TOPIC 1: CELL STRUCTURE Flashcards
CELLS AND ORGANELLES:
What is the function of a nucleus?
Controls the cell activities
DNA contains instructions to make proteins
The pores allows substances to move between the nucleus and the cytoplasm
The nucleolus makes ribosomes
CELLS AND ORGANELLES:
What is the function of a smooth endoplasmic reticulum?
Synthesis and processes lipids
CELLS AND ORGANELLES:
What is the function of a rough endoplasmic reticulum?
Folds and processes proteins that have been made at the ribosomes
CELLS AND ORGANELLES:
What is the function of a golgi apparatus?
It processes and packages new lipids and proteins
Also makes lysosomes
CELLS AND ORGANELLES:
What is the function of a lysosome?
Contains digestive enzymes
These are kepts seperate from the cytoplasm by the surrounding membrane
Used to digest invading cells or to break down worn out components of the cell
CELLS AND ORGANELLES:
What is the function of a mitrochondrion?
The site of aerobic respiration, where ATP is produced
Mitrochondrion are found in large numbers in cells that are very active and require a lot of energy
CELLS AND ORGANELLES:
What is the function of a ribosome?
The site where protein synthesis are made
CELLS AND ORGANELLES:
What is the function of a centrioles?
Involved with the seperation of chromosomes during cell division
CELLS AND ORGANELLES:
What is the function of a cell surface membrane?
Regulates the movement of substances into and out of the cell
It also has receptors molecules on it, which allows it to respond to chemicals
CELLS AND ORGANELLES:
What is the function of a cillia?
The microtubles allow the cillia to move
This movement is used by the cell to move substances along the cell surface
CELLS AND ORGANELLES:
What is the function of a flagellum?
The microtubles contract to make the flagellum move
Flagellum are used like outboard motors to propel cells forward
CELLS AND ORGANELLES:
What is the function of a chloroplast?
absorbs sun light energy
Where photosynthesis occurs
Some photsynthesis occurs in the grana, and other parts happen in the stroma
CELLS AND ORGANELLES:
What is the function of a cell wall?
Supports the plants
CELLS AND ORGANELLES:
What is the function of a cytoskeleton?
Strengthen the cell and maintain its shape
Keep them in position
Cause the cell to move
Transports organelles and materials within the cell
CELLS AND ORGANELLES:
What is the function of a plasma membrane?
Regulates the movement of substances out of the cell
It also has receptor molecules on it, which allows it to respond to chemicals like hormones
CELLS AND ORGANELLES:
What is the function of a vesicle?
Transports substances in and out of the cell and between organelles
Some are formed by the Golgi apparatus or the endoplasmic reticulum while others are formed at the cell surface
attached to the cytoskeleton and moved by protein motors called dymein
ORGANNELS WORKING TOGETHER:
Explain protein production within cells?
Proteins are made at the ribosomes - and these ribosomes on the RER make proteins that are excreted or attached to the cell membrane , whereas the free ribosomes in the cytoplasm make proteins that stay in the cytoplams
New proteins produced at the RER are folded and processed in the RER
Then they’re transported from the RER to the golgi apparatus in the vesicles
At the golgi apparatus, the proteins may udergo further processing
The proteins enter more vesicles to be transported around the cell
ORGANNELS WORKING TOGETHER:
What are the four main functions of the cytoskeleton?
1) The microtubles and microfilaments support the cell’s organelles keeping them in position
2) They help to strengthen the cell and maintain its shape
3) As well as this, they’re responsible for the transport of organelles and materials within the cell
e.g the movement if chromosomes when they seperate during cell division depends on contraction of microtubules in the spindle
the movement of vesicles around the cell relies on cytoskeletal proteins
4) The proteins of the cytoskeleton can also cause the cell to move
e.g. The movement of cillia and flagella is caused by the cytoskeletal protein filaments that run through them.
PROKARYOTIC CELLS:
Prokaryotic VS Eukaryotic
PROKARYOTIC:
Single celled
No nucleus- nucleotide instead ( free in cytoplasm )
No membrane bound organelles
Respiration occurs in the mesosome
Naked DNA
Peptidoglycan, cell wall ( aka murein )
( Some have ) flagellum
70s Small ribosomes ( 20nm or less )
No cytoskeleton
Ave size: 0.5-2 um
EUKARYOTIC:
Often found in a tissue
Membrane bound nucleus
Membrane bound organelles present
Respiration occurs in the mitrochondria
DNA is bound to proteins to form chromosomes
Cellulose cell wall in plants, Chitin in fungi
( Some have ) cillia or undulipodia
80S Ribosomes ( 22nm )
Cytoskeleton
Ave size: 20-40 um
HOW MICROSCOPES WORK:
What is the calculation for microscopes?
I - Image size
O - Object size
M - Magnification
Image size = Object X Magnification
Object size = Image / Magnification
Magnification = Size of image / Size of real object ( aka actual size )
- Measure the image - always measure in mm
- Convert the measurement in mm into whatever units
- Calculate using the formula
HOW MICROSCOPES WORK:
How to calculate the units?
cm –> X10 mm –> X1000 um –> X1000 nm
nm –> /1000 –> um –> /1000 mm –> /10 cm
HOW MICROSCOPES WORK:
What is magnification?
How much an image is enlarged
( this refers to how much larger the image is than the object )
HOW MICROSCOPES WORK:
What is resolution?
How well two close objects can be seen in an image
( refers to how much detail can be seen in an image, smaller the distance - the more detail seen )
HOW MICROSCOPES WORK:
What are the features of a light microscope?
Maximum magnification: X1500
Maximum resolution: 200.0 nm
Type of radiation: Light
Radiation medium : Air
Pathway of radiation: Goes through the specimen
What focusses the radiation: Lens
Seen using: Human eye
Dimension of image : 2D
Colour of image produced : Colourless unless natuarally colourful or dyes added
Stained used: Chemical dyes
Preparation of the sample : Cut, Stain and mount onto a slide
Advantages : Cheap, can view living cells, Don’t need much training
Disadvantage: Lower resolution than electron microscopes ( limited resolution )
HOW MICROSCOPES WORK:
What are the features of a transmission electron microscope?
Maximum magnification: X1000000 +
Maximum resolution: 0.2nm
Type of radiation: Electron beam
Radiation medium : Vaccum
Pathway of radiation: Reflects off the specimen
What focusses the radiation: Elecromagnets
Seen using: Fluorescent screen
Dimension of image : 3D
Colour of image produced : Black and white, but can be added artificially afterwards by computer software
Stained used: Leads salt
Preparation of the sample : Complex preparation. Firm specimen in glutaraldehyde, dehydrate, embed in resin, cut with diamond blade, stain and mount
Advantages : Produce 3D image, Provide high resolution, Used to look at internal structure of organelles in detail
Disadvantage: Needs to be quite thinly sliced, Expensive, Complicated preparation of specimens, Lots of training required to operate
HOW MICROSCOPES WORK:
What are the features of a scanning electron microscope?
Maximum magnification : X500,000
Maximum resolution: 2.0 nm
Type of radiation: Electron beam
Radiation medium : Vaccum
Pathway of radiation: Reflects off the specimen
What focusses the radiation: Electromagnets
Seen using: Fluorescent screen
Dimension of image : 3D
Colour of image produced : Black and white, but can be added artificially afterwards by computer software
Stained used: Lead salts
Preparation of the sample : Complex preparation. Firm specimen in glutaraldehyde, dehydrate, embed in resin, cut with diamond blade, stain and mount
Advantages : Can view contours of cells and cellular arrangements
Disadvantage: Needs to be quite thinly sliced, expensive, complicated preparation of specimens, lots of training required to operate
HOW MICROSCOPES WORK:
What is the timeline for microscopes?
Late C 16th - light/optical microscope
1930s - elecron microscope (TEM & SEM )
- transmission electron microscope (TEM)
- scanning electron microscope (SEM)
1980s - laser scanning confocal microscope (LSCM)
USING MICROSCOPES:
What is cellular staining ?
It is a technique that can be used to better visualize cells and cell components under a microscope
By using different stains, one can preferentially stain certain cell components
USING MICROSCOPES:
Why use stain cells?
Cells that are stained is to enhance vizualization of the cell or certain cellular components under a microscope
Can highlight metabolic processes or to differentiate between live and dead cells in a sample
