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dna & reproduction& meiosis (sexual reproduction produces…
dna & reproduction& meiosis
chromosomes are really long molecules of dna
3) so its what's in your DNA that determines what inherited characteristics you have
4) DNA is found in the nucleolus of animals and plant cells in really long structures called chromosomes
2) it contains coded information basically all the instructions to put an organism together and make it work
5) chromosomes normally come In pairs
1) DNA stands deoxyribonucleic acid its the chemical that all of the genetic material in a cell is made up from
6)DNA is a polymer its made up of two strands coiled together in the shape of a double helix
every organism has a genome
2) scientists have worked out the complete human genome
3) understanding the human genome is a really important tool for science and medicine for many reasons
2) knowing which genes are linked to inherited diseases could help us to understand them better and could help us to develop effective treatment for them
3) scientists can look at genomes to trace the migration of certain populations of people around the world all modern humans are descended from a common ancestor who lived in Africa
1) it allows scientists to identify genes in the genome that are linked to different types of diseases
1) genome is just the fancy term for the entire set of genetic material in an organism
sexual reproduction produces genetically different cells
4) the egg and sperm cell then fuses together to form a cell with the full number of chromosomes
SEXUAL REPRODUCTION INVOLVES THE FUSION OF MALE AND FEMALES GEMETES BECAUSE THERE ARE TWO PARENTS THE OFFSPRING CONTAINS A MIXTURE OF THEIR PARENTS GENES
3) in humans each gamete contains 23 chromosomes half the number of chromosomes in a normal cell
5) this is why the offspring inherits features from both parents its received a mixture of chromosomes from its mum and its dad
2) in sexual reproduction the mother and father produce gametes by meiosis egg and sperm cells in animals
6) the mixture of genetic information produces variation in the offspring
1) sexual reproduction is where genetic information from 2 organisms is combined to produce offspring which genetically different to either parent
7) flowering plants can reproduce this way too they also have egg cells but their version of sperm is known as pollen
asexual reproduction produces genetically identical cells
3) the new cell has exactly the same genetic information as the parent cell its called a clone
IN ASEXUAL REPRODUCTIONS THERES ONLY ONE PARENT THERES NO FUSION OF GAMETES NO MIXING OF CHROMOSOMES AND NO GENETIC VARIATION BETWEEN PARENTS AND OFFSPRING THE OFFSPRING ARE GENETICALLY IDENTICAL TO THE PARENT THEY ARE CLONES
2) asexual reproduction happens by mitosis an ordinary cell makes a new cell by dividing in two
4) bacteria some plants and some animals reproduce asexually
1) in asexual reproduction there's only one parent so the offspring are genetically identical to that parent
gametes are produced by meiosis
1) gametes only have one copy of each chromosomes so that when gamete fusion takes place you get the right amount of chromosomes again
2) to make gametes which only have half the original number of chromosomes cells dividing by meiosis this process involves two cell division in humans it only happens in the reproductive organs
the cell produces by gamete fusion replicates itself
2) mitosis repeats many times to produce lots of new cells in an embryo
3) as the embryo develops these cells then start to differentiate into the different types of specialised cell that makes up a whole organism
1) after 2 gametes have fused during fertilisation the resulting new cell dividing by mitosis to make a copy of itself