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difference between mitosis and meiosis
mitosis is one divison and meiosis is 2 division
mitosis produce 2 genetically identical daughter cell whereas meiosis produces 4 genetically different cells.
mitosis contains the same number of chromosome as parent cell whereas meiosis only contains half the chromosome.
mitosis are diploid and meiosis are haploid
meiosis involves in how many divisons
2
how does meiosis involve in 2 divisions
in the first generation, chromosome that carry the same gene pair up (homologous chromosome), These then separate into 2 chromosome
in the next division, chromosome move apart from each other to form a new pair of daughter cell
when does mitosis and meiosis occur after
they occur after interphase
what do meiosis result in
genetic variation by producing different combination of gamete allelss
genetic variation
crossing over
during meiosis 1.
homologous chromosome are close to each other for the chromatid of each pair to twist around each other, spliced and rejoin to the other. This can result in new allele combination
independent assortment
homologous pair line up random. This randomises the chromosomes end up in each daughter cell
habitat
place where an organism lives
community
population of different organisms in a habitat
species richness
number of species in a community
index of diversity
N(N-1) / sum of n(n-1)
N = total number of organisms in the community
n = total number of organisms in a particular species
gene pool
all the alleles in the population
allele frequency
probability of an allele appearing in the gene pool
hetrozygous
Ff
homozygous can be either
Homozygous dominant - FF
Homozygous recessive - ff
the frequency of dominant and recessive homozygous would always be
homozygous dominant + homozygous recessive = 1
hardy weinberg equation
p squared 2 + 2pq + q squared 2 = 1
p squared 2 = homozygous dominant
q sqaured 2 = homozygous recessive
if only either q OR P is given then use p+q =1 to work out the other and then use the hardy weinberg equation
tutipotent
differentiate into any cell type
pluripotent
differentiate into many cell type
differentiate into all cell except extra embryonic
multipotent
differentiate into limited cell type
unipotent
differentiate into one cell type
stem cell
treats disease as they produce healthy cells needed by the patients and prevent the production of faulty cell, and due to single stem cells keep on dividing which means single treatment has long term impact
ethical issues of embryos
destroyed during stem cell collection
ethical issues of foetus
foetus must be aborted or miscarried
ethical issues of adult bone marrow
harvesting adult bone marrow is painful and can be risky for donor
induced pluripotent
formed from unipotent cell whivch are genetically altered to enable translation of additional in the cells DNA, these behave like a pluripotent cell
what does SER
synthesises and processes lipids
the look similar to RER but have no ribosomes
what does RER
folds and processes proteins that have been made at the ribosomes
ribosomes
80s is eukaryotic and 70s is prokaryotic
site where the proteins are translated
lysosomes
contains digestive enzyme
Golgi apparatus
process and packages new lipids and proteins
looks more like a wifi
centrioles
separation of chromosomes
structure of prokaryotic cell
cytoplasm, plasma membrane, cell wall, pili, mesosomes, chromosomal DNA, flagellum
pili
hair like structure
help to stick other cells
prophase
chromosomes condense
nuclear envelope breaks down
metaphase
chromosomes line up along the middle of the cell
becomes attached to the spindle by their centromere
anaphase
centromere divide, seperating each pair of sister chromatid
telophase
chromatids reaches the opposite poles on the spindle
they uncoil and long
nuclear envelope forms around each groups of chromosomes
mitotic index
number of cells with visible chromosmes / total number of cells
behavioural
ways an organisms acts that increases chances of survival
physiological
proceeses inside a organisms body that in crease its chances of survival
anatomical
structural features of an organisms body that increases its chance of survival
advantages of seedbanks
its cheaper to store seeds then fully grown plants
large number of seeds than fully grown plants because they need less plants
seeds can be stored anywhere
disadvantages of seedbanks
testing the seeds for viability can be expensive and time consuming
may be difficult to collect seeds from plants as they may grow in remote collections
xylem cells
transports water and mineral ions and also provides support
formed from dead cells
have hallow lumen and have no end walls which allows water and mineral ions to pass through easily
their walls are thickened with lignin
water and mineral ions move into and out of the xylem through pits in the walls where there is no lignin
Schlerenchyma
made up from dead cells
have hallow lumen and have a end wall
they are also thickened by lignin but have no pits
they have more cellulose
ploem
arranged in tubes like xylem
contains types of sieve tubes and companion cells
translocation
sieve tube in the phloem
are living cells and joined end to end.
the seive parts are the end walls which have a lot of holes which allows solutes to pass through
lack of nucleus and lack of other organells means they can survive alone and there is a companion cell for every sieve tube cells
companion cells
carry the living function for both themselves and their sieve tube elements.
starch
alpha glucose - amylose and amylopectin
amylose - unbranched chain of alpha glucose, coiled making it compact
amylopectin - branched chain of alpha glucose
starch is insoluble, glycosidic bonding
cellulose
long, unbranched chains of beta glucose joined by 1-4 glycosidic bond
cellulose chains are straight
primary cell wall
cellulose microfibrils in a net like struc
secondary thickening of the cell wall
secondary cell wall is thicker than the normal cell wall as it has more lignin
vacuole
contains cell sap and surrounds tonoplast.
cell wall
made up of cellulose
captive breeding programme
which endagered species are carefully bred to increase genetic diversity and population size
genetic diversity is maintained by
keeping stud books, prevent interbreeding
magnesium ions
involved in chlorophyll production
nitrate ions
supply nitrogen for RNA, DNA, Proteins, Chlorophyll
calcium ions
are a component of the plant cell wall, they form calcium pectate
