Cells Flashcards
What is structure and function of the nucleus?
Nucleus - site of DNA replication and transcription and contains genetic code for each cell
Nuclear envelope - double membrane
Nuclear pores - holes on outside
Nucleoplasm - jelly like material on outside
Chromosomes - protein bound, linear DNA
Nucleolus - small sphere where RNA production occurs and makes ribosomes
What is structure and function of golgi apparatus?
Golgi apparatus
Structure: Folded membranes
Secretary vesicles pinch off cristae
Function:
Make glycoproteins by adding carbohydrates to proteins
They are then packaged into golgi vesicles and are transported to cell surface membrane
They then fuse with the membrane and the contents are released
What is structure and function of mitochondria?
Structure:
Double membrane
Inner membrane called the cristae
Fluid centre called the matrix
Loop of mitochondria RNA
Function:
Site of ATP production and aerobic respiration
DNA to code for enzymes needed in respiration
What are the structure and function of chloroplasts?
Structure:
Surrounded by double membrane
Contain thylakoids - folded membranes embedded with pigment
Stroma contain enzymes for photosynthesis
Function:
Site for photosynthesis
What is structure and function of a plasma membrane?
Structure:
Phospholipid bilayer: molecules embed within and attached on the outside
Function:
Controls entry and exit of molecules
What is function and structure of the Endoplasmic reticulum?
Structure:
RER and SER both have cristae
RER contains ribosomes on outside
Function:
RER - Site of protein synthesis
SER - synthesis and stores lipids and carbohydrates
What is structure and function of lysosomes?
Structure:
Bags of digestive enzymes
Function:
Secrete enzymes to outside of cell to destroy materials
What is structure and function of ribosomes?
Structure:
80s larger ribosomes found in eukaryotic cells
70s smaller ribosomes found in prokaryotic cells
Function:
Site of protein synthesis
What is structure and function of vacuole?
Structure:
Filled with fluid surrounded by single membrane
Function:
Make cells turgid for support and pigments colour petals to attract pollinators
What is structure and function of cell wall?
Structure:
Plants: made of microfibrils of cellulose polymer
Fungi - made of chitin
Function - provide structural strength to wall
What are differences between prokaryotic and eukaryotic cells?
Prokaryotic cells are smaller
Have no nucleus
No membrane bound organelles
Smaller ribosomes
Cell wall made of murein
Some prokaryotic cells contain
Plasmids
Capsule around the cell
Flagella
What is murein?
A glycoprotein
What do prokaryotic cells have instead of a nucleus?
Single circular DNA molecule which is free from cytoplasm
What is binary fission of prokaryotes?
- DNA and plasmids replicate.
- Cell elongates and DNA moves to opposite poles of cell
- Cytoplasm begins to divide and new cell wall forms
- Produces 2 daughter cells. Each contain identical DNA loop but have different number of plasmids as they don’t split evenly
What is a bacteriophage and its properties?
Virus which attacks bacteria
1000x smaller than bacteria and needs living cell
Consists of RNA protected by protein coat called capsid
Attachment proteins attach to host cells to recognise them
What is process of virus replication?
- Detects host cell by recognising protein marker on membrane and attach with attachment proteins
- Virus injects genetic material into cell
- Cell reproduces genetic material and reads it creating new viral proteins
- Virus leaves cell by destroying cell and affects different cells
What is function of plasmids, capsule and the flagella?
Plasmids are small loops of DNA which only carry a few genes
Capsule - slimy layer made of protein which prevents bacteria drying out
Flagella - rotates allowing bacteria to move
What is cell fractionation?
Where cells are broken up to release different organisms they contain
How are cells separated?
They are separated based on their sizes via gravity
What are steps of ultracentrifugation?
Step 1 (homogenisation) - cells are broken using a blender - cells must be in a solution
Step 2 (filtration) - blended material is filtered to remove large debris
Step 3 (centrifugation) - Solution is placed in a centrifuge and uses gravity to separate organelles by weight by spinning at different speeds
Each time, the liquid is removed (supernatant) and process is repeated at faster speeds until all organelles are separated
What type of organelles are removed at slower speeds?
More dense organelles
Which organelles separate first?
- Nuclei
- Chloroplasts
- Mitochondria
- Lysosomes
- Endoplasmic reticulum
- Ribosomes
What properties must solution have in ultracentrifugation?
Solution must be:
Ice cold - reduces enzyme activity which may break down cells
Buffered - reduces change in ph so enzymes don’t denature
Isotonic - prevents cells bursting via osmosis - water potential inside and out is equal
What are advantages/disadvantages of light microscopes?
A: Cheap and available in schools
Can observe live specimen
DA: Fewer details of cell structure can be observed
0.2 um resolution
X1500 magnification limit
What are advantages/disadvantages of electron microscopes?
A: 2 x 10(6) magnification limit
Can produce 3D images
Resolution of 0.1 nm limit
DA: Expensive and not available in schools
Can’t be used for live specimen
