cells and microscopy Flashcards
what is the function of the nucleus
- stores genetic information
- location where semi-conservative replication occurs
explain the 4 parts of the nucleus
- the nuclear envelope - double membrane that surrounds the nucleus. It controls the entry and exit of substances in and out of the nucelus
- nuclear pores - allow the passage of large molecules such as mRNA out of the nucelus
- chromatin - linear DNA which is protein(histone) bound
- nucleolus- manufactures rRNA and makes ribosomes
what is the function of the mitochondria
- where ATP is synthesised by aerobic respiration
what are the 4 structures a mitochondrion is made up of and explain them
- the double membrane - the 2 membranes control the entry and exit of molecules
- cristae - provide a large surface area for enzymes such as ATP synthase
- intermembrane space - the space between the inner and outer membrane
- matrix - contains proteins, lipids, mitochondrial DNA and 70s ribosomes
what is the difference between the rough and the smooth endoplasmic reticulum
the rough has ribosomes on the outer surface membrane
what are the 2 functions of the rough endoplasmic reticulum
- synthesis of proteins
- package proteins into vesicles
what are the 2 functions of the smooth endoplasmic reticulum
- synthesis, store and transport lipids
- synthesis, store and transport carbohydrates
what is the function of the golgi apparatus
sorts and modifies proteins which are then packages into vesicles
what are the functions of lysosomes
- they contain and release hydrolytic enzymes
- fuse with foreign materials ingested by phagocytic cells and then release its hydrolytic enzymes
- release enzymes to the outisde of the cell in order to hydrolyse and breakdown molecules outside of the cell
- they breakdown damages and worn out organelles so the useful molecules can be reused
- break down cells after they have died
what is the function of ribosomes
- synthesise proteins
what are the 2 different types of ribosomes and explain them
- 80s ribosomes - larger, found in eukaryotic cells
- 70s ribosomes - smaller, found in prokaryotic cells
what is the function of the cell surface membrane
controles the passage of molecules in and out of the cell
what are the 3 additional organelles called in a plant cell
- chloroplasts
- cell wall
- vacuole
what is the function of the chloroplast
carry out photosynthesis
explain the structure of chloroplasts
- double membrane surrounds the organelle known as the chlorplast envelope
- inside the chlorplasts, the grana are stacks of up to 100 disk like structures called thylakoids
- within the membrane is the photosynthetic pigment called chlorophyll
what is the function of the cell wall
provide strength and rigidity
what are the functions of vacuoles
- provide support, making cells turgid
- sugars and amino acids stored
- pigments may colour petals and attract pollinating insects
what are the different organisation levels in an organism
- specialised cell
- tissue
- organ
- organ system
- organism
give 4 differences between prokaryotic cells and eukaryotic cells
- prokaryotic cells have circular DNA whereas eukaryotic cells have linear DNA
- prokaryotic cells have no membrane-bound organelles whereas eukaryotic has membrane-bound organelles
- prokarytoic cells have no ‘true’ nucleus and the DNA is free in the cytoplasm whereas eukaryotic cells have a nucleus and the DNA is contained in a nuclear membrane
- prokaryotic cells contain 70s ribosomes whereas eukaryotic cells contain 80s ribosomes
what are features of viruses
- non-living
- require a living cell to replicate inside
- contain DNA or RNA
- the envelope contains attachment proteins
- they have no organelles
what is meant by resolution
the ability to distinguish between two objects that are close together
what are the two types of electron microscopes
TEM and SEM
explain how we can see specimens using a TEM
- the specimens are in a vacuum and stained using heavy metals
- specimens are fixed in resin and sliced thin
- electrons are fired through the specimen to enable the viewing of internal structures
- it is 2D
explain how we can see specimens using a SEM
- the electrons bounce off the surface of the specimen
- they produce a 3D image
compare light microscopes and electron miscroscopes by the following:
1. illumination
2. maximum magnification
3. what can you observe
4. specimens
5. staining process
Light on the left, Electron on the right
1. light rays, beam of electrons
2. x1500, x500000
3. larger organelles, smaller organelles
4. living, dead
5. easy, complex
