b1 cell biology

• prokaryotic cells do not contain mitochondria or cholroplasts
• eukaryotic cells are found in plants, animals, fungi and protists
• the cytoplasm is where most chemical reactions take place
• mitochondria are the organelles where the aerobic respiration happens
• the nucleus contains the chromosomes ; which contains the cells genetic material
• the permanent vacuole is a fluid-filled sac that stores water
• some bacteria have flagella - this is used for movement
• prokaryotic cells are smaller than eukaryotic
• in prokaryotic cells, DNA is stored in the cytoplasm
• cell differentiation is the process where a cell develops new sub-cellular structures to let it perform a specific function. When this happens the cell becomes specialised
• when a cell differentiates it becomes a different type of body cell
• plants keep the ability to differentiate throughout their life - they are always able to create new tissue
• the head of a sperm cell contains its nucleus. the nucleus carries one half of an organisms genetic material
• cell differentiation primarily happens in human embryos
• cell differentiation is rare in mature animals. their cells mostly divide to replace cells and repair damaged tissues
• a muscle cell contains lots of mitochondria to generate lots of energy for motion
• Root hair cells are specialised to increase the efficiency of water absorption and the uptake of minerals required for the plant’s survival.
• The xylem is specialised to transport water up the stem of a plant and into the leaves.
• Lignin (a substance) strengthens the cell walls of xylem cells.
• stages of the cell-cycle : mitosis, cell division, initial growth stage
• during mitosis chromosomes are pulled apart, the nucleus divides
• Mitosis ensures that both daughter cells have the same chromosomes as each other and the parent cell.
• in mitosis, chromosomes are copied during the initial growth stage and then pulled to opposite ends of the cell
• Stem cells are undifferentiated cells that have not yet specialised to perform a specific function.
• in human adults, stem cells can be found in the bone marrow
• oxygen is taken into the cell by the process of diffusion
• muscle cells in the wall of the stomach allow it to contract and churn food
• enzymes produced in the salivary gland are amylase and carbohydrase
• ribosomes produce protein
• hypertonic - more concentrated solution
• when a plant cell is placed in a hypotonic solution it is turgid
• when a plant cell is placed in a hypertonic solution it is flaccid
• if red blood cells were placed in a hypotonic solution they'd burst because they dont have a cell wall
• scientists think that the flagellum and the light sensitive spot work together: light sensitive spot detects light, tells flagellum to move towards light. more light = more photosynthesis
• larger surface area = smaller diffusion distance
• food molecules are absorbed through diffusion
• active transport requires energy
• substances transported in diffusion are : carbon dioxide, oxygen, water, food substances and waste
• substance transported through osmosis is water
• diffusion - Substances move from a high to a lower concentration down a concentration gradient