B3 Biology Flashcards
what is meiosis ?
the splitting of cells where the chromosomes in that cells are halved so there is only 23 chromosomes resulting in genetically unique cells.
How does Meiosis work?
Meiosis is the creation of ‘Gamete’ cells which only contain half the genetic material of a normal cell.
there are 2 divisions
the first division splits the 46 chromosome cell up into 2 genetically unique cells.
the second division is where one side of the chromosomes move to one pole of the cells and the other half to the other pole.
the cell then splits again, so there is now 4 genetically unique cells all with 23 chromosomes.
these then mix with another gamete e.g. sperm and egg and create a 46 chromosome cell
what is DNA ?
DNA is a polymer (made of lots of similar units put together)
what is DNA split into?
46 coiled sections to stop it getting muddled in the Nucleus. these are chromosomes
what is the 23rd pair of chromosomes specifically for?
sex cells
women- XX
men- XY
what is a gene ?
a gene is a small section of DNA that codes for a certain protein (small segment of a chromosome)
it codes for a sequence of amino acids and when the amino acids are formed in any particular way it creates a certain protein.
DNA determines which proteins the cells produce and what type of cell it will be for what is needed - e.g. - A red blood cell would need lots of the protein Haemoglobin because haemoglobin carries oxegen around the body
what is a genome ?
entire set of genetic material in an organism
what is an inherited disease?
a disease which is inherited through genes from your parents
what is an Allele ?
a gene code for a particular type of protein (multiple forms of the same protein) there is a diffrent genetic code for each of those forms of protein and we call these diffrent codes alleles
why do we have 2 alleles of the same gene ?
this is because we have 1 from each of our parents
these could both be the same allele or 2 diffrent alleles. if they are the same we would say their Homozygous and if they were diffrent they would be Heterozygous.
example - say we had a mouse who was heterozygous for the gene fur colour.
lets say the mum was green and the dad was purple. this would mean one of the alleles would be dominant and one would be recessive.
dominant one gets expressed.
Genotype ?
the entire collection of alleles we have
Pheotype?
characteristics you get from the genotype
