The Cell
- Created by: Amy Kirkness
- Created on: 19-11-12 08:47
What a cell needs to survive
To survive a cell needs:
- nutrients
- water
- oxygen
- ions
- substrates
These are taken from it's immediate environment. In plants this is the outside environment they are in, eg. a garden, a house. In animals this is sometimes taken from the outside environment and sometimes taken from the blood stream.
The Cell Membrane
aka. plasma membrane
- allows active and passive transport to take place
- stops the destruction of cells
- semi-permeable (allows certain molecules through protein channels)
- carries important information from nerves, hormones & in between cells
- has receptors that send certain signals to the cell
- bilayer of phospholipids and protein channels
- surrounded by a watery substance
- function: to protect the cell contents from the environment and control to entry & exit of substances
Cell Membrane Bilayer
Phospholipids
- hydrophilic head -> attracts water
- two fatty hydrophobic tail -> repels water
Protein Channels -> float within membrane, some rest against surface & some penetrate right through phospholipids
- transport proteins -> penetrate water & form channels for some substances to move through
- receptor proteins -> bind substances like hormones to bring about changes in cell's activities, means cells carry out different functions
- adhesion proteins -> allow cells to join together
- recognition proteins -> attached to carbohydrate molecules to form antigens which enable the immune system to identify foreign cells in the body
- carbohydrates -> on the outer surface & connected to proteins
Cholesterol Molecules -> give the membrane some water resistance decreasing permeability to small water soluble molecules, makes the cell membrane more rigid & make sure it doesn't break down
Generalised Cell
Nucleus
- contains chromosomes which control cell activities -> made of DNA & proteins, contain genetic information
- cell division
- cell growth
Mitochondria
- respiration -> oxygen + glucose -> chemical energy from glucose transferred into useable ATP
- energy transformers
Cytoplasm
- ions, enzymes, food molecules & organelles
- cytosol -> semi-fluid substance in which organelles are suspended
- cytoskeleton -> gives shape to cell & provides internal organisation, consists of network of filaments & tubules, cell movement & division
Generalised Cell cont...
Vacuoles
- filled with ions
- the solution inside cells
- storage, waste disposal & growth
Ribosomes
- manufacture proteins
- attached to endoplasmic reticulum -> network of membranes, continuous with outer membrane of nucleus,
- rough side -> involved in synthesis of lipids & carbohydrates, no ribosomes, not involved in protein synthesis
- smooth side -> ribosomes attached, involved in protein synthesis
Golgi Apparatus
- stores, modifies & packages proteins & adds carbohydrates to them to ensure they get to their correct destination
Generalised Coll cont2...
Chloroplasts
- contain green pigment: chlorofil
- only found in photosynthetic cells taking light energy, forming ATP & synthesising organic compounds from simple raw materials
Passive Transport
- doesn't require energy
- factors affecting: temperature, size of molecules, steep of concentration gradient
Diffusion
- the movement of particles from a region of high concentration to a region of low concentration
- particles moves across the concentration gradient until equilibrium is reached
Osmosis
- the movement of water from a region of high concentration to a region of low concentation
- water moves across the concentration gradient until equilibrium is reached
Facilitated Diffusion
- the movement of molecules down a concentration gradient with the aid of special transport proteins
- protein channels open & let larger molecules through into the cell -> they change the particles shape to allow it through
Types of Cell
- two types
- Eukaryotic -> plants, animals, fungi, protoctista -> clearly defined nucleus, found in all kingdoms excluding bacteria
- Prokaryotic -> monera (bacteria) -> no clearly defined nucleus
Active Transport
- require energy
- move particles against the concentration gradient
- uses protein channels
- pumping of molecules against concentration gradient with the expenditure of energy (ATP)
Vesicular Transport
- endocytosis (into the cell) -> the process by which a cell can take in material from its environment by first engulfing it with its cell membrane (eg. white blood cells) -> pinocytosis (liquids) & phagocytosis (solids)
- exocytosis (out of the cell)
Active Transport cont...
ATP
- oxygen + glucose = energy + carbon dioxide + water
- energy = ATP
- 36-38 ATP molecules for every 1 glucose molecule
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