Class Notes (836,163)
Canada (509,672)
York University (35,302)
Biology (2,253)
BIOL 2021 (203)
Lecture 9

Lecture 9 - Vesicular Transport - Feb 5.docx

4 Pages
Unlock Document

BIOL 2021
Patricia Lakin- Thomas

Lecture 9: February 5th, 2013 Chapter 13: Vesicular Transport  Figure 13-37  Lysosomes: o Marker: acid phosphatase o Function: Digestion of macromolecules by hydrolytic enzymes (acid hydrolyses)  Require acid pH  V-type ATPases o Creates protein gradient and acidifies the contents  Transport proteins used to carry digestion products away to the cytosol  Figure 13-36  How does the low pH of lysosomes protect the rest of the cell from lysosomal enzymes in case the lysosome breaks? o Lysosomal enzymes are acid hydrolyses with optimal pH of 5.0 and therefore will be inactive at pH 7 in the cytosol  Figure 13-39  Plant and fungal vacuoles are a kind of lysosome o Used for storage o Ex. Proteins in peas and bean seeds, flower pigment, garlic flavor--> all stored in vacuoles that are like lysosomes o Degradation o Important for maintaining osmotic pressure and size regulation (plant will take water into is vacuole and expand to grow)  Formation of Lysosomes: o Digestive enzymes delivered from Golgi to endosomes o Figure 13-42a o 1) Starts out as endosome from endocytosis pathway (piece of plasma membrane wraps around something the cell wants to digest)  Early endosome receives enzymes from golgi and thus becomes a lysosome  Or 2) Phagocytosis= cell eating o Phagosome then fuses with endosome or lysosome-->becomes lysosome  Or 3) Autophagy: self eating o Used to degrade old cell components or faulty components o Autophagosome fuses with lysosome-->lysosome o Figure 13-42a  Lysosomes have a marker- Mannose-6-phosphate: M6P o Recognized by M6P receptor  Trans golgi faces OUTWARDS , cis Golgi faces nucleus  Figure 13-43  Figure 13-44  1. N-linked oligosaccharide added in ER  2. Transported in golgi  3. Enzymes in golgi recognize the signal patch in the protein  4. Mannose phosphorylated in Golgi  5. M6P receptor in trans-golgi binds to M6P and adaptor proteins  6. Clathrin coated vesicles bind then immediately fall off --- coat lost  7. Vesicles fuse with endosomes and deliver the hydrolytic enzyme to endosome  8. M6P released from receptor at low pH (endosome)  Reason receptor can pick up at one place and let go of it at endosome= pH gradient  9. M6P dephosphorylated  10. Receptors recycled back to trans-Golgi Endocytosis  Taking up large particles from exterior of cell o End up in lysosomes for digestion  2 kinds: o phagocytosis= cell eating o Pinocytosis= cell drinking  Phagocytosis: o Ingesting microorganisms or dead cells (sometimes cells die on purpose for their neighbors to eat them) o Protozoa use this as a means for eating o Animal cells: only occurs in specialized cells  Scavenging dead cells, or defend against invaders  Cells of the immune system: macrophages, neutrophils  Figure 13-47 o This process requires a trigger  Receptors on phagocyte bind on particle to be eaten  Activates signals inside the cell  Cause actin polymerization (will push pseudopods outwards and form hyaline cap)  Pinocytosis: o
More Less

Related notes for BIOL 2021

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.