Summary

This document provides an overview of cell biology, including the cell theory, prokaryotic and eukaryotic cells, cell structures, functions of organelles, and cell membrane transport mechanisms. The content also includes topic questions.

Full Transcript

BIO TEST NUMBER 2 : Test checklist The cell theory Prokaryotic cell Eukaryotic cell Animal vs plant cells Cell organelles and their basic function Cell membrane structure membrane transport - passive Osmosis and tonicity CELL THEORY :...

BIO TEST NUMBER 2 : Test checklist The cell theory Prokaryotic cell Eukaryotic cell Animal vs plant cells Cell organelles and their basic function Cell membrane structure membrane transport - passive Osmosis and tonicity CELL THEORY : 1. All organisms are made up of cells 2. All life functions of an organism happen within the cell 3. All cells come from other cells that are already existing PROKAYOTES CELLS : Prokayotes are unicellular organisms who belong to the domain of bacteria or archaea. They are the smallest and oldest form. They are the most numberous organisms and have an amazing diversity of adaptation Cell membrane : creates a barrier between the outside and inside environments of the cell. It selects what goes in and what comes out. Cytoplasm: fluid-like get that fills the inside of the cell. It contains biomolecules and inorganic substances Nucleoid : area within the cytoplasm where genetic material is found in a dense state. (DNA). No barrier holding it Ribosomes : small granular particles that create protein (protein synthesis) necessary for cell functions. Cell wall : many bacteria have a rigid cell wall, which provides protection and mechanical structure to the cell Capsule : a thick casing made of viscous sticky mucus which further protects the cell Flagella : a long and thin structure used for movement Pili : short and thin filaments which allow the cell to anchor themselves to other cells. EUKARYOTIC CELLS: eukaryotic cell: 10x bigger than the prokaryotic cell, organisms: protists,plants,fungi, animals , in the structure presence of internal compartments called organelles which all have their own membrane , different cells which are specialised in their form, side and function. Two structures that are unique and essential to eukaryotic cells Nucleus : the centre for genetic control during the life of the cell. Inside the nucleus we can find the genetic material (DNA) Mitochondria : powerhouse of the cell because they make energy through the process of aerobic respiration. Animal cell : plant cell: cytoplasm - cytoplasm nucleoid - nucleoid cell membrane - cell membrane ribosome - ribosome - cell wall TOPIC QUESTIONS: What is a cell : cells are tiny unit of life that are like specialized factories, full of machinery designed to accomplish the business of life. Cells make up every living thing, from blue whales to the archaebacteria that life inside volcanoes. Cells make up your organs and tissues. They do important jobs like digesting food , pumping blood , making bones. What is a eukaryotic cell : eukaryotic cells contain a nucleus. Prokaryotic cells don’t. Eukaryotic cells are found in the eukaryotes , which include animals , plants, fungi and protists. Eukaryotic cells differ depending on the organism. Two main types of eukaryotic cells are animal cells and plant cells What is a cell organelles : cells contain tiny structures called organelles that perform specific jobs within the cell, just as organs in our bodies perform as parts of our body systems What makes animal and plant cells different : plants cells contain two additional types of structures. The cell wall surrounds the cell membrane. it protects the cell and gives it shape. The chloroplasts convert solar energy into chemical energy in the process of photosynthesis. CELL ORGANELLES : Organelle : structures within a cell that have certain jobs to do for the cell Membrane : thin tissue that surrounds and contains an organelle Membrane bound : an organelle that is surrounded by a membrane Nucleus : membrane bound structure inside eukaryotic cells that contains DNA. Runs all of the functions inside the cell Endoplasmic reticulum : network of tube like canals. There is smooth and rough endoplasmic reticulum (er) Golgi bodies : a system of flattened membrane sacs. packages substances for transport inside or out the cell. Acts like a mail delivery system Ribosomes : small granular particles that create protein (protein synthesis ) necessary for cell functions Mitochondria : bean shaped organelle with an outer and inner membrane. Mitochondria have their own DNA. Where cellular respiration takes place. Releases energy from glucose for the cell. Lysosome : small spherical organelles free floating in the cytoplasm. Found mostly in animal cells. Contains digestive enzymes that dissolve cellular waste. Acts like a garbage disposal system. Vacuole: membrane bound sacs. Usually much large in plant cells. used to store water , food or waste. In plant cells, they help keep the from wilting. THE CELL MEMBRANE : The cell membrane is present in all types of cells. It main function is to create a barrier between the inside and the outside environments of the cell. We define this membrane as semi-permeable barrier. It acts in two ways : 1. Blocks the entrance of any harmfull substance or organism 2. Allows the passage of useful substances e.g nutrients, water ect STRUCTURE : The cell membrane is made out of four main types of molecules that, together, form a protective layer. Each of these molecules us stuck inside the membrane like the piece of a mosaic, but is not held rigidly in place and can move around when necessary. Phospholipids : Most of the membrane is made out of simple phospholipids. These are positioned as a double layer, with each phospholipid facing their ‘tails’ towards each other and their ‘heads’ away from each other. The head of the phospholipid is bydrophilic , meaning it attracts water. The tail of the phospholipid is bydrophobic meaning it repels water. Cholesterol : Cholesterol molecules are only found in the membranes of anima cells. This molecule controls the fluidity and the flexibility of the membrane, affecting its resistance Protein : Every cell membrane contains its own unique compostion of proteins , which have specific properties according to the type of cell. These molecules have various functions : - Determine the identity of the cell - Determine the duty of the cell - Communicate or attach to other cells - Receive messages from outer sources - Transport molecules across the cell membrane Types of proteins : - Signal protein - Enzyme protein - Channel protein - Transport protein - Recognition protein - Cell adhetion protein Lipid and Carbohydrate chains : Lipid and carbohydrate chains are often found on the outer surface of the membrane , either attached to a phospholipid (called a glycolipid ) or attached to a protein (called a glycoprotein ) Their main function is to give the cell a kind of fingerprint and act as communicators to other cells. MEMBRANE TRANSPORT : The passing of molecules across a memrane can happen in two ways : - Passive transport is when the process is spontaneous and does not require energy consumption - Active transport is when the process requires energy in order for anything to happen Diffusion : Molecules moving to distribute /spread evenly across a substance The speed of the rate of diffusion varies accorfing to : - The size of the molecules - The temperature - The size of the container - The concentration gradient Concentration: Amount of substance per volume (g/L) Gradient : Difference between two places or across a membrane Concentration gradient : Difference in concentration across two places or a membrane. Diffusion across a membrane happens so that the substance reaches equal concentation in all places (sides of the membrane ) Passive transport can occur via different types, which can require the help from a membrane protein who will speed up the passsage of molecules : These types of transport are : 1. Simple diffusion 2. Facilitated diffusion Limitations for facilitated diffusion : - Only one molecule can pass at a time - One direction per channel protein - Each molecule has its own channel protein OSMOSIS AND TONICITY : Solution = mix of substances Solvent=most present (water) Solute = least present (salt) Osmosis : Movement of H2O across a membrane. The process of osmosis is the same for solute , it just depends on its concentration Tonicity : A type of comparative measurement of osmotic pressur between two solutions which are separated by a membrane. The state of tinicity can be : Isotoci cell : C2 = C1 Hypertonic cell : C1> C2 ---- cells gains water Hypotonic cell : C1

Use Quizgecko on...
Browser
Browser