cells unit 2 Flashcards
what is the structure of a nucleus?
- nuclear envelope
- nuclear pores
- nucleoplasm
- chromosomes
- nucleolus - site of RNA production
what is the function of the nucleus?
- site of DNA replication and transcription
- contains the genetic code for each cell
what is the structure of the endoplasmic reticulum?
- rough and smooth both have folded membrane’s called cisternea
- rough have ribosomes on the cisternae
explain the structure of the Golgi apparatus and vesicles
- folded membranes making cisternae
- secretary vesicle pinch off from the cisternae
explain the functions of the golgi apparatus and vesicles?
- add carbohydrates to portions to form glycoproteins
- produce secretory enzymes
- secrete carbohydrates
- transport, modify and store lipids
- form lysosomes
- molecules are ‘ labelled’ with their destination
- finished products are transported to cell surface in golgi vesicles where they fuse with the membrane and the contents in released.
explain the structure of lysosomes?
bags of digestive enzyme - can contain 50 different enzymes
explain the function of lysosomes?
- hydrolyse phagocytic cells
- completely break down dead cells
- exocytosis - release enzyme to outside of cell to destroy them
- digest worn out organelles for reuse of materials
describe the structure of mitochondria?
- double membrane
- inner membrane called the cristae
- fluid centre called the mitochondrial matrix
- loop of mitochondria DNA
explain the function of mitochondria?
- site of aerobic respiration
-site of ATP production - DNA to code for enzymes needed in respiration
describe the structure of ribosomes?
- small
- made up of protiens and rRNA
describe the functions of ribosomes?
- site of protein synthesis
describe the structure of a vacuole
- filled with fluid surrounded by a single membrane called a tonoplast
describe the functions of the vacuole
- make cells turgid and therefore provide support
- temporary store of sugars and amino acids
- the pigments may colour petals to attract pollinators
describe the structure of chloroplasts
- surrounded by a double membrane
- contains thylakoids ( folded membranes with pigments )
- fluid filled stroma contains enzymes for photosynthesis
- found in plants
describe the functions of chloroplasts
site of photosynthesis
describe the structure of a cell wall
plants - made of microfibrils of the cellulose polymer
fungi - made of chitin, a nitrogen- containing polysaccharide
describe the function of a cell wall
provide structural strength to the cell
describe the structure of the plasma membrane
- found in all cells
- phospholipid bilayer- molecules embedded within and attached on the outside
describe the function of the plasma membrane
- controls the entrance and exit of molecules
what are the key differences between prokaryotic cells and eukaryotic cells?
- the cells are much smaller in P
- no membrane bound organelles in P
- smaller ribosomes
- no nucleus
- cell wall is made of murrain
whats the structure of a virus?
- genetic material
- capsid
- attachment protein
where do viruses replicate?
inside of host cells
what are the three main types of microscopes?
- optical light microscope
- transmission electron microscopes
- scanning electron microscopes
define magnification
how many time larger the image is compared to the object.
define resolution
the minimum distance between two objects in which they can still be views as separate.
describe the optical light microscope?
- a beam of light is condensed to create an image
- poor resolution due to light having a long wave length
- lower magnification
colour images can be seen - can view living samples
describe the electron microscope
- a beam of electrons is condensed to create an image
- higher resolving power as electrons have a short wavelength
- higher magnification
- black and white images
- sample must be non-living
difference between transmission electron and scanning electron microscope
- TEM - extremely thin specimens are used and electrons pass through the specimen
- SEM - specimens do not need to be thin and 3D images can be uncovered. electrons are beamed onto the surface and scattered in different directions.
how do you calculate magnification?
image size = actual size x magnification
I=AM
converting units
metre (M) -> millimetere (mm) -> micrometre (um) -> nanometre (nm)
what is the purpose of the eye piece graticule?
can be used to measure the size of objects you are viewing under the microscope
what is the reason for cell fractioning ?
- used to isolate different organelles so they can be studied
- this enables individual organelle structure and functions to the studied.
