Basic components of living systems Flashcards
How expensive are light/optical microscopes, Scanning electron microscope, Transmission electron microscope
Light - inexpensive to purchase and operate
SEM & TEM - Expensive to purchase and operate
What radiation is used in each type of microscope
Light - light
SEM - Beams of electrons
TEM - Beams of electrons
What is the size of each type of microscope
Light - Small & portable
SEM - Large
TEM - Large
Maximum magnification of each type of microscope
Light - x1500
SEM - x100,000
TEM - x500,000
Maximum resolution of each type of microscope
Light - 200nm
SEM - 0.2nm (newer ones can go up to 0.1nm)
TEM - 0.1nm
Type of image produced in each type of microscope
Light - 2D
SEM - 3D
TEM - 3D
Sample preparation of each type of microscope
Light - simple
SEM - More complex but does not have to be as thin as TEM
TEM - Extremely thin and complex
Is a vacuum needed for each microscope
Light - No - can view living species
SEM & TEM Use o- Yes - sample must be dead
Explain the function and utility of gram staining
- Used to distinguish between two types of DNA - Gram-positive and Gram-negative bacteria
- Gram-positive bacteria is susceptible to penicillin which inhibits the formation of cell walls, gram negative bacteria have thinner cell walls and are not susceptible to penicillin - think of possible implications and uses therefore
How do you carry out gram staining
- Apply Crystal violet on bacterial specimen on slide
- Apply iodine to fix the dye
- Wash slide with alcohol, gram-positive bac will retain the dye and appear blue/purple under a microscope. The Gram-negative bac will lose the dye due to their thinner cell walls
- Apply Safranin dye (acts as a counter-stain) - makes gram-negative bac appear red
- Gram-positive = blue/purple
- Gram-negative = red
Explain the function and utility of Acid-fast staining
- Used to differentiate between species of mycobacterium from other bacteria
How do you carry out acid-fast staining
- lipid solvent used to carry carbol fuchsin dye into cells
- Cells washed with dilute acid - alcohol solution
- Mycobacterium are not affected by the alocohol solution and retain the carbol fuchsin dye - appearing red
- Other bacteria lose the stain and are exposed to methylene blue (counter-stain) making them appear blue
- Mycobacterium - bright red
- Other bacteria - blue
Magnification formula
Magnification = Image size/ object size
Units
nm x1000 = micrometre x1000 = mm x10 = cm x 100 = M
What is the difference between magnification and resolution
Magnification = how large the image is compared to actual size Resolution = The ability to distinguish between two distinct points on an image - the amount of detail
Structure of nucleus
Contains: Double nuclear envelope Nuclear pores Nucleolus Chromatin
Function of nucleus
Nucleus - contains DNA (chromatin) which controls activity of cells and also allows replication and copy for cell division, Attached to rough endoplasmic reticulum allowing MRNA to go to ribosome for protein synthesis
Nucleolus - Made by RNA and protein - produces ribosomes
Nuclear envelope - Double membrane - compartmentalises DNA - protecting it from damage
Nuclear pores - Allows molecules to enter and leave nucleus
Structure of Endoplasmic Reticulum
Rough Endoplasmic Reticulum -
System of interconnected hollow tubes and membrane bound sacs which stack to form sheets of cisternae
Attached to nucleus
Have ribosomes attached to them
Smooth Endoplasmic Reticulum -
System of interconnected hollow tubes and membrane bound sacs which stack to form sheets of cisternae
Do Not have ribosomes attached to them
Function of Endoplasmic Reticulum
Rough Endoplasmic Recticulum - site of protetin synthesis
Smooth Endoplasmic Recticulum - Carbohydrate and lipid synthesis and storage
Structure of Golgi Apparatus
Stack of flattened membrane bound sacs stacked to form sheets of Cisternae
Continuously formed from ER and constantly budding off as Golgi vesicles from the other end
Function of Golgi Apparatus
Allows internal transport
receives protein from RER
Modifies and processes molecules (coming from ER) and after modifying them they package them into vesicles and send them to where they are needed.
Makes lysosomes - one kind of vesicle the Golgi apparatus can make - these stay in the cell
Makes Secretory vesicles - another kind of vesicle the Golgi apparatus can make - these leave the cell
Structure of Ribosome
2 subunit organelle Made from RNA and Protein very small - 22nm not membrane bound Free floating in the cell or attached to the rough endoplasmic reticulum
Function of Ribosome
Makes proteins - assemble amino acids to proteins in chains using mRNA
Structure of Mitochondrion
Oval shaped
double membrane
inner membrane contains finger-like structures called cristae - increases surface area for reactions to happen quicker
Solution inside = matrix - contains enzymes for respiration
contains mitochondrial DNA - to replicate enzymes
Function of Mitochondrion
Site of aerobic respiration Produces ATP (energy carrier in cells) - Because of respiration
Structure of Lysosomes
Spherical sacs surrounded by single membrane
Function of Lysosomes
Contains powerful hydrolytic digestive enzymes - called lysozymes
Lysozymes - break down worn out components, digest invading cells
Structure of Centrioles
Component of cytoskeleton
Made of 9 rings of triplet microtubules
Small hollow cylinders - occur in pairs next to nucleus
Animal cells only
Function of Centrioles
Copy itself during cell division and form the spindle in cell division
Structure of Cilia
Hair-like extensions protruding from some animal cell types
In cross section they have an outer membrane and a ring of nine pairs of microtubules and two microtubles in the centre - 9+2 arrangement - allows movement
Function of Cillia
Sensory function (e.g. nose)
beat creating a current to move
For locomotion
Structure of Plasma Membrane
Found on surface of animal cells
Found inside cell wall of plant and prokaryotic cells
Phosholipid Bilayer - composed of proteins & Lipids
Contains cholesterol
Function of Plasma Membrane
Regulate substances entering and leaving the cell
Receptor molecules allows hormones and reacts to hormones etc.
Structure of Cytoskeleton
Has 3 structural components - Microfilaments (made of actin), Microtubules (made of tubulin), Intermediate Fibres
Function of Cytoskeleton
Microfilaments - Actin - movement during cytokinesis
Microtubules - Tubulin - determine shape of cell by polymerising, act as tracks for movement for organelles
Intermediate Fibres - gives strength to cells, helps maintain integrity
Structure of flagella
- Similar to cilia but longer
- Stick out of cell surface and surrounded by plasma membrane
- 9 + 2 arrangement - 9 rings of pair microtubules around and 2 rings of microtubules in the centre
Structure of Chloroplast
- Double membrane encloses stroma
- Membrane-bound flattened sacs called thylakoids in stroma - stacked together = grana - contain chlorophyll, linked together by lamellae
- Contains - starch grains, Lipid stores DNA, RNA, Ribosomes
Function of chloroplast
- Photosynthesis
Structure of Cell wall
- Cellulose microfibrils - complex carbohydrate
- Fully permeable
- Thin layer of middle lamella - marks boundaries between adjacent cells and cements them together
Function of cell wall -
- Mechanical strength, cell support and shape
- Plant cell components can push against cell wall giving cell good support - turgidity
Interrelationships - Production and Secretion of proteins
- DNA in nucleus contains code to make protein
- Copy of the code is taken away from the nucleus by coping it onto the mRNA which goes to the ribosome on the rough ER
- Protein is synthesised on the ribosome
- Protein goes to cisternae of the of the rough ER and is packaged into a vesicle
- Vesicle goes to the golgi apparatus via the cytoskeleton and fuses - spilling it`s contents into the golgi apparatus
- Golgi processes and structurally modifies protein
- Golgi repackages protein into a secretory vesicle
- Secretory vesicles fuse with the cell surface membrane
- Contents of vesicle released out of the cell by exocytosis
How to calibrate eyepiece graticulate
- Place the stage micrometre on stage and fit the eye piece graticulate on the eye lens
- Find a point where both scales align and then following that point look carefully for when the scales align again
- Work out how many eyepiece graticulate units are between the 1 division of the stage micrometre we found aligned earlier. If for example there are 40 eyepiece units division than 40 EPU = 0.1mm/ 10 micrometre
- Then when/if moving on to other objective lens power you must recalibrate the eyepiece graticulate.
Name the features of the prokaryotic cell structure
- Plasma membrane
- Circular DNA
- Cytoplasm
- Ribosome
- Cell wall
- Plasmid*
- Pili*
- Flagellum*
- Mesosome*
- Slime capsule*
- Infolding of plasma membrane*
- = not always present
Prokaryotic and Eukaryotic cell comparison
- Nucleus - Not present - Present
- Chromosome Shape - Circular - Linear
- DNA Organisation - Proteins fold and condense DNA
—- Associated with proteins called histones - Extra chromosomal DNA - Stored in Circular DNA
called Plasmids - Only present in specific organelles
such as chloroplasts and mitochondria - Organelles - Non membrane-bound - Both membrane-bound and non-membrane-bound
- Cell wall - Present in all prokaryotic cells and made of peptidoglycan - Chitin in Fungi - Cellulose in plants and not present in animals
- Ribosomes - Smaller 70S - Larger 80S
- Cytoskeleton - present - present but more complex
- Reproduction - Binary fission - asexual or sexual
- Cell type - unicellular - unicellular and multicellular
- Cell-surface membrane - present - present
