Cell and Tissue Structure 2 Flashcards
which three organelles are involved in production of functional proteins?
ribosomes, SER and RER, golgi apparatus
where are ribosomes found?
- free floating in cytoplasm
- bound to the surface of the RER or nuclear envelope
describe structure of ribosomes
- made of 2 subunits
- composed of proteins and rRNA
what is function of ribosomes?
synthesis of polypeptide chain by attaching a.a. in sequence as directed by DNA
what does ER do?
describe structure of ER?
function:
ER very important in folding chain of a.a. into correct functional protein
structure:
- composed of membrane that is continous with the nuclear envelope
- forms folds of membranes called cisternae
- describe what happens to polypeptide chains in the RER (2)
- which proteins are processed by RER?
(translation happens in ribosomes) immediately goes into RER:
- most proteins are tagged e.g glycosylation (addition of carb)
- folded into their specific 3D structure
- almost all cellular and secretory proteins are processed by RER
what are the general functions of SER?
but…?
generally important for synthesis of carbs and lipids -> can breakdown lipids and synthesis new fatty acids
BUT: have specific functions in different cell types
- e.g. SER in muscle cells regulates calcium ion storage.
what is role of golgi apparatus?
modify and package proteins for transport to different areas of the cells / vesicles to leave the cell
what are two ends of GA called?
GA has the:
- cis surface: PROTEINS IN HERE
- trans surface: PROTEINS LEAVE AFTER THE STACKS
general summary of protein pathway
nucleus: DNA -> RNA
Ribosome: RNA -> Protein
RER: Protein modification
GA: protein packed and futher modified
the secreted
what are secretory pathways aka?
exocytosis
what are the three general secretory pathways?
- Constitutive secretion: unregulated secretion e.g. secretion of extracellular matrix proteins
2. Regulated secretion / signal mediated : requires a signal for secretion to occur. e.g. hormones
3. Lysosomal secretion: lysosomes need to be activated
where are lysosmes produced?
Golgi Apparatus
define lysosomes
membrane bound vesicles containing digestive enzymes
what can enzymes in the lysosomes do?
- break down food or other organelles (autophagy)
- breakdown invading organisms (bacteria)
- breakdown cell itself (autolysis)