ER?

maturing or trans

Where do vesicles exit the golgi apparatus?

modifies and packages molecules for secretion, renews or modifies membrane, packages enzymes within lysosomes

golgi apparatus functions

exocytosis

Vesicle contents released from cell through what?

proteins, enzymes, or hormones

packaged into secretory vesicles by golgi

carbohydrates

golgi may add or remove this from proteins

proteins synthesized on free ribosomes

Which proteins do not enter the golgi?

lysosome

enzyme containing vesicle that digests biomolecules

hydrolases

hydrolytic enzymes found in lysosomes

cleaning up inside cells and autolysis

lysosomal functions

break down and recycle damaged organelles and other macromolecules, destroy harmful microbes

How do lysosomes "clean up" inside cells?

autolysis

self-destruction of damaged cells

primary and secondary

types of lysosomes

primary

lysosome formed by golgi apparatus and containing inactive enzymes

secondary

lysosome fused with damaged organelle or endosome with activated enzymes, contents are digested with products reabsorbed for recycling and waste ejected via exocytosis

4.5-5.0

pH for digestive enzyme activation inside lysosome

acidic pH

required for digestive enzyme activation inside a lysosome due to action through proton pumps

peroxisomes

enzyme containing vesicles that break down branched and very long chain fatty acids

oxidases and catalases

enzymes carried by peroxisomes (names of the enzymes)

break down branched long chain fatty acids

primary role of peroxisomes

oxidative enzymes

What type of enzymes do peroxisomes carry?

hydrogen peroxide

produced and consumed by peroxisomes

division of exisiting peroxisomes that originated from the ER

How do peroxisomes replicate?

disposing of wastes, recycling of cellular components, specialized metabolism, detoxification

Whereas lysosomes' primary function is ___________________ and __________________, the role of peroxisomes is ___________________ and ___________________

unusual double membrane, matrix, cristae

mitochondria structure

numerous folds called cristae

What does the inner mitochondrial membrane contain?

matrix

fluid filled space enclosed by inner mitochondrial membrane

mitochondria

principal source of cellular energy

glycolysis, citric acid cycle, electron transport chain

parts to ATP production from glucose

mitochondrial matrix

Where does the citric acid cycle take place?

inner mitochondrial membrane

Where is the electron transport chain located?

oxidative phosphorylation

process through which the electron transport chain produces ATP

mtDNA and ribosomes

Mitochondria are special in that they contain their own what?

code for some energy production enzymes

What does mitochondrial DNA do?

nucleus

largest organelle

cell structure and functions it can perform

What does the cell nucleus determine?

protein synthesis

What does the nucleus control to determine what functions a cell can perform?

nuclear envelope

double membrane around the nucleus, connected to rough ER

doubled and connected to rough ER

What is the nuclear membrane like?

perinuclear space

space between the two phospholipid bilayers of the nuclear envelope; continuous with lumen of the ER

lumen of ER

What is the perinuclear place continuous with?

nuclear pores

communication passages in nuclear envelope for RNA, nuclear receptors, proteins etc

DNA

nucleic acid holding genetic information

nucleoplasm

fluid in the nucleus containing ions, enzymes, nucleotides, RNA, DNA

nuclear matrix

support filaments of the nucleus

cytoskeleton

What is the nuclear matrix similar to on a smaller level?

nucleolus

primarily composed of RNA and proteins, synthesizes rRNA and ribosomal subunits

RNA and proteins

nucleolus composition

rRNA and ribosomal subunits

synthesized in nucleolus

chromatin

loosely coiled DNA

not dividing

In the chromatin form of DNA, what is happening with cells?

chromosomes

tightly coiled DNA

dividing

In the chromosome form of DNA, what is happening with cells?

cells that manufacture large amounts of proteins like liver and muscle cells

Where are nucleoli most prominant?