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chromosomes and mitosis& diffusion (cell membrane (big molecules like…
chromosomes and mitosis& diffusion
chromosomes contain genetic information
3)each chromosome carries a large number of genes different genes control development of different characteristics
4) body cells have 2 copies of each chromosome one from the mother one from the father humans have 2 copies of chromosomes
2) chromosomes are coiled up lengths of dna molecules
5) humans have 23 pairs of chromosomes
1)most cells in a body have a nucleolus contained genetic material in the form of chromosomes
cell cycle
multicellular organisms use mitosis to grow and develop to replace cells that have been damaged
the end of the cell cycle results in two new cells identical to the original cell with the same number of chromosomes
the stage of the cell cycle when the cell divides is called mitosis
growth and dna replicates--------> mitosis--->
body cells in multicellular organisms divide to produce new cells as parts of a series of stages called the cell cycle
growth and DNA REPLICATION
before it divides the cell grows and increases the amount of subcellular structure and such mitochondria and ribosomes
in then duplicates its dna so there's one copy for each new cell the dna is copied x shape chromosomes each arm of the chromosome is an exact duplicate of the other
in a cell that's not dividing dna is in long strings
mitosis
lastly the cytoplasm and cell membrane
MEMBRANES from around each of the sets of chromosomes these become the nuclei of the two new cells the nucleus has divided
cell produces 2 daughter cells daughter cells contain exactly the same dna dna is identical to parent cell
chromosomes line up at the centre of the cell and cell fibres pull them apart the two arms of each chromosome go to opposite end of the cell
diffusion
DIFFUSION IS THE SPREADING OUT OF PARTICLES FROM AN AREA OF HIGHER CONCENTRATION TO AN AREA OF LOWER CONCENTRATION
happens in solutions and gases particles are free to move about randomly
2)natural tendency for stuff to spread out
simplest type is when different gases diffuse each other when a smell of perfume diffuses through a room
1) gradual movement of particles from places where there are lots of them to place where there are fewer of them
bigger the concentration grade the faster the diffusion rate a higher temperature will also give a faster diffusion rate because of the particles have more energy so move around faster
cell membrane
big molecules like starch and protein cant fit through the membrane
particles flow through the cell membrane from where there's a higher concentration to where there's lower concentration
only small molecules can diffuse through cell membrane through things like oxygen glucose, amino acid and water
moving about randomly and go both ways if there are a lot more particles on one side of the membrane theres a net movement from that side
dissolve substances can move in and out of the cells by diffusion
the larger the surface area of the membrane faster the diffusion rate because more particles can pass trough at once
cell membranes are clever as they hold the cell together and let stuff in and out