AQA A-Level Biology. Study 3.2 - Cells.2023AQA A-Level Biology. 3.2 - Cells.

AQA A-Level Biology. Study 3.2 - Cells.2023AQA A-Level Biology. 3.2 - CellsStructure of Nucleus. - ANSWER 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 Nucleus. - ANSWER 1. Controls cell's activities - produces mRNA and tRNA - protein synthesis. Controls entry and exit of materials, and contains nuclear reactions. 2. Retains genetic material in the form of DNA and chromosomes. 3. Manufactures ribosomal RNA and ribosomes. Structure of Mitochondria. - ANSWER 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. Functions of Mitochondria. - ANSWER 1. Sites of Krebs Cycle and oxidative phosphorylation pathway in aerobic respiration - responsible for ATP production. NB = found in high numbers in metabolically active cells which require much ATP. Structure of Chloroplasts. - ANSWER Found in plants and algae. 1. Chloroplast envelope - double plasma membrane, highly selective, surrounds the organelle .