LECTURE 4 WHY AND HOW CELLS DIVIDE Flashcards
Recall cell structures from last time
- Membranes
- Nucleus (and nucleolus)
- Chromosomes
- Ribosomes
- Endoplasmic Reticulum (RER and SER)
Golgi Apparatus
- Polarized stack of membranes
- Enzymes modify proteins from ER
- Add & modify sugars
- Material moves between stacks via transport vesicles
- Many final destinations
Protein synthesis occurs in different places
Cytoplasmic proteins
- Made of free ribosomes in the cytoplasm
* Proteins are soluble (hydrophilic)
Protein synthesis occurs in different places
Membrane proteins and secreted proteins
- Made on ribosomes bound to the ER
- Sorted in the Golgi apparatus
- Membrane proteins are hydrophobic or amphipathic
- Secreted proteins can be either hydrophilic or hydrophobic (or amphipathic!)
Lysosomes: Acidic organelles
Digest food & polymers to recycle monomers
Phagocytosis
Autophagy
Mitochondria:
makes ATP (energy for the cell)
Cytoskeleton: support for the cell
- Microtubules (tubulin)
- Microfilaments (actin)
- Intermediate Filaments (keratins +)
How do cells divide?
Bacteria and mitochondria
- Binary fission
- One small circular chromosome is copied
- Cell pinches between DNA molecules
- Cytoplasm/matrix divides
How do cells divide?
Eukaryotic cells
- Many long linear chromosomes
* Need to evenly divide DNA so daughter cells get all info •After DNA is divided, cytoplasm and organelles divide
Eukaryotes have two types of cell division
Growth and repair = MITOSIS
Two identical daughter cells
Eukaryotes have two types of cell division
Reproduction = MEIOSIS
4 non-identical haploid cells from a diploid cell (sperm, eggs)
THE CELL CYCLE
INTERPHASE:
G1 – grows, make proteins, lipids, and carbohydrates
THE CELL CYCLE
•S
synthesizes DNA
THE CELL CYCLE
•G2 –
finishes making proteins, membranes, gets ready to divide
THE CELL CYCLE
Cytokinesis
the rest of the cell divides
