paper 1 practice Flashcards
suggest why the development of monopolar mitotic spindle would prevent successful mitosos
no seperation of centromeres
chromatids all go in one directions
doubles chromosomes number in daughter cells
difference between SEM and TEM and explaination
3D image in SEM and 2D in TEM, this is because electrons pass through the cell
why is the resolution in electron microscope higher than in resolution image of optical one
shorter wavelength between electrons
structures found in all bacteria and not in plant cells
glycoproteins,
circular DNA,
70s ribsomes (good one to remember)
peptidoglycan cell wall
scientist inject lab mice with cotinine, explain how this allwos the mice to produce antibodies against cotinine
cotinine is an antigen
antigen/ cotinine binds to specific t-cell
t -cell activates B- CELL –> the specific b -cell is activated
b cell divide by clonal expansion –> forms plasma cells to produce antibodies
explain why antibodies only bind to (antigen in question)
antigens have a specific BINDING site, due to its TERTIARY structure of the poplypeptide. so because of its specific shape for (antigen in question) so only continine fits
explain why azt deosnt destroy hiv but slows developement of aids
person wtih hiv has it hiv in their dna, new hiv particles are still made so it cant destroy it. azt inhibits reverse transcriptase -> this stops hiv forming more NEW hiv in their dna
advantage of using haart to treat hiv
slows/stops th e development of aids, because hiv is resistant to azt, so prevented from replicating
no new hiv particles are made, as haart interferes with viral protein synthesis
how does high doses of haart lead to muscle wastage
fewer mitochondria so LESS aerobic respiration
muscles recieve LESS ATP so wasted muscle
how is mRNA made by transcription in eukarytoes
-hydrogen bonds broken between DNA bases
- and one strand acts as a template –>
- free RNA nucleotides align by complementary base pairings –uracil base pairs with adenine on DNA
-RNA polymerase joins adjacent RNA nucelotides
descibe how polypeptide is formed by translation of mRNA
-mRNA attatches to ribosomes /attaches to rough ER
-anticodons bind to complementary mRNA codons
-tRNA brings a specific amino acid
-amino acids join by peptide bonds
-with the use of ATP
-tRNA released
-ribosome moves along the mRNA to form polypetide
define gene mutation
is a change in sequence of chromosomes results in a new formation of new allele
how can gene mutation have no effect on an indiviudal
-mutation is done on intron which is non coding region, going to get spliced
-mutation changes amino acid has nothing to do with r group that changes tertiary structure
-dna is degenerate so multiple codons code a specific amino acid no effect
how can gene mutation have positive effect on individual
change in polypeptide, creates good properties, like increases SURVIVAL or REPRODUCTIVE success
describe how vaccine leads to production of antibody against HPV
-vaccine contains inactive antigen form displayed on APC
-specific helper t cells stimulate specific b-cell
- b cells undergo mitosis (clonal expansion) to give plasma cells
- plasma cells produce antibody
why do we use t test
compares two means shows means are signficant
give two ways doctors can use base sequences to compare different types of HPV
-compare dna and mrna
look for mutations that change base sequence
how is mrna production in eukarotyes differnt to ones in prokarytoes
pre mrna is only eukaryotic cells
splicing occurs only in eukaryotic
introns arent present in prokaryotic cells
how does pna affect transctiption of dna
pna forms base pairs with DNA, preventing RNA polymerase activity and binding
explain the role of ATP in translation of protien synthesis
provides energy for peptide bonds to form between amino acids
explain how phosphodieter bonds form between teo nucleotides within DNA molecule
join in a CONDENSATION reaction on ladder of DNA phosphodiester bonds are formed between PHOSPHATE and DEOXYRIBOSE sugar and WATER is produced, this is catalysed by DNA POLYMERASE
name the protein assosciated with DNA in chromosome
histone
in the process of semi conservative replication how do the strands seperate to make template strands
breaks HYDROGEN bonds, between BASE pairs
why did the scientist express their results as percentage of lipid in plasma by plasma membrane by mass
divide mass of each lipid by total mass of all lipids multiply by one
whats an advnatage of mroe cholesterol in RBC compared with cells lining ileum
RBC free in blood so cholesterol helps maintain shape
e coli has no cholesterol in cell surface membrane, the cell maintains constant shape tho???
cell is unable to shape, cell has cell wall, wall is rigid and made of peptidoglycan
explain the change in mass of potato tissue at highest conc
water leaves through osmosis
water potential is less than inside
describe how to find water potetial of potatoe tissiue
-plot data on graph, label concentrationon x- axis, and percentage change on y axis
-find concentration where curve crosses the axis where percentage change is zero
