Cell Biology: Cell Structure
- Created by: princesseve
- Created on: 09-12-17 21:41
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- Cell Structure
- Eukaryotes and Prokaryotes
- Eukaryotic cells have a cell membrane, cytoplasm and DNA enclosed in a nucleus.
- Prokaryotic cells have cytoplasm and a cell membrane surrounded by a cell wall.
- DNA is not enclosed in a nucleus. It is a single loop and there may be one or more small rings of DNA called plasmids.
- Diameter: Plant- 0.1mm Animal- 0.02mm Prokaryotic- 0.002mm
- Animal and Plant Cells
- Organelles..
- chloroplasts- absorb light to make glucose by photo-synthesis
- ribosomes- site of protein synthesis
- mitochondria- where aerobic respiration takes place
- cell membrane- controls the passage of substances into and out of the cell
- cytoplasm- where most chemical reactions take place
- a permanent vacuole filled with cell sap- supports the plant
- nucleus- controls cell activity and contains DNA
- cell wall- made of cellulose, which strengthens the cell
- Organelles..
- Cell Specialisation
- Animals
- SPERM- fertilises egg; head contains DNA and an enzyme to help penetrate the egg cell membrane: middle section has mitochondria for energy; tail for movement
- MUSCLE- lots of mitochondria to release energy that can be used for contraction
- NERVE- long and thin to transmit electrical impulses long distances in the body
- Plants
- ROOT HAIR- absorb water + nutrients from soil; cytoplasmic extensions increase SA which enables more contact to be made with surrounding soil to maximise the rate of absorption; large vacuole stores absorbed water
- XYLEM- transport water from roots throughout plant; hollow with v. thin cytoplasm makes space for water to move through them; lignin in cell walls makes them waterproof to prevent water loss
- PHLOEM- carry products of photo-synthesis from leaves to rest of the plant; tissues allow glucose to be moved long distances through plant; walls between cells contain pores for glucose to pass through
- Animals
- Cell Differentiation
- As a cell differentiates, it acquires different sub-cellular structures to enable it to carry out a certain function
- Microscopy
- light microscope- 16th century electron microscope- 1933
- Scientists can study how structures inside mitochondria and chloroplasts work.
- Ribosomes and their role in making proteins can be discovered
- magnification = image / real object
- Culturing Micro-organisms
- Bacteria multiply by binary fission every 20 mins if they have enough nutrients and a suitable temperature.
- Bacteria can be grown in a nutrient broth solution or as colonies on an agar gel plate.
- Uncontaminat-ed cultures of micro-organisms are required for investigating the action of disinfectants and antibiotics
- Eukaryotes and Prokaryotes
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