Lecture 5 - Organelles

Question 1

DNA storage in eukaryote vs prokaryote

Answer 1

eukaryote: stored in a membrane-bound nucleus
prokaryote: DNA is folded into a compact structure within cytoplasm called the nucleoid

Question 2

Do prokaryotes have internal membranes?

Answer 2

no

Question 3

Plasma membrane

Answer 3

defines cell boundaries and retains contents
- contains at least 3 macromolecules

Question 4

What organelles provide energy for animal and plant cells?

Answer 4

animal cell: mitochondria
plant cell: chloroplast

Question 5

Mitochondria

Answer 5

• make energy for animal cell
• TCA cycle
• ETC => ATP
• 2 membranes
  - inner and outer
• cristae = invaginations made from the larger inner membrane folding
• matrix
  - enzymes
  - mtDNA => encodes SOME mitochondrial proteins that are made in mitochondria

Question 6

Chloroplasts

Answer 6

• fix carbon
  - CO2 + light => sugars
  - stroma
• 3 membranes
• stroma
  - enzymes
  - cpDNA
• thylakoids
  
  • photosynthesis
  • chlorophyl
• cpDNA => encodes SOME chloroplast proteins that are made in chloroplast

Question 7

Endomembrane system

Answer 7

synthesizes proteins for a variety of cellular destinations

1. mRNA leaves the nucleus
2. translates into a protein in ribosomes of ER
3. goes to Golgi
4. gets sorted and secreted through vesicles

Question 8

Endoplasmic reticulum

Answer 8

• tubular membranes and flattened sacs
• cristae and lumen
• rough ER = ribosomes
  - synthesizes proteins
• smooth ER = no ribosomes
  - synthesis of lipids and steroids

Question 9

Golgi apparatus and secretory vesicles

Answer 9

• sugar coats proteins
• sorts proteins according to those coats
• sacs of Golgi are not connected, things must be transported from one sac to next by vesicles

Question 10

Secretory pathway

Answer 10

used to secrete molecules

Question 10

Lysosome

Answer 10

• contain powerful enzymes that degrade molecules
• digests molecules
• acidic
• enzymes are pH sensitive => therefore pH must be low
• inside of membrane is glycosylated
• this separate structure is needed to prevent everything from being digested

Question 11

Peroxisome

Answer 11

• catalase converts hydrogen peroxide into water and oxygen
• deal with oxidizing agents in the cell
• break fatty acid chains

Question 12

Lipid droplets

Answer 12

transport and store lipids

Question 13

Extracellular matrix and cell walls

Answer 13

located outside of plasma membrane
- extracellular matrix => animals
- cell walls => plants and fungi

extracellular matrix:
- collagen fibrils
- proteoglycans: proteins with many disaccharide units
- much larger than plasma membrane
- glues cells and tissues

cell walls:
- cellulose: polysaccharide