Cell and Tissue Structure 2

Question 1

which three organelles are involved in production of functional proteins?

Answer 1

ribosomes, SER and RER, golgi apparatus

Question 2

where are ribosomes found?

Answer 2

• free floating in cytoplasm
• bound to the surface of the RER or nuclear envelope

Question 3

describe structure of ribosomes

Answer 3

• made of 2 subunits
• composed of proteins and rRNA

Question 4

what is function of ribosomes?

Answer 4

synthesis of polypeptide chain by attaching a.a. in sequence as directed by DNA

Question 5

what does ER do?

describe structure of ER?

Answer 5

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

Question 6

• describe what happens to polypeptide chains in the RER (2)
• which proteins are processed by RER?

Answer 6

(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

Question 7

what are the general functions of SER?

but…?

Answer 7

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.

Question 8

what is role of golgi apparatus?

Answer 8

modify and package proteins for transport to different areas of the cells / vesicles to leave the cell

Question 9

what are two ends of GA called?

Answer 9

GA has the:

• cis surface: PROTEINS IN HERE
• trans surface: PROTEINS LEAVE AFTER THE STACKS

Question 10

general summary of protein pathway

Answer 10

nucleus: DNA -> RNA

Ribosome: RNA -> Protein

RER: Protein modification

GA: protein packed and futher modified

the secreted

Question 11

what are secretory pathways aka?

Answer 11

exocytosis

Question 12

what are the three general secretory pathways?

Answer 12

1. 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

Question 13

where are lysosmes produced?

Answer 13

Golgi Apparatus

Question 14

define lysosomes

Answer 14

membrane bound vesicles containing digestive enzymes

Question 15

what can enzymes in the lysosomes do?

Answer 15

1. break down food or other organelles (autophagy)
2. breakdown invading organisms (bacteria)
3. breakdown cell itself (autolysis)

Question 16

what do defects in lysosomes cause?

how many diseases?

Answer 16

lysosomal-storage diseases

50 childhood diseases

Question 17

what is endocytosis? what does it require?

Answer 17

process by which substances / organisms can entre cells surrounded by a membrane formed from internal budding of cell membrane. requires energy

Question 18

what are the three types of endocytosis?

Answer 18

1. phagocytosis (cell eating)
2. pinocytosis (cell drinkin)
3. receptor mediated or clathrin mediated endocytosis. clathrin are proteins found under cell membrane. can signal cell membrane to pinch off at that point

Question 19

what are peroxisomes?

where originate?

what do they specifically contain?

Answer 19

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)

Question 20

what is a perixosomal disorder?

Answer 20

diseases where get accumulation of hydrogen peroxide due to absence of peroxisomes

e.g. Zellweger syndrome

Question 21

does mitochondria have its own DNA?

Answer 21

yes - codes for most of proteins in mitochondria

Question 23

apart from ATP production, what else mitochondria used for?

Answer 23

initiating apoptosis

Question 24

what do mitochondria disorders commonly effect?

• how many?
• can be caused by mutations in what?

Answer 24

• muscle and nervous systems (high energy requirements)
• over 40 diseases
• mutations in mtDNA or nuclear DNA