Lecture 1 Flashcards
What are the three domains of life + their similarities?
-Archaea -Eukaryotes -Bacteria (prokaryotes) Archaea + eukaryotes have the same DNA replication enzymes. Archaea + prokaryotes both have a single circular chromosome + binary cell division mediated by the divisome.
How does the divisome work?
Constricts the middle of the cell after the two genomes have been segregated to the poles.
State the features of a eukaryotic cell.
- Well defined organelles, each defined by a membrane. - Complex tubular network of interconnecting membranes (ER). - Single-lipid protein containing cell membrane. - Cytosol containing ions, organic molecules, proteins + nucleic acids.
State the organelles of a eukaryotic cell (10).
- Nucleus. - Nuclear pores. - Nucleolus. - Smooth ER. - Rough ER. - Ribosomes. - Golgi apparatus. - Lysosomes. - Mitochondria. - Cytoskeleton.
Outline the function of the nucleus.
- Surrounded by a nuclear envelope comprised of two membranes (inner + outer). - Outer membrane is continuous with the membranes of the ER. - Contains genetic material (DNA) in the form of chromosomes, formed from DNA-protein complexes forming chromatin.
Outline the function of the nuclear pores.
- Allow the controlled transport of molecules in and out of the nucleus.
Outline the function of the nucleolus.
- Synthesis + processing of rRNAs required for the assembly of ribosomes. - Formation of small + large ribosomal subunits.
Outline the function of the smooth and rough ER.
- Extensive network of interconnecting membranes extending from the outer nuclear membrane to the cell membrane. - In conjunction with the golgi, is involved in the transport + maturation of proteins. - Rough ER has ribosomes attached. - Smooth ER buds off to form small transport vesicles carrying proteins to the golgi.
Outline the function of the ribosomes.
- Found free in the cytosol + bound to the membrane of the rough ER. - Large nucleoprotein complexes. - Sites of protein synthesis.
Outline the function of the golgi.
- Network of flattened smooth membranes, sacs + vesicles. - Protein transport. - New membrane synthesis. - Formation of lysosomes.
Outline the function + structure of the lysosomes.
- Intracellular digestion of externally endocytose materials OR old organelles + intracellular material. - Single membrane. - Acidic internal matrix. - Rich in hydrolyse enzymes that breakdown proteins, lipids, carbohydrates + nuclei acids.
Outline the function + structure of the mitochondria.
- Site of ATP synthesis. - Internal matrix (mitosol), with its own mtDNA for 13 mitochondrial proteins + some RNAs. The site of metabolic pathways. - Inner membrane is highly selective with several transport systems. Convoluted to form cristae, with ATP synthase embedded within extending into the mitosol. - Enzymatic components of the electron transport system + oxidative phosphorylation embedded in the inner membrane. - Outer membrane has large porins that permit access of large molecules. - Maternally inherited.
Outline the function of the cytoskeleton.
- Consists of dynamic filaments that assemble + disassemble depending on the needs of each cell. - Maintain + change cell shape. - Mediates cellular movement, division + intracellular transport.
What are microtubules + microfilaments in the cytoskeleton?
- Microtubules are multimers of tubulin (a protein that rapidly assembles + disassembles). - Microfilaments are dynamic multimers of actin, forming F-filaments in response to ATP binding + hydrolysis.
What are the features of a prokaryotic cell?
- No nucleus; a single chromosome contains the genome compacted by DNA-binding proteins to form the nucleoid. - Often have extrachromosomal elements (plasmids). - Single flagellum for motility. - Pili; promote intracellular direct communication via contacts that mediate exchange of DNA and/or proteins. Have a hollow centre through which they exchange proteins. - No ER.
