Cell Structure and Organisation Flashcards
(56 cards)
List the organelles in an animal cell - there are 10
Golgi body, SER, RER, centrioles, mitochondria, lysozyme, nucleus, ribosomes, cell membrane and cytoplasm
List the organelles of a plant cell - there are 10
Plasmodesmata, chloroplasts, cytoplasm, golgi body, mitochondria, RER, nucleus, ribosomes, SER and vacuole
How to workout total magnification?
eyepiece x objective
Why must the sample be thin?
To allow light to pass through
Why must the sample be stained?
To see the organelles clearer and more visible
Why might staining be a disadvantage?
can be toxic and harm/kill organisms
State the structures of a nucleus - there are four
nuclear envelope, nucleoplasm, chromatin and nucleolus.
Give the function of each structure in a nucleus (there are 4)
Nuclear envelope: double membrane with pores to allow transport of mRNA and ribosomes out of nucleus to cytoplasm
Nucleoplasm: cytoplasm-like material within nucleus containing chromatin
Chromatin: made up of coils of DNA bound to histone protein, during cell division chromatin condenses forming visible chromosomes
Nucleolus: one or more spherical bodies which synthesise rRNA
What is the function of mitochondria?
to release energy in the form of ATP during aerobic respiration
describe the structure of mitochondria.
has a double membrane with a narrow fluid-filled intermembrane space
inner membrane folds inwards forming extensions called cristae which increase surface area for ATP synthesis to occur
has an organic matrix containing chemical compounds e.g. lipids, proteins, small 70s ribosomes and a small circle of DNA for self-replication in response to energy needs of the cell
Where do the stages of aerobic respiration occur in the mitochondria?
in the matrix and on inner membrane
where are large numbers of mitochondria usually found in the body?
liver and muscles (break down toxins and contraction)
What are the 2 sizes of ribosomes and which belongs to eukaryotes/prokaryotes?
80s(eukaryotes) and 70s(prokaryotes)
How is a ribosome structured?
a small subunit on a large subunit made of rRNA and protein.
How does protein synthesis occur?
in translation, mRNA fits in the groove between the 2 subunits and provides the code for a sequence of amino acids.
where are ribosomes found in a cell?
free in cytoplasm or associated with RER
What is the function and structure of RER?
an internal system of flattened membranous sacs/cisternae which are continuous with nuclear membrane and linked to golgi body to help transport substances
function is protein synthesis and transport of proteins so present in large numbers to synthesise large quantities
What is the function and structure of SER?
similar in structure to RER but has no ribosomes
involved in synthesis and transport of lipids and cells which store large quantities of carbohydrates, proteins or fat
loads of SER
Describe the golgi body including structure and function in 8 points
made up of interconnected flattened membranous sacs
vesicles containing polypeptides pinch off from RER and fuse with the Golgi body
proteins are modified and packaged into vesicles and at the other end of the GB, vesicles containing the modified proteins bud off / modify and package proteins into secretory vesicles for secretion from the cell
produce glycoproteins
form lysosomes
transport and store lipids
secrete carbohydrates for formation of plant cell walls
Give function and structure of lysosomes.
single membrane-bound vesicles that contain hydrolytic enzymes and produced by golgi body
isolate potential harmful digestive enzymes from remainder of the cell and release hydrolytic enzymes when cell needs to break down worn-out organelles
digest material that has been taken in the cell e.g. lysosomes fuse with the vesicle made when white blood cell engulfs bacteria by phagocytosis and their enzymes digest the bacteria
Link the function of the organelles - there are 11 points to make
DNA in nucleus contains genetic code to make proteins/mRNA
nuclear pores in nuclear envelope allow mRNA to leave nucleus and attach to ribosomes in RER or cytoplasm
mRNA transported through RER
protein synthesis occurs on ribosomes
vesicles pinched off from RER are transported to Golgi body
vesicles fuse with golgi membrane and contents are shed into golgi sacs
proteins formed into more complex molecules
vesicles containing modified proteins bud off at end of golgi body
vesicles fuse with cell membranes
proteins are secreted - by exocytosis
lysosomes may be produced - digestive enzymes
How are phospholipid molecules arranged on the membrane of cells?
as a bilayer
fatty acid tails of both layers point towards inside of the membrane
hydrophilic heads point outwards, interacting with the tissue fluid/blood plasma
What are the 3 other structural components of the cell membrane?
protein - globular, can be found on the surface/partly embedded/extending completely across both layers (extrinsic and intrinsic)
carbohydrates - found pointing outside of the cell, attached to either glycoproteins or glycolipids and collectively known as the glycocalyx
cholesterol - type of liquid found between phospholipids in animal cell membranes and controls membrane fluidity
Why is the cell membrane model called the fluid mosaic model?
fluid - individual phospholipid molecules can move around relative to one another
mosaic - proteins embedded vary in size and are arranged in a random pattern
