Cells and Life Processes PDF

Cells and Life Processes Pearson Edexcel Cell Theory All living things are made up of cells. Cells are the smallest working units of all living things. All cells come from preexisting cells through cell division. Level of organisation in organism  Key definitions cell m...

Cells and Life Processes Pearson Edexcel Cell Theory All living things are made up of cells. Cells are the smallest working units of all living things. All cells come from preexisting cells through cell division. Level of organisation in organism  Key definitions cell membrane: thin outer covering of a cell that controls what enters and leaves it cell wall: a tough layer of material around some cells that is used for protection and support and in plant cells it is stiff and made of cellulose chlorophyll: green substance found inside chloroplasts that traps energy from light chloroplast: green cell structure in which glucose is produced by photosynthesis chromosome: structure inside the nucleus that contains genes cytoplasm: watery jelly inside a cell where the cell’s activities take place enzyme: a protein that controls a chemical reaction in the cytoplasm gene: section of genetic material (usually DNA) that controls part of the activity of a cell mitochondrion: cell structure in which respiration using oxygen occurs and the plural is mitochondria nucleus: cell structure that controls the cell organelle: small part of a cell that has a certain function and chloroplasts, nuclei and mitochondria are all organelles partially permeable membranes: membranes that allow some substances through them but not others ribosome: cell structure that makes proteins vacuole: space surrounded by a membrane in the cytoplasm of cells. Plant cells have a large permanent vacuole, which stores water and nutrients, and helps to support the plant by keeping the cells rigid.  Key definitions concentration gradient: the difference in the concentration of molecules between two regions in a solution. There will be an overall movement of particles down a concentration gradient, from higher concentration to lower concentration. diffusion: the random movement and spreading of particles. There is a net (overall) diffusion of particles from regions of higher concentration to regions of lower concentration. dilute: a dilute solution contains few solute molecules in a certain volume of solvent flaccid: when a cell has lost internal pressure, so that the cytoplasm no longer pushes out against the cell membrane (and cell wall, in plants) osmosis: the overall movement of solvent molecules in a solution across a partially permeable membrane, from a dilute solution to a more concentrated one partially permeable: describes a membrane that allows certain small particles through it but not larger ones turgid: when a cell has high internal pressure, so that the cytoplasm pushes out against the cell membrane (and cell wall, in plants) Prokaryotic Do not have structures surrounded by membranes Few internal structures One-celled organisms, Bacteria Eukaryotic Contain organelles surrounded by membranes Most living organisms “Typical” Animal Cell and Plant Cell 11 Chloroplast Important points when summarising cell parts Cell part Function Description In animal cells, plant cells or both? cell membrane controls what enters and thin outer covering of a cell both leaves cell wall protection and support cellulose in plants plant cells chloroplast photosynthesis/ makes contains green chlorophyll plant cells food cytoplasm most of cell’s activities watery jelly both occur here mitochondrion respiration using oxygen usually not seen with light both microscope nucleus controls the cell contains chromosomes both ribosome makes proteins cannot be seen with light both microscope vacuole supports the cell large and permanent in plant cells stores water and nutrients plant cells CELL MEMBRANE thin outer covering of a cell that controls what enters and leaves it KEY WORD concentration gradient: the difference in the concentration of molecules between two regions in a solution. There will be an overall movement of particles down a concentration gradient, from higher concentration to lower concentration. diffusion: the random movement and spreading of particles. There is a net (overall) diffusion of particles from regions of higher concentration to regions of lower concentration. osmosis: the overall movement of solvent molecules in a solution across a partially permeable membrane, from a dilute solution to a more concentrated one partially permeable: describes a membrane that allows certain small particles through it but not larger ones  Diffusion Particles of gases and liquids constantly move in all directions. In a solution, some solute particles move from regions of lower concentration to regions of higher concentration. However, many more solute particles move from higher to lower concentration. There is an overall movement of particles down the concentration gradient (from higher to lower). This overall movement is called diffusion. Equal concentrations Diffusion causes the concentration of solute particles in a solution to even out until all parts are at the same concentration. At this point: diffusion stops (there is no overall movement of particles in one direction), but all the particles continue to move. Osmosis Partially permeable membranes A partially permeable membrane allows some molecules to pass through but stops others. The cell membrane is partially permeable. It allows small water molecules to pass but not larger molecules. Osmosis is a special case of diffusion. It is the movement of water molecules (or other solvent molecules) down a concentration gradient through a partially permeable membrane. Effects of Osmosis on Animal and Plant Cells  NUCLEUS The Nucleus is the large membrane bounded organelle that contains genetic material, nuclear bodies, and nucleoplasm. LIFE PROCESS – CELL DIVISION Cell division is a process that divides a parent cell into two or more daughter cells. The purpose of cell division is to increase the number and type of cells, or to form other cells for a specific purpose. It is essential for growth, development, and tissue repair in organisms. Cell division is divided into three types, namely amitosis, mitosis, and meiosis. Mitosis, which results in genetically identical cells, and meiosis, which produces genetically diverse gametes for reproduction. Mitosis occurs in the somatic cells, while meiosis occurs in the germ cells. MITOSIS MEIOSIS DIFFERENCES BETWEEN MITOSIS AND MEIOSIS RIBOSOME Types of RNA Step of Protein Synthesis Translation ENDOPLASMIC RETICULUM Types of ER : 1) Rough Endoplasmic Reticulum (RER) 2) Smooth Endoplasmic Reticulum (SER) ENDOPLASMIC RETICULUM Golgi Body/Golgi Apparatus The Endomembrane System CHLOROPLAST chloroplast is an organelle within the cells of plants and certain algae that is the site of photosynthesis Photosynthesis is the process of making or forming food carried out by plants, especially plants that contain green leaf substances, namely chlorophyll, with the help of energy from sunlight. Photosynthesis Light reaction The light reaction or hill reaction is a reaction that requires light. This light reaction occurs in the thylakoid membrane of the chloroplast. Dark reaction The dark reaction or calvin reaction is a photosynthesis reaction that does not require sunlight. The dark reaction occurs in the chloroplast stomata. Light-Dependent Reactions 1. Chlorophyll absorbs sunlight which excites electrons in the chlorophyll molecules. 2.Water molecules (H₂O) are split into oxygen (O2), protons and electrons where oxygen is released into the atmosphere while electrons are sent into the ETC. 3.Excited electrons move through the ETC where energy is created to pump protons into the thylakoid lumen. 4.ATP is made by the protons flowing back into the stroma through enzyme ATP synthase. 5.NADPH is formed after the electrons combine with NADP+ and H+, later used in the Calvin cycle. Calvin Cycle / Dark Reaction 1. Fixation: CO2 enters through the stroma and will be bound with RuBP (5C) and will become a short-lived 6C molecule. 2. Reduction: -NADPH & ATP (from light reaction) used -Broke into two 3 PGA 3.Regeneration: Some 3 carbon mollecules will bond to make glucose -other 3 carbon molecules will recombine to make 5 carbon molecule -Process restrart MITOCHONDRIA Present in eukaryotic animal and plant cells. Their primary function is as a powerhouse. It produces most of the chemical energy needed to power the cell's biochemical reactions through cellular respiration (ATP production). LIFE PROCESS → Respiration Two Type of Cellular Respiration 1) Aerobic respiration Aerobic respiration requires oxygen to break down glucose and release energy. It is a series of reactions that occur in mitochondria and the products are water and carbon dioxide. We can summarise it using a word equation: glucose + oxygen ➔ carbon dioxide + water + energy (C6H12O6 + 6O2 ➔ 6CO2 + 6H2O + Energy) In aerobic respiration, a molecule of glucose produces 38 molecules of ATP.Some energy is not stored in the ATP but escapes into the surroundings. This energy increases the temperature of the surroundings. In humans, this helps to maintain a constant body temperature. 2) Anaerobic respiration There is another type of respiration that occurs in the cytoplasm of cells all the time. It does not need oxygen and is called anaerobic respiration. The product is lactate (often called ‘lactic acid’). glucose➔lactate The energy released by respiration is used to add phosphates to ADP. This forms ATP molecules, which store the energy. ATP can release energy very quickly.  Glycolysis : Glucose is Broken Down Inputs - 1 Glucose - 2 ATP Outputs - 2 Pyruvate Acid - 2 NADH - 2 ATP Occurs - In the Cytoplasm  Pyruvate Oxidation / The Link Reaction Inputs - 2 Pyruvate Outputs - 2 Acetyl CoA - 2 NADH - 2 CO2 Occurs - In the Matrix Mitochondria  Krebs Cycle (Citric Acid Cycle) Inputs - 2 Acetyl CoA Outputs - 2 ATP/GTP - 6 NADH - 2 FADH2 Occurs - In the Matrix Mithochondria  Electron Transport Chain/OXIDATIVE PHOSPHORYLATION Inputs - 10 NADH - 2 FADH - 6 Oxygen Outputs - 34 ATP - 6 H20 Occurs - In the Cristae (Mitochondria) Simple Pathway of Aerobic Respiration  SUMMARY AEROBIC RESPIRATION GLYCOLYSIS PYRUVATE KREBS ELECTRON OXIDATION CYCLE/CITRIC TRANSPORT CHAIN / ACID CYCLE OXIDATIVE PHOSPHORYLATION DESCRIPTION Phosporylation and Decarboxylation Cyclical pathway Production of ATP splitting of glucose and with enzyme – through oxidation of dehydrogenation of controlled hydrogen atom pyruvate reaction LOCATION Cytoplasm Matrix of Matrix of Cristae of Mitochondria Mitochondria Mitochondria INPUT Glucose (C6) 2 Pyruvate Acid (C3) 2 Acetyl Co A (C2) 10 NADH 2 FADH 6O2 OUTPUT 2 Pyruvate Acid (C3) 2 Acetyl Co A (C2) 2 ATP 34 ATP 2ATP 2NADH 6 NADH 6 H20 2NADH 2CO2 4 CO2 2 FADH