Flashcards in B3 Living and Growing INCOMPLETE Deck (85)
contains the dna in the form of chromosomes.
define cell membrane fuction
hold the cell together and controls what goes in and out
what is a ribosome and where is it found?
it is where protiens are synthesised. found in animal cells
what is cytoplasm
a gel-like substance whre chemical reactions happen inside cells
what are mitrochondria and where are they found?
it is where most respriation reactions take place inside animal cells
musicle and lover clees need lots of respration so have lots of mitrochondria in their cells
what makes an plant cell different to an animal cell
it has chlorplasts cell wall and vacuole
green blobs where photosynthesis takes place
define cell wall
it is made of cellulose and supports the plant cell
a relatively large structure that contains cell sap.( a weak sollution of sugar and salts
what do bacteria cells have.
cytoplasm, cell membrane, cell wall, dna strand, no chlorolast or mitrochondria
what do bacteria cell not have?
what is a chromsome made up of/
dna coiled up
what is the shape of dna
a double helix on a sugar phosphate backbone
what are the four bases on dna
A C T G
what are the base pairs
AT (straght ones)
CG (curvy ones)
these are complimentray base-paring
orgainsims with just one cell (BACTERIA)
what is a chlorplasts made of
green pcgments that asorb energy. they are enbeded in disks like structures and arranged in stacks (thyiakoids)
what is a triplet codon?
a series on 3 base pairs.
what odes a triplet codon do.
codes for a spesific type of amino acid
what do amino acids produce
protiens. each protein has a different shape/ numer of amino acids. thus they all have different fuctions
what is they type of amino acid made dependnet on.
the order of the base pairs
who are watson and crick ad what did they do?
discovered the model for dna
how does dna replicate itself/
the cell divides. the doible helix "unzips"/ spearates.
new nucleotides (MRNA) join on using compilmetary base pairs.this makes and exact copy of the dna on the other stand
this results in two double stranded molecules of dna that are idnetical to the orginal.
how are protiens made?
by readingthe code in dna
free floating in the nucleus. its a small molecue containing bases.
what is a gene
a section of dna that codes for a particular protein
what decides the order of amino acids in a proein/
the order of bases in a gene
WHAT IS RNA
DNA with no t but a u instead
how does protein synthesis happen
the dna unzips
RNA joins up with it
RNA coppies the gene
it is now MRNA a messenger
it goes to the ribosomes where the triplet condon/genes are read
the correct amino acid is produced and joined into a chain
amino acids released into cytoplasm where the join in chains to make a protien
what do ribosomes use.
code in dna that the mrna/rna has coppied.
why does the rna have to take coppies on the dna codes. and how?
the dna cont move out of the nucleus as its realy big so the code need to get from the nucleus to the ribosomes.the mrna acts as a messenger by copping the code.
what can dna control
a cell by controling protein production. they can switch off certain genes to stop procuctionin cells.
what do switched on genes determine/
the type of cell. there is a full set on genes i each cell but no all are needed. a mucsle cell doesnt need never, skin or bone genes so thye are tuened off but muclse cell procuction are turned on.
what is a mutation.
a change in the base order.
addition, removal or substutuional
this changes the triplet codon so the amino acid code had changes too and thus the protien too
how does mutatuon of dna occur
radiation and chemicals
name four types of protiens
what is a carrier molecule
haemaglobin is used to transport oxygen around the blood.
used to transport smaler molecues
what is a hormone used for
to cary messages around the body. eg insulin is released into the blood by the pnacreas to regulate blood sugar levels.
what is a structual proteins job/
to be physically srtong.EG. collagen strengthen connective tissues ike ligaments and cartilage and tendons.
what is an enzymes job
a BIOLOGICAL CATALYST that controls chemical reactions in cells.
a substance that speeds up a reaction.it is not changed or used up in the reaction
every biological reaction has its own what....
enzyme designed spesifically for it. each enzymes is coded for by a differnt gene and has a unique shape for its job
the moelcue changed in the reaction
define active site
the part where the enzymes joins the substrate
enzymes have a high ....
high specifity for their substrate
usally only work with one substrate.
what has to work to allow the enzymes to work.
the substarte has to fit into the active site on the enzyme. otherwise it wont be catalysed.this is the lock and key mechanism theory.
what do enzymes need to work?
the correct temperature and PH
chaning the temp of a reaction alters the.....
the rate of an enzymes catalysed reaction
high temp= faster reaction and vice versa
what is an enzymes optimun temperature.
30-40 human enymes like 37 degrees
why does a higher temp cause a fater reaction
the more heat means enzymes and substrate has more energy.this makes them move about more so they collide more and react. HIGHER COLLISION RATE
what will happen if the reaction get too hot?
some of the bonds holding the enzymes together will break. the enyme will lose shape (denature) and the active site will not fit the substrate any more and it is not catalysed.
what happens if the Ph of an enzyme reaction is too high or low?
it interferes with the bonds holding the enzymes together.. this changes the active site and it denatures.
what is an enymes optimun PH?
often neurtral (7) but it can differ. pepsin works best at Ph2 and acidic conditions
what is Q10?
it shows the rate of reaction and how it changes with temperature
wats the formulae of Q10?
rate at higher temperature
rate at lower temperature
what des at Q10 of 2 mean/show?
te rate doubles when the tep of raised by 10degres. a Q10 of 3 means it trebles/triples
what can mutations cause? in reprodcutive cells and body cells.
in reproductive cells the baby might develop abnormay or die
in body cells the mutated cells can multiply uncontralbly and invade the body(cancer)
how can mutations be beneficial?
it ca casue an improvemnt that gives the organism a survival advantages.this is natural selection and evolution at work
what is the main cause of mutaions. ad where do they come form and what do they cause.
sometime it ca happen spontaneously whn a chromosome doesnt copy properly
usaly due to radiation (xrays, ultraviolet light or radioactive substances)
or due to chmicals such as mutagen or carcinogens (cigarette smoke) these cause cancers
what are the advantages of being muticellular?
how is being a bigger organiams helpful
you can travel further, get nurtiens in lots of ways, fewer thinks can eat or squash you.
how is having cell differentiation helpful/
you have differtn cells for certain jobs.ad they are adapted for their jobs
how is being a more comlex orgainsm good?
you can have specialised organswith different shapes ad behaviour.. this allows us to be adapted for or environemt particualry
making new cells for growth and repair.
cells reproducing by splitting to form two identical offspring
what are the5 stages of MITOSIS?
what happens at the first stage of MITOSIS?
the dna in the cell is replicated INTERPHASE
what happens at the scond stage of MITOSIS?
the dna coils into double armed chrosmosomes. these are exact coppies of the same dna (the left and right arm are the same) PROFASE
what happnes at the 3rd stage of MITOSIS?
the chosmomes line up at the center of the cells and divide as fibers pull them appart.
the fibers apull the chromsomes to the opposite ends (poles) of the cell. ANAPHASE
what is the last stage of MITOSIS
the cytoplasm divides and you get two new cells containg the same genetic information. TELEPHASE
cell division to create sex cells/ gametes
where are gamets made.
in the ovaries and testes by meiosis
body cells. two copies of each chromsome in the nucleus- one from each parent
Diploid = double
gametes. only have one cipy of each cromsomes. so wen the egg and sperm combine they form a diploid cell
what the first stage of meiosis/
the dna replicates and curls up to form double armed chromosomes
whats the second stage of meiosis after the dna replicates?
the chromosomes arrange into pairs (23pairs / 46 alltogether)
what happens in meiosis after the chromosomes arrange into pairs?
in the first division the pairs split up nd move to oppostie poles of the cell.in each new cell there are no pairs just one of each. each new cell ends up with a mixture of your parents chromosomes but only half the usual number of chromosomes
wha are the basic stages of meiosis?
ne pair of chromosomes before division, they replicate. the cell thendivides into 4 (new sex cells)
what does fertilisation create?
a diploid cell called a zygote
what controlls of characterisitics of a zygote?
the combination of genes on its chrmosomes
whats an allele?
a gene code for differnt characterisitics
what type of cell os a sexcell?
what is a sperms fuction?
to transport the males dna to the females egg
why do sperm have tails?
to help them swim, it used a flicly motion to move quickly
how do sperm have energy?
lots of mitochondria in the mid piece that produce lots of energy