2.1.1 Cell Structure COMPLETE Flashcards
Characteristics of living things
Movement
Respiration
Sensitivity
Growth Reproduction Excretion Nutrition Homeostasis
Cell Ultrastructure
The detail revealed by the electron microscope. The structures inside are called organelles
Division of Labour
Each organelle has a specific role with in the cell, they work together in the cell for survival
How the light microscope works
Light reflects from the lamp so it passes through the condenser and focusses
It then goes through the stage and travels up the lens until it reaches the eyepiece
This can be adjusted to focus it
Stains
Coloured chemicals that bind to molecules in a specimen
e.g. iodine solution can be used for live plant cells
Eosin goes pink to show cytoplasm
Magnification
The number of times larger an image is compared to the actual size of the object
=Image/Actual
Resolution
Ability to distinguish between two separate points that are very close together, gives clarity
Max. resolution for Light and Electron microscopes
Light: 200nm
Electron: 0.1nm
Unit changes
1m = 1000mm 1mm = 1000um 1um = 1000nm
Laser Scanning Microscopes
A laser is projected onto a pinpoint target in a specimen
Specimens are tagged with fluorescent dyes
Target area is scanned rapidly to produce a 3D image at different focal planes
Use of Scanning Microscopes
- Developing drugs as isn’t invasive and you can see living cells
- Can see specific parts of the cell
- Can look at the whole cell
Electron Microscopes
Takes place in a vacuum so electrons aren’t disrupted, specimen must be dead as coated in gold to attract electrons
Transmission so passes through surface producing a 2D B&W image
Nucleus
Has a nuclear envelope with pores
The nucleoplasm contains chromatin
The outermsmbrane is continuous with the rough ER
Function:Enclose DNA, manufactures Ribosomes, cell division
Endoplasmic Reticulum
A system of hollow tubes and sacs
Rough is covered in ribosomes for protein synthesis which can then be transported
Smooth lacks ribosomes and synthesises lipids
Ribosome
2 protein subunits of rRNA
Synthesised in the nucleus
Function: Protein synthesis, provides binding sites for mRNA, contains enzymes
2 types for eukaryotes and prokaryotes (smaller)
Golgi apparatus
Flattened membrane with bound cavities called cisternae stacked on top of each other
Function: Modifies carbohydrates, packages proteins into vesicles
Lysosomes
Vesicles containing hydrolytic enzymes
Function: Isolate potentially harmful enzymes from cels, breakdown material ingested by phagocytic cells, breakdown old organelles
Mitochondria
Double membrane, the inner folds in to form cristae
The inner matrix contains ribosomes, DNA and enzymes
Function: Isolates aerobic reactions to produce ATP
Chloroplast
Double membrane with membrane bound sacs called thylakoids inside. They stack to form grana and are connected by lamellae. Stroma contains enzymes, starch grains, ribosomes, DNA, lipid droplets
Function: Photosynthesis
Centrioles
Found in pairs and are composed of 9 sets of three tubules. 2 sets are found in every animal cell
Function: Forms spindle fibres for nuclear division
Cytoskeleton
Composed of microtubules and microfilaments
Function: Enable movement of vesicles, proteins, organelles
Also help support the cell and maintain shape
Flagella and Cilia
Composed of two central microtubules and surrounded by nine more
The sliding of the microtubule leads to movement with ATP, found in respiratory tract and oviduct
Vacuoles
Contain cell sap (water, sugar, oil, protein, pigment)
Have a special membrane called a tonoplast
They maintain turgor for support and also store things
Plant cell walls
Rigid and permeable for protection
Made of cellulose and modified by lignin, prevents osmotic bursting
Process: Division of Labour
- Nucleus- mRNA copy instructions
- mRNA leaves the nucleus through pores
- mRNA attaches to ribosome to read how to make protein
- Insulin molecules are pinched off in vesicles to travel towards the golgi
- Vesicle fuses with the Golgi
- Golgi processes and packages the insulin
- Packages insulin pinched off and moves towards the surface membrane
- Vesicle fuses with the surface membrane
Prokaryote features
Always: Circular DNA, Plasma membrane, Cytoplasm where anaerobic respiration, ribosomes, cell wall
Additional: Pilli, plasmid, capsule, mesosome, Flagellum
