Topic 2 - Cells, Viruses and Reproduction Flashcards
Define Cell Theory
The universally accepted theory that living organisms are made up of cells, that are the basic structural/organisational unit of all organisms, and that all existing cells come from previously existing cells
Describe the structure of gram positive cell walls
Gram positive cell walls have one phospholipid bilayer with a thick layer of peptidoglycan with teichoic acid above it. The peptidoglycan layer has surface proteins across it.
Describe the structure of gram negative cell walls
Gram negative cell walls have two phospholipid bilayers with a thin layer of peptidoglycan in between them. There are proteins in and on the surface of both bilayers, and the outer layer has lipopolysaccharides on its surface.
Describe the structure and function of the nucleolus
The nucleolus is a very dense area of DNA and protein in the nucleus that is involved in the production of ribosomes and the control of growth and division.
Describe the structure and function of the Rough Endoplasmic Reticulum, RER
The RER is an endoplasmic reticulum covered in 80s ribosomes that is involved in the production, isolation and transport of proteins
Describe the structure and function of the Smooth Endoplasmic Reticulum, SER
The SER is an endoplasmic reticulum with a smooth tubular structure, and is involved in the synthesis and transport of lipids and steroids in the cell
Describe the structure and function of the Golgi Apparatus
The golgi apparatus consists of a stack of membranes that modify and separate proteins into vesicles for transport to other organelles or for exocytosis. It also produces the materials for plant cell walls and insect cuticles.
Describe the structure and function of the tonoplast
The tonoplast is a specialised membrane that surrounds the permanent vacuole of a plant cell, and it controls the movement of substances into and out of the cell sap
Describe the structure and function of lysosomes
A lysosome is an organelle full of digestive enzymes used to break down worn out cells or organelles, or to digest food in simple organisms.
Describe the structure and function of centrioles
Centrioles are bundles of tubules found near the nucleus and are involved in cell division by producing a spindle of microtubules that move the chromosomes to the ends of the cell
Describe the process of gram staining
Cells are heat fixed onto a slide, and flooded with crystal violet dye, followed by Gram’s iodine to trap it in the cell, if it is gram positive. The slide is then rinsed with alcohol or acetone, and if the cells are gram negative they will lose the purple stain. The cells are then counterstained with safranin, and gram negative cells will turn red/pink.
Give the order of events in the cell cycle
Interphase (G1, S and G2)
Mitosis: Prophase, Metaphase, Anaphase, Telophase
Cytokinesis
