topic 2 - cells Flashcards
what is the structure and function of the endoplasmic reticulum?
rough and smooth both have folded membranes called cisternae
rough have ribosomes on the cisternae
function - rough - protein synthesis
smooth - synthesis and store lipids and carbohydrates
What is structure and function of the nucleus?
nuclear envelope - double membrane nuclear pores
nucleoplasm - jelly like material
chromosomes - protein bound linear DNA
nucleolus - small sphere inside the site rRNA production and makes ribosomes.
function - site of DNA replication and transcription.
contains genetic code for each cell.
what is the structure and function of the Golgi apparatus and vesicles?
folded membranes making cisternae
secretary vesicles pinch off from the cisternae
function - add carbohydrates to proteins to form glycoproteins
produce secretory enzymes
secrete carbohydrates
transform, modify and store lipids
form lysosomes
molecules get labelled with their destination
finished products transported to the cell surface through vesicles.
what is the structure and function of the lysosomes?
bags of digestive enzymes, up to 50
function - hydrolyse phagocytic cells
completely break down dead cells
exocytosis - release enzymes to outside the cell to destroy material
digests worn out organelles for reuse of material
what is the structure and function of the mitochondria?
double membrane
inner membrane - cristae
fluid centre - mitochondria matrix
loop of mitochondria DNA
function - site of aerobic respiration
site of ATP production
DNA to code for enzymes needed in respiration
what is the structure and function of ribosomes?
small made up of 2 subunits of protein and rRNA
80s - large ribosome’s found in eukaryotic cells
70s - smaller found in prokaryotic cells, mitochondria and chloroplasts
function - site of protein synthesis
what is the structure and function of the vacuole?
filled with fluid surrounded by a single membrane - tonoplast
function - makes cells turgid and provides support
temporary store of sugars and amino acids
pigments may colour petals
what is the structure and function of chloroplasts?
surrounded by a double membrane
contains thylakoids
fluid filled stroma contains enzymes for photosynthesis
function
site of photosynthesis
what is the structure and function of the cell wall?
plants - made of microfibrils on the cellulose
fungi - made of chitin, nitrogen containing polysaccharide
function - provides structural strength to cell
what is the structure and function of the plasma membrane?
found in cells phospholipid bilayer - molecules embed within
function - controls exit and entrance of molecules
what is interphase?
the longest stage in the cell cycle, when the organelle doubles the cell grows then it replicates.
what is nuclear division?
can either be mitosis creating 2 identical diploid cells or meiosis creating 4 genetically different haploid cells
what is cytokinesis?
final stage of cell division, division of the cytoplasm to create the new cells
what is prophase?
chromosomes condense and become visible, in animals the centrioles separates and move to opposite ends of the pole. (stage 1)
what is metaphase?
the chromosomes align along the equator of the cell, the spindle fibres are released from the poles now attach to the centromere and chromatid. ( stage 2)
what is anaphase?
the spindles start to retract and pull the centromere and chromatids, they are now bound to opposite poles. causes centromere to divide into 2 and individual chromatids are pulled to each opposite pole.
this stage requires ATP provided by respiration (stage 3)
what is telophase?
the chromosomes are now at each pole and become longer and thinner, spindle fibres disintegrate and the nucleus starts to reform.
the cytoplasm spilts into 2 to create 2 genetically identical cells. (stage 4)
what is cell fractionation?
cell are broken open to release the contents and organelles are separated.
the cells must be prepared in cold, buffered, isotonic solution.
this will reduce enzyme activity and reduce damage to the organelles, will also reduce osmosis.
what are the stages of cell fractionation?
step 1 - homogenisation
the cells must be broken open which is done by using a blender, this is done is cold isotonic buffered solution.
step 2 - ultracentrifugation
the filtered solution is spun at high speeds in a centrifuge, this separates the organelles due to their density.
what happens in a centrifuge?
it spins at high speeds which causes pellets of the most dense organelle to form at the bottom of the tube.
the process is then repeated at increasingly faster speeds removing the supernatant and leaving the pellet.
the supernatant is then spun again in the centrifuge and the process is repeated.
what are the components of a membrane?
the phospholipids align as a bilayer due to the hydrophilic heads being attracted to the water and hydrophobic tails being repelled by the water.
cholesterol may also be present which will restrict lateral movement of the other molecules in the membrane. this makes the membrane less fluid at higher temperatures and prevents water leaking out the cell.
