Topic 2 - cell structure Flashcards
What are the 3 different types of microscopy
Light microscope
Scanning electron microscope
Transmission electron microscope
What mediums do each microscopes use
Light microscope - light beam
Scanning electron microscope - electron beam
Transmission electron microscope - electron beam
What dimensions do each microscopes use
Light microscope - 2D
Scanning electron microscope - 3D
Transmission electron microscope-2D
What is the max magnification of each microscope
Light microscope - x1,500
Scanning electron microscope - x200,000
Transmission electron microscope - x2,000,000
What is the max resolution of each microscope
Light microscope - 200nm
Scanning electron microscope - 20nm
Transmission electron microscope - 0.1nm
What is magnification and state its equation
Magnification is how much bigger the image is compared to the original object viewed with the naked eye
Magnification = (size of image)/(size of object)
What is resolution
Resolution is how well a microscope distinguishes between two points that are close together.
To prepare slides for light microscopy, the specimen must be: (4 marks)
- Dehydrated
- Embedded in wax and sectioned
- Stained
- Mounted
Why is staining used when preparing light microscope
Staining is used to increase contrast in a specimen, in order to observe transparent and colourless structures.
How does staining work when preparing microscope slides
Stains work by binding to different types of molecules or cell structures. This allows different components of cells to be identified, and is known as differential staining
What are eukaryotic cells and 3 examples of eukaryotic groups
Eukaryotic cells are those cells that contain a nucleus and organelles enclosed by a plasma membrane (membrane bound organelles)
Includes animals, plants and fungal cells
Function of cell surface membrane
- Controls passage of entry of substance into the cell
- Site of cell communication via receptors
Function of the nucleus
- Stores DNA
- Nuclear pores allow mRNA & ribosomes to pass through
Function of the mitochondria
- carry out aerobic respiration to produce ATP
Function of lysosomes
Contains digestive enzymes to break down pathogens, old organelles, cells & food molecules
Function of ribosomes
Site of protein synthesis
Function of rough endoplasmic reticulum (RER)
- provide a large surface area for protein synthesis
Function of smooth endoplasmic reticulum (SER)
- Synthesise, store and transport lipids and carbohydrates
Function of Golgi apparatus
- modifies proteins
- sort, package and transport molecules around the cell
Function of chloroplasts and the organisms in which they are present
- site of photosynthesis
present in plants and algae
Function of the cell vacuole and the organisms in which they are present
- Maintains cell structure
- Acts as a temporary energy store
Present in plants
Function of the cell wall and the organisms in which it is present
- Provides supports and mechanical strength
Present in plants (cellulose) and algae (cellulose) and fungi (chitin) prokaryotes (murein)
Where is the cytoskeleton found
in the cytoplasm
What is the cytoskeleton made up of
a complex network of proteins
(1) are composed of repeating (2) subunits. Important to (3…)
CYTOSKELETON
1 - Microfilaments
2 - actin
3 - maintain cell shape and give mechanical strength
(1) are composed of repeating (2) subunits. Involved in (3…)
CYTOSKELETON
1 - Microtubules
2 - tubulin
3 - organelle and substance movement
(1) fibres are made of (2) fibres. Helps (3…)
CYTOSKELETON
1 - Intermediate
2 - interlocking protein
3 - anchor the nucleus in the cytoplasm and stabilising tissues
In complex multicellular organisms, eukaryotic cells become (1) for specific functions.
1 - specialised
What are specialised cells organised into and continue this chain until organ systems
Specialised cells are organised into tissues, tissues into organs and organs into systems.
What are prokaryotic cells
Prokaryotes have no membrane-bound organelles (so no mitochondria, Golgi, endoplasmic reticulum, nucleus etc). Their DNA floats freely in the cytoplasm. Their DNA consists of a single circular chromosome whereas DNA in eukaryotes is linear and wrapped around chromosomes.
Eukaryotic vs prokaryotic
Presence of a nucleus
Eukaryotic - present
Prokaryotic - absent
Eukaryotic vs prokaryotic
DNA
Eukaryotic - linear and packaged into chromosomes in the nucleus
Prokaryotic - circular and freely floating in cytoplasm
Eukaryotic vs prokaryotic
Presence of cell membrane
Eukaryotic - Present
Prokaryotic - Present
Eukaryotic vs prokaryotic
Presence of membrane bound organelles
Eukaryotic - Present
Prokaryotic - Absence
Eukaryotic vs prokaryotic
Presence of ribosomes and size
Eukaryotic - Present (80S)
Prokaryotic - Present (70S)
Eukaryotic vs prokaryotic
Presence of cell wall and make up
Eukaryotic - sometimes (cellulose or chitin)
Prokaryotic - present (peptidoglycan)
Eukaryotic vs prokaryotic
Presence of chloroplasts
Eukaryotic - Sometimes
Prokaryotic - Absent
Eukaryotic vs prokaryotic
Presence of flagellum
Eukaryotic - Absent
Prokaryotic - Sometimes
Eukaryotic vs prokaryotic
Presence of capsule
Eukaryotic - Absent
Prokaryotic - Sometimes
Eukaryotic vs prokaryotic
Presence of plasmid
Eukaryotic - Absent
Prokaryotic - Sometimes (Bacteria)
