Cell Structure Flashcards
Define Magnification
How many times bigger the image observed is in comparison to the actual size
Define Resolution
The ability to distinguish between two points
What is the equation for magnification ?
Image size = Actual Size x Magnification
How do light microscopes work ?
Lenses focus rays of light and magnify the view of a specimen
Reflected light is transmitted to the observer via the objective lens and eyepiece
How do transmission electron microscopes work ?
Projects an electron beam through a sample. An electromagnetic beam of electrons is projected onto the sample, and a 2D image is formed.
How do scanning electron microscopes work ?
Scanning Electron Microscopes directs an electron beam across a sample. SEM is different from TEM in that it projects electrons across a specimen instead of simply passing electrons through it. Electrons from the specimen which are captured in a special instrument known as a cathode ray tube. Can be used to produce a 3D image
Why do samples need to be stained for light microscopes ?
Coloured dye binds to the structures, which facilitates the absorption of wavelengths of lights to produce an image. Staining allows for the differentiation between features
What is the magnification and resolution of a Light microscope ?
Resolution - 200 nm
Magnification - x1500
What is the magnification and resolution of a Transmission Electron Microscope ?
Resolution - 0.5 nm
Magnification- x500,000
What is the magnification and resolution of a Scanning Electron Microscope ?
Resolution - 5 nm
Magnification - x500,000
Describe the structure of the nucleus
Surrounded by a nuclear envelope, double membraned
Contains nuclear pores
Nucleolus made of RNA
What is the function of the nucleus ?
Controls the activities of the cells by controlling transcription
What is the structure of the Rough Endoplasmic reticulum ?
Formed from continuous folds of membrane
Contains Ribosomes
What is the Function of the Rough Endoplasmic Reticulum ?
Involved in Processing and packaging Proteins into vesicles
What is the structure of the Smooth Endoplasmic Reticulum ?
Formed from continuous folds of membrane
Doesn’t contain ribosomes
What is the function of the Smooth Endoplasmic Reticulum ?
Involved in the production, processing and storage of lipids
What is the structure of the Golgi ?
Flattened sacs of membrane
What is the Function of the Golgi ?
Modifies proteins and lipids before packaging them into vesicles
What is the Structure of Ribosomes ?
Two Subunits of RNA
What is the function of Ribosomes ?
The Main site of protein synthesis
How are Proteins produced ?
DNA is transcribed into mRNA
The mRNA exits the nucleus via nuclear pores
mRNA travels to Ribosomes located on the Rough Endoplasmic Reticulum
The Rough Endoplasmic reticulum packages them into vesicles
The Vesicles are transported to the Golgi where they’re modified and repackaged into vesicles
The vesicles travel to the plasma membrane where they fuse with it and exit the cell vis exocytosis
What is the structure of the mitochondria ?
Double membraned with the inner membrane folded to cristae
The matrix formed by the cristae contains enzymes needed for aerobic respiration
What is the Function of the mitochondria ?
Produces ATP as a result of aerobic respiration
What is the structure of the chloroplast ?
Double membraned
What is the function of Chloroplast ?
The main site of photosynthesis
What are lysosomes ?
Membrane bound sac containing digestive enzymes which break down waste materials such as organelles
Describe the structure and function of the plant walls ?
Made of cellulose to provide strength and prevent cell from bursting when water enters the cell
What are vesicles ?
Membrane bound sac for transport and storage
What are bacterial and fungal cell walls made of ?
Fungi : Chitin
Bacteria : Peptidoglycan
What are centrioles ?
Hollow fibres made of microtubules
Two centrioles at right angles to each other form a centrosome, which organises the spindle fibres during cell division
Not found in flowering plants and fungi
What is the plasma membrane ?
The plasma membrane controls the exchange of materials between the internal cell environment and the external environment
The membrane is partially permeable
Plasma membrane is formed from a phospholipid bilayer
What is the flagella ?
Made of longer microtubules
Contracts to provide cell movement
What is the Cillia ?
Hair-like projections made from microtubules
Allows the movement of substances over the cell surface
Why is the cytoskeleton important ?
Provides mechanical strength
Aids transport within cell
Enables cell movement
What are similarities between eukaryotes and prokaryotes ?
Both have;
Cell Membrane
Cytoplasm
Ribosomes
Differences between eukaryotic and Prokaryotic
Prokaryotes have no membrane bound cells or nucleus
Prokaryotes have small (70s) Ribosomes and Eukaryotes have (80s)
Prokaryotes have Circular DNA
