cell biology

• ribosomes are where proteins are made
• Ribosomes are involved in protein synthesis.
• mitochondria produce energy through respiration
• chloroplasts contain chlorophyll to absorb light energy from sunlight
• bacteria is an example of prokaryote
• a cell wall provides structural support and protection against pathogens
• cell membrane regulates what enters or leaves the cell, maintains internal conditions, and protects the cell's contents
• cytoplasm is the fluid inside the cell that contains organelles and other substances necessary for cellular functions
• plant cells also contain a permanent vacuole, chloroplasts and a cell wall
• bacteria cells do not contain a nucleus but have a single string of DNA held in the cytoplasm
• bacteria cells also have small rings of DNA called plasmids
• formula for magnification

  
• light microscopes allow us to see larger subcellular structures like the nucleus as they have a smaller magnification
• electron microscopes have a higher resolution and magnification allowing us to see much smaller things in detail like the ribosomes
• sperm cells have a long tail and streamlined head to be able to swim to the egg
• nerve cells have branched connections to connect with other nerve cells and are long to cover more distance
• muscle cells have lots of mitochondria so that they can produce energy when contracting
• muscle cells are long so they have space to contract
• root hair cells have 'hairs' which increases the surface area for absorbing minerals and water
• the xylem and phloem are hollow and have very little subcellular structures so stuff can flow through them
• this is to grow and replace cells that have been damaged

  A) cell cycle

  
• before a cell divides it will grow and increase the amount of mitochondria and ribosomes it has
• it will duplicate its DNA before mitosis
• during mitosis membranes will form around each sets of chromosomes, meaning the nucleus has now divided
• the cell membrane and cytoplasm divide as the last step of mitosis
• stem cells are found in early human embryos
• stem cells could be used to replace faulty cells in people
• stem cells can have the same genetic information as the patient so it wouldn't harm them and wouldn't be rejected
• reasons why some people are against the use of stem cells is because it could be a possible human life
• people believe scientists should try develop different ways instead of using stem cells
• diffusion is the movement of particles from an area of high concentration to low concentration
• a high temperature will give a faster diffusion rate as particles will have more energy

  
• only small molecules can diffuse through cell membranes
• osmosis is the movement of water particles across a partially permeable membrane from high concentration to low
• won't allow molecules like sucrose to pass

  
• the alveoli have a large surface area, thin walls and are surrounded by capillaries to make sure the rate of diffusion is high
• root hair cells take in water and mineral ions from the soil using their hairs
• the plant needs energy from respiration so active transport can take place to bring nutrients against a concentration gradient
• in leaves the stomata will swell if water is being lost faster than being replaced
• carbon dioxide diffuses into the air spaces in the leaves