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)
what do defects in lysosomes cause?
how many diseases?
lysosomal-storage diseases
50 childhood diseases
what is endocytosis? what does it require?
process by which substances / organisms can entre cells surrounded by a membrane formed from internal budding of cell membrane. requires energy
what are the three types of endocytosis?
- phagocytosis (cell eating)
- pinocytosis (cell drinkin)
- receptor mediated or clathrin mediated endocytosis. clathrin are proteins found under cell membrane. can signal cell membrane to pinch off at that point
what are peroxisomes?
where originate?
what do they specifically contain?
def: membrane bound vesicles containing a number of catalytic enzymes responsible mainly for break down of fatty acids
originate: from RER
contain: catalase -> break downs hydrogen peroxide (common product of enzyme peroxisome)
what is a perixosomal disorder?
diseases where get accumulation of hydrogen peroxide due to absence of peroxisomes
e.g. Zellweger syndrome
does mitochondria have its own DNA?
yes - codes for most of proteins in mitochondria
apart from ATP production, what else mitochondria used for?
initiating apoptosis
what do mitochondria disorders commonly effect?
- how many?
- can be caused by mutations in what?
- muscle and nervous systems (high energy requirements)
- over 40 diseases
- mutations in mtDNA or nuclear DNA
