Topic 2A - Cell Structure And Division Flashcards
Identify 3 structure of a eukaryotic cell
Has a nucleus
Has a clear nuclear envelope
DNA is associated with histones
No plasmid
Membrane bound organelles
80s ribosomes
No capsule
Cell wall mostly cellulose (chitin in fungi)
Chloroplasts present in algae and plant cells
Identify 3 structures of a prokaryotic cell
No true nucleus
DNA not associated with histones or proteins
DNA found in plasmids
No membrane bound organelles
70s ribosomes
Cell wall made of murein
Can have a slime layer called a capsule
No chloroplast
Describe and give the functions of a mitochondrian cell
Description:
They’re usually oval shaped. They have a double membrane, the inner membrane folds to from a cristae. Inside the cristae is the matrix, the matrix contains enzymes involved in respiration.
Function:
The site of aerobic respiration aerobic respiration produces ATP - a common energy source.
Describe and give the functions of a chloroplast cell
Description:
A small flattened structure found in plants cells and algal cells. It’s surrounded by a double membrane, and also has membranes inside called thylakoid membranes. These membranes are stacked up is some parts of the chloroplast to form a grana . Grana are linked together by lamella - thin, flat pieces of thylakoid membrane.
Function:
The site where photosynthesis takes place. Some parts of photosynthesis happen in the grana and other parts happen in the stroma (a thick liquid found in chloroplast).
Describe and give the functions of the Golgi apparatus
Description:
A group of fluid-filled membrane-bound flattened sacs. Vesicles are found at the end of the sacs.
Function:
it processes and packages new lipids and proteins. It also makes lysosomes.
Describe and give the function of vesicles
Description:
A small fluid filled sac in the cytoplasm, surrounded by a membrane and produced by the Golgi apparatus.
Function:
Stores lipids and proteins made by the Golgi apparatus and transports them out of the cell.
Describe and give the function of lysosomes.
Description:
A round organelle surrounded by a membrane, with no clear internal structure. It’s a type of Golgi vesicle.
Function:
Contains digestive enzymes called lysozymes. These are kept separate from the cytoplasm by a surrounding membrane, and can be used to digest invading cells and break down worn out cells.
Describe and give the functions of the rough endoplasmic reticulum
Description:
A system of membranes enclosing a fluid filled space. The surface is covered with ribosomes.
Function:
Folds and processes proteins that have been made at the ribosomes.
Describe and give the functions of the smooth endoplasmic reticulum
Description:
A system of membranes enclosing a fluid filled space.
Functions:
Synthesises and processes lipids.
What happens during homogenisation?
Homogenisation is the breaking up of the cell
Tissue is put in an ice-cold, isotonic, buffered solution
You put the tissue into a blender
This breaks up the cell membrane and release the organelles into the solution
This is called the homogenate
Describe the purpose of an ice-cold, isotonic, buffered solution.
Ice cold - Reduce enzyme activity so it doesn’t damage the cell and organelles
Isotonic - Stop osmotic activity. So water doesn’t move into the cell and damage the organelles by bursting.
Buffered - Keep the pH constant so enzyme activity isn’t increased and it doesn’t damage the cell.
Describe filtration during cell fractionation.
The homogenised solution is passed through a gauze to remove large cell debris, large tissue and unbroken cell
The organelles will pass through the gauze as they are much smaller
What is ultracentrifugation?
The solution which contains the organelles are poured into a test tube.
The test tube is then spun in a centrifuge at a high speed. The most dense organelle (the nucleus) forms a thick sediment at the bottom of the tube - called a pellet.
Above the pellet remains a solution which contains the other organelles - the supernatant.
They supernatant is the removed and poured into another tube. It is then put into a centrifuge where it is spun at a higher speed. The most dense in the solution then forms a pellet at the bottom of the tube (mitochondria).
Remove the supernatant and put into another test tube. Spin at higher and higher speeds until all organelles are separated out.
What are the characteristics of a prokaryotic cell
70s ribosomes
Capsule
No chloroplast
Cell wall made of murein
DNA is in plasmids
No membrane bound organelles
Proteins are not associate with histones
What are the characteristics of a eukaryotic cell
80s ribosomes
No capsule
Has chloroplast
Cell wall made of cellulose (made of chitin in fungi)
DNA contained within nucleus
Has membrane bound organelles
Proteins are associate with histones
Explain the process of binary fission
Step 1 - circular DNA and plasmids replicate. Main DNA loop only replicate once but plasmids replicate as many times as they want
Step 2 - cell gets bigger and the DNA loops move to opposite ‘poles’ of the cell
Step 3 - the cytoplasm begins to divide and new cell walls begin to form
Step 4 - the cytoplasm divides and two daughter cells are produced, each daughter cell has one copy of circular DNA but a variable number of plasmids
What is the structure of viruses?
Genetic material
Attachment protein
Capsid
