Mod 2 Chap 2: Cell Structure and Microscopy Flashcards
How do you convert from mm to micrometers?
X 1000
How do you convert from micrometers to mm?
divide by 1000
How do you convert from micrometers to nm?
X 1000
How do you convert from nm to micrometers?
Divide by 1000
What does epu stand for?
Eye piece units across
What is the equation needed for magnification calculations?
I
AM
I = image size A = actual size M = magnification
So I = A x M
A = I / M
M = I / A
Answer these questions for a light/ optical microscope: Source of image: How the beam is focused: Max effective magnification: Max resolution: Can a live specimen be used: Section / external view: Cost: Staining of specimen required:
Source of image: BEAM OF LIGHT How the beam is focused: LENSES Max effective magnification: X 1500 Max resolution: 200 nm Can a live specimen be used: YES Section / external view: SECTION Cost: CHEAP Staining of specimen required: NO
Answer these questions for transmission electron microscope (TEM): Source of image: How the beam is focused: Max effective magnification: Max resolution: Can a live specimen be used: Section / external view: Cost: Staining of specimen required:
Source of image: ELECTRON BEAM How the beam is focused: ELECTROMAGNETS Max effective magnification: X 500,000 Max resolution: 0.2nm Can a live specimen be used: NO Section / external view: SECTION Cost: EXPENSIVE Staining of specimen required: YES WITH METAL SALTS
Answer these questions for a scanning electron microscope (SEM): Source of image: How the beam is focused: Max effective magnification: Max resolution: Can a live specimen be used: Section / external view: Cost: Staining of specimen required:
Source of image: ELECTRON BEAM How the beam is focused: ELECTROMAGNETS Max effective magnification: X 100,000 Max resolution: 10 nm Can a live specimen be used: NO Section / external view: EXTERNAL Cost: EXPENSIVE Staining of specimen required: COATED WITH GOLD
List the four types of microscope
Scanning Electron Microscope
Light / Optical
Transmission Electron Microscope
Laser
Define Magnification:
How many times larger the image is than the actual size of the object being viewed.
Define Resolution:
The ability to see individual objects as separate entities.
Which types of microscope can produce 3D images?
Scanning (SEM)
Which microscope uses fluorescent dyes to stain specimens?
Laser scanning
What are the organelles present in animal cells?
Plasma membrane Nucleus Nucleolus Nuclear envelope Nuclear pore Peroxisome Ribosome Golgi complex Lysosomes Secretory vesicle Mitochondrion Cytoplasm Centrioles Cytoskeleton - filaments Microtubules Smooth endoplasmic reticulum Rough endoplasmic reticulum
What are the organelles present in plant cells?
Plasma membrane Cytoplasm Mitochondria Cytoskeleton: micro tubules, filaments Nucleus Nucleolus Nuclear envelope Nuclear pore Rough endoplasmic reticulum Smooth endoplasmic reticulum Golgi complex Peroxisome Cell wall Chloroplast Permanent vacuole: tonoplast Plasmo desmata Ribosomes
What is the function of the centrioles?
Component of the cytoskeleton involved in assembly and organization of spindle fibers during cell division
Describe the preparation and examination of slides used in light microscopy.
- sample placed on a slide + allowed to air dry
- then heat fixed by passing through a flame
- specimen then adheres to microscope slide + takes up stains
Describe the various methods in which samples and specimens can be prepared for examination by light microscopy.
- dry mount: specimen place onto slide dry + covered with a slip
- wet mount: specimens suspended in liquid such as water + covered with a slip
- squash slides: wet mount is prepared, cover slip is pressed down with a lens tissue, damage to cover slip can be avoided using two microscope / squash slides
- smear slides: edge of a slide used to smear sample on another slide, cover slip then placed on top.
Describe the importance of the cytoskeleton in terms of its structure.
- it’s a network of protein structures within cytoplasm
CONSISTS OF:
- rod like MICROFILAMENTS made of subunits of protein actin, they are polymers of actin.
- INTERMEDIATE FILAMENTS about 10nm in diameter
- MICROTUBULES that are straight and cylindrical, made of subunits of protein tubulin
- CYTOSKELTAL MOTOR PROTEINS: myosins, kinesins, and dyenins are molecular motors, they are enzymes that allow hydrolysis of ATP as the energy source.
- cytoskeleton is present in all eukaryotic cells
- network of fibers necessary for shape and stability of cell
- holds organelles in place
- controls cell movement and movement of organelles within cells
Describe the importance of the cytoskeleton in terms of cell movement.
- movement of cells like phagocytes depends on activity of actin filaments in cytoskeleton
- filament lengths change w/ addition + removal of monomer subunits. (Rate these subunits added is diff at each end of filament)
- so at certain concentrations, subunits added at one end + removed at other, called ‘treadmilling’, causing cells to move in a particular direction.
Describe the differences in structure and ultra structure of prokaryotic and eukaryotic cells.
Eukaryotic Prokaryotic
-Has membrane bound organelles. -Does not
-Has a nucleus. -Does not
-Large ribosomes. -Small ribosomes
-DNA on linear chromosomes. -DNA on circular
chromosomes
-DNA within cytoplasm. -DNA within nucleus
-ATP production in folded regions of. -ATP production in
cell membrane called mesosomes. mitochondria
-cellulose based cell wall. -peptidoglycan based
cell wall
- may have undulipodia. - may have flagella
(Cilia and flagella)
What is differential staining?
It can distinguish between two types of organisms that would otherwise be difficult to differentiate between different organelles of a single organism within a tissue sample.
What techniques can be used when staining samples in microscopy?
Gram Stain Technique - separates bacteria into two groups
Acid-fast technique - differentiates species of Mycobacterium from other bacteria.
What is the function of ribosomes?
- constructed of RNA molecules made in nucleolus
- site of protein synthesis
What is the function of chloroplasts?
- responsible for photosynthesis in plant cells
- have internal network of membranes forming flattened sacs called thylakoids, several thylakoids stacked together = granum (plural grana)
- grana contain chlorophyll pigments, where light dependant reactions occur in photosynthesis.
- contain DNA + ribosomes so can make own proteins
What is the function of cilia?
- stationary cilia present on surface of many cells, have important functions in sense organs e.g. nose.
- mobile cilia beat rhythmically to create current + move fluids or objects away from cell
- cilia = hair like
- flagella = whip like
What is the function of the Golgi apparatus?
- role in modifying proteins + packaging them into vesicles, (secretory vesicles if proteins are destined to leave cell /lysosomes, which stay in cell).
What is the function of the rough endoplasmic reticulum? Describe it.
- has ribosomes bound to surface + is responsible for synthesis + transport of proteins
- is network of membranes enclosing flattened sacs called cisternae
- connected to outer membrane of nucleus
What is the function of the smooth endoplasmic reticulum? Describe it.
- responsible for lipids and carbohydrate synthesis and storage
- a network of membranes enclosing flattened sacs called cisternae
- connected to outer membrane of nucleus
What is the function of lysosomes and Peroxisomes?
Lysosomes:
- contain hydrolytic enzymes, responsible for breaking down waste materials in cells
- responsible for breaking down pathogens ingested by phagocytic cells
- play important role in programmed cell death or ‘apoptosis’
Peroxisomes:
- contain same digestive enzymes (hydrolytic enzymes) to get rid of nasty toxins.
What is the function of the nucleus, nucleolus, nuclear envelope and nuclear pores?
Nucleus:
- contains coded genetic material in form of DNA molecules
Nuclear envelope:
- contains double membrane w/ DNA to protect DNA from damage in cytoplasm
Nuclear pores:
- allow molecules to move into + out of nucleus
What is the function of mitochondria?
- essential organelles, site of final stages of cellular respiration
- are where molecule ATP makes energy stores in bonds of complex organic molecules for cell to use
- can produce their own enzymes + reproduce themselves
What is the function of the cell wall?
- made of cellulose
- permeable so allow substances into + out of cells through them
- give plant cells shape
- acts as defense mechanism, protecting cell contents against invading pathogens
- present in all plant cells
What is the function of a vacuole?
- important in maintenance of turgor (so contents of cell push against cell walls + maintain rigid structure)
- membrane of vacuole, (tonoplast), = selectively permeable so only allows some molecules to pass through it
What is the function of the centrioles?
- composed of microtubules
- component of cytoskeleton
- two associated centrioles form centrosome, which is involved in assembly and organization of spindle fibres during cell division.
Describe the process of protein synthesis.
- gene w/ coded instructions for the protein is transcribed into a length of messenger RNA (mRNA)
- many copies of mRNA made + pass out of pores in nuclear envelope
- mRNA attaches to a ribosome, which is attached to RER, ribosome reads instruction to assemble protein insulin (process called translation)
- insulin molecules pass into cisternae of RER + along these hollow sacs
- insulin molecules ‘pinched off’ in vesicles + travel via microtubules + motor proteins to Golgi apparatus
- vesicle fuses w/ Golgi apparatus
- Golgi apparatus processes + packages insulin molecules ready for release
- packaged insulin molecules ‘pinched off’ in vesicles from Golgi apparatus + move towards plasma membrane
- vesicle fuses w/ plasma membrane
- plasma membrane opens to release insulin molecules outside.
