Aqa A-Level Biology: Cell Structure & Function The Comple

AQA A-LEVEL BIOLOGY: CELL STRUCTURE & FUNCTION - THE COMPLETE EXAM SUCCESS GUIDE AQA A Level Cells Structure of Nucleus 1. Nuclear envelope: double membrane surrounding nucleus, outer membrane continuous with the (R)ER of the cell. 2. Nuclear pores: allow the passage of larger molecules, such as mRNA, out of the nucleus. 3. Nucleoplasm: granular, jelly-like material making up the bulk of the nucleus. 4. Chromosomes: protein-bound, linear DNA. 5. Nucleolus: small spherical region(s) in nucleoplasm. Manufactures ribosomal RNA and assembles ribosomes. Function of the Nucleus 1. Controls cell's activities - produces mRNA and tRNA - protein synthesis. Controls entry and exit of materials, and containsnuclear reactions. 2. Retains genetic material in the form of DNA and chromosomes. 3. Manufactures ribosomal RNA and ribosomes. Structure of Mitochondria 1. Double membrane surrounding organelle - controls entry and exit of material. 2. Cristae - extensions of the inner membrane, providing a large surface area for the attachment of enzymes and other proteins during respiration. 3. Matrix - makes up the remainder - contains proteins, lipids, ribosomes and DNA (allows mitochondria to produce own proteins) and some respiratory enzymes. Function of the Mitochondria 1. Sites of Krebs Cycle and oxidative phosphorylation pathway in