Module 1 ^O^ Flashcards
What makes something alive?
Movement Respiration Sensitivity Growth Reproduction Excretion Nutrition
Compare prokaryotes and eukaryotes
Prokaryotes: simplest and most ancient type of cell - means ‘before nucleus’ (i.e. organelles not enclosed in a membrane)
Eukaryotes: evolved from prokaryotic cells - ‘true nucleus’ (i.e. enclosed in membrane)
Prokaryotes: 0.1-5.0um in size
Eukaryotes: 10-100 um
Prokaryotes: form single celled organisms such as archae bacteria and eubacteria
Eukaryotes: forms multicellular and unicellular organisms such as protsists, fungi, plants, animals
History of prokaryotes and eukaryotes
- 3000mya meteorites that landed in the ocean released minerals and amino acids, causing single celled bacteria to form
- 2000 - 1500 mya: more complex life (eukaryotes) developed –> Theory is that prokaryotic cell engulfed another prokaryotes and the bacteria took on the role of producing energy for the host cell
Magnification definition
The degree to which a lens can make an object appear larger
magnification = image size / actual size
Resolution definition
The ability to see two objects as separate from one anotehr
Field of view definition
What you can see in the microscope
To calculate cell width:
diameter of field of view / number of cells that fit across it
Compare light microscopes to electron microscopes
Magnification:
L - light pass through the biconvex lens and is refracted toward eye (1500x)
E - a beam of electrons creates an image of the specimen (1 000 000x)
Resolution:
L - up to 0.2 micrometres
E - up to 0.0002 micrometres
Advantages and Disadvantages of the light microscope and electron microscope
Light Microscope
Advantages = able to observe living things, is portable and affordable, efficient preparation of samples, coloured stains can be used for contrast
Disadvantages = limited magnification, poor resolution
Electron microscope:
Advantages - resolution and magnification increase
Disadvantages - expensive to use, preparation takes longer, uses a vacuum which kills living organisms
TEM vs SEM
Transmission electron microscope:
Electrons transmitted through specimen
Image produced in 2D
Scanning Electron Microscope:
Bombards with a beam of electrons, causing emissions of secondary surface electrons.
Image produced in 3D
Cell Theory: initial theory
Proposed by Aristotle: spontaneous generation i.e. life arises from non-living matter
Cell Theory Points
- All living things are made of cells
- Cells are the smallest part of life
- All living things arise from pre-existing cells
- Cells contain hereditary information which is passed on during cell division
- Cells have the same basic chemical composition
- All energy flow (resulting form chemical reaction) of life occurs within cells
Technological Advances that formed the Cell Theory points: “All living things are made of cells”
Schleiden and Schwann discovered plant and animal tissues all had the same structural build i.e. cells
Technological Advances that formed the Cell Theory points: Cells are the smallest part of life
Hooke observed cork using a very simple microscope and discovered ‘cells’. Leeuwenhoek used an improved microscope (300x) and discovered cells as living things (animalcules)
Technological Advances that formed the Cell Theory points: All living things arise from pre-existing cells
Spontaneous generation theory refuted by Virchow who discovered that cells ‘divided’ to reproduce - exposing broth to air experiment
Technological Advances that formed the Cell Theory points: Points 4, 5, 6
Invention of electron microscope allowed for a higher magnification and resolution and resulted in a better understanding of the structures and processes of cells.
Animal Cell Structures
Nucleus Endoplasmic reticulum Lysosomes Golgi bodies Mitochondria
Plant cell structures
Cell Wall
Chloroplast
Nucleus
Function = control and information centre
- stores DNA needed to control cell activities through proteins
- double nuclear membrane with pores
- a copy of DNA called MRNA is posted out of the pores to the building location
Endoplasmic Reticulum
Transport
- Rough ER: transport of proteins (network of flattened interconnected membranes that make up pathways) covered in ribosomes
- smooth ER: produces lipids used for membrane repair
Lysosomes
Small fluid filled sacs which act like cellular incinerators - single membrane and filled with digestive enzymes
- break down worn out cell organelles - membrane prevents the lysosome from digesting the rest of the cell