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
THE CELL CYCLE
Cytokinesis
the rest of the cell divides
Phases of MITOSIS
- PROPHASE
- METAPHASE
- ANAPHASE
- TELOPHASE AND CYTOKINESIS
Apoptosis
regulated cell death
Meiosis
creates 4 non-identical haploid cells from 1 diploid cell
Meiosis:
Interphase
DNA is replicated
* During S phase!
Meiosis:
Meiosis I:
(Reductional division)
Homologous chromosomes separated
Meiosis:
Meiosis II:
(Equational division)
Sister chromatids separated
Mitosis
Prophase 1
- Crossing over
* Creates recombinant chromosomes
Mitosis
•Anaphase I:
•Separates homologouschromosomes•(Mitosis separates sister chromatids)
